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#1
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Radford SC-2 / STA15
Hello,
I´m entirely new to this NG and have a single question: does anybody have a picture of Radford SC-2/STA15 or STA25? I happen to have found some and I´m not sure what it is, esp. the power amp has no label on it (but a serial number). Yes, believe it or not: somebody trashed it, along with a Thorens TD124MkII equipped with a SME 3009 - fortunately I spotted it in the dumpster before that was emptied. But half the tubes are smashed or missing... Since I very much like the sound of my 1961 braun csv-13 :-) I´d like to get the radford back to life, and there´s a site with schematics on the net... Now I have to identify the power amp first... ....any help greatly appreciated! TIA Walther Please feel free to respond personally at in4tec dot de. |
#2
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Walther wrote:
Hello, I´m entirely new to this NG and have a single question: does anybody have a picture of Radford SC-2/STA15 or STA25? [...] from what I learned now it´s more likely a STA25. It has some BIAS adjustment gear on the front side. Still not quite sure... ordered me some EF86, ECF82 & EL34. Hope this will do (I have no clue of tube valve electronics). Please feel free to respond personally at in4tec dot de. |
#3
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My G...! - How lucky can a man get?!!!
Regarding diagrams, look he http://www.drtube.com/audioamp.htm Does wery much hope it helps You ;-) Good luck with You'r find... - By the way, - wheres that dumpster?!! Best regards Tonni "Walther" skrev i en meddelelse ... Hello, I´m entirely new to this NG and have a single question: does anybody have a picture of Radford SC-2/STA15 or STA25? I happen to have found some and I´m not sure what it is, esp. the power amp has no label on it (but a serial number). Yes, believe it or not: somebody trashed it, along with a Thorens TD124MkII equipped with a SME 3009 - fortunately I spotted it in the dumpster before that was emptied. But half the tubes are smashed or missing... Since I very much like the sound of my 1961 braun csv-13 :-) I´d like to get the radford back to life, and there´s a site with schematics on the net... Now I have to identify the power amp first... ...any help greatly appreciated! TIA Walther Please feel free to respond personally at in4tec dot de. |
#4
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I took a look at the schematics. Looks like a darn good amp. Consider that
most of the value of a tube amp is in the iron (transformers). Capacitors are not so expensive, nor are the tubes if You think a good one (*) can last 10,000 hours. I think it's really worth the pain to try and make it 100% functional again. Pay attention before powering on, maybe a shorted cap is waiting for You to blow. Check with a voltmeter to find "gross" shorts, then power up GENTLY. It was in the garbage, after all. A cheap trick is to put a lamp in series along the line cord to drop the voltage. Start with a high resistance one (say 25W or less) and then go up to 100W or more (this is applicable only if You do not have a Variac). A thread on this took place some times ago on this NG. Pay attention, these are TUBES, it means 400+ Volts are in there. I tasted some 430VDC once, not my cup of tea for sure! As per the Thorens, it will be more difficult to decide if it's worth a workover. I own a 126MkIII and I'd sell my soul before it, but if the table support bearing is worn, well, I suppose no Swiss watchmaker will ever be able enough to fix such a piece of old-time art. I'll plan a trip to some German landfill one of these days... maybe I'll get the Telefunken tubed tuner I'm looking for! Ciao Fabio (*) "good" does not mean necessarily "Tiffany's". Plain, current production Sovteks, JJ or Svetlanas are good enough for any purpose, unless You want to keep the amp a "collector's item". "Walther" ha scritto nel messaggio ... Hello, I´m entirely new to this NG and have a single question: does anybody have a picture of Radford SC-2/STA15 or STA25? I happen to have found some and I´m not sure what it is, esp. the power amp has no label on it (but a serial number). Yes, believe it or not: somebody trashed it, along with a Thorens TD124MkII equipped with a SME 3009 - fortunately I spotted it in the dumpster before that was emptied. But half the tubes are smashed or missing... Since I very much like the sound of my 1961 braun csv-13 :-) I´d like to get the radford back to life, and there´s a site with schematics on the net... Now I have to identify the power amp first... ...any help greatly appreciated! TIA Walther Please feel free to respond personally at in4tec dot de. |
