A "New" old amp followed me home today too!

tiller · March 24th, 2005, 09:03 PM

I aquired a circa 1964 Gibson GA8T Discoverer Tremolo Amp today in a trade for an old single shot shotgun that was givin to me. The fellow told me that the amp lost volume after it was first turned on. Upon getting it home I tossed in a couple of EL-84,s I had around and fired it up. Wow! This thing has a clear and open sound and remains pretty clean till about 8 on the volume. After 8 it gets a very full low gain style overdrive that is super responsive to picking dynamics. It has a strange tube compliment in like a lot of old Gibson amps, 2x6EU7 preamp tubes(the second might be the phase inverter),2xEL84 power tubes and a 6CA4 rectifier tube. It has a Jensen blue label 12inch speaker and it loves my 52RI and my 72RI thinline equally well. This amp is rated at 15 watts and I cannot wait to take it to rehersal or some blues jams. Information on these old Gibson amps is a bit spotty on the internet and Gibson apparently made all kinds of changes on models of the same name over it's production life. Some versions of this model have a 12AX7 and 6V6 tubes and i would love to hear one of those. I think this new "toy" is gonna keep me smiling for a while!

jhundt · March 25th, 2005, 02:58 AM

it was given to me many years ago, and it started me on the road to tube amp madness. Mine is called a Discoverer but has no tremelo. I tried to figure out the circuit (with absolutely NO electronics knowledge or background). I was really stumped because it didn't resemble any diagram I could find, then I realized that the two 6V6s are wired in parallel, NOT push-pull like 99.9% of multiple-tube guitar amps. So it's like a Champ but with two tubes. I confirmed this observation when I found a diagram for a Gibson Gibsonette amp. I really liked the sound, but switched to a tweed Deluxe after a while. I think Gibson changed circuits, tube types, and model names quite freely back then.

Flipped Mustang · March 30th, 2005, 09:43 PM

I can't imagine Gibson making a U.S. amp in the 60's using EL84's. Does the amp have a tube chart or markings on the chassis with the tube I.D.'s? It could've been modded to use El84s (which would be a pretty cool mod) :)
Rich

trag-o-caster · March 30th, 2005, 10:37 PM

Quote:

Originally Posted by Flipped Mustang

I can't imagine Gibson making a U.S. amp in the 60's using EL84's. Does the amp have a tube chart or markings on the chassis with the tube I.D.'s? It could've been modded to use El84s (which would be a pretty cool mod) :)
Rich

I think that Gibson made the very first guitar amp to use the EL84's ever, with the 79RVT, or whatever it's called. I believe those were from the late 50's-early 60's. They had strange V shaped front. Cool lookin' amp that's now one of the more sought after collectables nowdays.

Flipped Mustang · March 31st, 2005, 02:15 AM

Interesting! Thanks for the information. Were the amps made in the U.S.? I wonder why they would use British style valves. Maybe they bought a big batch on the cheap.

P.S. Just did an internet search and found a '66 Gibson Skylark that used El84s also.

I'll be darned! Just when you think it's all making sense :)

Poppatwang · March 31st, 2005, 09:56 AM

I've got an old Epi amp made by Gibson. Has a single
EL82 for power. Two knobs. One for volume & the
other for tremelo intensity. One of life's simple pleasures.

tiller · April 1st, 2005, 10:12 PM

I've had the GA-8T for a week now an I love just as much as when I first fire it up. Tommorow I'll be taking it to band rehersal and can't wait to see the looks this thing will get. Most of the information I got on this amp and dating it came from a site called "Holiday for Strings". I have seen one on sale at Gbase for $350.00. I've not been able to find a schematic for the EL-84 circuit that I have, only the 6V6 version. As stated in my original post Gibson was all over the map on the configuration of their amps vs. Fender who was much more documented and conservative in design.

