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#1
Posted to rec.audio.tubes
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KT120 from New Sensor, bargain or rip off?
I see New Sensor is putting out Tungsol KT120 tubes whch bias like
KT88 but have Pda = 60W. I read a few forums comments and I guys are happy with the new tubes. BUT, they will cost a bomb. About twice the price of a 6550. And when I saw the anode curves for the KT120 it was all horrible to look at. But then these curves had quite irregular shapes to part of them and look like they were drawn up by someome who does not know what they are doing. Plus the voltage range over which the tubes were tested to get the curves did not extend to the max Ea and max Eg2 which are both +650Vdc. So I whoever made the tests and drew the pictures does not have a very good test set or the experience of those genuine people of the 1960s who spent their lives testing tubes. The new tube seems aimed at guitar people who like rugged tubes and where the distortion does not matter; in fact the more THD the better as long as nothing clips. The KT120 looks like the the insides simply have a 35% taller plate structure and taller bottle than a KT88. So with a taller plate there is more area to get rid of heat hence the improved Pda. But what about the rigidity of the longer cathode tube and the alignment of grid to cathode spacing? With extra length there must be more tendency for the hot structure to bend or sway with disatrous results. The Electro Harmonix KT90 had Pda of 55W and looks just like a KT88/6550 but with taller plate but straight sided glass, like an EL34 which has been fed steroids for a year. Initially, the KT90 were a reasonable buy because the price wanted was only a bit more than a 6550. But that seemed to change. Seems to me New Sensor is again "stretching" the KT 88 upwards even more than they did with KT90. But if a 6550/KT88 is $30, then when stretched upwards, it should only cost for the extension in height of 35% so $40.50, not $70 being talked about. Two KT88,6550 will cost less than one KT120 and the Pda of the two KT88/6550 = 84W, and so a quad of KT88/6550 are going to beat the pants of a pair of KT120. But for those that must have the latest gizmo, you know where to go to spend up. But don't expect any more power or fidelity than you are getting now with KT88/6550. The curves I could see do not indicate any more anode voltage swing is available if you just switch to KT120. Are the curves as good as for the NOS KT88? I don't think so. Many makers are already pushing their luck by running 6550 with Ea too high and RL too low. There seems to be an absurd trend where there is never enough power, even with so called hi-fi amps they are set up in nearly all class B working with low load and high Ea to get the sales figures and to hell with the idea that for hi-fi about 50W max is all that should be ever asked from a pair of KT88/6550. I found the Sovtek small bottle 6550 and KT88 were excellent value for the price. The guts of these didn't change when the bottle size increased for the Electro Harmonix name range. OK, It was all a marketting ploy eh, to get away from the old association of Sovtek and the evil empire of the Soviets and USSR. I wonder how Mike mathews is getting on with the Russian Mafia boyos who tried to put the squeeze on him for a rouble or three. Maybe Mike needs the money, but then we could all say that. Patrick Turner. |
#2
Posted to rec.audio.tubes
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KT120 from New Sensor, bargain or rip off?
