1947? Gibson BR-6 advice.....

[Deric]

Picked up this cool old Gibson BR-6 a while back. Have no intention of keeping it... plan on selling it. It sounds OK, very little noise (some hum) but it's very quiet. Speaker code is 285652 so I'm guessing 52 week of 1946 as the BR-6 was gone by 1954. Transformer is 138622. No code on the pot that I can find. Appears to be mostly original except for the HUGE Sprague caps and maybe an input jack. Not sure if the pot is original but the solder looks very clean.

Plan on swapping the power cord first thing and probably the Sprague caps.

Any other suggestions? Comments?

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[Luthierwnc]

I rehabbed a BR-1 about 15 years ago. Very cool amp. More powerful than the one you have but pretty similar in construction. There are two things I'd recommend you pay attention to: some of the wires going to the field coil speaker are at full B+ and probably pretty beat. Be careful of cracks in the insulation and be prepared to replace them --especially near chafing areas. The other thing is to secure the filter caps. They are just kind of hanging loose in there. It isn't pure vintage but cinch them in place with some wire ties.

While I was refreshing my memory on the job I found this:

http://www.chambonino.com/work/gibson/gib1.html

It is a worthwhile read. Have fun with it, Skip

[FUCHSAUDIO]

Filter and coupling caps, 3-prong cord (remove death cap if present), and do it one part at a time, as Gibson amps are not consistent and often don't match their schematics either.

[butwhatif]

If you're not keepin it, let the buyer decide how much he wants to change stuff, most vintage guys want to do this--

[Deric]

If you're not keepin it, let the buyer decide how much he wants to change stuff, most vintage guys want to do this--

I agree...don't want to mess with it too much, but....

I won't keep anything I won't play...maybe I'd keep it if it worked right and sounded decent. (?) I also have one friend who's pretty interested but doesn't want it if it's not working.....

Swapped the power cord, pulled the death cap, swapped the filter caps and the cathode cap on the first tube. Fired it up and it sounds MUCH better. Still a little on the quiet side for a 10 watter but a HUGE improvement. Measured about 1vdc after the first coupling cap so swapped that too.

Working thru this thing it seems to follow the schematic pretty close except for one big difference......the .05 coupling cap from pin 5 of the phase inverter (the plate of the top half of the 6SN7 in the schematic posted above) to the grid of the 6v6 is missing.... Best I can tell it was never there.....hmmmmm. Am I right in thinking it NEEDS to be there? Would that explain the volume issue?

[Phil_S]

Yes, put in the .05 coupling cap.

[butwhatif]

i'm not lookin at the print, but if that's not there, it's a big issue. that's one coup cap that is usually leakin dc

[FUCHSAUDIO]

Replace the bad/old parts and give them to the customer in a zip lock bag. Lots of the collector types like to have the old parts, although it's doubtful they would use them for anything. Who wants a rubber line cord that's cracking up and dry/dangerous. I just restored an 18 watt 2 x 10 Marshall that a customer bought at auction. It was Richard Gere the actor's amp. He wan't crazy about all the parts (mostly electrolytics) that I changed, but he was thrilled with how it sounded, and he had the old parts in case he sold it.
All good. It restored the power output to spec, fixed a non working tremolo, stopped some pots from scratching, and sounded terrific. I told him it would not have worked out if I didn't change all these parts

[Richie]

If you do repairs its always a fine line. The owner needs to realize if he wants the amp to work properly or if they want to put the amp in a showcase and look at it. Either,you going to play it,or just collector showpiece. Seems everyone goes through this. Sometimes you may be able to find the exact componet to be replaced and it look all original. Alot of times it just isn't possible. So like Andy mentioned,any parts removed,replace them with new parts to get the amp working like it should.
The removed parts can be placed in a bag,and saved if someone wants to keep all original parts. Same with speakers. If your going to play the amp,and the old speakers are shot. So many good speakers to choose from today that will help the amp sound better. Keep the old speaker And install a new one. Or some will recone the old speaker. Usually you can buy a new better speaker than what was used when the amp was built. Some people think an old amp can be repaired but not have to change any parts.
Thats almost always not the case.

But as for the amp posted. That amp is very clean inside. I've seen much worse.

[Deric]

Thanks for the replies guys! I plan on keeping all the parts. I'm trying to replace as little as possible to get it working correctly. That'll pretty much be every cap and the power cord. The original cord is so bad it's cracked and falling apart in several places.

Got a chance to clip that missing cap in last night. Big difference. Sounds pretty good with a decent growl when cranked up - bottom end holds together pretty good too. Got to clean it up - for now just tacked parts in place one at a time with a few clip leads holding it all together. Looks like a mess....

Thanks again for the help!

[Structo]

Some guys get real crafty and hollow out the existing caps and place new ones inside to preserve the whole look of the amp.

[vibratoking]

Some guys get real crafty and hollow out the existing caps and place new ones inside to preserve the whole look of the amp.

I know. I have never really understood why, except to deceive someone that doesn't know any better. Beyond that, I don't get it.