#5
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Fabio Berutti wrote:
I took a look at the schematics. Looks like a darn good amp. [...] Thank you (all) for all the advice and information you gave! When I first spotted it in that dumpster I thought it must be. Sure I will keep this thread alive while working on the STA25 (which it turned out to be), and put some pics on my website. BTW, for enthusiasts from all over the world now going to flock on german landfill sites... we got pretty much thermal handling of waste here these days thanks to excessive politician bribing by a now imprisoned local recycling tycoon. So it is most likely this STA25 would have gone up in smoke or picked out by a giant magnet and smashed (makes me shudder). Cheers Walther at in4tec in Germany I have to apologize - the address above is faked, sorry! I´d like to know a better way to get rid of spammers. |
#6
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Hello again,
anybody interested in having a look at the "trash" I pulled from the rubble - feel free to do! Here´s a link to some pics of that find (caveat: bandwidth required since these pictures are quite large): http://www.in4tec.de/PICS/RADFORD/luckyfind.html Anything I better should know about these amps (I´m a rookie)? |
#7
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Walther said:
Hello again, anybody interested in having a look at the "trash" I pulled from the rubble - feel free to do! Here´s a link to some pics of that find (caveat: bandwidth required since these pictures are quite large): http://www.in4tec.de/PICS/RADFORD/luckyfind.html Anything I better should know about these amps (I´m a rookie)? Nice find! This looks like a STA25. There must be a GZ34 rectifier in as well. The SC22 preamp is powered from the main amp, looks like they even left the octal cable in there for you :-) Before powering up, check if the bent sheet of the SC22 doesn't cause any short circuit somewhere. Also, check the main amp's innards for any damage Despite the use of an indirectly heated tube rectifier, it's still best to power it up through a variac if possible, or use a 100W lightbulb in series with the mains. That way, you can monitor whether there are any bad supply capacitors. Secondly, check the output tubes' bias, there are bias testpoints at the rear. Keep open the possibility of leaking coupling caps to the grids of the EL34s. In that case, they'll draw excessive current and will soon be worn out. Check for red glowing plates and/or screen grids of the EL34s. If everything looks OK, you can check if the supply voltage is OK. I think it ought to be in the 380...400V range at the first supply cap. Viel Spass mit deinen Verstaerker , er hat ein wirklich guten Klang wenn alles stimmt und ist immer noch sehr beliebt bei vielen Musikfreunde :-) -- Sander deWaal "SOA of a KT88? Sufficient." |
#8
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Since these items are worth around $1,000 in good condition, it might be wise
to take it to someone familiar with them before doing anything. You may want advice on how to restore it to start with, before retro fitting anything and chucking anything away. Keep all the bits, whatever you do - this kind of item needs to be in original condition as much as possible for the real money. There are support groups for these amps - you can ask on the Leak group, which is === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
#9
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Andy Evans wrote:
Since these items are worth around $1,000 in good condition, it might be wise to take it to someone familiar with them before doing anything. You may want advice on how to restore it to start with, before retro fitting anything and chucking anything away. Keep all the bits, whatever you do - this kind of item needs to be in original condition as much as possible for the real money. There are support groups for these amps - you can ask on the Leak group, which is === Andy Evans === Thanks a lot Andy, I´m a newbie to tube amp restauration but not to restauration at all, normally I prefer working on motorcyles - the oldest of which, a BMW R25/3 with sidecar has a few years more than the STA25. I begun cleaning and examining the power amp today and now all the dirt has vanished it looks really great! The paint is fine, the metal parts not corroded, the chrome shiny again :-). Nothing broken, bent or gone up in smoke, the inside looks pretty complete and functional. The tubes still present are Mullard GB (EL34, EF86) and Mullard Canada (ECF82), one EL34 was Valvo. I guess the Mullard was originally fitted. I´m going to replace with Philips8 EF34, EF86) and Siemens (ECF82) NOS. Hope this doesn´t make a difference or bother the purists. One 8µ8F Capacitor and a small Resistor near its Counterpart on the other side seem to have been replaced in an early age of the amp - they do not match left/right but look as ancient as the rest of the parts. As far as I can measure with my multimeter no big capacitors are short-circuited, both speaker outputs measure 0.8 Ohm - with no tubes yet fitted. I would be glad to hear that this is the correct value and no shortcut or something... I´m going to proceed as adviced and power up with limited current first to see if there are any leakages which are likely to lead to a damage. And I´ll gladly put some more pictures of the restauration process on my web site - watch out at http://www.in4tec.de/PICS/RADFORD/luckyfind.html Thanks a lot everybody for being very helpful! Walther |
#10
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Walther wrote:
[...] I have now updated some pictures of the "restoration" process of what turned out to be a Radford STA25 power amplifier at http://www.in4tec.de/PICS/RADFORD/luckyfind.html feel free to take a look - but some bandwidth is required. Any good advice of yours for the rebuild greatly appreciated! Walther |
#11
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Hi Walther,
I'm enjoying your journey through this classic amp. They're sure fun to resurrect. I've done two pairs of McIntosh MC-30s, a Citation II (thanks to Jim McShane) and various others. Only one suggestion: Please resize your images so they're easier to see and faster to load on the html page (800 pixels?) and put links to the full-sized images for those who want close-ups. Have fun, Raymond Walther wrote: Walther wrote: [...] I have now updated some pictures of the "restoration" process of what turned out to be a Radford STA25 power amplifier at http://www.in4tec.de/PICS/RADFORD/luckyfind.html feel free to take a look - but some bandwidth is required. Any good advice of yours for the rebuild greatly appreciated! Walther |
#12
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Hi RATs!
Yup, my favorite phrase: "Just take it, nobody wants tubes anymore ." 8 uF or 8.8uF mox nix. Era caps were typically rated at =/- 50 % ... Just make sure the replacement caps are rated at same, or higher, voltage. Any EL34 will work. Which one you find or like the sound of is up to you You can get used tubes cheap, and tested & guaranteed from Antique Electronic Supply: www.tubesandmore.com I just got a new looking Harman-Kardon Allegro off eBay. Mono P-P EL84 Happy Ears! Al PS Hey, Ray, get a faster link, dude. This is: The Future PPS Now Playing is hot rodded Fisher X-101-B and 12" Utah Micro Gap full range AlNiCo drivers - wow 8^) Alan J. Marcy Phoenix, AZ PWC/mystic/Earhead |
#13
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Raymond Koonce wrote:
[...] Please resize your images so they're easier to see and faster to load on the html page (800 pixels?) and put links to the full-sized images for those who want close-ups. I will do soon - promised. You have been warned, though, haven´t you? [...] Have fun U2! Walther |
#14
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Walther wrote:
Raymond Koonce wrote: [...] Please resize your images so they're easier to see and faster to load on the html page (800 pixels?) and put links to the full-sized images for those who want close-ups. I will do soon - promised. You have been warned, though, haven´t you? [...] Have fun U2! Walther Hi Walther and Hi Al, The load speed is not a problem for mre, it's just that the images take up more than my monitor can display so I have to scroll around to get the whole pic. I do like the hi-res photos. You have a good camera Walther. Best regards, Raymond |
#15
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Hi RATs!