Patrick Turner wrote:
I see New Sensor is putting out Tungsol KT120 tubes whch bias like KT88 but have Pda = 60W. I read a few forums comments and I guys are happy with the new tubes. BUT, they will cost a bomb. About twice the price of a 6550. And when I saw the anode curves for the KT120 it was all horrible to look at. But then these curves had quite irregular shapes to part of them and look like they were drawn up by someome who does not know what they are doing. Plus the voltage range over which the tubes were tested to get the curves did not extend to the max Ea and max Eg2 which are both +650Vdc. So I whoever made the tests and drew the pictures does not have a very good test set or the experience of those genuine people of the 1960s who spent their lives testing tubes. Or has a better test set and/or greater knowledge. Or knows how to test but falls short of the standards set in the 60s for genuinely fiddling the results. The new tube seems aimed at guitar people who like rugged tubes and where the distortion does not matter; in fact the more THD the better as long as nothing clips. Er, not quite. If distortion were the only objective they would use transistors. The KT120 looks like the the insides simply have a 35% taller plate structure and taller bottle than a KT88. So with a taller plate there is more area to get rid of heat hence the improved Pda. But what about the rigidity of the longer cathode tube and the alignment of grid to cathode spacing? With extra length there must be more tendency for the hot structure to bend or sway with disatrous results. Just what I thought. There are quite a few modes of vibration...side to side, up and down, and rotation about three axis, each for lots of bits relative to lots of other bits, etc. etc. All in all, however, we have the impression that long thin things, including "pin ended" beams like bridges or joists, are weak or floppy. If they compensate by making the grid support rods thicker, they risk changing the characteristics of the valve perhaps. Maybe they use modern material to make stiffer thin structures despite the change in aspect ratio. Or maybe they just make everything longer and hope they recoup the investment before anyone notices they sound bad and fall apart in no time. The Electro Harmonix KT90 had Pda of 55W and looks just like a KT88/6550 but with taller plate but straight sided glass, like an EL34 which has been fed steroids for a year. Initially, the KT90 were a reasonable buy because the price wanted was only a bit more than a 6550. But that seemed to change. Seems to me New Sensor is again "stretching" the KT 88 upwards even more than they did with KT90. But if a 6550/KT88 is $30, then when stretched upwards, it should only cost for the extension in height of 35% so $40.50, not $70 being talked about. Ah, but not if they've actually solved the problem of retaining stiffness. Maybe they've used an exotic titanium/carbon nano-tube composite for the grid support rods, so they're twice as stiff and half the weight. Or they just put the price up because there are fewer rich people now, but each of them has more money. Two KT88,6550 will cost less than one KT120 and the Pda of the two KT88/6550 = 84W, and so a quad of KT88/6550 are going to beat the pants of a pair of KT120. As would a hundred EF96. But you need to include the cost of extra bases, wiring, bias provision, heater current, chassis work, and the general perception that fewer, bigger valves are better. But for those that must have the latest gizmo, you know where to go to spend up. But don't expect any more power or fidelity than you are getting now with KT88/6550. The curves I could see do not indicate any more anode voltage swing is available if you just switch to KT120. Are the curves as good as for the NOS KT88? I don't think so. Many makers are already pushing their luck by running 6550 with Ea too high and RL too low. There seems to be an absurd trend where there is never enough power, even with so called hi-fi amps they are set up in nearly all class B working with low load and high Ea to get the sales figures and to hell with the idea that for hi-fi about 50W max is all that should be ever asked from a pair of KT88/6550. Something to do with modern speakers in big rooms maybe. The room size of the average audiophool is much bigger now. I found the Sovtek small bottle 6550 and KT88 were excellent value for the price. The guts of these didn't change when the bottle size increased for the Electro Harmonix name range. OK, It was all a marketting ploy eh, to get away from the old association of Sovtek and the evil empire of the Soviets and USSR. I wonder how Mike mathews is getting on with the Russian Mafia boyos who tried to put the squeeze on him for a rouble or three. Maybe Mike needs the money, but then we could all say that. Erm, logic has never been you're strong point. Why wait for the collapse of the "evil empire" before changing the name? The Soviet Union, and several of its dominions, had a reputation for the mass production of primitive but famously tough and serviceable engineered goods, such as tanks, rockets, planes, cameras, machine tools, and valves. "Soviet" was a very successful fashionware label here. It had a kind of heroic ring to it. They did, after all, win the war against Fascism. Incidentally, the UK's new Conservative government is pushing the idea of soviets to replace parts of local councils, but they don't use the word, obviously. For example, they reckon they can get parents' commitees to set up schools. It would be cheaper if it worked, but naturally it won't, and in some of the more sordid suburbs, the results wouldn't be what we might hope for anyway. I guess the idea is just one of many imaginative ways they are finding to blame the poor for the **** we're in. It's a lot easier to take £1 from 60 million people than it is to take £60m off one rich *******. Meanwhile, since I'm digressing, that's my pension washing up on Florida beaches. Perhaps we should all call it a day and make digital stuff instead. You argue that energy profligacy is OK because there aren't many valve amps in the world, but that's a typical capitalist fat cat argument if ever there was one. By the same token, they'll be able to keep their useless powerboats and private jets when the proletariat are forced to ride bicycles to save the planet. Except we can't make digital stuff, because the active bits are so small we can hardly see them and certainly can't solder them. Shame coz, being so short, I guess they're pretty stiff. All in all, if you're wondering where valve technology is going, the answer is clear. Nowhere. Ian |
#3
Posted to rec.audio.tubes
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KT120 from New Sensor, bargain or rip off?
