'61 GA-5 is very sick

I have a 1961 Gibson GA-5 amp that is sick. When I turn it on it has an extremely loud buzzing hum and when I try to play through it, it sounds horribly out of tune, distorted, muddy, etc... I know it needs new wires, but could it also be the tubes. If so will I still be able to find tubes for this amp. If you need more info about the amp just let me know. Any help will be greatly appreciated.

Probably needs a cap job, new tubes also. Take it to a tech, get it done right.

The rectifier is failing, allowing AC to get past it to the filter capacitors, which are dying a loud and painful death, taking your output tube(s) with them... turn it off, take it to a tech, and repeat after me:

It doesn't get better on its own. It doesn't get better on its own. It doesn't get better on its own... It doesn't get better on its own... It doesn't get better on its own...

Hey Lord... you must think I'm a complete dumb a$$. I've only cut it on once after finding it again. It's not like I sit here all day cutting it on and off saying "come on baby I know you can do it". Please. I'm not that naive. Would a local music shop be likely to have the know how to fix it and roughly what kind of cost for repair will I be looking at?

edgranholm I'm sorry. Yours sounded like the kind of story I get all too often from non-tech folk who seem to think "It just needs to warm up." After all, you did leave it on long enough to try to play through it. Also, bear in mind that I write my replies as much for the rest of the people who 'look in' as the actual questioner. Not an excuse; an explanation.

The caps are likely to be toast. Exact replacements are unlikely to be new production, meaning that an identical part is probably just as old as the one that failed. New caps are usually much higher values (number of uF), rated for lower voltage. That requires using two or more in series, both to lower the effective value, and to tolerate the higher voltage. That gets tricky, because the caps need to be matched for value in order to ensure that they 'share' evenly.

The rectifier tube may have been damaged by the high current draw caused by the failing filter capacitors. The 5Y3 is a fairly robust SOB, so you may be in luck. Its a common, readily available tube, so no worries, even if you need a new one. :cool:

The (undated) schematic I have, shows only 165 volts being applied to the plates of both sections of the 12AX7 preamp tube. There's enough series resitance between the plates and the supply to be fairly sure its OK. Heavy ripple on this supply line would make a hell of a lot of noise, though! :eek:

Now then, about that 6V6... if the rectifier is letting AC through, the output tube is now a nice souvenir of a bad time. The good news is that you can get them for less than $10 from a lot of online dealers. :)

The power transformer probably got a more vigorous workout than its used to, but if it didn't get too hot, its probably none the worse for wear. Ditto the O/P. ;)

Bottom line? Even if all of the tubes are replaced, they won't cost more than $35-$40. The capacitor bank will have to be hand-crafted, which puts you at the mercy of the tech. You're looking at a couple of hours work, plus parts. If the wiring is original, its way past its 'best before' date! The tech time to replace it costs a pretty penny, but your life is worth the expense, no?

The GA-5 is a nice, simple, low-power amp that should be every bit as famous and revered as the Fender Champion. Let us know how you fare with it.

Thanks alot Lord... I really appreciate the wealth of knowledge you have instilled in my technically incompetant mind.lol got another question, in good condition, how much would this amp be worth? and by the way, I wasn't the bright one who tried playing through it. It was just impossible NOT to hear what it sounded like.lol

Originally posted by edgranholm
...in good condition, how much would this amp be worth?...

That's one of those questions you can answer after you've sold it. (This is one of those answers that takes a long time to say "I haven't got a clue!") :)

edgranholm said something in his second post, He said he had only turned on the amp once since finding it again,

Attention All Tube Amp Owners, if you have amps sitting around not being played, shoved back in the closet or back at Grandma's house, About 2 or 3 times a year you need to turn on the amp, and play it for a few hours, this will keep your filter caps formed and in good shape, Ed's amp is probaly suffering the effects of old age as much as anything else, but your new amps will age prematurely if a charge isn't kept up on those capacitors, transistor amp owners disreguard, just kick your amp real hard occassionly

Good catch, pstring! I missed the inference that this amp had probably been dragged out of a dark, dusty corner, and plugged in. That would cause the filter caps to fail right away! :eek:

believe it or not I'm edgranholm. I had to be away for awhile and couldn't remember my password, and wanted a new name anyway. I wish I had an update for you on the amp, but I don't. I have however found someone who workes on old amps like that, but haven't contacted him about it. I really want this amp working again, but I just don't know if it's going to be worth the trouble. maybe someday I'll be back to let you know how it's doing.

check out the blue book for guitar amps, maybe they have the pricing for that amp.