Gibson Schematics

GA-1RT Maestro Reverb-Echo, 8W 1×8″ Combo

With reverb-echo.

Schematic with 1x 12AX7, 1x 6BM8 & 1x 5Y3GT, (Gibson).

GA-1RVT Maestro Reverb-Echo, 8W 1×8″ Combo

With reverb-echo and tremolo.

GA-2RVT Maestro Deluxe Reverb-Echo, 16W 1×12″ Combo

With reverb and tremolo.

Schematic with 4x 6EU7, 1x 12AU7A, 2x 6V6GT & 1x 5Y3GT, (Gibson).

GA-3RV Reverb III

All transistor pre-amp with reverb and tremolo.

Schematic, (Gibson).

GA-4RE Reverb Echo

Pre-amp with reverb.

Schematic with 2x 6EU7 & 1x 12AU7, (Gibson).

GA-5 Les Paul Junior, 5W 1×10″ Combo

The Gibson amplifier model GA-5 has had many incarnations. The first model GA-5 Les Paul was introduced in 1954. The circuit of this amp is an almost identical copy of the Fender Champ (5C1 circuit). It was fitted with a Jensen 10″ field coil speaker. It had a “TV” style cabinet.

Schematic with 1x 6SJ7, 1x 6V6 & 1x 5Y3, (Gibson).

Schematic with 1x 6SJ7, 1x 6V6 & 1x 5Y3, (Joe Piazza).

Schematic of Fender 5C1 Champ Amp, (Fender Musical Instruments).

GA-5 Skylark, 5W 1×8″ Combo

GA-5T Skylark Tremolo, 5W 1×8″ Combo with Tremolo

The GA-5 Les Paul was renamed to Skylark in 1957. This Skylark lasted till 1961. The 10″ speaker was changed to an Jensen 8″ ‘special design’ speaker. The input circuitry was changed too. In 1962 the Skylark underwent a major redesign.

Schematic with 1x 12AX7, 1x 6V6 & 1x 5Y3 (1957), (Joe Piazza).

Check out John King’s GA-5 page if you’re looking for more info on the GA-5 amps.

GA-6

This amp is very similar to the Fender Tweed Deluxe (5C3).

GA-6 Lancer, 14W 2×12″ Combo

This amp replaced the BR-6. The circuit is identical to that of the GA-14.

Schematic with 2x 12AX7, 2x 6V6 & 1x 5Y3.

GA-7 Les Paul TV, 4W 1×10″ Combo

Introduced in 1955/56. It used the same circuit as the GA-5 Les Paul Junior amp.

GA-8 Gibsonette, 9W 1×10″ Combo

Photograph of a 1952 Gibsonette.

GA-8 Discoverer, 9W 1×10″ Combo

There were at least two different models GA-8 Discoverer.

GA-8T Discoverer Tremolo, 9W 1×10″ Combo

The first GA-8T was in production from 1954 upto 1961. It was covered with tweed, and used a 12AX7, two 6BM8 triode/pentode tubes and a 5Y3 rectifier. The second GA-8T was part of the
Crest Line range of amps and was in production from 1962 upto 1966 and used two 6EU7’s, two 6BQ5 pentodes and a 6CA4 rectifier. This was the same amp as the Epiphone EA-35T Devon.

Schematic of the first GA-8T with 1x 12AX7, 2x 6BM8 & 1x 5Y3.

Photograph of 1962 GA-8T Discoverer Tremelo.

GA-9, 10W 1×10″ Combo

This amp replaced the BR-9. It used a 6SJ6 pentode on the input, two parralled 6V6 tubes as a single ended power amp and 5Y3GT rectifier.

GA-14 Titan, 14W 1×10″ Combo

The circuit of this amp is identical to that of the GA-6 Lancer and the Epiphone EA-30 Triumph amp.

GA-15 Maestro, 14W Amp

This amp was introduced in 1955.

Schematic.

GA-15RV Maestro, 14W 1×12″ Combo

GA-15RVT Explorer

With reverb and tremolo. This is the same amp as the Epiphone EA-32RVT.

Schematic.

GA-16T Maestro Viscount, 14W 1×10″ Combo

Schematic.

GA-17RVT Scout

Schematic.

GA-18T Explorer, 15W 1×12″ Combo

With tremolo.

GA-19RVT Falcon

Schematic.

GA-20 Crest, 14W 1×12″ Combo

This amp was introduced in 1950. This amp is almost identical to the Epiphone EA-25 Century amp.

Schematic.

GA-20T Ranger, 16W 1×12″ Combo

This amp was introduced in 1956. With tremolo. This amp is almost identical to the Epiphone EA-25T Century amp.

GA-20RVT MinuteMan

With reverb and tremolo.