OK, Ray, get a new monitor and video card 1280x1024 seems OK ... Happy Ears! Al Alan J. Marcy Phoenix, AZ PWC/mystic/Earhead |
#16
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Raymond Koonce wrote:
[...] Hi Walther and Hi Al, The load speed is not a problem for mre, it's just that the images take up more than my monitor can display so I have to scroll around to get the whole pic. I do like the hi-res photos. You have a good camera Walther. Best regards, Raymond I´m done now with the additional work you requested... ....nice little pics that only inflate when clicked! My camera is a 1975 OM-2 (no tube valves inside, though). Enjoy! Walther |
#17
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Walther wrote: snip I´m done now with the additional work you requested... ...nice little pics that only inflate when clicked! My camera is a 1975 OM-2 (no tube valves inside, though). Enjoy! Walther Nice work! You're a lot better at html than I am! Do you scan prints from your camera to publish on-line? Those transformers are very nice looking. Are they wound by Radford or outsourced? Best regards, Raymond |
#18
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Raymond Koonce wrote:
Nice work! You're a lot better at html than I am! Do you scan prints from your camera to publish on-line? I spoiled it in the meantime and added lots of boaring nonsense to it. BTW, I speak not a single word of HTML - that´s SGI´s Cosmo Create :-(. The lab processing the film additionally supplies a CD with the prints. They do this not only at no costs but in fact _cheaper_ than without. Those transformers are very nice looking. Are they wound by Radford or outsourced? how can I tell? I didn´t find any writing besides the felt tip notes! Does anybody else know? With transformers like these one could easily build STA-25 clones, am I right? That has not happened yet AFAIK. Cheers! Walther |
#19
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Walther wrote:
Raymond Koonce wrote: Nice work! You're a lot better at html than I am! Do you scan prints from your camera to publish on-line? I spoiled it in the meantime and added lots of boaring nonsense to it. Not boring, interesting to see an amp I've never run across before. BTW, I speak not a single word of HTML - that´s SGI´s Cosmo Create :-(. Thanks for the tip. I'll have to look that up. I hate trying to compose in HTML, it never seems to work the way I intended. The lab processing the film additionally supplies a CD with the prints. They do this not only at no costs but in fact _cheaper_ than without. I guess that's the regular thing these days. It's been a long time since I shot any 35mm film. I'm all digital these days. Those transformers are very nice looking. Are they wound by Radford or outsourced? how can I tell? I didn´t find any writing besides the felt tip notes! Does anybody else know? With transformers like these one could easily build STA-25 clones, am I right? That has not happened yet AFAIK. Sounds like a good project :-) Cheers! Walther Best regards, Raymond |
#20
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Hello again,
I´m going to replace the tubes with a set of Philips matched ones. Any objections against this anybody? Are Mullards far better? Walther Please feel free to respond personally to me at in4tec dot de. PS: I put some text and images about me + my Radford STA-25 MkIII on http://www.in4tec.de/PICS/RADFORD/luckyfind.html |
#21
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Walther said:
Hello again, I´m going to replace the tubes with a set of Philips matched ones. Any objections against this anybody? Are Mullards far better? Walther Please feel free to respond personally to me at in4tec dot de. PS: I put some text and images about me + my Radford STA-25 MkIII on http://www.in4tec.de/PICS/RADFORD/luckyfind.html Just wait for the results of the Nachbaur poetry contest. There are 4 AEG EL34s waiting for you ;-) FWIW, your submission is one of the best IMO, but I fear not many voters do read German......... -- Sander deWaal "SOA of a KT88? Sufficient." |
#22
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Walther wrote:
Hello again, I´m going to replace the tubes with a set of Philips matched ones. Any objections against this anybody? Are Mullards far better? If the Philips tubes are European ones, they are the same as Mullard. Mullard is a Philips brand (like Valvo and many others). American Philips tubes are quite different - they are often Sylvania tubes. Best regards, Mikkel C. Simonsen |
#23
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Hello everybody,
(me again...) _good_ news: I got the little amp up and running! After I had followed all the precautions you advised me to, e. g. a 25W lightbulb in series (and an amperemeter) - I was courageous enough to switch it on - nothing happened (33V). With a 60W bulb I had 185mA current - and a hardly audible click came from the speaker. 100W - and there came music from both speakers... I finally omitted the lightbulb. Only then I placed the speakers (braun L550, about 1970 - just at hand for testing) into a stereo position, and me in the middle - and off I went listening for hours... My source: a cheap AIWA portable CD player. OK, I have no direct comparison yet... but my impression is indeed: that amp is _fantastic_! Horowitz in Moscow: with eyes closed I had the impression of sitting backstage near the Steinway (must be quadro to have the coughs of the audience from behind). A CD from a jazz trio I happen to know personally named Swinger Club - Monsters of Jazz. Up with volume and the sound is not much far from being right in front of a gig. Can´t say where this comes from, without high-level speakers. Maybe it is just that: a simple but efficient two-way speaker. One thing is for su I will keep this amp, at least until a better one shows up. Next action will be to compare directly with half a dozen others and a little audience invited. I´ll post their vote here then! And add more pictures to http://www.in4tec.de/PICS/RADFORD/luckyfind.html. Wish I could add authentic audio there... Cheers! Walther |
