Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: fenderguy81 on January 07, 2022, 12:33:48 pm
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So I bought an old Audio Guild (Similar to Magnatone, not Guild) that needs a bit of work. I can't find a schematic for my specific model and the output is no longer wired the way it was from the factory. It is my understanding that most of these amps came with a single 12" speaker and a single 8" with individual amps that allow you to mix in the separate speakers. This model came with a single 12" speaker and no sign that an 8" was ever installed in the cabinet. Here is the only other example I've been able to find with the same configuration:
https://reverb.com/item/42918319-vintage-1960-s-audio-guild-corp-magnatone-panaramic-universal-bonham-tube-amp-amplifier-hand-wired?utm_source=rev-ios-app&utm_medium=ios-share&utm_campaign=listing&utm_content=42918319
The previous owner was running it out of the ext. 1/4" jack to a single 8 ohm 12" replacement Celestion speaker. I was able to source a mini amphenol plug and would like to wire it up to a single speaker (anyway to tell if 8 ohms would be sufficient)? Here are some gut shots of the amp with the chassis mounted reverb tank removed (there is another reverb tank in the cabinet and I will reattach the chassis mounted Gibbs tank when I put everything back). Any help would be greatly appreciated!
(https://live.staticflickr.com/65535/51806040373_542e741fb6_k.jpg)
(https://live.staticflickr.com/65535/51806040348_d8df70e75d_k.jpg)
(https://live.staticflickr.com/65535/51806040328_8c3de9dc4c_k.jpg)
(https://live.staticflickr.com/65535/51806040288_579cb2a1d7_k.jpg)
(https://live.staticflickr.com/65535/51806040243_c812d5e136_k.jpg)
(https://live.staticflickr.com/65535/51806650840_87cd075ab6_k.jpg)
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First time I see this amp
Look here ( or you may know ? ) http://magnatoneamps.com/audioguild.html
Some schematics ; http://magnatoneamps.com/schematics.html
Found here; https://www.tdpri.com/threads/audio-guild-amp-schematics.543389/
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It has 4 6L6 and *two* output transformers. Running just one speaker is "wrong"", and risks ruining vintage iron.
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It has 4 6L6 and *two* output transformers. Running just one speaker is "wrong"", and risks ruining vintage iron.
4 7591 tubes, but your point is well taken. It's odd that some left the factory with dual output transformers into a single speaker. I guess I'll have to find a suitable 8" speaker and modify the baffle as I don't want to inadvertently damage one of the output transformers. Thanks for the input!