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Gibson's Western Frontier: The 1955 - 1958 GA-70 Amplifier

Gibson's Western Frontier:  The 1955 - 1958 GA-70 Amplifier

Is the Gibson GA-70 the coolest vintage amp of all time?

The year 1955 was a big one for country music. The charts were dominated by the likes of Webb Pierce, Eddy Arnold and Hank Snow. The classic song “Sixteen Tons” by Tennessee Ernie Ford rode to the top of the charts and the Sun gang from Memphis—Elvis Presley, Carl Perkins, and Johnny Cash—was just getting started with regional hits that would soon sell across the nation. And as music began dominating popular culture, the airwaves were filled with the sweet sounds of twangy six-strings.

The Sincerest Form of Flattery

To get those kinds of sounds, guitars gotta have amps, of course—and not just any old amps. To twang, you need the right unit. In the mid-1950s, Leo Fender and his tweeds all but dominated the market in terms of treble response. Most of the country, rock, and rockabilly players were using Fender Twin, Bassman, or Pro amps. Gibson, seeing the possibilities of the niche, responded with a new amp that was a significant departure from the smooth-sounding brown boxes it had been producing since the end of World War II. That amp was the GA-70 Country Western, and it was produced between 1955 and 1958.

While Gibson shipping records indicate that one unit shipped in 1955—most likely it was a sample to corporate parent Chicago Musical Instruments (CMI)—the GA-70 was formally introduced in the 1956 full-line catalog. The most immediately striking feature of the GA-70 was its cabinet. It stood 22-1/2" wide by 20- 1/2" high and 10-1/2" deep. It had a brown-and- tan, buffalo-grained fabric covering and a rectangular speaker opening that extended from the bottom of the amp to the top and was flanked by two solid panels. At the top of the speaker opening, glued onto the woven saran grille, was a brown bakelite badge with the Gibson logo and a suede steer head. The western theme continued on the control plate, where a silk-screened lariat outlined the edge of the chromed panel. Like other Gibson cabinets of the time, the front, sides, and bottom were 1/2" solid wood, while the top panel was of denser plywood. Robert Chwaliszewski of Buffalo Amplifiers has both restored and built replicas of dozens of ’50s Gibson amps, and he believes the GA-70 cabinet contributed directly to the tone of the amp. “The shape of the cabinet, the panels on the front, the height, the materials—all those things gave the GA-70 a unique tone and a lot more oomph out of that Jensen.”

Mint 1955 GA-70 "Country and Western" amp.
The first series GA-70 was called “Country and Western” in the 1956 catalog, and it was almost a direct clone of the 1955 Fender Pro. The tube complement consisted of two 6L6s in the power section; a 12AU7, a 12AY7, and a 7025 in the preamp section; and a 5V4 rectifier. Series one also had beefy transformers and ran very hot at the plates—around 475 volts. Other similarities to the Pro included three knobs (not including the power knob)— Instrument Volume, Microphone Volume, and Tone—two inputs each for instrument and microphone, and a 15" Jensen P15N Concert Series speaker. The amp was cathode bias and used a paraphase inverter. Like the Pro, the GA-70 had sufficient power and volume to play in a band setting. It had clear highs, tight lows, and a tendency to break up early.

Cessation of Imitation
The 1957–58 version of the GA-70 was a totally different animal—and it was possibly the best, most influential (albeit indirectly) amp Gibson ever made. Its name was changed to the “Country Western,” and the new GA-70 looked almost the same as the first series, despite the fact that it had a completely redesigned circuit. It used two slightly more robust 5881 power tubes and a cathode phase inverter, and they gave it more headroom and a wider dynamic range than the ’56 version. The addition of a power choke helped keep the current stable and also contributed to the increased headroom. The new GA-70 also had a five-knob control layout with a tone stack of Bass, Treble, and Fidelity controls along with the two Volume controls. Significantly, this tone stack was copied almost exactly by Vox for the classic AC30 design—right down to a “mistake” in the fidelity control. For some reason, on the GA-70 the treble wipers were wired 180 degrees in reverse, with the result being less treble as you turned the control clockwise. Making the best of this anomaly, Vox would come to call this a “Cut” control.

Rear views of 1955 (left) and 1958 (right) Gibson GA-70s.

The 1958 Gibson catalog described the work of the tone circuit as follows:

A separate control has been provided for control of the bass or low frequencies and for the treble or high frequencies. The use of these two controls allows the player to obtain the maximum combinations from a beautiful clear treble to a deep resonant bass. Setting the “BASS” control at maximum and the “TREBLE” at minimum, produces the deepest, fullest bass tone. Setting the “TREBLE” control at maximum and the “BASS” at minimum produces a chime-like tone rich in higher harmonics and will enable the artist to pick harmonics with greater ease. When both “BASS” and “TREBLE’’ controls are set at minimum the middle register predominates.

To modern ears, the ’57–’58 five-knob GA-70 has some of the best tone, response, and range of any vintage amp you’re going to hear. While it has more power than the first series, at 35 peak watts the five-knob won’t fill a room like a blonde Vibrasonic, which has 40 full watts. But what it lacks in overall volume it makes up for in tone. Plug in any P-90- equipped guitar and you get a growling, perfectly twangy tone reminiscent of Link Wray. With a single-coil-outfitted guitar, the GA-70 plays clean and scooped, with beautiful high-end response. Fully cranked with either of the above guitars, it yields creamy sustain, overdrive, and crunch—almost like a Marshall. And the tone controls are wonderfully dynamic, which means you can find a number of pleasing settings across the spectrum.

A Short-Lived Legend
In all, 160 first-series Country and Western units were built, while only 172 Country Westerns ever saw the light of day before the GA-70 was discontinued at the end of 1958. It seems Gibson couldn’t sell the buying public on the concept of twang coming from Kalamazoo. But with a superlative tone and amazing retro looks, the GA-70 Country Western gets my vote for coolest amp of all time.

Thanks to Robert Chwaliszewski of Buffalo Amplifiers and Russell DuFresne of Savage Audio.