Analyzing the Quad Pickup:
30 Years Later

Way back in 1978 Jol Dantzig of Hamer Guitars had a problem - how to turn an excessive, almost ridiculous fantasy into a reality. The request was from Cheap Trick bassist Tom Petersson, and the concept in question was a quadraphonic pickup for the newly-conceived 12-string bass. Over the top.

Dantzig enlisted long-time friend and guitar pickup guru Seymour Duncan to tackle the task of creating a pickup that could send four independent signal - one for each group of strings. Each of these signals would be sent to an onboard preamp and mixing console built into the instrument that would be designed by electronics wiz Rex Bogue. "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”, says Dantzig.

From this mixing console each independent signal would leave the instrument via a 5-pin XLR cable and be sent to an interface box that would act as a four-way splitter and send each signal to its own amplifier. This way each group of strings could be independently controlled and manipulated by both volume and tone.

Looking at a Quad pickup, one gets the impression that it is a single unit but this is not the case. While they are mounted to a single base plate, the Quad pickup is actually four separate single-coil pickups side by side. Each pickup consists of a standard white bobbin that was cut down and then bonded back together in order for it to fit within the confines of a standard humbucker pickup ring.

Each of these modified bobbins were wound with copper wire in a traditional manner and given three pole-pieces each. "It never functions as a single pickup. It's four separate pickups, one each for the four courses of strings.” states Dantzig. Even though it has multiple side-by-side bobbins, the Quad pickup has no humbucking qualities.

Typical humbucking pickup construction minus wire

Pickups are wound differently to achieve different tonal and power capabilities. When asked about this Dantzig explained, "They were not wired to be hot, as they were going to be fed into the Balz Deluxe preamps which had tons of gain." This would most likely mean that they are very similar to standard single-coil pickups found in many common guitars, and due to the coils acting completely independently of each other they would generate the typical 60-Hz hum that is characteristic of single-coil pickups. Add this to the high-gain of the Balz-Deluxe preamp and it is very likely that this is a noisy combination.

Pickup configuration of an "8-Knob" Quad bass

The Quad pickup unit is not the only pickup in the bass. There is also a standard humbucker positioned next to the Quad pickup for mono use. It has been reported that the Quad function of the bass is not very useful and that during live performances Tom Petersson used the mono function of the standard pickup exclusively. It may have been that the Quad function was excessively noisy in a live environment and this aided in Petersson’s decision to run the Quad 12 mono.

It has recently been confirmed that the Quad function was not used during Cheap Trick recording sessions either.

Since the pole pieces in each of the four pickups are in line with the string courses, some strings are directly over all three poles and others are off to either side. The Quad pickup unit provides no adjustment for this and consequently the sound from string course to string course is likely to be very uneven.

Rendering of a single Quad pickup

The Hamer Quad bass was a challenge to create. For its day it pushed the limits but by today’s standards it seems somewhat archaic in function albeit very cool from an innovative standpoint. Today the same effect can be achieved with piezo pickups much more successfully, but with little interest in running quadraphonic sound no company has as yet produced a new quadraphonic 12-string bass. So for now the original Hamer Quads will remain as sought-after timepieces that will continue to hold a fascination with 12-string bassists for years to come.