On Jun 13, 12:29*pm, "Ian Iveson"
wrote: Patrick Turner wrote: I see New Sensor is putting out Tungsol KT120 tubes whch bias like KT88 but have Pda = 60W. I read a few forums comments and I guys are happy with the new tubes. BUT, they will cost a bomb. About twice the price of a 6550. And when I saw the anode curves for the KT120 it was all horrible to look at. But then these curves had quite irregular shapes to part of them and look like they were drawn up by someome who does not know what they are doing. Plus the voltage range over which the tubes were tested to get the curves did not extend to the max Ea and max Eg2 which are both +650Vdc. So I whoever made the tests and drew the pictures does not have a very good test set or the experience of those genuine people of the 1960s who spent their lives testing tubes. Or has a better test set and/or greater knowledge. Or knows how to test but falls short of the standards set in the 60s for genuinely fiddling the results. Nobody in the tube making industry invests enough money on quality control and data preparation. There are reasons of course; probably because there isn't the volume there once was, and all the old testing labs were junked when transistors came in. The new tube seems aimed at guitar people who like rugged tubes and where the distortion does not matter; in fact the more THD the better as long as nothing clips. Er, not quite. If distortion were the only objective they would use transistors. The musos regularly drive their amps well into class C. This happens when the coupling caps stay charged up with grid current effects. The amp makes a basic square wave. The speaker does the rest to give you that driving sound so liked by the rockers and rollers. But well before the point and up to clipping on sine waves the distortion of tubes is cherished because it is so much better sounding than bjts. So distortion that occurs in beam tetrodes can be quite high level or low level and it all sounds better than bjts. So if the new ball tearing KT120 make a bit more THD than a pair of KT88s at 10 watts it won't matter. The KT120 looks like the the insides simply have a 35% taller plate structure and taller bottle than a KT88. So with a taller plate there is more area to get rid of heat hence the improved Pda. But what about the rigidity of the longer cathode tube and the alignment of grid to cathode spacing? With extra length there must be more tendency for the hot structure to bend or sway with disatrous results. Just what I thought. There are quite a few modes of vibration...side to side, up and down, and rotation about three axis, each for lots of bits relative to lots of other bits, etc. etc. All in all, however, we have the impression that long thin things, including "pin ended" beams like bridges or joists, are weak or floppy. If they compensate by making the grid support rods thicker, they risk changing the characteristics of the valve perhaps. Maybe they use modern material to make stiffer thin structures despite the change in aspect ratio. Or maybe they just make everything longer and hope they recoup the investment before anyone notices they sound bad and fall apart in no time. In the old days they tested things arduously for months on end or years to see how things failed. This was done BEFORE launching a product on the market. I doubt we will ever see honest reports about tests Mike Mathews has conducted on KT120. The Electro Harmonix KT90 had Pda of 55W and looks just like a KT88/6550 but with taller plate but straight sided glass, like an EL34 which has been fed steroids for a year. Initially, the KT90 were a reasonable buy because the price wanted was only a bit more than a 6550. But that seemed to change. Seems to me New Sensor is again "stretching" the KT 88 upwards even more than they did with KT90. But if a 6550/KT88 is $30, then when stretched upwards, it should only cost for the extension in height of 35% so $40.50, not $70 being talked about. Ah, but not if they've actually solved the problem of retaining stiffness. Maybe