#24
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"Walther" wrote in message ... Hello everybody, (me again...) _good_ news: I got the little amp up and running! After I had followed all the precautions you advised me to, e. g. a 25W lightbulb in series (and an amperemeter) - I was courageous enough to switch it on - nothing happened (33V). With a 60W bulb I had 185mA current - and a hardly audible click came from the speaker. 100W - and there came music from both speakers... I finally omitted the lightbulb. Only then I placed the speakers (braun L550, about 1970 - just at hand for testing) into a stereo position, and me in the middle - and off I went listening for hours... My source: a cheap AIWA portable CD player. OK, I have no direct comparison yet... but my impression is indeed: that amp is _fantastic_! Horowitz in Moscow: with eyes closed I had the impression of sitting backstage near the Steinway (must be quadro to have the coughs of the audience from behind). A CD from a jazz trio I happen to know personally named Swinger Club - Monsters of Jazz. Up with volume and the sound is not much far from being right in front of a gig. Can´t say where this comes from, without high-level speakers. Maybe it is just that: a simple but efficient two-way speaker. One thing is for su I will keep this amp, at least until a better one shows up. Next action will be to compare directly with half a dozen others and a little audience invited. I´ll post their vote here then! And add more pictures to http://www.in4tec.de/PICS/RADFORD/luckyfind.html. Wish I could add authentic audio there... Cheers! Walther Congrats Walther. I really love stories like that. keep up the website as you integrate this thing into your system. its fun for me to read about others getting things to work. one Day I will have to learn how to make a website and get the pics of my rig up there. Doug |
#25
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Doug Schultz wrote:
Congrats Walther. I really love stories like that. keep up the website as you integrate this thing into your system. its fun for me to read about others getting things to work. one Day I will have to learn how to make a website and get the pics of my rig up there. Doug Hi Doug, thank you very much for your kind response - I needed some motivation! It is kind of fun to share an experience like with this radford stuff, and I again have to apologize for mixing personal sentiments into it. Of course I update my site - new pics soon to come - from time to time. If you like to do your own web site, go ahead! It´s quite simple. First you have to get (or buy) some webspace and/or a domain name. All you have to do then is put your content there, using an ftp program. The pictures are e. g. jpegs and referrenced to in html text through img src="(some image location anywhere on the web)" tags. No secret. I´d very much recommend Thomas Münz´ http://www.selfhtml.org to acquire a minimum of html knowledge - a nice and easy tutorial to html and a complete reference to everything a good web designer needs to know. The more lazy ones - like me - avoid this using web design tools, with the fatal consequence of browser-crashing creepy animated gizmo nonsense now spread infinitely all over the web... Walther |
#26
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Walther wrote:
Doug Schultz wrote: Congrats Walther. I really love stories like that. keep up the website as you integrate this thing into your system. its fun for me to read about others getting things to work. one Day I will have to learn how to make a website and get the pics of my rig up there. Doug Hi Doug, thank you very much for your kind response - I needed some motivation! It is kind of fun to share an experience like with this radford stuff, and I again have to apologize for mixing personal sentiments into it. Of course I update my site - new pics soon to come - from time to time. If you like to do your own web site, go ahead! It´s quite simple. First you have to get (or buy) some webspace and/or a domain name. All you have to do then is put your content there, using an ftp program. The pictures are e. g. jpegs and referrenced to in html text through img src="(some image location anywhere on the web)" tags. No secret. I´d very much recommend Thomas Münz´ http://www.selfhtml.org to acquire a minimum of html knowledge - a nice and easy tutorial to html and a complete reference to everything a good web designer needs to know. The more lazy ones - like me - avoid this using web design tools, with the fatal consequence of browser-crashing creepy animated gizmo nonsense now spread infinitely all over the web... Walther Sorry, some addendum: selfhtml seems to be all-german, to my very surprise I found no international version of it. Or is there eventually? Walther |
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