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i need help , i have a no name strange tube amp

F

FILIMENTHEAD

New Member
I have this no name amp with the numbers 2222 on it , no other markings , possible tone cabinet or guitar amp .
can anybody help . i would like to restore it and i need a schematic .
the transformers were made in kitchener ontario by STANDARD RADIO PRODUCTS OF KITCHNER ONTARIO .
never heard of this company , in google search it does not show up or exist .2222 tube no name amp 050.JPG2222 tube no name amp 053.JPG2222 tube no name amp 047.JPG2222 tube no name amp 043.JPG2222 tube no name amp 058.JPG
 
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^^ yep

riveted sockets makes me suspect its a factory-build. Quite possibly low volume though, based on the screws holding the other hardware in place.


6H6 is an interesting thing to find in an amp. Its a full wave rectifier, but very low current. Normally those were used for things like FM ratio detectors, VTVM, etc where there was very little current involved. Datasheet says 100 volts and 4 ma. I guess you might be able to use it as a bias supply, but being indirectly heated it would come up slower than the 5U4G. It would be a near thing if the 6H6 would get the grids negative before the 6L6 started to conduct.
 
Restore for what purpose? It could be piece of interior in a pub (find any tubes what fits and push into sockets), but to restore to working condition worth only if you have sentimental memories, but it is not a case, if you do not know what it is :) Power amplifier from 50s with THD about 10%, more or less, and frequency range up to 8khz is not what you want to hear today.
 
gadget73 said:
^^ yep

riveted sockets makes me suspect its a factory-build. Quite possibly low volume though, based on the screws holding the other hardware in place.


6H6 is an interesting thing to find in an amp. Its a full wave rectifier, but very low current. Normally those were used for things like FM ratio detectors, VTVM, etc where there was very little current involved. Datasheet says 100 volts and 4 ma. I guess you might be able to use it as a bias supply, but being indirectly heated it would come up slower than the 5U4G. It would be a near thing if the 6H6 would get the grids negative before the 6L6 started to conduct.
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It's an old version of the current 6AL5. I think 6AL5 can do a bit more plate current than the 6H6 could handle.
 
true but both are odd choices of things to find in an audio amp. Other than a bias supply I don't know what you'd do with one, and with the slow warmup I don't know that I'd want to use one for that task.
 
zackthedog said:
6H6s were used in automatic volume control circuits. Maybe that's what it's for here?
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I guess you could use it to change the screen voltage on a pentode and alter the gain that way. Some tube compressors work that way.

AVC is typically a radio term though, and it works very differently there. The stronger the signal, the more negative voltage it produces, which is fed to the RF and/or IF amp sections to reduce gain. It changes volume, but not by messing with anything in the audio frequency stages.
 
gadget73 said:
I guess you could use it to change the screen voltage on a pentode and alter the gain that way. Some tube compressors work that way.

AVC is typically a radio term though, and it works very differently there. The stronger the signal, the more negative voltage it produces, which is fed to the RF and/or IF amp sections to reduce gain. It changes volume, but not by messing with anything in the audio frequency stages.
Click to expand...

I see. Thanks for the explanation!
 
gadget73 said:
I guess you could use it to change the screen voltage on a pentode and alter the gain that way. Some tube compressors work that way.

AVC is typically a radio term though, and it works very differently there. The stronger the signal, the more negative voltage it produces, which is fed to the RF and/or IF amp sections to reduce gain. It changes volume, but not by messing with anything in the audio frequency stages.
Click to expand...

I think the same method used for AVC at RF (rectify the AC output signal, use it to vary the grid bias) can be applied at AF as well. The Federal AM-864/U compressor, for instance, works this way.
 
yeah that would work too I suppose, though that looks more like a limiter than a compressor. I suppose its going to have some amount of compression as it approaches the point where the limiting action kicks in, but below that it wouldn't really change much. Still better than how they did it on CB radios, just a diode and a resistor at the output of the modulation amplifier. Above a point and the diode switches on, dumping any excess signal to ground. It sounds like absolute poop.

I was thinking more of a getup that pulled down the screen voltage as needed to work as a kind of variable mu deal. Would have to involve a high value resistor from B+ and another to the diodes, and as the diodes conduct it would pull down the screen voltage and drop the gain on the pentode. Depending how you set it up you could suck all of the dynamic range right out then call it a remastering amplifier :)


actually thinking about it it might have to go the other way, bump the screen voltage as the grid would swing negative in order to counter-act the input voltage but you get the idea. I'm sure someone has actually designed such a thing.
 
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