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#41
Posted to rec.audio.tubes
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Where did all the tubies go?
robert casey wrote: Yech! Gotta be tough to play in this sandbox.... That's my point. It is a disgrace that RAT is now more of an obstacle course for real tubies than a facilitating mechanism. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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#42
Posted to rec.audio.tubes
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Where did all the tubies go?
mueller wrote: Like many, I got tired of being blasted for asking a question. Seems to be tp many short sighted and narrow minded people here , who get really upitty when things do not follow their beliefs. So I moved on to forums that welcome different views. Mike Mueller I get letters from lurkers sometimes and they really seem to take the general debility of RAT hard. The heavy posters among the real tubies have long since developed thick skins just to survive the chiselling of the sneerers and jeerers. But it is easy to see that RAT isn't a good recommendation to anyone of sensitive disposition. And that is a prizewinning understatement! Andre Jute |
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#43
Posted to rec.audio.tubes
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Where did all the tubies go?
Hi Andre,
I built a pair of speakers each using 3 oval drivers each, stacked vertically. Nothing fancy cabinet wise, simple ported bass reflex enclosures. They are very, very sensitive, but bass drops off fairly rapidly since they have a higher than advertised resonant frequency, and I didn't get the port tuning quite right. From about 200Hz until 10kHz though, they are quite flat, and sound very natural with certain types of music. I am planning to re-mount the speakers on an open baffle, and try that meathod of attack, however, still need to figure out how to get a sheet of MDF home in a compact car. What a reality check at the lumberyard today - wood prices have gone through the roof in recent years! "Andre Jute" wrote in message oups.com... Hey, Max, did you in the end build the horns or some other high sensitivity point source speaks? -- Andre Jute maxhifi wrote: "Andre Jute" wrote in message oups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review I'm still here, sort of, (wow I've been posting for almost 10 years now) As a hobby, it (tube audio) hits the law of diminishing returns once you get a great sounding setup. When people already have great amplifiers, and then turn to worrying too much about things like wire, capacitor choices, power cords, etc... the discussion to me becomes quite boring. Similarly, the old questions UL vs Triode vs Pentode have been discussed to death over the years. NFB vs no NFB is another one, and same with contrasting EL34/KT88, etc. Anyone involed in the hobby for a while has likely tried them all and drawn their own conclusions. Lately I've been entertained by reading a foreign language forum, where people interested in DIY still seem to have the DIY spirit of making something out of nothing... using strange tube types, winding their own transformers, and building non-conventional speakers. I think it mostly has to do with people having more free time, and less money, but it's sure more interesting to read, and reminds me of my earlier enthusiasm for tube audio! The most important part is on that site everyone is constantly building and trying things, and then posting photos, so there's a lot more interesting content. |
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#44
Posted to rec.audio.tubes,uk.rec.audio
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Where did all the tubies go? Constructing a Golden Calf
"Jon Yaeger" wrote in message ... in article , Andre Jute at wrote on 4/9/07 9:32 AM: The garage vermin Jon Yaeger (aka John Yaeger, aka Jono Yaeger) wrote: Oh Papa! I missed you so much! But I keep a copy of your shadowy photo above my bed, and I cooked my favorite dish, your pasta puto from your web recipe every evening while you were gone. Tell me, did you see Elohim while you were on the mount? And did he inscribe some indelible commandments on silicon for you to share with your flock? Master, I await your next (and every) word. I am your tool. Send your soul postage-paid in a paddy bag, Yaeger, and I will dispose of it thoughtfully in an incinerator. Andre Jute Nobless oblige Jutey-Fruity, Thank you for your kind offer. I really don't understand how someone with your credentials, i.e. South African mercenary, Mossad agent, MI-5 commando, etc. would have obtained a visa to visit Egypt? Why don't you give us a clever (fictional) answer . . . not that 3rd rate pulp that you publish under vanity press? J Like I said Jon, jealousy is a terrible thing. Your transparency is showing again. Perhaps if and when you grow up, your bait will become more luring. Don't feel too bad if Andre doesn't bite. w |
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#45
Posted to rec.audio.tubes
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Where did all the tubies go? Constructing a Golden Calf
Andre Jute wrote: tubegarden wrote: Hi RATs! Oh, uh, Jute, I just got a CPAP machine and am sleeping it on ... What is a CPAP machine. Did you DIY it? What is all this tubie business? We have wandered far afield from thermionic joys. I am listening to an SS contrivance from McIntosh, Most of us listen to solid state all the time. What do you think a CD player is? I also have a reliable, solid Quad 405 Mk II power amp and a solid, reliable full-featured (mono switch, anyone? -- very useful for DIY in the rest of the chain) Quad 34 control amp sitting permanently at my left hand. The tube amp de jour stands on top of or beside that lot. Well, there is no accounting for taste. I have to humbly say that the 405/34 combo doesn't bring the best music to my ears. I had to fix a set using those last week and afterwards i had the pleasure if switching to tube gear, and nothing convinces me the 405/34 combo is better. Same thing has happened with 303. Its the classic case of measuring well, running cool, and no more music. Right now I'm listening to Stax headphones via a (horrors) bought silicon amp; it is actually excellent. I designed and built a nice octal tube OTL to drive my Stax but that is now in Japan (all the good audio gear migrates East -- even the Quad II set I'm keeping for my old age was repatriated from Japan) and I got distracted from building the revised version by bicycling matters. I have a row of related designs to drive electrostatic earphones but you can see in this thread why I can't be bothered to publish them and discuss them on RAT. I am building ESL speakers and this week am testing the first panel again after re-doing the membrane for the 4th time. I did initially get nothing special on the first try, (3rd membrane). Lots of arcing and sputtery noises and EHT could not go above 2,000V so I resorted to Isonel 642 and applied two coats to the stators already powedercoated, and hopefully EHT can be up to 5,000V without arcing all over the panels. The first sound test of mebrane no3 was utterly dismal; I figured sensitivity was 74dB/W/M and they would not go louder than my dynamics at 1 watt without terrible noises and distortions. If this attempt fails, I am not sure i will know what to do, but placing the lot in the dumper bin has come to mind. I have to say that ESL building isn't something I recommend to many people here. There is a certain level of practical capablity and thinking ability required. Too many mindless little scumbags sitting around without any intention of sharing information and goodwill, merely waiting for someone to fail so they can gloat. One has to wonder about the quality of their lives -- but not for long; they are depressingly common. This is the fact of life wherever men gather to discuss anything. Try Parliament, its a rabble. Board room meetings can be hot and tawdry i hear; never been to one, I ain't never gonna make it to no board of directors. But here sometimes I get bored of directions. I bought it on Ebay and shipped it home for a rebuild, I am too old to dare freshen a three legged fuse, nor its neighbors. That reminds me. I have a Velleman Digital Preamp that my boy started work on but lost interest in after fitting a handfull of parts. I put it aside to complete later but a few years later my eyes and patience are not up to soldering that many tiny joints. You want it, Sander, it's yours for the postage. Digital preamps should be better than digital power amps because there is no low speaker impedance at the end of the signal path... Maybe digital eclipses all the existing SS, so it will all fade away leaving only digital, and leaving ppl wondering why we didn't go straight to digital in 1948, the year after the bjt was invented. He,he, tubes will remain with us..... It is a gift to the kid. He may accept thermionic conversion, one day, but this gives his ear good vibes in the interim. Or interegnum, it he persists ... he married a beautiful Catholic, the Earth spins ... Still? Good God, what shocking news from Phoenix, Father. Sounds good enough. Not the same as tubes, but, decent. We train ourselves to hear anomolies in the sound and then scream foul. Silly bitch hi-fi martyrs. Actually, one of the very worst amps that I ever heard is a Leak Stereo 30 Plus, an early silicon amp. You'd think with Harold Leak's experience in building excellent tube amps... But no, it is utmost crap. I stripped it out to turn the plugs, sockets and switches into a control center for comparison testing of review gear and DIY builds. It's in photos in my reviews in Glass Audio, if you care all that much for late 50's British "styling" -- buttons all over the facia, zero ergonomics, zero integration. Still, it save me drilling and folding a box. Bit silly, really. Home audio is a desperate pleasure at best. Often it teaches only disgust and fear. You may be taking a very long time to die, Al, but I'm only about two thirds through my life and I'm not an audiophile (try this test: I can't even begin to count my discs, and they are certainly worth more than even my excess of plutocratic audio gear). I'm listening to my first box of Haendel, about 250-300 discs, and hearing only the soaring joy (if Haendel feared the eternal fire, he certainly hid it well), and I'm riding in the spring saying hallo to the animals I know in the countryside, or at least their offspring. Unfortunately my pike, a ferociously hungry fish, which lived in a culvert I often sit on to eat my lunch, appears to have migrated to a fatter stream or to have died. Still, another will come along. My herons are now such a flock, I can no longer tell them apart even with the aid of a long lens. You'll enjoy this. I'm sitting on a bridge, hard at work on my fitness, when some old chappie stumbles past, fists pumping 2rpm below his knees, bent over so low you can almost imagine him disappearing slowly into the road until nothing but the illusion of his passing remains. In these parts you make a greeting when you meet people on the road (blow-ins, foreigners and suchlike are the ones who don't greet you even from their cars, a few fingers raised from the wheel being considered polite). So I said to this old chappie, four klicks from town, "You will surely live to be ninety, sir," and he snapped right back, "I'm already over ninety, sonny." Hoping spring arrives and you are taken by unforseen passion. It is pleasant enough here, but the only news is sleep. See above. I'll publish a photo essay of one of my rides; it's sitting on my desktop awaiting formatting as soon as I finish coresponding. (Sure, I can spell correspondent. I like the pun on unforeseen passion better.) I often think I should post a picturescope of my rides and maybe people would be drawn to my town just because its about the only place in Oz with a lot of dedicated cycle tracks that take you to wild and bushy places only a km or two from the town centres. I'd probably bore most people to tears though, and I have no time... too many other projects. And I can't include the stench of dead kangaroos by the roadsides, killed in the hundreds by car drivers during winter, and then ponging the roads up as the weather warms up in spring, and winter carion begins to rot in earnest. And last year between July and November I was attacked by magpies every day I went out. One day I had seven attacks from seven different birds during a 50 mile ride, one bright enough to land on my shoulder, and attempt to peck my brain out through my ear. But it didn't realised how grim his pickings were; only some wizened up amp maker brain in there.... The Lord gave the Oz, a huge mainly empty place to the birds, yet they quarrel over each square inch, and hate harmless cyclists who don't eat their tucker. Go figure. No math, if you don't mind. Computer models are good, and a tame engineer chained under the table who gets no food until he finishes my math. The whole point about intelligence is that it can be used to invent labour-saving devices. .....but seldom does mean labour is saved. Patrick Turner. Happy Ears! Al Slainte! Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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#46
Posted to rec.audio.tubes,uk.rec.audio
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Where did all the tubies go?
