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Old 7th December 2012, 01:42 AM   #1
trigger is offline trigger  United States
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Default recognize this old amp?

i purchased this old amp and was curious if anyone knew the make? any help would be much appreciated.

1958 Vintage Stereo Tube Power Amp Project 4 x EL84 Cool | eBay
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Old 7th December 2012, 02:01 AM   #2
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Hello trigger, I cannot tell you what brand the amp is or what it came out of. I can tell you the guys description of the tube types is wrong on at least two of the tubes. There is no 6AV6 or 6CA4. The 6CA4 is a nine pin rectifier and this amp has an 8 pin rectifier tube which is most likely a 5U4. Mickeystan
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Old 7th December 2012, 02:18 AM   #3
trigger is offline trigger  United States
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yeah figured it was a tall 5u4 and maybe a 12ax7 with a quad of 6bq5's, it looks similar to a magnavox or rca.. i am curious to find a schematic for it.

Last edited by trigger; 7th December 2012 at 02:21 AM.
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Old 7th December 2012, 02:36 AM   #4
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Trigger,

That almost certainly came from a console. When you have the unit in your hands, look for a power connector that fed a tuner/preamp.

I'm guessing the circuitry in that chassis is a "concertina" phase splitter for each channel into a pair of PP "finals". I agree with the 6BQ5/EL84 O/P tube assessment.

If my circuitry guess is correct, the "beast" could be made "self contained" by using a 12AX7 to form voltage amplifiers for the 2 channels and installing MOSFETs to take on the "concertina" phase splitter duties.
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Old 7th December 2012, 02:47 AM   #5
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I can't say who made the amp but I'd bet ya $5 that those green Tropicaps are leaky.
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Old 7th December 2012, 04:34 AM   #6
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Yeah, and ditch the cheapo wafer sockets.
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Old 7th December 2012, 05:28 PM   #7
trigger is offline trigger  United States
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Quote:
Originally Posted by Eli Duttman View Post
Trigger,


If my circuitry guess is correct, the "beast" could be made "self contained" by using a 12AX7 to form voltage amplifiers for the 2 channels and installing MOSFETs to take on the "concertina" phase splitter duties.
thank you much for your well informative response.

this is my first dabble into a concertina, so please bare with me.

so without a double triode or mosfet to feed the concertina circuit there will be no gain?

i will research this for the next few days. is there a simple mosfet circuit that can easily be applied in general push pull amp applications?
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Old 7th December 2012, 05:53 PM   #8
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Quote:
Originally Posted by trigger View Post
thank you much for your well informative response.

this is my first dabble into a concertina, so please bare with me.

so without a double triode or mosfet to feed the concertina circuit there will be no gain?

i will research this for the next few days. is there a simple mosfet circuit that can easily be applied in general push pull amp applications?
The pre-amp section chassis had the actual VA driver and then that was cabled down to the splitter tube. By the looks of that amp, the best route would be to strip it for the iron and tubing and start a new build, chassis and all.
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Old 7th December 2012, 06:17 PM   #9
trigger is offline trigger  United States
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a complete rebuild would be fun and ideal yet i feel that would be a bit more than i can handle at the current time. being a long time running noob, i have no second eyes with electronics available, using the net as a learning tool only, Ive just never run into anyone interested in audio electronics. so far i have worked with several old pulled amps, made them plug and play, recapping... last winter i assembled a tda7294 feebay kit.

maybe i should give it a try. cabin fever is setting in and my home theater is a cheep china 4ch powered subwoofer,...lol
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Old 7th December 2012, 06:37 PM   #10
20to20 is offline 20to20  United States
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Quote:
Originally Posted by trigger View Post
a complete rebuild would be fun and ideal yet i feel that would be a bit more than i can handle at the current time. being a long time running noob, i have no second eyes with electronics available, using the net as a learning tool only, Ive just never run into anyone interested in audio electronics. so far i have worked with several old pulled amps, made them plug and play, recapping... last winter i assembled a tda7294 feebay kit.

maybe i should give it a try. cabin fever is setting in and my home theater is a cheep china 4ch powered subwoofer,...lol
There is room on the corner to add a driver tube. But this one won't be as simple as adding some RCA jacks and a switch and a recap.
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