they've used an exotic titanium/carbon nano-tube composite for the grid support rods, so they're twice as stiff and half the weight. Or they just put the price up because there are fewer rich people now, but each of them has more money. I agree that the longer something is made with respect to its width, the more likely you will get unwanted bending especially if it is metal and its at 300C of higher. I would have though the GFC would have dampened down tube sales. Hell, maybe the tube makers are having a hard time, so they need to think of something new..... Two KT88,6550 will cost less than one KT120 and the Pda of the two KT88/6550 = 84W, and so a quad of KT88/6550 are going to beat the pants of a pair of KT120. As would a hundred EF96. But you need to include the cost of extra bases, wiring, bias provision, heater current, chassis work, and the general perception that fewer, bigger valves are better. If I were to make a 100W amp I can put in a pair of EL34 with RLa-a 12k, Ea = 900Vdc, and Eg2 = 400V and flog the damn things to death. Before they die they teeter on the edge of bias failure and arcing sockets. Same goes for using a pair of KT88/6550. Its a bit dodgy. And this amount of power can only come with high THD with the near class B working. To get right away from such garbological thinking and doing, I never build crap like everyone else. I will use a cheap six pack of EL34 to make the 100W or a quad of KT88/6550/KT90. The majority of the cost is NEVER in the extra 2 tube sockets and output tubes but in the transformers and rugged chassis to carry the weight needed for 100W. I hapen to think that a six pack of EL34 with Ea at a relaxed 440V max is fine. Its easy to get the first 30W in pure class A with very little THD. If one want so get 100W even with just a pair of KT120, and you plan to run them at Ea = 600V, then Pda would not want to be more than 30W per tube if it was a hi-fi amp and maybe only 20W if in a guitar amp. If you do your sums the amount of class A into the load one needs to get 100W in class AB is tiny. The musos don't mind the distortion. I most certainly do mind the distortion. So if KT120 were any good, then I'd sure like to use them because you coud probably run a pair at Ea 400V and 90mA safely for 36W Pda so that the class max available would be 30W from the total Pda of 72W from the pair. In class A SE amps I have made the efficiency is up to 45%. The SE35 I made with 4 x 6CA7/EL34 has each output idling along with Pda = 21 W. I made amps last year with 6 x 6550 in SE mode for 60W. Pda was 24W per tube. The use of KT120 would not mean I could have 3 tubes instead of 6 x 6550. And if I was able to use 3 tubes instead of 6 for 60W of class A then I'd expect the price to be the same: ie, the cost of the KT120 not more than twice the price of a 6550. But if the KT120 has only 30% more bang for the buck then I doubt I'll ever buy any. I do quite like the KT90EH. But gees, its expensive, and not much more bang for buck, so I have only ever bought any when a client asked me to because he'd read somewhere that they gave better bass. I have no reson to believe he was right. But I just do what people ask me to. In hifi amps the extra power one might get by changing from KT88/6550 to KT120 may be tiny because of the loading. The KT120 curves don't tell me there is some magical source of heaps more power which justifies their purchase. BTW, should anyone like to make a class Ab2 amp with Ea at 800V, they could do worse than use TT21 which are KT88 internally but with anode top caps to prevent arcing, 140W can be had this way. I'm not interested though. My next large project is a pair of monblocks with one pair of PP 13E1. Although just one pair is capable of 250W, I will only want 85W max with lots of class A. These tubes are unlikely to ever be made again but they are far more rugged than any KT88, KT90, or KT120 could ever be. At the time when th 13E1 was developed ppl wanted something capable of high Pda per tube and no high voltages. Industry had many uses for such gut busting tubes. When you look at the 13E1, it is so much more rugged than anything else in Octal land. It has two cathodes, massive anode. They last very well even when spending many years running at Pda = 75W. Another great beam tetrode of that era was the QE208A with a pair of carbon anodes on rods each side of 3 cathodes. Tubes like 13E1 allowed high power at low voltages that would otherwise needed things like 813........ Hopefully the KT120 actually does have much better TRIODE curves than the ones I have so far seen seem to indicate. If so then they should be good for hi-fi even if like most beam tetrodes and pentodes they are not very linear in beam tet or pentode mode. Patrick Turner. But for those that must have the latest gizmo, you know where to go to spend up. But don't expect any more power or fidelity than you are getting now with KT88/6550. The curves I could see do not indicate any more anode voltage swing is available if you just switch to KT120. Are the curves as good as for the NOS KT88? I don't think so. Many makers are already pushing their luck by running 6550 with Ea too high and RL too low. There seems to be an absurd trend where there is never enough power, even with so called hi-fi amps they are set up in nearly all class B working with low load and high Ea to get the sales figures and to hell with the idea that for hi-fi about 50W max is all that should be ever asked from a pair of KT88/6550. Something to do with modern speakers in big rooms maybe. The room size of the average audiophool is much bigger now. I found the Sovtek small bottle 6550 and KT88 were excellent value for the price. The guts of these didn't change when the bottle size increased for the Electro Harmonix name range. OK, It was all a marketting ploy eh, to get away from the old association of Sovtek and the evil empire of the Soviets and USSR. I wonder how Mike mathews is getting on with the Russian Mafia boyos who tried to put the squeeze on him for a rouble or three. Maybe Mike needs the money, but then we could all say that. Erm, logic has never been you're strong point. Why wait for the collapse of the "evil empire" before changing the name? The Soviet Union, and several of its dominions, had a reputation for the mass production of primitive but famously tough and serviceable engineered goods, such as tanks, rockets, planes, cameras, machine tools, and valves. "Soviet" was a very successful fashionware label here. It had a kind of heroic ring to it. They did, after all, win the war against Fascism. Incidentally, the UK's new Conservative government is pushing the idea of soviets to replace parts of local councils, but they don't use the word, obviously. For example, they reckon they can get parents' commitees to set up schools. It would be cheaper if it worked, but naturally it won't, and in some of the more sordid suburbs, the results wouldn't be what we might hope for anyway. I guess the idea is just one of many imaginative ways they are finding to blame the poor for the **** we're in. It's a lot easier to take £1 from 60 million people than it is to take £60m off one rich *******. Meanwhile, since I'm digressing, that's my pension washing up on Florida beaches. Perhaps we should all call it a day and make digital stuff instead. You argue that energy profligacy is OK because there aren't many valve amps in the world, but that's a typical capitalist fat cat argument if ever there was one. By the same token, they'll be able to keep their useless powerboats and private jets when the proletariat are forced to ride bicycles to save the planet. Except we can't make digital stuff, because the active bits are so small we can hardly see them and certainly can't solder them. Shame coz, being so short, I guess they're pretty stiff. All in all, if you're wondering where valve technology is going, the answer is clear. Nowhere. Ian- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - |
#4
Posted to rec.audio.tubes
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KT120 from New Sensor, bargain or rip off?