Andre Jute wrote: Seems to me the good tubies went cycling and swimming and built a pre- amp and a headphone amp and plotted a SET (1), while the wannabes and trolls and silicon slime sat around waiting for someone to build something so they could drain the glee from his hobby. What despicable people they are! Andre Jute Scum is as scum does (1) There was a time when the projects in progress by RATs required more than the fingers of one hand to count, when the actual makers of stuff outnumbered the pondscum 30:1. Blokes turned 55, and secumbed to later midlife crisis, after not very well enduring prvious life crisises. They say men don't have a menopause, but methinks many men pause from being men at about 55, their waist spreads obscenely, their wit dimishes, their speed and agility atrophy, and some even to believe their own BS. Society tends to waste ppl over 55; try getting a real job after 55 if your'e sacked. Not easy. Hence prescriptions for depression pills are at an all time high. But the Net went mainstream, and SNR in public groups went off the scale, as well as the challenging of ordinary mortals by ppl like Allison, a Net troglodite with club if ever there was one, and so all these little groups which require secret passwords sprang up like mushrooms, and where not much of anything happens, but its a great place for many blokes over 55 to hang out and slowly endure brain death, for serious challenge to them is forbidden. I have no regrets about becoming a born again cyclist, for about the 4th time in my life. I hope to forget most BS, and learn new stuff which better compares to the old BS. I eak a living from making stuff, and if I don't make a big wage then not many others would be either. Manufacturing anything at all here is difficult because of the reduction of buying power of wages. Chinese produce is wheeled in for the masses.... Patrick Turner. |
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#47
Posted to rec.audio.tubes
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Where did all the tubies go?
Andre Jute wrote:
mueller wrote: Like many, I got tired of being blasted for asking a question. Seems to be tp many short sighted and narrow minded people here , who get really upitty when things do not follow their beliefs. So I moved on to forums that welcome different views. Mike Mueller I get letters from lurkers sometimes and they really seem to take the general debility of RAT hard. The heavy posters among the real tubies have long since developed thick skins just to survive the chiselling of the sneerers and jeerers. But it is easy to see that RAT isn't a good recommendation to anyone of sensitive disposition. And that is a prizewinning understatement! Andre Jute Has nothing to do with a sensitive disposition. It has to do with the refusal of the heavy poster to keep their mouths shut when they have no clue as to what they are saying and to let the knowlegable poster help. It's a public newsgroup with no moderator. Thats the price too pay to wade through the B.S. I had recieved some great advice from RAT up until 3 years ago. RAT over the last 3 years has gone too the ignorant,blowhards that feel degrading a person who does not agree with the so called "gods" is not allowed to be here. Or, maybe there is a different way of doing something and uit scares them. RAT has become a place to defame other posters. Interestingly, I had admired a few posters originally for their knowledge. Even a few of those have turned to defaming others. It's just sad. Mike Mueller |
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#48
Posted to rec.audio.tubes
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Where did all the tubies go?
mueller wrote: Like many, I got tired of being blasted for asking a question. Seems to be tp many short sighted and narrow minded people here , who get really upitty when things do not follow their beliefs. So I moved on to forums that welcome different views. Mike Mueller But when I have followed after those who left r.a.t to their little forums, I found myself yawning, and amoung time wasting ppl who didn't build much, say much, or know much. They couldn't even find the time to construct their forums to work as easily on screen as the public usernet groups all do, and I saw silly emoticons and pictorial BS that thinking people don't like because its is all banal distraction. And at r.a.t, when i was attacked by unruly crews of thugs, I did my best to leave out bowls of rat poison, and armed myself with rat gun, proceeded to pick them off and remain here unpeturbed, even ever forgiving, because only a stupid man nurses his war wounds for a lifetime. If I were to walk into a room full of brain surgeons discussing latest techniques in cranial hole drilling, and come with the credentials of the local butcher, I could not expect a favourable response to any questions I may raise. But were I able to show them a fabulous technique for boring a hole in a skull, and I had all the facts, details and terminology right, perhap's they'd listen rather than bite. Thus I could come to r.a.t, after having spent from 19 to 50 working as a construction designer builder. Then I established a website with real content after gaining some experience. I am grateful for all the knowlegable ppl in tube craft who preceded me, and who have gathered around me since I left the building trade to help me transfer my competence to another field. Maybe I will give up tubes and take up painting pictures any day soon. I reckon painting nude women and landscapes, people in the park, all day, would be quite enthralling. So try to expand your mind to accept and be accepted, to me this is better than running way to hide from the blasts you'll get if your ideas don't add up, or seem to naive. One cannot expect to be accepted, let alone nurtured or cared for immediately, anywhere you go when you arrive there. The locals will only slowly accept you, only maybe, so think about mainly what depends on you. Patrick Turner. |
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#49
Posted to rec.audio.tubes
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Where did all the tubies go?
mueller wrote: I had recieved some great advice from RAT up until 3 years ago. RAT over the last 3 years has gone too the ignorant,blowhards that feel degrading a person who does not agree with the so called "gods" is not allowed to be here. Who are the 'gods' here ? Technically I particularly respect Patrick and Sanders' comments but I hadn't noticed they required worshipping. Or, maybe there is a different way of doing something and uit scares them. Very often the smart designer will find some new method of adapting circuitry. It's far more fun than building by rote. Graham |
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#50
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Andre Jute wrote:
Nick Gorham wrote: That reminds me, as you are again posting to URA, I noticed you run the 300b fills at 4.8v in your design. I know you have mentioned Steve Bench in relation to this, but I wondered, have you done any measurement of the actual effect of running the fill at a 4% reduced voltage? -- Nick The filaments in my T39 Ultrafi design (see my netsite, URL under my sig) are closer to 8 per cent reduced from book spec. It is essential to anyone else's understanding of this discussion that you view the T39 Ultrafi circuit and also read the Starved Filament document on Steve Bench's site. Yes, I have read Steves docs, thats why I ask, as I note that he commented that the technique was not applicable to power tubes, as you say, the effect of reducing the max emmission of the fil causes the curves to fall back leading to a area of lower distortion. And another problem I can see with the modified curves, is they are likely to loose any improvement once a eliptical load line is considered. Again, another reason why its not applicable to power stages. My associate Bill May made some tests with starved filaments. I've never made much of a song and dance about it because a) we didn't find anything Steve Bench isn't telling everyone who is interested, and b) that sort of thing is simply too subtle to discuss with the soundbiters hovering on RAT to ruin every thread and drain everyone's glee in this hobby with their luddite sneering and jeering and their sullen incomprehension of what really matters. Ok, but what did you find? as I have repeated Steve's work with 300b's and found no real difference in 2nd and 3rd harmonic spectra at normal power outputs. I like a very silent amp and am not afraid to pay a price for it in power not extracted from the tube, so I do starved fils even with 300B, even though I know that the effect, at margins to which I will never drive the tube, will not be huge on such an already very silent tube. All those little margins of silence add up to the refinement that lesser designers must seek in negative feedback. Of course, it also means that the overload characteristic of my amp is extended, and made more refined. I agree a low noise floor is important, but I don't see how the use of starved fillaments leads to lower noise? In the search of lower noise, would a DC heating scheme not lead to improved noise figures? Assuming its done of course so there are no sonic costs (other than the spreading of harmonics across the spectrum). Steve Bench is a great benefactor to DIY tube audio. The other idea I got from Steve that is incorporated in my T39 is the four separate grid resistors on the 417A. Yes, agreed, Steve is a goldmine of usefull ideas. I should get around to building one of his matrix amps some time for fun. -- Nick |
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#51
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Nick Gorham wrote: In the search of lower noise, would a DC heating scheme not lead to improved noise figures? Assuming its done of course so there are no sonic costs (other than the spreading of harmonics across the spectrum). DC heating of a DHT would have some consequences for the device characteristics I would imagine. How about ultrasonic heater cuurent ? Graham |
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#52
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Eeyore wrote:
Nick Gorham wrote: In the search of lower noise, would a DC heating scheme not lead to improved noise figures? Assuming its done of course so there are no sonic costs (other than the spreading of harmonics across the spectrum). DC heating of a DHT would have some consequences for the device characteristics I would imagine. Why? I agree that just a simple bridge and cap stands the chance of replacing a nice (ish) pure 100hz sine wave with a huge wash of harmonics. And voltage regulation doesn't seem to be without its sonic cost, but I have found (to my ears anyway) that a current regulator doesnt sound bad. There is some interesting stuff here http://www.clarisonus.com/Research%2...upplyTest.html How about ultrasonic heater cuurent ? Tried that, though only at 50k or so, maybe higher would be better, but at 50k I found there was IM with the audio causing problems with the top end. Easy to hear if you sweep the amp with a sig gen. It certainly is a easy way of getting the 20v@3A for something like a GM70, though I am using what seems to be a reliable current reg setup for them at the moment. -- Nick |
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#53
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Nick Gorham wrote:
Andre Jute wrote: Nick Gorham wrote: That reminds me, as you are again posting to URA, I noticed you run the 300b fills at 4.8v in your design. I know you have mentioned Steve Bench in relation to this, but I wondered, have you done any measurement of the actual effect of running the fill at a 4% reduced voltage? -- Nick The filaments in my T39 Ultrafi design (see my netsite, URL under my sig) are closer to 8 per cent reduced from book spec. It is essential to anyone else's understanding of this discussion that you view the T39 Ultrafi circuit and also read the Starved Filament document on Steve Bench's site. Yes, I have read Steves docs, thats why I ask, as I note that he commented that the technique was not applicable to power tubes, That's not what Steve says at all, Nick. Try reading it again. The relevant passage is in the first paragraph: "This effect seems [to] occur on all forms of directly heated tubes, from power tubes to small signal tubes, to "battery" tubes. The effect, for reasons shown later, can be exploited in small signal applications, but is more difficult to realize in power applications." -- Steve Bench at http://members.aol.com/sbench102/dht.html Steve doesn't say that the effect of starved filaments doesn't work in power tubes, he says it is more difficult to reap the benefits with a power tube. That's just a practical problem to be solved, not an exclusion in physics. We should take a brief digression here about our terminology. Ask yourself what is a power tube and what is not. Several versions of my most recent project use 6SN7 tubes as power tubes. The T39 300B Ultrafi amp I published at http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm is merely a detuned version of the booster or control stage of a much bigger amp, the Millennium's End, an SV-572-3 or -10 SE or PSE 25-80W amp to drive my ESL-63. I don't publish the bigger amp circuit any more because I discovered that people were considering building it with the soldering iron and DMM they bought that morning... In this case, the 300B is part of the preamp. Steve found the same effect in the 1619, a powertube similar to the 6L6 (according to him -- I've never even seen a 1619. never mind owned one). as you say, the effect of reducing the max emmission of the fil causes the curves to fall back leading to a area of lower distortion. Sure, that's what I say because that is what Bill found. I'm not qualified to argue with Steve and Bill about what the instruments clearly tell them. And another problem I can see with the modified curves, is they are likely to loose any improvement once a eliptical load line is considered. Again, another reason why its not applicable to power stages. Your