Gibson Amps, someone educate me

[beasleybodyshop]

Ive been seeing lots of posts about vintage gibson amps. I recently picked up a few books on them, and while i rarely ever see them listed for sale, can someone who has owned some give me the scoop? From what I have read Gibson's thought was to create amps with very little breakup - Is there a model that produces good overdriven tones? Anyone ever build any from scratch? I realized they had several models of amps, but i would like some thoughts on them.

[xtian]

I just replaced caps in a Gibson Explorer GA18T. Overdrives starting at 3 on the volume, and just gets better and better. Nice deep tremolo. 10" Jensen AlNiCo. Very cool.

[Phil_S]

The white panel series (1965-67) are the ones with the nasty notch filter. There is a current thread in the Technical section. Nothing very special about these, IMO, but they are decent platforms and with not too much work can probably be made to sound decent.

I have a GA17-RVT Scout (1964 or 1965) from the Crestline series. A cap job, couple of good old stock USA 6AQ5's (replaced spent RCA's) and a Celestion G10L-35 made this one a winner in my book. IMO, the Crestline series, in general, are good amps with a little TLC.

The older amps are hit and miss. There are some old tweed ones that I imagine are quite decent. They go for a good sum on eBait. Others are just oddball types by modern standards.

You can read spec info here: http://www.superiormusic.com/page199.htm

[overtone]

I have a '54 and a '56 GA40. Nicknamed chocolate thunder, they have a thick early break up which can certainly make you grin a little bit too much. I like them, but side by side with a '58 Deluxe I find the Fender more versatile.

The '56 has a tag-board with components on both sides, so you have to pull it to get to anything on the side mounted against the chassis. The '54 is pure PTP and easier to work on.
There are schematics for these out there but it seems that Gibson preferred to sub-contract and the schematics may not always match what you see when you open one up.

I also made a home-brew GA5 Les Paul Jr with the grid leak 6SJ7 which is a great little amp to have around.

[billc]

I bought a thashed BR-6 from Ebay and rebuilt it as a BR-6F (changed the first tube from a 6SC7 to a 6SJ7), MUCH louder and better tone to my ear. Built a GA-30 from scratch liked it too but it was very similar to the BR-6F so I recently reworked it into a scratch built GA-9, 6SJ7 plus parallel 6V6's. about 9W...my favorite of several amps I've owned or built over the years and more or less a 5C1 Champ or Les Paul Jr. with an extra tube but twice the power and way better tone for me (also built a 5C1 awhile back). All of my Gibson builds have had a warm 50's jazz/blues tone which is exactly what I want but they might be too clean for other styles...but in any case the 6SJ7's have a sound of their own and are definitely worth experimenting with and FWIW the metal can helps a lot with keeping noise and hum low.

[Phil_S]

I forgot earlier. I built this: http://home.comcast.net/~psymonds/GA20.htm
The schematic is accurate to the final build but pictures are not. I rebuilt it with another PT and I fiddled with the resistors in the power supply and maybe on the 6SJ7 to raise the voltage there, so it doesn't conform to the Gibson schematic exactly, but it's close. This is a fun amp to have. Very Jimi-like in a really good kind of way.

[Jack Hester]

As the only schematics that I could find for the '52 -> '54 were poor, I hand-traced and made my own. I tried to make it look as close as possible to the original schematic.

Jack

[billc]

As the only schematics that I could find for the '52 -> '54 were poor, I hand-traced and made my own. I tried to make it look as close as possible to the original schematic.

Jack

Very nice! much better than the barely legible schematics for many Gibsons out on the web. FWIW some of the scans of original Gibson schematics on "The Tube Amp Book" CD are better quality than what I've seen at various web sites including Gibson's.