Gibson GA-95 RVT

[sunnydaze]

Has the low output problem been resolved? If so, what was the problem.

thanks
Mike

[Maçon]

[Travst]

Has the low output problem been resolved? If so, what was the problem.

thanks
Mike

I haven't revisited this thread in a while and apologize for the delay in answering this question. I ended up setting the amp aside after my little practice amp blew and haven't gotten back to it. In the meantime, I built a tweed Super and the small Eagle Premium kit as well as a guitar. I need to get back on this after I get an MA-50 off my bench! One of the past owners of the Gibson spotted this thread and contacted me about the amp, so I should have some history on it soon.

[Travst]

I went through all the fixes and tests suggested in this thread, and improved the sound dramatically after replacing a pot, several resistors, and doing a cap job. I also checked the trannies and other components. I thought the amp still sounded thin and weak, so it sat for a while before I got back to it. I decided to take it to Sam Timberlake (Samamp) for him to check out. Sam checked the power output and it was at spec. After giving it a once over, he returned it to me with no changes. He's a fantastic tech and a great guy.

It seems that the fixes provided here worked and I suppose I was expecting something more like a Twin and kept searching for a cure after finding it. Each little fix improved the amp, so I think that there were at least 3 problems that were fixed during the course of repair. I was relieved and surprised when Sam gave it a clean bill of health.

I want to thank everyone here for being such a valuable resource. Your input was invaluable during this process. Frankly, I was in over my head, but I learned a great deal from this experience with your help. You guys rock.

[Phil_S]

John,
I've very glad to hear you got things worked through and that all is well. Some of the Gibson amps of that era just aren't much to shout about and you probably have one. To give it a boost, you might try a pedal between the guitar and the amp, or you might attempt to mod the amp.

I am an amateur, so I don't fully understand things the way some folks here do. IMHO, the bottleneck in this amp is the interstage transformer. I don't know if you tried other tubes in V5. Because V5B is part of the tremolo circuit, I recommend against a 12AX7. I think maybe a 12AT7 would be a good choice.

You might try a 12AX7 and if you like it, consider using a 12DW7, which is 1/2 12AX7 and 1/2 12AU7. You might have to rewire to get the U7 half on the trem and the X7 half driving the i/s tranny.

Try plugging a short instrument cable from channel 1 to channel 2. Turn the reverb on, even if it is all the way down. This will increase your volume.

It will also help to raise C3 from 5u to 20u.

Good luck.

Phil

[Travst]

Thanks Phil, I appreciate all your help on this. Now that I know everything is ok, I'll begin experimenting with tube swaps, mods, and pedals. I have a good selection of old tubes to try out in the amp. The old amp isn't worth much (and I have about $300 in it), so there's no reason not to make it a mod platform and learn some more.

I did remove the notch filters during this process and believe it is definitely possible to tweak into a good amp. I also have quite a few 12" speakers that I can try out as well. The stock speakers didn't come with the amp.

As a side note, I was able to find an original footswitch cheap.