conclusion, besides being based on a misconstruction of what Steve actually concluded, is far too firm. I said that this is a subtle; it is subtle for more reasons than merely that it is too difficult to discuss with the clowns hovering on RAT. I don't know if you were around when the Magnequest Scum challenged me to design contest. I humiliated them, of course. They ran away before more than the power stages were published. I published only the circuit, not the analysis or the actual measurements because I knew that the kneejerk sneerers and jeerers would have a field days screeching that no tube could be that silent. But John Byrns published an independent analysis showing that the third and higher harmonics left by my "HIGH" concept (high voltage, high current, high load = silence) amounted to something like 0.03 per cent. (If you want to look it up, search on RAT for "Bubbaland 300B" which was the derisory name we gave Mike Lafevre and Bob C.'s wretched entry.) Consequently, when you test a 300B at those conditions (400V+ plate voltage, 80+mA current, load 5K6), or indeed any realistic modern operating conditions from 65mA up, the observable change in the most important harmonics (third and higher) is either very small or off the bottom of your measuring instrument because you're trying to measure a change in something that is already very small. I seem to remember that I said to Bill the first time we did it (300B driving an 845, can't remember my type number now; I installed it on a friend's motor yacht) that we were chasing fireflies and that the slightly more observable, because the smaller difference is on a bigger base, change in the 2nd harmonic,was irrelevant to me; I don't care how much second harmonic is left (people can't hear it until it amounts to nearly 2% and my amps are carefully specified with their speakers never to approach even half of that); I care about the level and composition of the odd and higher harmonics, which are sublimininally most disturbing at even vanishingly minuscule levels. My associate Bill May made some tests with starved filaments. I've never made much of a song and dance about it because a) we didn't find anything Steve Bench isn't telling everyone who is interested, and b) that sort of thing is simply too subtle to discuss with the soundbiters hovering on RAT to ruin every thread and drain everyone's glee in this hobby with their luddite sneering and jeering and their sullen incomprehension of what really matters. Ok, but what did you find? as I have repeated Steve's work with 300b's and found no real difference in 2nd and 3rd harmonic spectra at normal power outputs. As I explained above, we found what you found, not a huge difference. We just interpreted it more cautiously than you did, and that opened an opportunity for us to turn a small advantage into a much bigger advantage. Since the 300B was a driver for a transmitting tube we could test the starved fils in a complete circuit on which we already had a lot of data. And here, at the end of a chain, it made a perceptible difference; the difference was magnified. The end result at the speaker is the point of all the effort, not the bragging rights of what you can read off an instrument. On the early 845 amp the starved fils on the 300B driver reduced the higher harmonics at the output of the entire amp at full output by about 11 per cent and the second harmonic hardly. At 2W (well above any expected output with the horns also supplied to use with the amp) or about 11 per cent of available power, the difference was tiny, which was as expected. The effect of starved fils (9V rather than the blueprint 10V) on the 845 was more easily measurable than on the 300B (it is practically difficult to make an 845 as silent as a 300B, mainly due to difficulties with winders, though we shouldn't go overboard, the 845 is still a very linear tube) but didn't make as much difference to the output. Part of the advantage that small signal DHTs with starved fils have is clearly the magnifier effect, and more stages following for it to take effect. You might say that I gained very little for my effort, an 11 per cent reduction in a number most engineers would consider already so far below the threshold of perception that it isn't worth bothering about. You would be wrong; any reduction in the third and higher harmonics is worth a lot of effort. I like a very silent amp and am not afraid to pay a price for it in power not extracted from the tube, so I do starved fils even with 300B, even though I know that the effect, at margins to which I will never drive the tube, will not be huge on such an already very silent tube. All those little margins of silence add up to the refinement that lesser designers must seek in negative feedback. Of course, it also means that the overload characteristic of my amp is extended, and made more refined. I agree a low noise floor is important, but I don't see how the use of starved fillaments leads to lower noise? Eh, Nick? You want to reconsider that sentence? Noise anywhere in an amplifier is, not to put too fine a point on it, multiplied through subsequent devices. (You believe in consciously applied harmonic cancellation? -- hey, I got this bridge in Brooklyn I can let you have cheap!) I've just demonstrated above how we got a handle on an effect, which you say you could hardly see, by considering our reasons for trying starved filaments, which was silence at the *output* of the amp. Isolating effects is good science, but you don't *have* to consider tham in isolation; in fact, in audio you'd better not because, if you do, your amp will almost certainly sound like ****. In the search of lower noise, would a DC heating scheme not lead to improved noise figures? Assuming its done of course so there are no sonic costs (other than the spreading of harmonics across the spectrum). It is not difficult to build a tube amp that sounds exactly like a silicon amp, minus only the creaking of the huge ali heatsinks. Just regulate every voltage like a martinet. DC heaters on any DHT is a very large step in that direction. AC heaters on DHT are substantially responsible for their attractive tonal quality. (There's more to it than that; the matter was recently discussed on RAT; Chris Hornbeck made some intriguingly vague remarks that made me wonder if he knew more that he wasn't saying.) Steve Bench is a great benefactor to DIY tube audio. The other idea I got from Steve that is incorporated in my T39 is the four separate grid resistors on the 417A. Yes, agreed, Steve is a goldmine of usefull ideas. I should get around to building one of his matrix amps some time for fun. -- Nick I hope this helps. I can't find Bill's notes, so I'm operating on memory; Bill's gone to maintain the Electricity Grid in Heaven (the neon tubes in all those haloes...), so I can't ask him. It is a pity this place is too unpleasant to invite Steve Bench to. But Steve's a very helpful guy; you could just write to him. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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#54
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
On Apr 10, 12:17?am, Eeyore
wrote: How about ultrasonic heater cuurent ? Graham Hi RATs! A friend built a fancy RF filament supply and was quite pleased with the sound. Then, he went back to DC and realized the amp sounded good, either way. That is a constant hazard with tube circuits. They may sound pleasant in many configurations. Happy Ears! Al |
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#55
Posted to rec.audio.tubes
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Amps for long-distance listeners
Patrick Turner wrote: Andre Jute wrote: Most of us listen to solid state all the time. What do you think a CD player is? I also have a reliable, solid Quad 405 Mk II power amp and a solid, reliable full-featured (mono switch, anyone? -- very useful for DIY in the rest of the chain) Quad 34 control amp sitting permanently at my left hand. The tube amp de jour stands on top of or beside that lot. Well, there is no accounting for taste. I have to humbly say that the 405/34 combo doesn't bring the best music to my ears. I had to fix a set using those last week and afterwards i had the pleasure if switching to tube gear, and nothing convinces me the 405/34 combo is better. Same thing has happened with 303. Its the classic case of measuring well, running cool, and no more music. You're blase (acute on the e), Patrick. You want something extra from the sound, you want to be struck dumb. The Quad 405 Mk2 and the 34 control amp and their associated ESL-63 speakers are for an entirely different class of listener, the long- distance music lover. He doesn't want to be startled, he doesn't want his amp or his speakers to have personality, he wants the plain unadorned music given to him straight up, just the window on the concert hall and send the trimmings to some "audiophile" eejit who substitutes money and possessions for confidence. It is a setup you can listen to for 16 hours straight -- I often do when I'm on a roll with one of my books -- and never have it intrude on your space. I try to make my tube amps that neutral because it is clear to me that a tube amp that stuns you will also soon tire you. I test tube amps by playing them for hours on the periphery of my attention, wallpaper; if I look up, it must be to smile at some pleasing passage in the music, not something the amp shouted out, or stole, to attract my attention. Andre Jute The trouble with most people is not what they don't know, but what they know for certain that isn't true. ---Mark Twain |
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#56
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Andre Jute wrote:
Nick Gorham wrote: Andre Jute wrote: Nick Gorham wrote: That reminds me, as you are again posting to URA, I noticed you run the 300b fills at 4.8v in your design. I know you have mentioned Steve Bench in relation to this, but I wondered, have you done any measurement of the actual effect of running the fill at a 4% reduced voltage? -- Nick The filaments in my T39 Ultrafi design (see my netsite, URL under my sig) are closer to 8 per cent reduced from book spec. It is essential to anyone else's understanding of this discussion that you view the T39 Ultrafi circuit and also read the Starved Filament document on Steve Bench's site. Yes, I have read Steves docs, thats why I ask, as I note that he commented that the technique was not applicable to power tubes, That's not what Steve says at all, Nick. Try reading it again. The relevant passage is in the first paragraph: "This effect seems [to] occur on all forms of directly heated tubes, from power tubes to small signal tubes, to "battery" tubes. The effect, for reasons shown later, can be exploited in small signal applications, but is more difficult to realize in power applications." -- Steve Bench at http://members.aol.com/sbench102/dht.html Steve doesn't say that the effect of starved filaments doesn't work in power tubes, he says it is more difficult to reap the benefits with a power tube. That's just a practical problem to be solved, not an exclusion in physics. Ok, yes, maybe I went too far the other way. I was not suggesting that the effect wasn't present in power tubes, but that its use was not as simple as picking a load line where the lines were parallel. I was interpreting the text: "The flattening out of the characteristics also implies that this effect would be harder to implement in a power amplifier situation." My take was that in a power situation you were less likely (though you could) to want to be some way down the curves, as the power output would be greatly reduced. We should take a brief digression here about our terminology. Ask yourself what is a power tube and what is not. Several versions of my most recent project use 6SN7 tubes as power tubes. The T39 300B Ultrafi amp I published at Agreed its not a real distinction, but in the case of the starved fils, I took the (what seems sensible) distinction of a device that is likely to suffer from a reactive load, and therefor not have a simple load line, and also one that would tend to have the operating conditions up near the limits of the device. And those two conditions were what I took to be Steve's reason for suggesting it would be harder to implement. In fact I would suggest that there was every chance that the result could lead to poorer results in fact. http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm is merely a detuned version of the booster or control stage of a much bigger amp, the Millennium's End, an SV-572-3 or -10 SE or PSE 25-80W amp to drive my ESL-63. I don't publish the bigger amp circuit any more because I discovered that people were considering building it with the soldering iron and DMM they bought that morning... In this case, the 300B is part of the preamp. Steve found the same effect in the 1619, a powertube similar to the 6L6 (according to him -- I've never even seen a 1619. never mind owned one). Ok, I can certainly see that it would work there, as in this case it may be that the 300b is not in the conditions that I described as a "power stage". What I was asking about though was its use in the KISS circuit, wheer it certainly would be seeing a reactive load, and as far as I can see is being driven moderatly hard. as you say, the effect of reducing the max emmission of the fil causes the curves to fall back leading to a area of lower distortion. Sure, that's what I say because that is what Bill found. I'm not qualified to argue with Steve and Bill about what the instruments clearly tell them. Ditto, but the difference is that Steve has published what he found, I was just wondering what the basis of your use in the KISS amp was. As under similar conditions I could detect no significant measurable or audible difference (the difference _was_ measurable, but less than the difference between two matched 300b's from the same manufacturer). And another problem I can see with the modified curves, is they are likely to loose any improvement once a eliptical load line is considered. Again, another reason why its not applicable to power stages. Your conclusion, besides