Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ElPedro on November 22, 2015, 09:36:14 am
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I just built the Twin based off of the AB763 circuit. I apologize for no pics, as I took the amp to a tech to have it looked at.
Here is the general problem:
The amp acts like it has a big noise gate on it. If I lightly strum a string, no sound. If I hit it hard, it'll come on at full volume and then decay off really fast - no sustain.
When I checked voltages vs the schematic things were generally in the ballpark.
Obviously, something is all jacked up somewhere l, but I couldn't find it. I'm pretty new to amp building having only built a handful of champs and an 18 watt Marshall.
Has anyone run across this issue? Any ideas on what to look for?
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I took the amp to a tech
That's a good move, if the tech is willing, I'd try and be there when your amp gets worked on, ask questions, maybe even offer a couple bucks or equivalent barter to learn. 1st hand learning has ALWAYS been my best education.
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You have a wrong resistor value.. probably in the phase inverter area... you may have used a 470K instead of the 470 ohm.. a common mistake
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It's a long shot but I had something similar when I snipped the ground wire on the volume pot lug.