There seems to be an absurd trend where there is never enough power, even with so called hi-fi amps they are set up in nearly all class B working with low load and high Ea to get the sales figures and to hell with the idea that for hi-fi about 50W max is all that should be ever asked from a pair of KT88/6550. Something to do with modern speakers in big rooms maybe. The room size of the average audiophool is much bigger now. I forgot to answer the rest of your post. Yep, houses are getting bigger an dspeakers are getting less sensitive. I found the Sovtek small bottle 6550 and KT88 were excellent value for the price. The guts of these didn't change when the bottle size increased for the Electro Harmonix name range. OK, It was all a marketting ploy eh, to get away from the old association of Sovtek and the evil empire of the Soviets and USSR. I wonder how Mike mathews is getting on with the Russian Mafia boyos who tried to put the squeeze on him for a rouble or three. Maybe Mike needs the money, but then we could all say that. Erm, logic has never been you're strong point. Why wait for the collapse of the "evil empire" before changing the name? The Soviet Union, and several of its dominions, had a reputation for the mass production of primitive but famously tough and serviceable engineered goods, such as tanks, rockets, planes, cameras, machine tools, and valves. Yeah, remember the Paris Air Show in 1972? I recall the Russian copy of Concorde fell out of the sky. Then there was Chernoble in 1986. The Soviet era was remarkable for huge amount of clunker junk it made so very inefficiently and at huge cost to environments. But the West wasn't much further ahead in refinements though. A book I have was written in the USA about 1961 about reliability of electronics in the US armed forces. If we had had a world war in 1961, we could onlt have ever had 1/3 of a war because so much electronics just didn't work well. Think of the benefits. We all would have been onlt 1/3 dead, wonderful, really. "Soviet" was a very successful fashionware label here. It had a kind of heroic ring to it. They did, after all, win the war against Fascism. Indeed. Some ******* had to do the real dirty work. Sure wasn't gonna be us. Incidentally, the UK's new Conservative government is pushing the idea of soviets to replace parts of local councils, but they don't use the word, obviously. For example, they reckon they can get parents' commitees to set up schools. It would be cheaper if it worked, but naturally it won't, and in some of the more sordid suburbs, the results wouldn't be what we might hope for anyway. I guess the idea is just one of many imaginative ways they are finding to blame the poor for the **** we're in. It's a lot easier to take £1 from 60 million people than it is to take £60m off one rich *******. Yeah, but Europe's in a mess right. Debts all over and everyone wanting to live like kings but nobody can pay for that. Instead everyone in Europe has to be his or her own servant. Meanwhile, since I'm digressing, that's my pension washing up on Florida beaches. Its OK, once they drain the water out of the Gulf there abd fill it with oil they'll be plenty oil for all. Perhaps we should all call it a day and make digital stuff instead. You argue that energy profligacy is OK because there aren't many valve amps in the world, but that's a typical capitalist fat cat argument if ever there was one. By the same token, they'll be able to keep their useless powerboats and private jets when the proletariat are forced to ride bicycles to save the planet. Well, I figure tube amps should be allowed like having a few old sailing ships and steam trains. The % of tube amps is tiny compared to all other types that are much more efficient. Old people should be allowed to live until they get old. We could instead just shoot everyone who didn't work, or who got old. Maybe shoot everyone who isn't enviromentally correct, or politically correct for that matter, or sick, or mentally retarded. Let's just shoot each other more often. It does the world a favour to get rid of people if they won't get rid of their bad habits. But Hitler tried a few things such as Drastic Change, and he didn't get far. So did Stalin and Mao. Now we prefer to just consume the planet bare of anything worth saving. Except we can't make digital stuff, because the active bits are so small we can hardly see them and certainly can't solder them. Shame coz, being so short, I guess they're pretty stiff. All in all, if you're wondering where valve technology is going, the answer is clear. Nowhere. Its going in plenty of directions. I'm getting old and I don't have to put on the agony and put on the style. Following, and aiding and abetting the relentless arrow of Progress won't make me feel better or get me a good ****. There are huge changes slowly unfolding on our planet due technology. Most are bypassing me. So I don't need to have a fixed bias against change. Patrick Turner. Ian- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - |
#5
Posted to rec.audio.tubes
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KT120 from New Sensor, bargain or rip off?