being based on a misconstruction of what Steve actually concluded, is far too firm. I said that this is a subtle; it is subtle for more reasons than merely that it is too difficult to discuss with the clowns hovering on RAT. I don't know if you were around when the Magnequest Scum challenged me to design contest. I humiliated them, of course. They ran away before more than the power stages were published. I published only the circuit, not the analysis or the actual measurements because I knew that the kneejerk sneerers and jeerers would have a field days screeching that no tube could be that silent. But John Byrns published an independent analysis showing that the third and higher harmonics left by my "HIGH" concept (high voltage, high current, high load = silence) amounted to something like 0.03 per cent. (If you want to look it up, search on RAT for "Bubbaland 300B" which was the derisory name we gave Mike Lafevre and Bob C.'s wretched entry.) Consequently, when you test a 300B at those conditions (400V+ plate voltage, 80+mA current, load 5K6), or indeed any realistic modern operating conditions from 65mA up, the observable change in the most important harmonics (third and higher) is either very small or off the bottom of your measuring instrument because you're trying to measure a change in something that is already very small. I seem to remember that I said to Bill the first time we did it (300B driving an 845, can't remember my type number now; I installed it on a friend's motor yacht) that we were chasing fireflies and that the slightly more observable, because the smaller difference is on a bigger base, change in the 2nd harmonic,was irrelevant to me; I don't care how much second harmonic is left (people can't hear it until it amounts to nearly 2% and my amps are carefully specified with their speakers never to approach even half of that); I care about the level and composition of the odd and higher harmonics, which are sublimininally most disturbing at even vanishingly minuscule levels. My associate Bill May made some tests with starved filaments. I've never made much of a song and dance about it because a) we didn't find anything Steve Bench isn't telling everyone who is interested, and b) that sort of thing is simply too subtle to discuss with the soundbiters hovering on RAT to ruin every thread and drain everyone's glee in this hobby with their luddite sneering and jeering and their sullen incomprehension of what really matters. Ok, but what did you find? as I have repeated Steve's work with 300b's and found no real difference in 2nd and 3rd harmonic spectra at normal power outputs. As I explained above, we found what you found, not a huge difference. We just interpreted it more cautiously than you did, and that opened an opportunity for us to turn a small advantage into a much bigger advantage. Yes, good, but I am asking how that small advantage was turned into anything in the case of KISS, I can see how it is of use when the 300b is used to drive another valve, the work I am doing on 300b's started as a driver stage for a GM70, but thats not the case I am discussing. Since the 300B was a driver for a transmitting tube we could test the starved fils in a complete circuit on which we already had a lot of data. And here, at the end of a chain, it made a perceptible difference; the difference was magnified. Yes, I can see that, but I still don't see in KISS what you have done that makes the use of starved fillaments to any advantage. You might say that I gained very little for my effort, an 11 per cent reduction in a number most engineers would consider already so far below the threshold of perception that it isn't worth bothering about. You would be wrong; any reduction in the third and higher harmonics is worth a lot of effort. I like a very silent amp and am not afraid to pay a price for it in power not extracted from the tube, so I do starved fils even with 300B, even though I know that the effect, at margins to which I will never drive the tube, will not be huge on such an already very silent tube. All those little margins of silence add up to the refinement that lesser designers must seek in negative feedback. Of course, it also means that the overload characteristic of my amp is extended, and made more refined. I agree a low noise floor is important, but I don't see how the use of starved fillaments leads to lower noise? Eh, Nick? You want to reconsider that sentence? Noise anywhere in an amplifier is, not to put too fine a point on it, multiplied through subsequent devices. (You believe in consciously applied harmonic cancellation? -- hey, I got this bridge in Brooklyn I can let you have cheap!) Well, it seems to work as described in the case of push pull amps. What I have found, is that in the conditions where you have two stages producing mainly 2nd harmonic, that very small changes in operating conditions can lead to large observed changes in harmonic distortion. I am not claming that this works as well (or at all) under real use, but I have learnt that it can be deceptive. What looks like a reduction in harmonics (which you describe in the 300b/845 case) could well have been the result in cancelation, and not the result of the starved fill effect Steve documented. I've just demonstrated above how we got a handle on an effect, which you say you could hardly see, by considering our reasons for trying starved filaments, which was silence at the *output* of the amp. Isolating effects is good science, but you don't *have* to consider tham in isolation; in fact, in audio you'd better not because, if you do, your amp will almost certainly sound like ****. Well, with respect, you havent demonstrated that, what you have shown (at least in what you have written) is that you found that varying fill voltage reduced the measured harmonic output in the 300b/845 case. What I am not sure you have proved to any extent just what effect is causing your measured results. In the search of lower noise, would a DC heating scheme not lead to improved noise figures? Assuming its done of course so there are no sonic costs (other than the spreading of harmonics across the spectrum). It is not difficult to build a tube amp that sounds exactly like a silicon amp, minus only the creaking of the huge ali heatsinks. Just regulate every voltage like a martinet. DC heaters on any DHT is a very large step in that direction. AC heaters on DHT are substantially responsible for their attractive tonal quality. (There's more to it than that; the matter was recently discussed on RAT; Chris Hornbeck made some intriguingly vague remarks that made me wonder if he knew more that he wasn't saying.) Ok, its always possible to make an amp sound like crap, but devil is in the detail. Personally I find that once you remove the cloying coloration caused by LF AC heating, then the real joy of DHT's starts to shine through, but I would never says that view is anything but IMHO. Steve Bench is a great benefactor to DIY tube audio. The other idea I got from Steve that is incorporated in my T39 is the four separate grid resistors on the 417A. Yes, I saw that, whats does that do? I hope this helps. I can't find Bill's notes, so I'm operating on memory; Bill's gone to maintain the Electricity Grid in Heaven (the neon tubes in all those haloes...), so I can't ask him. It is a pity this place is too unpleasant to invite Steve Bench to. But Steve's a very helpful guy; you could just write to him. Yes, I could, but in reality I wasn't questioning Steve's work, just what you have done to make it applicable to the KISS design. -- Nick |
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#57
Posted to rec.audio.tubes
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Amps for long-distance listeners
Andre Jute wrote: Patrick Turner wrote: Andre Jute wrote: Most of us listen to solid state all the time. What do you think a CD player is? I also have a reliable, solid Quad 405 Mk II power amp and a solid, reliable full-featured (mono switch, anyone? -- very useful for DIY in the rest of the chain) Quad 34 control amp sitting permanently at my left hand. The tube amp de jour stands on top of or beside that lot. Well, there is no accounting for taste. I have to humbly say that the 405/34 combo doesn't bring the best music to my ears. I had to fix a set using those last week and afterwards i had the pleasure if switching to tube gear, and nothing convinces me the 405/34 combo is better. Same thing has happened with 303. Its the classic case of measuring well, running cool, and no more music. You're blase (acute on the e), Patrick. You want something extra from the sound, you want to be struck dumb. Well yes, I do like being struck dumb occassionally, but hopefully not by anyone taking a swing at me here though. The Quad 405 Mk2 and the 34 control amp and their associated ESL-63 speakers are for an entirely different class of listener, the long- distance music lover. He doesn't want to be startled, he doesn't want his amp or his speakers to have personality, he wants the plain unadorned music given to him straight up, just the window on the concert hall and send the trimmings to some "audiophile" eejit who substitutes money and possessions for confidence. So that's what I was listening to when I last heard a pair of ESL63 with ARC amps and reasonable CD player. Funny thing though, we prefered vinyl on that day from a very plain MM cart... It is a setup you can listen to for 16 hours straight -- I often do when I'm on a roll with one of my books -- and never have it intrude on your space. I try to make my tube amps that neutral because it is clear to me that a tube amp that stuns you will also soon tire you. Well, I tire of the big wide brassy sound of the '63s and prefer my own dynamics. And the sound of simpler tube gear than ARC manages. I dunno why, I just do. I have faith, and so much faith I am building an ESL kit for a client and I have fingers crossed.... I test tube amps by playing them for hours on the periphery of my attention, wallpaper; if I look up, it must be to smile at some pleasing passage in the music, not something the amp shouted out, or stole, to attract my attention. There are times when I want the system prompt me to ask Askenazy away from his piano, it is dinner time, except that he ain't there.... Oh well, I'll drink his glass of wine then. Patrick Turner. Andre Jute The trouble with most people is not what they don't know, but what they know for certain that isn't true. ---Mark Twain |
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#58
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Yeah, I see what you're getting at, Nick. Okay. Here's a summary of
what I know from proof, with speculation beyond observation clearly separated. 1. Starved filaments works with DHT power tubes. At conservative starvation the effect is not huge. 2. It works with a 300B as the output tube in-circuit. The effect is to lower the already low third and higher harmonics probably proportionally to the reduction in filament voltage; I've always just worked with about ten per cent starvation, which is good for a measurable but slight decrease in third and higher harmonics; no change in second. I have never seen the adverse effect on distortion that you posit and don't expect to; I pay zero attention to thermionic doomsayers. (When fools derive all their self-importance from negativity then each one competes to be more negative than the next clown; vide the comedy act environmental "scientists" at the IPCC -- Impersonating Professional Clowns dot Com -- are putting on for our entertainment, trying to outshout each other by predicting ever more dire worldsplitting catastrophes when everyone can see things are getting better decade on decade.) 3. I have calculated and drawn a worst-case eliptical loadline for a 300B. I consequently don't share your belief that the starved fils effect in 300B can be reduced by an eliptical loadline. Maybe on a fundamentally less linear tube, but then the gain from starved fils will also be so much greater that the residual after the eliptical load takes its toll will be well worth having, and bigger absolutely than on 300B. 4. When you already have a really silent amp, whatever further margin of silence you gain by slightly desperate means like starved fils will be *marginal*. Whether you want it, and where you stop, is a matter of taste. On the T39 I had power to spare (the amp is intended for 101dB/ m horns) and therefore could afford the luxury of a small power loss for an even more advantageous distribution of harmonics. Of course, the many small margins add up and sometimes multiply together... 5. There is no magic bullet, only years of work. When the amp is built, it is a small soldering job for you to starve the fils and compare the measurements of the complete amp with all loads attached, including speakers, with those for unstarved fils. Let us know what you find. Personally, I no longer bother with meters much; my amps always work as the model I built in Excel predicts to within very small margins. I was in a shooting party once with a fellow once who had thousands of pounds of work done on the engine of his Ford LTD (the mid-60s 7 litre saloon was a sleeper among the great crosscontinental fast touring cars) and then choked it back to less effective horsepower than standard at the rear wheels with a wretchedly (in my opinion) over the top silencer system. He paid all that money for a truly silent car because that is what he sincerely desired. Starved filaments on tube amps fall at about the same level of obsession, wouldn't you say? HTH. