On November 29, the 10th anniversary of George Harrison’s death, Bonham’s in London announced the chance discovery of a rare Vox UL730 once owned by the former Beatle. Said to have been used in the Revolver and the Sgt. Pepper recording sessions, the auction house intends to offer the rare amplifier for sale at their Entertainment Memorabilia auction on December 15.

How does anybody know it was Harrison’s? Because his name, much in the way your mom used to write your name in the collar of your rain coat with magic marker is scratched into the amp’s metal chassis, a finding that was made by sheer accident.

In February the amplifier, favored for a sound unique only to that particular design had been loaned to Joy Division’s Peter Hook for a recording project by its current owner who has thus far remained anonymous. But the 45 year old amp broke down and was sent out for repair, and it was on the workbench that the discovery of past ownership was made. The repairman poked around inside some more and found another label with Harrison’s name on it and after that, the search for hard provenance was on.

Photos of the Beatles in the studio with that very amp were found (dings and chalk markings on the actual cabinet and on the one in pictures were used to verify,) and a friend of Harrison’s later vouched that the amplifier was indeed what it appeared to be.

Bonham’s, an auction house that dates back to the 1700s, thinks bidding for the amplifier may exceed $100,000 dollars. But Greg Dorsett says it will fetch much more. Exactly how much more, he can't say.

“In this market, I don’t know. A few years ago I could have told you, but right now I don’t know. It will be very interesting to see what happens with this amp.”

Dorsett, an ex-roadie, founded San Diego-based Rock Stars Guitars in 1996 with a London record producer and Hendrix afficionado named David Brewis. Rock Stars Guitars is bi-national; Brewis lives in the U.K., and Dorsett lives in the San Carlos area. The two deal exclusively in collectible guitars, amps, and tour gear.

In their private collection is Harrison’s 1964 Gibson SG Standard, a guitar seen in both the “Paperback Writer” and “Rain” videos, and that was played live at the Beatle’s final U.K. concert. It is likely that Harrison played that very guitar through the UL730 to be auctioned, if indeed it was his. The key to authentication of the amplifier, Dorsett says, lies in the provenance.

“If this is the actual Vox UL730 used by George Harrison on sessions for Revolver and Sgt. Pepper, this would have to be one of the most coveted and most valuable amplifiers in existence.”

Harrison would not have brought this amplifier to San Diego in 1965 when the Beatles played Balboa Stadium on August 28; UL730’s weren’t made available to the mop tops until the following year. More likely, Harrison played through a Vox AC30 on that night, the amplifier that was the sound of the British Invasion.

With dual Celestion speakers and something Vox called Top Boost circuitry, AC30’s were not as loud as their competitor, the Fender Twin, but they made up for it in tone and were used by the Stones, the Yardbirds, the Kinks, and most famously, the Beatles. Vox sponsored the Beatles from 1963 through 1966, and some rock historians think that several UL730’s were given to the Fab Four in 1966.

But John and Paul favored the wallop of the much larger Vox Super AC 100, a version of which was marketed in the U.S. as the Vox Super Beatle. For years, the Heartbreakers’ Mike Campbell and Tom Petty used Super Beatles on the road, along with much less powerful Fender Princetons and Vox AC30s, more so in later years when Campbell admitted to a reporter that he and Petty were no longer capable of singing over the sheer volume of the Super Beatles. Alas, the big cabinets became little more than road props.

With or without Harrison's past ownership the Vox UL730 in and of itself is an extremely rare item. In the late 1960s, the UL700 series represented the latest in solid-state technology combined with tube power and was intended to replace the AC15 and the AC30. But even with the Beatles’ backing they never sold well and what few were manufactured were subsequently taken off the market.

Actually, the phrase taken off the market is somewhat misleading. Vox is said to have destroyed close to 100 of the UL700 series amps that were returned to the factory, and it is estimated that there are fewer than 25 UL730 amplifiers in existence today. (I was only able to find one such amp listed online for sale. The asking price was not posted, and the seller could not be reached by press time.)

But one wonders why Harrison, who clearly did not have to pay for his equipment via the Vox endorsement would have felt the need to carve his name as proof of ownership inside of a speaker cabinet. Was he a compulsive labeler? Did he scratch his name into many other such secret places? Or, did a guitar tech, or John, or Paul, or even Ringo do it unbeknown to Harrison? Whatever the truth may be, we will possibly never know. But Greg Dorsett says it is not uncommon for musicians to identify their gear with paint or Dremel tools.

“I’ve seen it in the past, on certain guitars. I have seen things written inside cavities and amps before.”