Hamer Quadraphonic 12-String Bass

The Hamer Quad Bass is the "Grand Daddy" of all 12-string basses. Quads were made between 1978 and 1981 and only nine of them have thus far been documented. They have a separate pickup for each of the 4 groups of strings. The top is ½" maple with a mahogany body and neck. There are pre-amp and tone controls in a recessed panel on the top for each of the group of strings' output. The Quad had a single truss rod. The classic body, neck and distinctive "Split V" headstock designs of the Quad were all subsequently incorporated into the model B12S.

This page documents all known Hamer Quadraphonic basses. Much of what is known about the Quads was provided by Jol Dantzig of Hamer Guitars, as well as their current owners. We are proud that we were the first to publish photos and information about four of the six known "12-Knob" basses, plus, we were first to report the differences between the original Quad and the 'Trade Show' Quad.

Tom Petersson of the band Cheap Trick is now forever linked with the 12 since he was the first bassist to play one. He has played the 12-string bass for 30 years including many different Hamer basses and those of several other brands. Hamer's contributions to the design, style and engineering of the instrument are usually overlooked, as are their subsequent improvements. It should be remembered that without Hamer's substantial initial contributions plus their continuing efforts to design new models and promote the instrument, the 12-string bass certainly would not have achieved its current standing with bassists worldwide.

The Prototype: 10-String Bass

The Prototype 10-string bass with pickguard added

"Getting back to Tom Petersson, we were going to make him an 8-string bass and he said 'Why don’t you make a 12-string bass?'  We thought there would be too much tension on the neck and it would be difficult to control. I think I may have come up with the compromise saying, 'Why don’t we just triple the D and G strings?' and we can get away with that tension as a half -way measure. Tom agreed and we built a 10-string for him. It was a solid maple bass with a double cutaway style and it had a cool color: Pepto Bismol pink! The 10-string bass worked so well and the neck was so easy to adjust that we thought maybe the neck could stand two more octave strings."  Jol Dantzig - 2001

1977 Hamer Pepto Bismol Pink 10-String Bass Guitar - Serial # Unknown

From a Triad Magazine article in 1977

Rick Nielsen and the 10-String Bass

The "12-Knob" Quads

"We went ahead with the 12-string bass and we wanted to make it stereo, and Tom asked if we could make it Quadra-Phonic, and we said sure. So we built it with a pickup for each of the groups of strings. They were special coiled pickups that looked like half Strat pickups. We asked Seymour Duncan to build a pickup with four outputs and we built a control box on the top portion of the body like a little mixing console / board. The crazier we could make it, the more outrageous… the better! Each group of strings had its own pickup, volume, treble boost and cut, bass boost and cut and a switch to select the frequency the EQ worked at. That bass ended up being refinished a few times. It went from a blonde / natural to an emerald green to finally black..."  Jol Dantzig - 2001

The "Original" 1978 Hamer Quad Bass - Serial # Unknown

This is the very first 12-string bass made. It was owned by and made for Tom Petersson of Cheap Trick and was first heard on the song Heaven Tonight on the Cheap Trick album of that same name. It's distinctive sound was made famous on Cheap Trick's best selling album At Budokan.



Tom Petersson playing the first Quad bass, plus a Hamer magazine ad with the same bass shown in the black finish. The black color soon faded to dark green. Tom reports that he still owns this bass.


Backstage before a Budokan show in 1978
Photo from a Japanese music magazine


1978 Hamer "Trade Show" Quad Bass - Serial # Unknown

After the original Quad bass was made, Hamer built this bass to display at music industry trade shows. It has been consistently mistaken for Tom's original Quad bass for many years. Here are a few differences between the basses:

The original Quad has a prominent dark streak in the upper portion of the maple top on the body. The "Trade Show" Quad does not have this streak and has a significantly different wood grain pattern.

The location of the single mini-toggle switch is different on each of the basses. It is below and between knobs on the Original quad, but is positioned to the right of the knobs on the Trade Show bass.

The "Trade Show" Quad has extra wording on the headstock beyond the Hamer logo. This is believed to read, "Quad Bass". The original Quad said only "Hamer".

The Trade Show Quad also appears to have a rosewood fingerboard rather than the ebony that was used on the original quad bass.

1978 Hamer Quad Bass - Serial # 0096

This bass is in the sunburst finish with an ebony neck. "Tom Petersson Quadbass" is on the headstock. The current owner bought this bass at a pawn shop. It is still a mystery as to how it ended up there.

1979 Hamer Standard Quad Bass - Serial # 0139

This bass was custom made for John Entwistle of the band The Who. This bass was sold by Entwistle in the 1980's. It originally only had the quad pickup installed but later a humbucking DiMarzio pickup was added. Factory records list a completion date of this Quad bass of January 25, 1979. It was the first 12-string Standard bass made. See the Entwistle page for more details.

1979 Hamer Quad Bass Natural finish - Serial # 0143

Shown in this photo without strings. This bass was ordered in late 1978 by bassist Dave Denisar. It was made in the natural finish with the dot inlay neck. It has a factory-installed Bartolini pickup. Note that the switch and two knobs below the pickups have been moved closer to the edge of the body relative to the original Quad bass. This bass was completed in late January of 1979. Photo submitted by Dave Denisar.

1979 Hamer Quad Bass - Serial # 0144

This bass has been modified from its original state by the addition of a different bridge, and the string arrangement has been changed to the Inverted configuration.

The Quad Box

"The quad had five outputs, one mono and one for each group of strings. There was the ¼" output jack, and a canon jack that was a low impedance five-pin output with four hot and a common ground like a microphone connector or a DI. I know Tom never used the quad outputs live, he always used the mono output that he plugged into a guitar amp." Jol Dantzig - 2001

The Quad Box interface had a canon-type connector on one end and four ¼" jacks on the top. This enabled you to split each string / pickup to a separate output to effects, amps, or to pan it between multiple amps. There is a separate ¼" jack on the bass for the normal humbucker pickup output.

The "8-Knob" Quads

After the initial group of Quad basses were made, Hamer considerably simplified their quadraphonic electronics circuitry. The quad electronics were redesigned from a 12-knob / 8 switch format to an 8-knob / 4 switch arrangement, and the switches were also moved from below the knobs to above them. Only three of these "8-knob" Quad basses have been documented.

1980 Hamer Quad Bass - Serial # 0378

This bass was made in the cherry transparent finish. It has star inlays on the 5th and 12th positions.

Photo as yet unavailable

1980 Hamer Quad Bass - Serial # 0404

This bass was made in the cherry sunburst finish with the dot inlay neck.

1981 Hamer Quad Bass - Serial # 0426

'59 Burst finish with the dot inlay neck.
Hamer records the completion date on this bass as January 2, 1981.

"At the absolute most only ten Quads were ever made. They were such a pain in the ass to build and it was a hard enough sell being it was a 12-string bass. To this day I’ll show bass players the 12-string and they’ll say 'Wow, it's so much easier to play than I thought it would be!'' They just don’t view it as a viable instrument and let alone with the Quad it was kind of over the top. The Quad feature really wasn’t that useful. It was interesting when you played it alone. You could put the G string in the left channel and the E string in the right channel and the others in the middle, but there are other ways of doing that now. " Jol Dantzig - 2001