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Nick Gorham wrote: Andre Jute wrote: Nick Gorham wrote: Andre Jute wrote: Nick Gorham wrote: That reminds me, as you are again posting to URA, I noticed you run the 300b fills at 4.8v in your design. I know you have mentioned Steve Bench in relation to this, but I wondered, have you done any measurement of the actual effect of running the fill at a 4% reduced voltage? -- Nick The filaments in my T39 Ultrafi design (see my netsite, URL under my sig) are closer to 8 per cent reduced from book spec. It is essential to anyone else's understanding of this discussion that you view the T39 Ultrafi circuit and also read the Starved Filament document on Steve Bench's site. Yes, I have read Steves docs, thats why I ask, as I note that he commented that the technique was not applicable to power tubes, That's not what Steve says at all, Nick. Try reading it again. The relevant passage is in the first paragraph: "This effect seems [to] occur on all forms of directly heated tubes, from power tubes to small signal tubes, to "battery" tubes. The effect, for reasons shown later, can be exploited in small signal applications, but is more difficult to realize in power applications." -- Steve Bench at http://members.aol.com/sbench102/dht.html Steve doesn't say that the effect of starved filaments doesn't work in power tubes, he says it is more difficult to reap the benefits with a power tube. That's just a practical problem to be solved, not an exclusion in physics. Ok, yes, maybe I went too far the other way. I was not suggesting that the effect wasn't present in power tubes, but that its use was not as simple as picking a load line where the lines were parallel. I was interpreting the text: "The flattening out of the characteristics also implies that this effect would be harder to implement in a power amplifier situation." My take was that in a power situation you were less likely (though you could) to want to be some way down the curves, as the power output would be greatly reduced. We should take a brief digression here about our terminology. Ask yourself what is a power tube and what is not. Several versions of my most recent project use 6SN7 tubes as power tubes. The T39 300B Ultrafi amp I published at Agreed its not a real distinction, but in the case of the starved fils, I took the (what seems sensible) distinction of a device that is likely to suffer from a reactive load, and therefor not have a simple load line, and also one that would tend to have the operating conditions up near the limits of the device. And those two conditions were what I took to be Steve's reason for suggesting it would be harder to implement. In fact I would suggest that there was every chance that the result could lead to poorer results in fact. http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm is merely a detuned version of the booster or control stage of a much bigger amp, the Millennium's End, an SV-572-3 or -10 SE or PSE 25-80W amp to drive my ESL-63. I don't publish the bigger amp circuit any more because I discovered that people were considering building it with the soldering iron and DMM they bought that morning... In this case, the 300B is part of the preamp. Steve found the same effect in the 1619, a powertube similar to the 6L6 (according to him -- I've never even seen a 1619. never mind owned one). Ok, I can certainly see that it would work there, as in this case it may be that the 300b is not in the conditions that I described as a "power stage". What I was asking about though was its use in the KISS circuit, wheer it certainly would be seeing a reactive load, and as far as I can see is being driven moderatly hard. as you say, the effect of reducing the max emmission of the fil causes the curves to fall back leading to a area of lower distortion. Sure, that's what I say because that is what Bill found. I'm not qualified to argue with Steve and Bill about what the instruments clearly tell them. Ditto, but the difference is that Steve has published what he found, I was just wondering what the basis of your use in the KISS amp was. As under similar conditions I could detect no significant measurable or audible difference (the difference _was_ measurable, but less than the difference between two matched 300b's from the same manufacturer). And another problem I can see with the modified curves, is they are likely to loose any improvement once a eliptical load line is considered. Again, another reason why its not applicable to power stages. Your conclusion, besides being based on a misconstruction of what Steve actually concluded, is far too firm. I said that this is a subtle; it is subtle for more reasons than merely that it is too difficult to discuss with the clowns hovering on RAT. I don't know if you were around when the Magnequest Scum challenged me to design contest. I humiliated them, of course. They ran away before more than the power stages were published. I published only the circuit, not the analysis or the actual measurements because I knew that the kneejerk sneerers and jeerers would have a field days screeching that no tube could be that silent. But John Byrns published an independent analysis showing that the third and higher harmonics left by my "HIGH" concept (high voltage, high current, high load = silence) amounted to something like 0.03 per cent. (If you want to look it up, search on RAT for "Bubbaland 300B" which was the derisory name we gave Mike Lafevre and Bob C.'s wretched entry.) Consequently, when you test a 300B at those conditions (400V+ plate voltage, 80+mA current, load 5K6), or indeed any realistic modern operating conditions from 65mA up, the observable change in the most important harmonics (third and higher) is either very small or off the bottom of your measuring instrument because you're trying to measure a change in something that is already very small. I seem to remember that I said to Bill the first time we did it (300B driving an 845, can't remember my type number now; I installed it on a friend's motor yacht) that we were chasing fireflies and that the slightly more observable, because the smaller difference is on a bigger base, change in the 2nd harmonic,was irrelevant to me; I don't care how much second harmonic is left (people can't hear it until it amounts to nearly 2% and my amps are carefully specified with their speakers never to approach even half of that); I care about the level and composition of the odd and higher harmonics, which are sublimininally most disturbing at even vanishingly minuscule levels. My associate Bill May made some tests with starved filaments. I've never made much of a song and dance about it because a) we didn't find anything Steve Bench isn't telling everyone who is interested, and b) that sort of thing is simply too subtle to discuss with the soundbiters hovering on RAT to ruin every thread and drain everyone's glee in this hobby with their luddite sneering and jeering and their sullen incomprehension of what really matters. Ok, but what did you find? as I have repeated Steve's work with 300b's and found no real difference in 2nd and 3rd harmonic spectra at normal power outputs. As I explained above, we found what you found, not a huge difference. We just interpreted it more cautiously than you did, and that opened an opportunity for us to turn a small advantage into a much bigger advantage. Yes, good, but I am asking how that small advantage was turned into anything in the case of KISS, I can see how it is of use when the 300b is used to drive another valve, the work I am doing on 300b's started as a driver stage for a GM70, but thats not the case I am discussing. Since the 300B was a driver for a transmitting tube we could test the starved fils in a complete circuit on which we already had a lot of data. And here, at the end of a chain, it made a perceptible difference; the difference was magnified. Yes, I can see that, but I still don't see in KISS what you have done that makes the use of starved fillaments to any advantage. You might say that I gained very little for my effort, an 11 per cent reduction in a number most engineers would consider already so far below the threshold of perception that it isn't worth bothering about. You would be wrong; any reduction in the third and higher harmonics is worth a lot of effort. I like a very silent amp and am not afraid to pay a price for it in power not extracted from the tube, so I do starved fils even with 300B, even though I know that the effect, at margins to which I will never drive the tube, will not be huge on such an already very silent tube. All those little margins of silence add up to the refinement that lesser designers must seek in negative feedback. Of course, it also means that the overload characteristic of my amp is extended, and made more refined. I agree a low noise floor is important, but I don't see how the use of starved fillaments leads to lower noise? Eh, Nick? You want to reconsider that sentence? Noise anywhere in an amplifier is, not to put too fine a point on it, multiplied through subsequent devices. (You believe in consciously applied harmonic cancellation? -- hey, I got this bridge in Brooklyn I can let you have cheap!) Well, it seems to work as described in the case of push pull amps. What I have found, is that in the conditions where you have two stages producing mainly 2nd harmonic, that very small changes in operating conditions can lead to large observed changes in harmonic distortion. I am not claming that this works as well (or at all) under real use, but I have learnt that it can be deceptive. What looks like a reduction in harmonics (which you describe in the 300b/845 case) could well have been the result in cancelation, and not the result of the starved fill effect Steve documented. I've just demonstrated above how we got a handle on an effect, which you say you could hardly see, by considering our reasons for trying starved filaments, which was silence at the *output* of the amp. Isolating effects is good science, but you don't *have* to consider tham in isolation; in fact, in audio you'd better not because, if you do, your amp will almost certainly sound like ****. Well, with respect, you havent demonstrated that, what you have shown (at least in what you have written) is that you found that varying fill voltage reduced the measured harmonic output in the 300b/845 case. What I am not sure you have proved to any extent just what effect is causing your measured results. In the search of lower noise, would a DC heating scheme not lead to improved noise figures? Assuming its done of course so there are no sonic costs (other than the spreading of harmonics across the spectrum). It is not difficult to build a tube amp that sounds exactly like a silicon amp, minus only the creaking of the huge ali heatsinks. Just regulate every voltage like a martinet. DC heaters on any DHT is a very large step in that direction. AC heaters on DHT are substantially responsible for their attractive tonal quality. (There's more to it than that; the matter was recently discussed on RAT; Chris Hornbeck made some intriguingly vague remarks that made me wonder if he knew more that he wasn't saying.) Ok, its always possible to make an amp sound like crap, but devil is in the detail. Personally I find that once you remove the cloying coloration caused by LF AC heating, then the real joy of DHT's starts to shine through, but I would never says that view is anything but IMHO. Steve Bench is a great benefactor to DIY tube audio. The other idea I got from Steve that is incorporated in my T39 is the four separate grid resistors on the 417A. Yes, I saw that, whats does that do? I hope this helps. I can't find Bill's notes, so I'm operating on memory; Bill's gone to maintain the Electricity Grid in Heaven (the neon tubes in all those haloes...), so I can't ask him. It is a pity this place is too unpleasant to invite Steve Bench to. But Steve's a very helpful guy; you could just write to him. Yes, I could, but in reality I wasn't questioning Steve's work, just what you have done to make it applicable to the KISS design. -- Nick |
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#59
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Amps for long-distance listeners
Patrick Turner wrote: Andre Jute wrote: The Quad 405 Mk2 and the 34 control amp and their associated ESL-63 speakers are for an entirely different class of listener, the long- distance music lover. He doesn't want to be startled, he doesn't want his amp or his speakers to have personality, he wants the plain unadorned music given to him straight up, just the window on the concert hall and send the trimmings to some "audiophile" eejit who substitutes money and possessions for confidence. So that's what I was listening to when I last heard a pair of ESL63 with ARC amps and reasonable CD player. It might have been if you also had Quad amps to partner the ESL-63. As it was, you heard the signature of the ARC amp because Quad's ESL-63 is the second-most neutral speaker in the world, after its elder sister the ESL (aka ESL-57). Funny thing though, we prefered vinyl on that day from a very plain MM cart... What do you expect from a bunch bolshie brickies and other brucie yuppies? Democracy has a lot to answer for. It is a setup you can listen to for 16 hours straight -- I often do when I'm on a roll with one of my books -- and never have it intrude on your space. I try to make my tube amps that neutral because it is clear to me that a tube amp that stuns you will also soon tire you. Well, I tire of the big wide brassy sound of the '63s and prefer my own dynamics. Your finger must have slipped, Patrick, or perhaps you're testing whether I am awake. Even you can't be so deaf as to consider that the ESL-63 has a "big wide brassy sound". I have faith, and so much faith I am building an ESL kit for a client Well, I hope you haven't told your client you will give him a "big wide brassy sound" because you won't, not unless he has a room like a stadium with another of similar size backing it, and is willing to let you break out the wall in between and install an absolute wall of a Bessel array of ESL. I've stacked eight (8) ESL-63 and there as no "big wide brassy sound"; in fact, the sound became more refined because the bass reinforcement allowed us to turn the volume down and listen at a lower level for the same perceived effect. You just prefer dynamics because you have accustomed your ears to their dirty bass; electrostats have clean bass and enough of it if you stack enough panels. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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#60
Posted to rec.audio.tubes
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Where did all the tubies go?
