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Messages - boghymnal

#1
Thanks for this response -- I plugged a patch cable between the preamp output and power amp input jacks. Unfortunately it didn't result in any changes to the behavior/volume. This amp is currently at a practice space so I think at a minimum I need to take it home, open it up, and put it through a good cleaning and at least a visual inspection of the board.

Now I need to find another preamp and poweramp to move on to your next suggestion to try and narrow down where the volume loss might be happening. Also considering building an audio probe after seeing a couple youtube videos about using them to troubleshoot amps. This is my first amp repair after doing a lot of small scale electronics work (pedals, etc.).

Also, thanks for the schematic -- it's much clearer (particularly the power amp section) than the one I'd found elsewhere.

You seem to be familiar with this model -- any other typical issues that might be good to hone in on?

Thanks again!
#2
Looking for some repair/troubleshooting tips. I purchased a vintage Acoustic 220 bass amp a while back (without being able to test it) and finally got a cab to pair it with.

Based on several posts I've seen about this amplifier on different forums, I expected it to be LOUD (comments like "can't go past 9 o'clock without drowning out my band!"). However, even with the volume cranked I can speak over the sound of the amp. The actual tone seems fine and every knob and slider (aside from the bass pot which I assume is just a bad pot I can replace) affects the tone -- it's just the volume is quieter than expected. I've tried another head with the cab I'm using so I can confidently rule out the cab. I've tried both speaker outputs on the head and both have the same output volume.

Based on the symptoms, I'm assuming maybe something with the power amp section is bad? Any idea of what this might be? I'm having trouble finding a readable schematic.