On Jun 12, 11:26*am, Patrick Turner wrote:
I see New Sensor is putting out Tungsol KT120 tubes whch bias like KT88 but have Pda = 60W. I read a few forums comments and I guys are happy with the new tubes. BUT, they will cost a bomb. About twice the price of a 6550. And when I saw the anode curves for the KT120 it was all horrible to look at. But then these curves had quite irregular shapes to part of them and look like they were drawn up by someome who does not know what they are doing. Plus the voltage range over which the tubes were tested to get the curves did not extend to the max Ea and max Eg2 which are both +650Vdc. So I whoever made the tests and drew the pictures does not have a very good test set or the experience of those genuine people of the 1960s who spent their lives testing tubes. The new tube seems aimed at guitar people who like rugged tubes and where the distortion does not matter; in fact the more THD the better as long as nothing clips. The KT120 looks like the the insides simply have a 35% taller plate structure and taller bottle than a KT88. So with a taller plate there is more area to get rid of heat hence the improved Pda. But what about the rigidity of the longer cathode tube and the alignment of grid to cathode spacing? With extra length there must be more tendency for the hot structure to bend or sway with disatrous results. The Electro Harmonix KT90 had Pda of 55W and looks just like a KT88/6550 but with taller plate but straight sided glass, like an EL34 which has been fed steroids for a year. Initially, the KT90 were a reasonable buy because the price wanted was only a bit more than a 6550. But that seemed to change. Seems to me New Sensor is again "stretching" the KT 88 upwards even more than they did with KT90. But if a 6550/KT88 is $30, then when stretched upwards, it should only cost for the extension in height of 35% so $40.50, not $70 being talked about. Two KT88,6550 will cost less than one KT120 and the Pda of the two KT88/6550 = 84W, and so a quad of KT88/6550 are going to beat the pants of a pair of KT120. But for those that must have the latest gizmo, you know where to go to spend up. But don't expect any more power or fidelity than you are getting now with KT88/6550. The curves I could see do not indicate any more anode voltage swing is available if you just switch to KT120. Are the curves as good as for the NOS KT88? I don't think so. Many makers are already pushing their luck by running 6550 with Ea too high and RL too low. There seems to be an absurd trend where there is never enough power, even with so called hi-fi amps they are set up in nearly all class B working with low load and high Ea to get the sales figures and to hell with the idea that for hi-fi about 50W max is all that should be ever asked from a pair of KT88/6550. I found the Sovtek small bottle 6550 and KT88 were excellent value for the price. The guts of these didn't change when the bottle size increased for the Electro Harmonix name range. OK, It was all a marketting ploy eh, to get away from the old association of Sovtek and the evil empire of the Soviets and USSR. I wonder how Mike mathews is getting on with the Russian Mafia boyos who tried to put the squeeze on him for a rouble or three. Maybe Mike needs the money, but then we could all say that. Patrick Turner. I bought a pair of KT120's from The TubeDepot a few weeks back just for the heck of it. After about 24hrs operation one of the filaments opened up (really). I pulled the tube and checked it with an Ohm meter and noticed that when I move the tube the resistance changed. I took a soldering iron to the filament pins for a few seconds and that seemed to fix it. About 24hrs operation after that it happen again so I heated the pins up a second time. So far them seem to be working but quality control seems to be an issue. Aside from that, they do really sound good with a lot of top end. I'm running 500Vdc on the plates with 400Vdc on the screens in push-pull configuration at about 60 mA idle current. |
#6
Posted to rec.audio.tubes
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KT120 from New Sensor, bargain or rip off?
"NX211" wrote:
I bought a pair of KT120's from The TubeDepot a few weeks back just for the heck of it. After about 24hrs operation one of the filaments opened up (really). I pulled the tube and checked it with an Ohm meter and noticed that when I move the tube the resistance changed. I took a soldering iron to the filament pins for a few seconds and that seemed to fix it. About 24hrs operation after that it happen again so I heated the pins up a second time. So far them seem to be working but quality control seems to be an issue. Aside from that, they do really sound good with a lot of top end... *** Aha. I was wondering which end of the valve they'd extended. Ian |
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