"Andre Jute" wrote in message oups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS |
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#61
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Andre Jute wrote:
Yeah, I see what you're getting at, Nick. Okay. Here's a summary of what I know from proof, with speculation beyond observation clearly separated. 1. Starved filaments works with DHT power tubes. At conservative starvation the effect is not huge. Ok. 2. It works with a 300B as the output tube in-circuit. The effect is to lower the already low third and higher harmonics probably proportionally to the reduction in filament voltage; I've always just worked with about ten per cent starvation, which is good for a measurable but slight decrease in third and higher harmonics; no change in second. I have never seen the adverse effect on distortion that you posit and don't expect to; I pay zero attention to thermionic doomsayers. (When fools derive all their self-importance from negativity then each one competes to be more negative than the next clown; vide the comedy act environmental "scientists" at the IPCC -- Impersonating Professional Clowns dot Com -- are putting on for our entertainment, trying to outshout each other by predicting ever more dire worldsplitting catastrophes when everyone can see things are getting better decade on decade.) Ok. 3. I have calculated and drawn a worst-case eliptical loadline for a 300B. I consequently don't share your belief that the starved fils effect in 300B can be reduced by an eliptical loadline. Maybe on a fundamentally less linear tube, but then the gain from starved fils will also be so much greater that the residual after the eliptical load takes its toll will be well worth having, and bigger absolutely than on 300B. Ah, this is interesting, so do you have the plate curves to hand of the 300b with starved fillaments? I guess you must have to have plotted the loadline. I wasn't suggesting that the effect of starved fils to the plate load lines would be reduced by reactive loads, but that the combination of the two may negate any advantage that Steve measured. 4. When you already have a really silent amp, whatever further margin of silence you gain by slightly desperate means like starved fils will be *marginal*. Whether you want it, and where you stop, is a matter of taste. On the T39 I had power to spare (the amp is intended for 101dB/ m horns) and therefore could afford the luxury of a small power loss for an even more advantageous distribution of harmonics. Of course, the many small margins add up and sometimes multiply together... Oh, I agree. I am all in favour of (and indulge in myself) obsessive noise reduction. 5. There is no magic bullet, only years of work. When the amp is built, it is a small soldering job for you to starve the fils and compare the measurements of the complete amp with all loads attached, including speakers, with those for unstarved fils. Let us know what you find. Personally, I no longer bother with meters much; my amps always work as the model I built in Excel predicts to within very small margins. I can and will see what a minor reduction in fillament voltage provides. I was in a shooting party once with a fellow once who had thousands of pounds of work done on the engine of his Ford LTD (the mid-60s 7 litre saloon was a sleeper among the great crosscontinental fast touring cars) and then choked it back to less effective horsepower than standard at the rear wheels with a wretchedly (in my opinion) over the top silencer system. He paid all that money for a truly silent car because that is what he sincerely desired. Starved filaments on tube amps fall at about the same level of obsession, wouldn't you say? HTH. I am sure it has. Anyway, simple enough to try, I just wondered if you had any actual measurements to hand. If you are interested I will post my results. -- Nick |
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#62
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
I don't hang out here much, but interesting thread. I use DHT small
tubes a lot and have always run them slightly under ratings - reports are that this avoids microphonics. I haven't done any measurements so this is just anecdotal. Andy |
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#63
Posted to rec.audio.tubes
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Amps for long-distance listeners
Andre Jute wrote: Patrick Turner wrote: Andre Jute wrote: The Quad 405 Mk2 and the 34 control amp and their associated ESL-63 speakers are for an entirely different class of listener, the long- distance music lover. He doesn't want to be startled, he doesn't want his amp or his speakers to have personality, he wants the plain unadorned music given to him straight up, just the window on the concert hall and send the trimmings to some "audiophile" eejit who substitutes money and possessions for confidence. So that's what I was listening to when I last heard a pair of ESL63 with ARC amps and reasonable CD player. It might have been if you also had Quad amps to partner the ESL-63. As it was, you heard the signature of the ARC amp because Quad's ESL-63 is the second-most neutral speaker in the world, after its elder sister the ESL (aka ESL-57). Gee, when I last measured a '57, a few weeks back, apparently in good working order, ideally positioned, it was anything but flat at 3.5M away; rather like having a built in loudness contour. No wonder ppl like the "detail". I prefered my own dymamics, which do measure much flatter, and with much extended bass. But one cannot judge all ESL57 on just one old tired sample that has never been restored.....so I am told by a client who runs two ESL57 stackes with 3 speakers per stack. He uses one of my 8585 amps and says the sound is quite marvellous. The 3 pairs of '57 have been carefully all re-membraned by John Hall of Melbourne. Funny thing though, we prefered vinyl on that day from a very plain MM cart... What do you expect from a bunch bolshie brickies and other brucie yuppies? Democracy has a lot to answer for. Yup, ah gess ahem a bolshie brickie. But me mate's name is Gary, not Bruce Yuppie..... It is a setup you can listen to for 16 hours straight -- I often do when I'm on a roll with one of my books -- and never have it intrude on your space. I try to make my tube amps that neutral because it is clear to me that a tube amp that stuns you will also soon tire you. Well, I tire of the big wide brassy sound of the '63s and prefer my own dynamics. Your finger must have slipped, Patrick, or perhaps you're testing whether I am awake. Even you can't be so deaf as to consider that the ESL-63 has a "big wide brassy sound". Both myself and friend who listened with great expectations of the famous marque thought the whole experience was too "toppy", to the point of being edgy. The sound stage was impressive, the guy had matching subwoofers, but when we left, and returned to my place, we breathed a sigh of relief with my dynamics. Maybe it was just level, but I have heard the same toppy phenomena from some dynamics that have a suck out or broad null in the response of say -6dB from about 130Hz to 500Hz. I measured another guy's system just the other day and got this kind of effect. I have been to a live event at a local large hall where a 35 strong RAAF band played and augmented with some strings, and that sound was in fact as brassy as you'd ever expect, but acceptable and natural, and darn loud, with the usual military tunes played with panache. If only sound systems could do the same if asked to. I have faith, and so much faith I am building an ESL kit for a client Well, I hope you haven't told your client you will give him a "big wide brassy sound" because you won't, not unless he has a room like a stadium with another of similar size backing it, and is willing to let you break out the wall in between and install an absolute wall of a Bessel array of ESL. The client has an average sized room, but no wife, so he can place speakers where he wants. We are looking for accurate sound; something better than his Vienna Acoustic Motzarts. Its really just an exercize. If it turns out to be a vain exercize, it won't be because we didn't give it our best shot. Hopefully, I can add a page about it all at my website when I am done. But if it turns out a lemon, there won't be a page.... I've stacked eight (8) ESL-63 and there as no "big wide brassy sound"; in fact, the sound became more refined because the bass reinforcement allowed us to turn the volume down and listen at a lower level for the same perceived effect. Indeed that's what you should get. More bass than with one speaker as well. The client with 3 stacked says all this. He would not be using more volume than he ever did with just two speakers. So the speakers have it easy, and are cruising, never struggling. And the amp is untroubled.. http://www.turneraudio.com.au/8585-a...ober-2006.html It has KT90 in it at present. You just prefer dynamics because you have accustomed your ears to their dirty bass; electrostats have clean bass and enough of it if you stack enough panels. You have not heard the bass my speakers provide; anything but dirty. Everyone who listens remarks how good it is. Its not peaked up at 70Hz like so many designs are where they have tried to use too small a box, ie, the bean counter said no to the woodwork. A great number of speakers start out as an idea in a nice guys head, but by the time the design has been eaten and ****ted out by the accountant, then mauled in its implementation in the factory, what you do get is dirty bass with some speakers. Not with mine though. It sound natural, well integrated, and there isn't any need for a sub; response is a genuine 20Hz to 250Hz from the bass units with all reactive effects from reflexing well below 50Hz, and close to Fs, and drivers were chosen to give a flat response for where the box volume = VAS, and Fb = Fs. Its a simple recipe for good bass. I have two systems here, one with 135L cabs plus 300mm Electrovoice units from 1974, and the modern units with Al coned SEAS 200mm drivers in 55L. A bean counter would say I have built speakers that send companies broke. He'd be right. I don't care. He'd say use 25L for the SEAS unit, but then its ****ed, eh! There is no bloated fake bass, not a hint of "carlifornia boom"; bass sounds edible, one wants to eat it. Guys with subs still say my bass units are better because of the integration. Indeed stacked ESL have more bass, and it should be clean and tight. There is a bigger radiating area. Patrick Turner. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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#64
Posted to rec.audio.tubes
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Where did all the tubies go?
