Shopping Cart


Your shopping bag is empty

Go to the shop

1957 Gibson GA-20 Vintage Tube Guitar Amp 1x12 w/ Jensen P12Q


+ shipping

Up for sale, a 1957 Gibson GA-20 in excellent condition and in perfect working order. Featuring original two-tone cosmetics, a positively gleaming chrome faceplate, an era-correct Jensen P12Q speaker, and a very original and professionally serviced circuit, this GA-20 is the perfect mid-size combo from the golden age of tube amplification. In many ways analogous to Fender's narrow panel tweed amps of the same era, the GA-20 features a four input design with a 6V6 power tube pair, 5Y3 rectifier, and dual triode (12AX7, etc) tubes in the preamp.

Offering distinctly different voicings between the single Microphone input and the three Instrument inputs, the GA-20 is at its most aggressive via the Mic channel. While this input does offer a modicum of clean headroom, it quickly overdrives with a sizzling, chewy sound that's extremely smooth. The Tone control has an absolutely massive sweep, actually adding a bit more gain when turned up. Maxing out both Volume and Tone knobs yields a ripping, cutting sound that interacts equally well with single coils and humbuckers. The Instrument inputs have more range in the clean signal, with a full-bodied and sweet sound that works well with a host of effects pedals. Turning down the Tone knob on this channel and pushing the Volume can achieve a very nice bark and a spitty quality almost akin to certain fuzz boxes, depending on the guitar being used, and once again diming everything out delivers plenty of richness and roar.

The point-to-point circuit has been professionally serviced, and the preamp retains a trio of original yellow Astrons, the same capacitors used in Fender's narrow panel tweed circuits, and a key component in the musical nature of those preamps. There are a few modern Jupiter tubular caps in the preamp (which faithfully replicate the design and tonal properties of an Astron), and the power supply has been recapped with high quality F&Ts. The original output transformer is intact, and while it would have originally been mounted to the speaker frame, the transformer has been relocated to the chassis. The source-date code on the output transformer dates to the 14th week of 1957. The power transformer is a modern premium replacement courtesy of Mercury Magnetics, fitted with the original "GA-20"-embossed bell cover.

The speaker is an era-correct Jensen P12Q which has an extremely clean dark blue/green frame. While not original to the amp, the speaker has been fitted with the bell cover from the amp's stock Jensen speaker, complete with blue foil label. The date code on the edge of the frame dates this particular Jensen to 1950.

The original two-tone brown and fawn covering is remarkably clean, especially considering the fragility of this material compared to a conventional tolex or even tweed. The chrome plating on the faceplate is extremely nice, and the amp retains all of its original black silkscreen graphics. The gold Gibson badge is no longer present on the amp's face, and the luggage-style handle is present.