March 24th, 2005, 09:03 PM	#1 (permalink)
tiller TDPRI Member Join Date: Apr 2003 Posts: 35	A "New" old amp followed me home today too! I aquired a circa 1964 Gibson GA8T Discoverer Tremolo Amp today in a trade for an old single shot shotgun that was givin to me. The fellow told me that the amp lost volume after it was first turned on. Upon getting it home I tossed in a couple of EL-84,s I had around and fired it up. Wow! This thing has a clear and open sound and remains pretty clean till about 8 on the volume. After 8 it gets a very full low gain style overdrive that is super responsive to picking dynamics. It has a strange tube compliment in like a lot of old Gibson amps, 2x6EU7 preamp tubes(the second might be the phase inverter),2xEL84 power tubes and a 6CA4 rectifier tube. It has a Jensen blue label 12inch speaker and it loves my 52RI and my 72RI thinline equally well. This amp is rated at 15 watts and I cannot wait to take it to rehersal or some blues jams. Information on these old Gibson amps is a bit spotty on the internet and Gibson apparently made all kinds of changes on models of the same name over it's production life. Some versions of this model have a 12AX7 and 6V6 tubes and i would love to hear one of those. I think this new "toy" is gonna keep me smiling for a while!

March 25th, 2005, 02:58 AM	#2 (permalink)
jhundt Friend of Leo's Join Date: Mar 2003 Location: Netherlands Age: 54 Posts: 3,127 9 Photos	I have one w/ 6V6s it was given to me many years ago, and it started me on the road to tube amp madness. Mine is called a Discoverer but has no tremelo. I tried to figure out the circuit (with absolutely NO electronics knowledge or background). I was really stumped because it didn't resemble any diagram I could find, then I realized that the two 6V6s are wired in parallel, NOT push-pull like 99.9% of multiple-tube guitar amps. So it's like a Champ but with two tubes. I confirmed this observation when I found a diagram for a Gibson Gibsonette amp. I really liked the sound, but switched to a tweed Deluxe after a while. I think Gibson changed circuits, tube types, and model names quite freely back then.

March 31st, 2005, 09:56 AM	#6 (permalink)
Poppatwang Tele-Afflicted Join Date: Mar 2003 Location: St. Paul, MN Posts: 1,909 13 Photos	Epiphone Pacemaker I've got an old Epi amp made by Gibson. Has a single EL82 for power. Two knobs. One for volume & the other for tremelo intensity. One of life's simple pleasures. __________________ The Dieselfitters http://www.dieselfitters.com Roy Hubbs http://www.royhubbs.com

April 1st, 2005, 10:12 PM	#7 (permalink)
tiller TDPRI Member Join Date: Apr 2003 Posts: 35	After a week of ownership I've had the GA-8T for a week now an I love just as much as when I first fire it up. Tommorow I'll be taking it to band rehersal and can't wait to see the looks this thing will get. Most of the information I got on this amp and dating it came from a site called "Holiday for Strings". I have seen one on sale at Gbase for $350.00. I've not been able to find a schematic for the EL-84 circuit that I have, only the 6V6 version. As stated in my original post Gibson was all over the map on the configuration of their amps vs. Fender who was much more documented and conservative in design.

March 30th, 2005, 09:43 PM	#3 (permalink)
Flipped Mustang Tele-Meister Join Date: Mar 2004 Location: Nor Cal Posts: 312	I can't imagine Gibson making a U.S. amp in the 60's using EL84's. Does the amp have a tube chart or markings on the chassis with the tube I.D.'s? It could've been modded to use El84s (which would be a pretty cool mod) :) Rich

March 31st, 2005, 02:15 AM	#5 (permalink)
Flipped Mustang Tele-Meister Join Date: Mar 2004 Location: Nor Cal Posts: 312	Interesting! Thanks for the information. Were the amps made in the U.S.? I wonder why they would use British style valves. Maybe they bought a big batch on the cheap. P.S. Just did an internet search and found a '66 Gibson Skylark that used El84s also. I'll be darned! Just when you think it's all making sense :)