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previous: Sean Kilback Gibson Discoverer GA-8T thoughts -- 6/29/2000 8:00 AM View Thread

re: Gibson Discoverer GA-8T thoughts

6/29/2000 4:01 PM
re: Gibson Discoverer GA-8T thoughts
It sounds like its not too different, feature-wise, as well as tube complement-wise, from the GA-5T. The GA-5T is a GREAT sounding amp, IMO. I had a guitar student last year who asked me to restore his, and by the time I was finished, I was in love with that amp.  
As far as the deal goes, I'd say you definitely scored. Which is always highly groovulatory.  
All it took was putting it back to spec as I recall. I might have messed with the bypass cap values, but I didn't have to do much to get it sounding really nice. I remember I messed with the tone circuit, but in the end put it back to original, and concluded that it was actually very cool-sounding as-is.  
If you can't find a schematic, I urge you to draw one up yourself. You'll probably learn a lot in the process. If you don't want to draw one up, I'll see if I can find mine for the GA-5T, which may offer some help, but thats a bit of an assumption. One thing to look for: see if the filament supply is center-tap referenced to the top of the cathode resistor on the output tubes.  
I replaced the original (cheap) 10" speaker w/a reissue Jensen C10R and that was a HUGE improvement. I really liked the concise way that the board was laid out too. It was one of those that have the little cones for putting the component leads through instead of eyelets or turrets; Hammond organs used these.  
You might consider replacing the filter caps before popping in new tubes. Either that or power the amp up slowly over several hours using a variac if it hasn't been played in a while. Bad filter caps can cause other, more expensive problems, like tubes & transformers going tits-up.  
Good luck, and let us know how you progress...  
- P

Sean Kilback hi P,Thanks for the... -- 6/30/2000 12:58 AM