Mark S wrote: "Andre Jute" wrote in message oups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Maybe another Alan Kimmel will come along and "discover" another mu stage... -- Andre Jute Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS |
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#65
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Nick Gorham wrote: Andre Jute wrote: Yeah, I see what you're getting at, Nick. Okay. Here's a summary of what I know from proof, with speculation beyond observation clearly separated. 1. Starved filaments works with DHT power tubes. At conservative starvation the effect is not huge. Ok. 2. It works with a 300B as the output tube in-circuit. The effect is to lower the already low third and higher harmonics probably proportionally to the reduction in filament voltage; I've always just worked with about ten per cent starvation, which is good for a measurable but slight decrease in third and higher harmonics; no change in second. I have never seen the adverse effect on distortion that you posit and don't expect to; I pay zero attention to thermionic doomsayers. (When fools derive all their self-importance from negativity then each one competes to be more negative than the next clown; vide the comedy act environmental "scientists" at the IPCC -- Impersonating Professional Clowns dot Com -- are putting on for our entertainment, trying to outshout each other by predicting ever more dire worldsplitting catastrophes when everyone can see things are getting better decade on decade.) Ok. 3. I have calculated and drawn a worst-case eliptical loadline for a 300B. I consequently don't share your belief that the starved fils effect in 300B can be reduced by an eliptical loadline. Maybe on a fundamentally less linear tube, but then the gain from starved fils will also be so much greater that the residual after the eliptical load takes its toll will be well worth having, and bigger absolutely than on 300B. Ah, this is interesting, so do you have the plate curves to hand of the 300b with starved fillaments? I guess you must have to have plotted the loadline. I wasn't suggesting that the effect of starved fils to the plate load lines would be reduced by reactive loads, but that the combination of the two may negate any advantage that Steve measured. 4. When you already have a really silent amp, whatever further margin of silence you gain by slightly desperate means like starved fils will be *marginal*. Whether you want it, and where you stop, is a matter of taste. On the T39 I had power to spare (the amp is intended for 101dB/ m horns) and therefore could afford the luxury of a small power loss for an even more advantageous distribution of harmonics. Of course, the many small margins add up and sometimes multiply together... Oh, I agree. I am all in favour of (and indulge in myself) obsessive noise reduction. 5. There is no magic bullet, only years of work. When the amp is built, it is a small soldering job for you to starve the fils and compare the measurements of the complete amp with all loads attached, including speakers, with those for unstarved fils. Let us know what you find. Personally, I no longer bother with meters much; my amps always work as the model I built in Excel predicts to within very small margins. I can and will see what a minor reduction in fillament voltage provides. I was in a shooting party once with a fellow once who had thousands of pounds of work done on the engine of his Ford LTD (the mid-60s 7 litre saloon was a sleeper among the great crosscontinental fast touring cars) and then choked it back to less effective horsepower than standard at the rear wheels with a wretchedly (in my opinion) over the top silencer system. He paid all that money for a truly silent car because that is what he sincerely desired. Starved filaments on tube amps fall at about the same level of obsession, wouldn't you say? HTH. I am sure it has. Anyway, simple enough to try, I just wondered if you had any actual measurements to hand. If you are interested I will post my results. -- Nick Not to hand, Nick, to mind. It is not that I'm refusing to share the data with you, it is that I can't find the file. I've started rehousing my CD collection and some data storage discs in the same type of books-of-sleeves got mixed up; you can imagine the foulup. -- Andre Jute |
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#66
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Andy Evans wrote: I don't hang out here much, but interesting thread. I use DHT small tubes a lot and have always run them slightly under ratings - reports are that this avoids microphonics. I haven't done any measurements so this is just anecdotal. Andy No, this isn't about running tubes generally underspec. Quite the opposite. You won't see any advantage from starved filament operation unless you've built a really good clean amp already, and the way to do that (short of oodles of NFB, of course) is to run it at high voltage with lots of current and then to load it up with a high impdance primary on the output transfomer. So the only spec that is under book value is the filament supply. But otherwise it is right in your backyard because starved filaments and those double digit tubes you love were born for each other. You might however discover that in order to achieve noticeable results you might have to starve the filaments to the point where the power loss becomes a limiting factor. Nick and I are talking about very conservatively starved filaments, say up to 10 per cent under spec, which costs virtually nothing. HTH. Gotta sleep. Andre Jute Our legislators managed to criminalize fox-hunting and smoking; when they will get off their collective fat backside and criminalize negative feedback? |
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#67
Posted to rec.audio.tubes
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Where did all the tubies go?
"Mark S" wrote in message ink.net... Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS Hi Mark. My findings are completely the opposite. There seems to be more interest now in tube audio than there has been for thirty years:-) But how much of this is reflected at the practical DIY level, I cannot say. I know, from speaking to a high end dealer, that there are a good number of people willing to invest say Euro 30 000 in a high-end sound system. These are people whose children have left the nest, and whose mortgages are paid, and to whom music is important. They seem to use/prefer a separate room for home theatre. One would expect more people to be active on RAT. Many have a good reason for staying away:-)) Some pics of your monoblocs would be of interest . Best regards Iain |
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#68
Posted to rec.audio.tubes
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Where did all the tubies go?
"flipper" wrote in message ... On Tue, 10 Apr 2007 22:16:56 GMT, "Mark S" wrote: "Andre Jute" wrote in message groups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS No offense intended but I think the premise is inapplicable. By that I mean, most hobbyists, regardless of the hobby, are not 'inventing' new technology. Agreed, but I think the initial excitement that was the 90's "tube rush" has diminished and leveled off now. Maybe all the people that have posted to RAT over the years are in fact posting other places now. I don't know. Hmmm. Mark |
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#69
Posted to rec.audio.tubes
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Where did all the tubies go?
"MarkS" wrote in message link.net... Agreed, but I think the initial excitement that was the 90's "tube rush" has diminished and leveled off now. Maybe all the people that have posted to RAT over the years are in fact posting other places now. I don't know. Hmmm. Mark Many are sadly now in the great listening room in the sky. Others can still be found on closed groups. Many of the oldies keep in touch by e-mail. |
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#70
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Andre Jute wrote:
I am sure it has. Anyway, simple enough to try, I just wondered if you had any actual measurements to hand. If you are interested I will post my results. -- Nick Not to hand, Nick, to mind. It is not that I'm refusing to share the data with you, it is that I can't find the file. I've started rehousing my CD collection and some data storage discs in the same type of books-of-sleeves got mixed up; you can imagine the foulup. -- Andre Jute Ok, I have had a play, I have tried to replicate the 300b conditions you suggest, EH Gold Grid 300b, 82ma, 435v. Using a 5k load into a resistive (dummy) load. 0.1W output. This is the spectra I get with the fill at 5.00v http://www.lurcher.org/~nick/audio/s...0bSpect500.pdf And this is the spectra I get with it at 4.80v http://www.lurcher.org/~nick/audio/s...0bSpect480.pdf I can't detect any difference at all. It is possible that the driver stage is swamping the results (ecc40 into 6n6p aikido), but as it is constant between the two tests, I would have thought any difference would have been visible. You mention a 11% difference, so that much would clearly have been seen I think. -- Nick |
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#71
Posted to rec.audio.tubes
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Where did all the tubies go?
On Apr 11, 2:28 am, flipper wrote:
On Tue, 10 Apr 2007 22:16:56 GMT, "Mark S" wrote: "Andre Jute" wrote in message roups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps athttp://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS No offense intended but I think the premise is inapplicable. By that I mean, most hobbyists, regardless of the hobby, are not 'inventing' new technology.- Hide quoted text - - Show quoted text - That is certainly true, but I think you are using the wrong word. As with cooking, there are few new recipes. Even fewer if one is limited to a specific ingredient, fewer still if that particular ingredient is of a specific nature, however delicious that nature might be. That does not limit inventiveness, the combinations and permutations of even a few ingredients or approaches can be both many and intriguing. But creative? Not really. I think you really mean "create" as in bring forth or grow something *new*. As compared to "invent" as in coming upon or finding some for the first time. Only Jute-McCoy is capable of bringing forth Athena fully armored from its fevered brow... its KISS amp is proof of that. The rest of us are required to actually labor in the vinyards with our few available grapes in the hopes of producing something that actually has the capacity to make music. But better working results of hard labor and careful thought than the stillborn creations from such brilliance. Peter Wieck Wyncote, PA |
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#72
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Nick Gorham wrote: Andre Jute wrote: [snip] Ok, I have had a play, I have tried to replicate the 300b conditions you suggest, EH Gold Grid 300b, 82ma, 435v. Using a 5k load into a resistive (dummy) load. 0.1W output. That's your first mistake. Consider a set of Ia-Eb-Eg curves with a loadline on them. Starved fils, Steve tells us, make the transfer function more constant. Since the curves are more nearly parallel and equidistant around the middle of the sheet than at the bottom, the mechanism of starved fils is to make the curves straigher and more parallel at the bottom. You're not going to measure much, or correctly, at a tenth of a watt i.e. with a small signal. In fact, assuming the resolution of your machinery is good enough to give a true result, I'm amazed at the size of your result, as I shall demonstrate in a moment. This is the spectra I get with the fill at 5.00v http://www.lurcher.org/~nick/audio/s...0bSpect500.pdf And this is the spectra I get with it at 4.80v http://www.lurcher.org/~nick/audio/s...0bSpect480.pdf I can't detect any difference at all. That's because you've not discriminated a lumped result yet. You got a huge result, given that you were working irrelevant fractions from quiescence in the flattest part of the transfer function. It is possible that the driver stage is swamping the results (ecc40 into 6n6p aikido), but as it is constant between the two tests, I would have thought any difference would have been visible. Nothing was swamped. You just haven't extracted the relevant information from your result. You mention a 11% difference, so that much would clearly have been seen I think. I would be very surprised if with a different amp you manage to duplicate Bill's result, furthermore rounded off and processed through my memory. Your result is, in the light of your method, already much, much larger. -- Nick Right, let's work the numbers you have. You measure 71 parts in 10k difference as a result of starved fils. Let's just for the sake of argument say that your instrument at this level has a hundred per cent level of confidence. We already know from Steve and Bill and my experience that starved fils hardly touch second harmonic distortion; it works mainly on third and higher orders. We also can posit that a good high voltage, high current, high load 300B amp might have total harmonic distortion split about 3 parts in a 100 to third and higher harmonics and the rest to second harmonic. Thus your 71 parts in 10k of difference in fact works on roundabout 3 per cent of the total distortion. So the actual change you measured, once you discriminate and define what the change relates to, could be as high as .00071 times 33 or about 2.36 per cent change in third and higher harmonics due to starved fils at your tenth of a watt measuring level. That's an amazing result, not least because the third and higher harmonics appear to have been *increased* by applying starved fils... I'd be interested to hear what you discover when you measure at a signal level high enough to reach the parts of the transfer function you actually want to measure. I did warn you that this business is trickier than might appear at a quick glance. HTH. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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#73
Posted to rec.audio.tubes
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Where did all the tubies go?
"flipper" wrote in message ... On Wed, 11 Apr 2007 10:34:26 GMT, "MarkS" wrote: "flipper" wrote in message . .. On Tue, 10 Apr 2007 22:16:56 GMT, "Mark S" wrote: "Andre Jute" wrote in message legroups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS No offense intended but I think the premise is inapplicable. By that I mean, most hobbyists, regardless of the hobby, are not 'inventing' new technology. Agreed, but I think the initial excitement that was the 90's "tube rush" has diminished and leveled off now. Because it was 'new' then and now it's getting 'old'? Hehe If true that would be a nice bit of irony, don't ya think? Maybe all the people that have posted to RAT over the years are in fact posting other places now. I don't know. Hmmm. Mark I don't know. I missed it when it was 'new'  Yeah, missed out on all the good stuff huh? |
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#74
Posted to rec.audio.tubes
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Where did all the tubies go?
