may 2010

Vox''s least documented amp

Usually, when we refer to gear using the word “mystery,” it’s because we don’t know what the hell it is. But in the case of this Vox, it’s because it truly is a Mystery. Some refer to it as the “AC 20,” but Jim Elyea, author of VOX Amplifiers: The JMI Years, coined the name Mystery Amp.

Several of these apocryphal amps have been found, but none of them have had a matching serial-number plate. They may have been produced by JMI, or they may have been assembled from leftover parts by an unknown person. To quote Elyea, “All we know is that we don’t know.”

Here’s what we do know: The amp has three Goodman 10" speakers, each of which is marked with a red band around the magnet, and they’re set in a lightweight enclosure. This particular amp has many unique features, including an AC10 reverb circuit, a Parmeko transformer, a silkscreened front panel (some versions reportedly have anodized copper panels), and a chassis that’s not cut for a vibrato circuit. Its controls include Volume, Tone, Speed, Depth, and Reverb. It also has two inputs and a voltage selector.

Anyone have more information on this oddity?

Let us know!

Thanks to Rick and Randy of Guitar Hangar for listing this on Gear Search! Whether you’re looking for a vintage piece or a modern take on a classic, chances are it’s on Gear Search. More than 47,000 pieces of gear are listed here, including some of the hardest-to-get gear in the world.

Gibson''s short-lived, larger bodied SG made an appearance in the early ''70s

Dear Trash or Treasure:

This odd Gibson guitar was purchased sometime in the 1970s and, as far as I can tell, is all original. I think it is an SG because of the body style, but I have never seen another one like it with these pickups. I have the original case, but the bridge cover appears to be missing. The serial number is 972190 and it has “Made In USA” and a “2” stamped under the number. I’m not planning on selling this guitar, but I would like to know what it is and what it is worth.

Silver Spring, Maryland

Hey, Woody.

You’re right, this is an SG. And there’s a reason you don’t see many of these guitars: the SG-100, SG-200, and SG-250 were only produced for a little over a year in the early 1970s! Many Gibson enthusiasts agree that the 1970s were a dark period for Gibson guitar production, and most players and collectors don’t seek out these guitars. However, the SG continues to be a successful guitar for Gibson, and many performers have used them, including Tony Iommi, Pete Townshend, and, most notably, Angus Young of AC/DC.

The SG body style goes back to 1958, when Gibson redesigned the Les Paul Junior with its first-ever double-cutaway solidbody. At the time, the single-cutaway Les Paul wasn’t selling as well as Gibson had hoped, so the company planned to apply this new rounded double-cutaway style to the entire line. By 1960, the Junior and Special were renamed as SGs, which stood for “solid guitar.” According to folklore, SG was a temporary term for the body style, but Gibson never came up with another name and SG stuck.

In late 1961, Gibson introduced a different double- cutaway with pointed, beveled bouts that became the SG body style we know today. This new body style was applied to all Les Paul models available at the time, and they were labeled Les Pauls until 1963, when Gibson and Les Paul temporarily parted ways. Paul was never too crazy about the new design of the Les Paul model, and he didn’t renew the contract to use his name on three of Gibson’s guitars. In 1968, the Les Paul was reintroduced with the traditional single-cutaway design, but Gibson continued production of the SG as well. Ted McCarty left Gibson in 1966, which is widely known as the start of a downhill slide in Gibson’s production quality. By the 1970s, Gibson was beginning to experiment in research and development, and your guitar is a product of this experimentation.

Gibson discontinued the Melody Maker series in 1970 and replaced it in late 1971 with three new SG models, all sharing the same body and features: the SG-100, SG-200, and SG-250. Gibson steered away from traditional designs in these guitars, using a slightly larger body shape, no neck pitch, and single-coil pickups. Looking back, all these new features were essentially downgrades. While the body became more durable with maple construction, it was heavier and bulkier to play. The fingerboard, strings, and top of the body became parallel with each other, resulting in a high action over the body. The single-coil pickups sounded thin and tinny compared to humbuckers and P-90s. This new series wasn’t very well received and was quickly replaced in late 1972 with the SG-I, SG-II, and SG-III.

The SG-100, SG-200, and SG-250 all share these common features: maple body (mahogany has also been observed), set maple neck, 22-fret rosewood fingerboard with dot inlays, black headstock overlay with gold Gibson logo, three-per-side Kluson tuners with small buttons, Tune-o-matic bridge with an odd connected base plate and bridge cover, single-coil Melody Maker-style pickups with black covers inscribed with “Gibson,” and an angled control plate with Volume and Tone knobs. The SG-100 has a single pickup and was available in cherry or walnut finish. The SG-200 has two pickups with two slide switches and was available in black, cherry, or walnut finish. The SG-250 is identical to the SG-200 in electronics and construction, but features a cherry sunburst finish.

According to Gibson’s shipping records, just over 5,000 SG-100, SG-200, and SG-250s were shipped during their short production in 1971 and 1972. Serialization is not a very useful dating tool from this era, but it is likely that your guitar was made in 1971. A total of 2,448 SG-200s were produced in walnut finish, but only 23 were shipped in 1972. The “2” under the serial number indicates that the guitar was a factory second, meaning there was a flaw in the wood or finish. Instead of discarding the guitar, Gibson sold it at a discounted price with a full factory warranty. Today, your guitar is worth between $800 and $1000, as it appears to be in excellent condition. The SG-200 is not valued nearly what some of Gibson’s classics are today, but it is a Gibson nonetheless and an important part of their heritage and history. Perhaps more collectors and players will take notice of this guitar as the ’50s and ’60s models become more rare and expensive.

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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.