Schematic.

GA-25, 15W 1×12″ & 1×8″ Combo

This amp was introduced in 1947.

Schematic (1961) (Gibson).

GA-25RVT Hawk, Combo

Schematic (1963).

GA-30 Invader, 14W 1×12″ & 1×8″ Combo

This amp was introduced in 1948.

Schematic with 2x 6SJ7, 1x 6SC7, 2x 6V6 & 1x 5Y3

GA-30RV Invader, 14W 1×12″ & 1×8″ Combo

This amp was fitted with a P12R and a C8S speaker. It had a reverb. It used 3x 6EU7, 1x 12AU7, 2x 6V6 and 1x 5Y3 tubes.

GA-30RVT Invader, 25W 1×12″ & 1×10″ Combo

With reverb and tremolo.

GA-30B

Schematic.

GA-35RVT Lancer

With reverb & tremolo.

Schematic.

GA-40 Les Paul, 14W 1×12″ Combo

This amp was introduced in 1952. With tremolo. The speaker is a 12″ Jensen Concert.

GA-40T Les Paul, 25W 1×12″ Combo

This amp was introduced in 1955. With variable tremolo.

GA-45RV Maestro, 16W 4×8″ Combo

This amp was introduced in 1955. With reverb.

Schematic with 3x 6EU7, 1x 12AU7A, 2x 6V6GT & 1x 5Y3GT (courtesy of Keith Robb).

Photograph (courtesy of Keith Robb).

GA-45RVT Saturn?

With reverb and tremolo.

GA-45T Maestro, 16W 4×8″ Combo

This amp was introduced in 1955. With tremolo. It is essentially a GA-40 with a bass & treble tone control and a different speaker configuration.

GA-46T Super Maestro, 60W 2×12″ Combo

With tremolo.

GA-50, 1×12″ & 1×8″ Combo

This amp was introduced in 1948.

GA-50T, 1×12″ & 1×8″ Combo

With Tremolo. This amp was introduced in 1948.

GA-55, 18W 2×12″ Combo

This amp was introduced in 1954.

Schematic with 2x 12AY7, 1x 6SC7, 2x 6L6GA & 1x 5V4G.

GA-55V, 18W 2×12″ Combo

With vibrato. This amp was introduced in 1954.

GA-55RVT Ranger, 50W 4×10″ Combo

With reverb and tremolo.

GA-60 Hercules, 25W 1×12″ Combo

GA-70 Country Western, 25W 1×15″ Combo

This amp was introduced in 1955/56. It was fitted with a Heavy Duty Jensen 15″ Concert speaker with an Alnico V magnet.

GA-75 Recording, 25W 1×15″ Combo

This amp was introduced in 1950.

Schematic with 2x 6EU7, 1x 6C4, 1x 6FQ7 & 2x 6L6GC.

GA-77 Vanguard, 25W 1×15″ Combo

With a “high gain” channel.

Schematic.

GA-77RV Vanguard, 25W 1×15″ Combo

With reverb and high gain channel.

GA-78RV Maestro 30, 2x15W 2×10″ Combo

With reverb.

GA-79RV Stereo-Reverb, 2x15W 2×10″ Combo

With reverb and high gain channel.

GA-79RVT Stereo-Reverb, 2x15W 2×10″ Combo

With reverb, tremolo and high gain channel.

GA-80 Vari-Tone, 25W 2×15″ Combo

With improved tremolo and 6 preset tone control switches.

GA-83S Stereo-Vib, 2x18W 1×12″ & 4×8″ Combo

With stereo vibrato.

GA-85, 25W 1×12″ Combo

GA-86 Ensemble, 25W head with 1×12″ Cabinet

With removable control panel.

GA-87 Maestro Stereo, 2x18W 2×12″ Combo

Stereo accordion amp with reverb.

GA-88S Stereo Twin, 2x18W 2×12″Combo

GA-90, 25W Combo

This amp was introduced in 1953.

GA-100 Bass, 35W Head with 1×12″ Cabinet

The control panel is seperated from the speaker cabinet. This is the same amp as the Epiphone EA-70 Bass amp.

GA-200 Rhythm King, 60W 2×12″ Combo

Two channel high fidelity sound with built in compression circuit to prevent overloading.

GA-Super 400, 60W 2×12″ Combo

Three channel high fidelity sound with built in compression circuit to prevent overloading.

Check out Björn Anger’s The Gibson Amp Project site with lots of information on a lot of old Gibson tube guitar amps.

Check out John King’s GA-5 page if you’re looking for more info on the GA-5 amps.

Check out Gibson’s schematics page if you’re looking for more Gibson schematics.

If you want to see what Gibson is up to nowadays, you might want to check out the official Gibson site.