Gibson GA-8 Discoverer caps

[Resonator Guy]

This week I took delivery of a 1961 Gibson GA-8 that is in really nice shape. It still has the original Gibson branded tubes and 12" Jensen alnico speaker. I don't think the back has ever been off it before.
This one seems to be an early model as it has 2 6V6s, 1 12AX7 and a 5Y3 rather than the layout with 6AQ5 tubes as in the Gibson amp book. It is a Discoverer, not a Gibsonette, as it comes with its original instruction sheet , schematic and proper name on the control panel.
Unfortunately if still has the original electrolytics in it. It sounds amazingly good, but one look inside made me stop testing it.
My problem is, I can't find the proper caps for it, one of them anyway.
AES has one of them, a 10/10 @ 450 volts but not the other, a 20/10 @ 450. Weber doesn't have either. Those are my regular parts sources.
Does anyone know where I can get a 20mf/10mf @ 450 volt cap?
There isn't a lot of room in there to try and put two separate Mallory caps, plus the 10/10 and I would like to keep it as original looking as possible.
If not a 20/10, is there a source for a cap with a higher rating that wouldn't alter the sound too much?
Also, would it hurt to replace that 200 ohm strange cement looking resistor with a carbon film one? I know that won't look original but it is wired pretty tight to a cap that will be replaced.
Thanks from the wilds of Canada where its hard to find good replacement parts.

[pdf64]

From the tube lineup, I think this is the schematic
http://www.schematicheaven.com/gibso...gibsonette.pdf
The amp should be operating in class A, as the 2 6V6 are parallel single ended. Therefore there won't be much in the way of dynamic sag effects, so on that basis you could replace the 20uF / 10uF combo cap with a 22uF x 2 combo cap (or 2 single 22uF caps), and not change how it responds. And it should get rid of a little more hum.
That weird looking old power resistor is the cathode bias resistor on the power tubes. Any type of sufficient power rating will be ok - it may have 20V across it so will be dissipating 2 watts, so use a 4 or 5 watt resistor to keep it cool and happy. Metal film are my preference.
Leave some space for air to circulate between the resistor and cap, as heat from the resistor will age the cap.
Congratulations on a great find.

[Resonator Guy]

Thanks, I will give that a try. Now if I can find a 2X22uf cap. I think I am going to be stuck siliconing 2 caps together to hold them in place.
I will also not wire that resistor as tight to the new cap.

[ThermionicScott]

I bet you could fit a 10uF and a 22uF inside the shell of that original cap.

[Resonator Guy]

Now that is a good idea. The cardboard cover turns nicely. I will order a couple different sizes and see what I can do. That would look better than my original plans.

[Sweetfinger]

Those old Gibsons are the worst! I always end up having to silicone a cap here or there and stuff another cap somewhere else in the chassis. Leo has spoiled us all.

[Scott_F]

Get some of the TAD caps that Mojo is selling. They're very small but get the job done.

[maxwedge]

That Gibson is really nice! I have a 60 or 61 Gibsonette that's not nearly as nice as yours. I ended up making a small board to hold the new caps but I think re-stuffing the old caps is a good idea. If you're going to glue caps together use hot glue and not silicone.

[Resonator Guy]

I would think the hot glue would melt when the amp warmed up. I use a high heat silicone to keep things tidy.

[maxwedge]

I would think the hot glue would melt when the amp warmed up. I use a high heat silicone to keep things tidy.

It won't melt, unless it's right on a tube. I used it and didn't have a problem but you can use the silicone, you'll just have to wait for it to set up and dry.