Gibson GA-20

Gibson GA-20
Photos: Dave Ellis. Amp courtesy of Warren Hein.
• Preamp tubes: two 12AY7, one 12AX7.
• Output tubes: two 6V6, cathode-bias.
• Rectifier: 5Y3
• Controls: volume for each channel, shared tone.
• Speaker: Jensen Special Design P12R.
• Output: approximately 16 watts RMS.

Behold, this specimen that checks off all the right boxes for fans of vintage amps; beautifully clean, it has a watertight provenance and emerges from a heart-warming backstory. If we love anything more than a musty old tube amp in outstanding condition, it’s a musty old tube amp with a stirring history – a tale that takes us rapid-rewind style from the present day back to a time in the mid ’50s, when this Gibson GA-20 was first bought, played, and loved.

Add the fact the 1954 Gibson ES-175 that was purchased right along with it by this amp’s original owner is featured in Dan Erlewine’s “Dan’s Guitar Rx” column this issue and, well, this is something to get excited about.

Warren Hein, 77, of Joppa, Maryland, purchased this GA-20 and the accompanying ES-175 at a store in Baltimore in 1954, and made good use of the pair until he was drafted into the Army in ’57, when he stored them in his bedroom closet and set off to serve his country. After his discharge in 1960, life “got real,” as they say, and his earlier adventures in music remained on the back burner. Work and family kept Hein busy, and the years rolled by until one day recently when he took a notion to drag his old pals out of storage. What he found were two vintage Gibson pieces in impressive condition, but in need of a little repair and freshening up after their long hibernation. Hein then had a fortuitous encounter with vintage amp enthusiast and repairman Dave Ellis of nearby Bel Air, Maryland.

Gibson GA-20“I stopped in at [a consignment shop owned by Warren and his daughter] to see if they might have any old amps, radios, or stereos I could buy to work on,” Ellis said. “Conversation led to music equipment, and Warren mentioned that he had a Gibson guitar and amp that were in disrepair. He was beginning to experience problems with arthritis in his hands, and I asked if I could get the guitar and amp repaired [so he could] use them to keep his fingers flexible.”

Ellis picked up the set, got a willing Dan Erlewine in on the guitar repair, and set about servicing the 59-year-old GA-20.

Gibson made the GA-20 in various configurations between 1950 and ’61, with this two-tone rendition in buffalo-grain with woven Saran grille appearing from ’54 to ’59 (the only real visual alterations in that span being the loss of the “20” from the front logo and changes in the input legends in the final two years). Generating approximately 16 watts from a pair of 6V6s in cathode bias sparked up by a 5Y3 rectifier with a 12AY7 in each of the two channels and a 12AX7 in the phase-inverter slot, this 1×12″ combo sat either at the lower end of Gibson’s professional-grade lineup or (depending on how you look at it) the upper end of its student range. Either way, it was a head-to-head rival for Fender’s similarly powered and proportioned Deluxe, and did pretty well at the effort, with 949 sold the year Hein bought his. If you keep a weather-eye on vintage amp listings, you get the impression that a fair number of them are still doing service in the field, too – no major surprise once you check out the quality workmanship and components found inside.

Gibson GA-20
The Cornell-Dubilier “Grey Tiger” tone and coupling capacitors seen here would fade from use the following year.
Being sympathetic to non-invasive amp restoration, Ellis took great care in bringing the GA-20 back to life. Had it been played regularly throughout the intervening five and a half decades, there’s a chance it would have kept chugging along pretty well, but the repairman knew he’d need to be careful with the long-untested electrolytics, in particular. After trying (and failing) to bring them up to voltage with a Variac (because they were dried out), Ellis found it necessary to replace the filter caps – no surprise in an amp of this age. He did, however, manage to retain all the delectable Cornell-Dubilier “Grey Tiger” tone and coupling caps, which Gibson used in guitars and amps before switching to yellow Astrons in amps in ’56, and Bumblebees and Sprague Black Beauties later in the decade (the photos here were taken by Ellis prior to the restoration, and show the amp in its original state). Ellis also replaced a few resistors where necessary with new carbon-comp types, replaced the crumbling 200-ohm “dog bone” cathode-bias resistor with a new five-watt ceramic 220-ohm resistor (which would actually keep the amp operating more to spec with today’s higher-mains AC voltages), fabricated a new spacer for the pilot light, cleaned and re-tensioned the tube sockets and inputs, added a properly grounded three-prong cord, reconfigured the input grounding to take the guitarist out of any potential electrocution loop(!), replaced the deteriorating leather handle, and performed a few other items of routine old-amp upkeep. It all sounds like a lot, perhaps, but the work introduced nothing out of spec to alter the sonic character or original appearance of the amp, while keeping it playable – just as it should be.

All fired-up and running again, this little GA-20 has a rich, round tone when played clean, and one that’s perhaps a little warmer than its familiar Fender counterpart. Cranked into mild overdrive (a condition Gibson would have considered out of spec back in the day), it becomes reedy and meatily twangy with single-coils, creamy and thick with humbuckers. The original Jensen P12R speaker sounds great, Ellis reports (though the amp would gain headroom and girth with a replacement P12Q or P12N or any of a range of Celestion options, while also saving the vintage P12R from the grave).

Top to bottom, then, this a sweet and satisfying restoration, and a happy tale of the kindness and generosity of strangers… or, strangers who easily become friends. And we can’t wait to hear how the GA-20 greets the ES-175 when that connection is re-established.


This article originally appeared in VG July 2014 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.