"flipper" wrote in message ... On Thu, 12 Apr 2007 02:50:52 GMT, "MarkS" wrote: "flipper" wrote in message . .. On Wed, 11 Apr 2007 10:34:26 GMT, "MarkS" wrote: "flipper" wrote in message m... On Tue, 10 Apr 2007 22:16:56 GMT, "Mark S" wrote: "Andre Jute" wrote in message oglegroups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS No offense intended but I think the premise is inapplicable. By that I mean, most hobbyists, regardless of the hobby, are not 'inventing' new technology. Agreed, but I think the initial excitement that was the 90's "tube rush" has diminished and leveled off now. Because it was 'new' then and now it's getting 'old'? Hehe If true that would be a nice bit of irony, don't ya think? Maybe all the people that have posted to RAT over the years are in fact posting other places now. I don't know. Hmmm. Mark I don't know. I missed it when it was 'new' Yeah, missed out on all the good stuff huh? Now, why did you want to go and ruin it for me? I was happy before hearing there was 'good stuff' to have missed It's can still be pretty good. And there are clearly a healthy number of people still building tube projects. The only real difference is that most of them don't post to RAT anymo-(( Iain |
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#75
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Andre Jute wrote:
Nick Gorham wrote: Andre Jute wrote: [snip] Ok, I have had a play, I have tried to replicate the 300b conditions you suggest, EH Gold Grid 300b, 82ma, 435v. Using a 5k load into a resistive (dummy) load. 0.1W output. That's your first mistake. Consider a set of Ia-Eb-Eg curves with a loadline on them. Starved fils, Steve tells us, make the transfer function more constant. Since the curves are more nearly parallel and equidistant around the middle of the sheet than at the bottom, the mechanism of starved fils is to make the curves straigher and more parallel at the bottom. You're not going to measure much, or correctly, at a tenth of a watt i.e. with a small signal. In fact, assuming the resolution of your machinery is good enough to give a true result, I'm amazed at the size of your result, as I shall demonstrate in a moment. Well, I should point out that a curved line remains curved even if you look at a smaller part of it :-). But anyway, I decided to use the lower power in the test mainly because you have repeatedly mentioned that you use 100dB/W/m speakers, so I thought it would be closer to the conditions you actually use. I can repeat tonight at higher levels. I would be very surprised if with a different amp you manage to duplicate Bill's result, furthermore rounded off and processed through my memory. Your result is, in the light of your method, already much, much larger. We shall see, I personally think you are in the realm of noise by taking (as I assume you have) the gross THD figure and subtracting a nominal 2nd harmonic part. I would have expeceted a change in the tail of higher order harmonics. Steve used reductions in voltage in the order of 40% to get his reductions, I can't help thinking that running a 300b at 3v would not help us. I will post some more results later. You mention earlier that you normally us a 10% reduction in voltage, why does the KISS amp only use a smaller reduction? I guess the original question I am still asking, is given "Steve doesn't say that the effect of starved filaments doesn't work in power tubes, he says it is more difficult to reap the benefits with a power tube. That's just a practical problem to be solved, not an exclusion in physics." I still don't see just how this problem is "solved" in the KISS design. All it seems to have is a reduced fil voltage, I can't see any other process in place to "solve" the problem. Of course the converse of this is also potentially true and helpful, if by running a 300b at 4.8v there is no difference to its operations, it means running tham at 4.9v might make them last longer and make no difference to the end result :-). -- Nick |
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#76
Posted to rec.audio.tubes
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Where did all the tubies go?
"flipper" wrote in message ... On Thu, 12 Apr 2007 02:50:52 GMT, "MarkS" wrote: "flipper" wrote in message . .. On Wed, 11 Apr 2007 10:34:26 GMT, "MarkS" wrote: "flipper" wrote in message m... On Tue, 10 Apr 2007 22:16:56 GMT, "Mark S" wrote: "Andre Jute" wrote in message oglegroups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS No offense intended but I think the premise is inapplicable. By that I mean, most hobbyists, regardless of the hobby, are not 'inventing' new technology. Agreed, but I think the initial excitement that was the 90's "tube rush" has diminished and leveled off now. Because it was 'new' then and now it's getting 'old'? Hehe If true that would be a nice bit of irony, don't ya think? Maybe all the people that have posted to RAT over the years are in fact posting other places now. I don't know. Hmmm. Mark I don't know. I missed it when it was 'new' Yeah, missed out on all the good stuff huh? Now, why did you want to go and ruin it for me? I was happy before hearing there was 'good stuff' to have missed Yeah, I 'member the good old days, oh 10 years ago, when guys were makin' tube amps out of old toasters and them boys knew what hey were doin'! 8) M |
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#77
Posted to rec.audio.tubes
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Where did all the tubies go?
"Iain Churches" wrote in message . fi... "flipper" wrote in message ... On Thu, 12 Apr 2007 02:50:52 GMT, "MarkS" wrote: "flipper" wrote in message ... On Wed, 11 Apr 2007 10:34:26 GMT, "MarkS" wrote: "flipper" wrote in message om... On Tue, 10 Apr 2007 22:16:56 GMT, "Mark S" wrote: "Andre Jute" wrote in message ooglegroups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS No offense intended but I think the premise is inapplicable. By that I mean, most hobbyists, regardless of the hobby, are not 'inventing' new technology. Agreed, but I think the initial excitement that was the 90's "tube rush" has diminished and leveled off now. Because it was 'new' then and now it's getting 'old'? Hehe If true that would be a nice bit of irony, don't ya think? Maybe all the people that have posted to RAT over the years are in fact posting other places now. I don't know. Hmmm. Mark I don't know. I missed it when it was 'new' Yeah, missed out on all the good stuff huh? Now, why did you want to go and ruin it for me? I was happy before hearing there was 'good stuff' to have missed It's can still be pretty good. And there are clearly a healthy number of people still building tube projects. The only real difference is that most of them don't post to RAT anymo-(( Iain Iain, I cruise through audio asylum from time to time; what are some other sites to try out? Best Regards, Mark |
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#78
Posted to rec.audio.tubes,uk.rec.audio
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Starved filaments
Nick Gorham wrote:
Andre Jute wrote: Nick Gorham wrote: Andre Jute wrote: [snip] Ok, I have had a play, I have tried to replicate the 300b conditions you suggest, EH Gold Grid 300b, 82ma, 435v. Using a 5k load into a resistive (dummy) load. 0.1W output. That's your first mistake. Consider a set of Ia-Eb-Eg curves with a loadline on them. Starved fils, Steve tells us, make the transfer function more constant. Since the curves are more nearly parallel and equidistant around the middle of the sheet than at the bottom, the mechanism of starved fils is to make the curves straigher and more parallel at the bottom. You're not going to measure much, or correctly, at a tenth of a watt i.e. with a small signal. In fact, assuming the resolution of your machinery is good enough to give a true result, I'm amazed at the size of your result, as I shall demonstrate in a moment. Ok, same thing, repeated this time at 2w output, same conditions as before. Here is 5v fil http://www.lurcher.org/~nick/audio/s...0bSpect500.pdf Here is 4.8v fil http://www.lurcher.org/~nick/audio/s...0bSpect480.pdf And to use the 10% reduction mentioned, here is 4.5v http://www.lurcher.org/~nick/audio/s...0bSpect450.pdf Sadly, again, there seems to be no magic bullet in reduction of harmonics higher or not. One interesting thing is the 4.5v fil gave a small increase in output, but I am not at this moment sure if thats of any real import. Anyhow, nothing like the sort of changes Steve reported when not used in a power stage. -- Nick |
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#79
Posted to rec.audio.tubes
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Where did all the tubies go?
Andre Jute wrote: robert casey wrote: Yech! Gotta be tough to play in this sandbox.... That's my point. It is a disgrace that RAT is now more of an obstacle course for real tubies than a facilitating mechanism. Yet you did nothing to help facilitate west by contributing to the question he asked. Graham |
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#80
Posted to rec.audio.tubes
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Where did all the tubies go?
"MarkS" wrote in message nk.net... "Iain Churches" wrote in message . fi... "flipper" wrote in message ... On Thu, 12 Apr 2007 02:50:52 GMT, "MarkS" wrote: "flipper" wrote in message m... On Wed, 11 Apr 2007 10:34:26 GMT, "MarkS" wrote: "flipper" wrote in message news:invo13l18v8cebm2e780le4h67r6k8hlbr@4ax. com... On Tue, 10 Apr 2007 22:16:56 GMT, "Mark S" wrote: "Andre Jute" wrote in message news:1176043738.484704.164000@d57g2000hsg. googlegroups.com... Andy Evans is right. There used to be real tube talk on RAT. Now there's a bunch of tacky radio restorers and fools with a dire self- image shortfall. Yech! I go away for a couple of weeks to do bike electronics and return to find hardly anything worth reading and only one intelligent question -- from West -- worth answering. The same people are still beating internal NFB in triodes to death with pinpricks. Sheesh, fellers, either you believe the observable anomalies in triode results is caused by invisible NFB, or you conclude that pentodes are naturally, permanently and irredeemably (nice word on Easter Sunday) inferior. But neither party will convince the other. What a waste of time. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review Maybe the tube hobby has reached sort of an equilibrium in application of available knowledge. Got to admit, alot of the threads do seem to tread over previously traveled roads. The golden age rebirth is most certainly behind us now. Or maybe the latest Dolby 756456.2 home theater systems with ten cajillion speakers are picking off our numbers left and right. Or maybe not 8) My new mono blocks are coming along nicely, but I know what to do and there isn't much new to talk about within the design. MarkS No offense intended but I think the premise is inapplicable. By that I mean, most hobbyists, regardless of the hobby, are not 'inventing' new technology. Agreed, but I think the initial excitement that was the 90's "tube rush" has diminished and leveled off now. Because it was 'new' then and now it's getting 'old'? Hehe If true that would be a nice bit of irony, don't ya think? Maybe all the people that have posted to RAT over the years are in fact posting other places now. I don't know. Hmmm. Mark I don't know. I missed it when it was 'new' Yeah, missed out on all the good stuff huh? Now, why did you want to go and ruin it for me? I was happy before hearing there was 'good stuff' to have missed It's can still be pretty good. And there are clearly a healthy number of people still building tube projects. The only real difference is that most of them don't post to RAT anymo-(( Iain Iain, I cruise through audio asylum from time to time; what are some other sites to try out? If tube audio is your interest, RAT is as good as it gets on Usenet. You cannot access closed groups via Usenet. They are usually hosted by a university or other body. You need to be proposed and seconded even to get read-only status. Best regards Iain |
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