John Birch (luthier) - Pickups

Pickups

John Birch's guitar pickups had a unique construction compared to other pickups of the time. Normally, pickups use Alnico or Ceramic magnets, occasionally Samarium-Cobalt, as in Bill Lawrence's Fender SCN pickups, or even Neodymium, as in Q-Tuner's bass pickups. Birch used Cobalt Steel magnets, oversized to make up for their relative weakness as compared to Alnico. However there are Magnum, Hyperflux, multiflux and Biflux pickups with smaller Alnico magnets. (J1 Hyperflux/biflux, J1 Magnum/ biflux and J2 Multiflux build 1977 these guitars where all build short after John Diggins left JBG in 1977.) He also used much finer copper wire than most other pickups because finer wire allows more wire to be wound on the bobbins, which results in a more powerful sound. Finer than normal wire also accentuates high frequencies, though fine wire can have a "thin" sound if not compensated for in other ways, such as higher resistance, shorter coils, or more metal in the magnetic field to raise inductance. Also, he potted the pickups in black epoxy. (the 1977 pickups with the alnico magnets where all potted with a cream coloured epoxy.) to fight microphonic feedback caused by unwanted vibrations of the copper wire. The epoxy keeps the wire from moving. The covers to the pickups were stainless steel, which is non-magnetic and therefore won't cause eddy currents, which oppose the magnetic field of a pickup, causing it to sound weaker. Finally, Birch used a row of 9 instead of 6 balance screws as polepieces to create a broader area for the pickup to sense the vibrating string. With Fender single coils or Gibson humbuckers, the strings each have an individual pole piece. However, if the player bends a string, that string can move over an area where there is no pole, and the sound will get weaker.

On request, John Birch would make combination Multiflux pickups, like a Hyperflux with a Biflux, (serial plus a parallel humbucker pickup) in the same housing, or a Magnum with a Hyperflux in the same housing.

Apart from the pickups, John Birch applied a single knob bass-cut/treble-cut tone control at all his instruments, equivalent to the controls at 1940/50 Epiphone Electar guitars and early 1950 Gretsch guitars with DeArmond Dynasonic pickups. This JB-tone control however did not affect the frequency response when set to neutral, unlike the Gretsch and the Epiphone dual tone-controls.

All standard guitars like he J1, J2 and SG models are switchable for mono, stereo and anti-phase-mono operation, wired to a stereo phono output connector. The guitars where standard supplied with a 25 ft. stereo split cable(1977).

Here is a list of the pickups from the John Birch catalog in the late 1970s:

• SIMPLUX-Single coil intended to replace the old black covered Gibson P90 type fitted to Juniors and some SG’s, but having the continuous row of balance screws centrally. 30 Hz-14,000 Hz. Standard Impedance.
• HYPERFLUX-Double row of balance screws to accept impulses from string vibration over a wider area. 30 Hz-13,500 Hz. Standard impedance and long sustain due to high sensitivity.
• SUPERFLUX “G”-Single row of balance screws to accept impulses from string vibration over a narrow area to emphasize either treble or bass depending on location. 30 Hz-13,500 Hz. Standard impedance with long sustain due to high sensitivity.
• SUPERFLUX “B”-Single row of balance screws to accept impulses from string vibration over a narrow area to emphasize either treble or bass depending on location. 30 Hz-25,000 Hz. Approximately half standard impedance with long sustain due to high sensitivity.
• SUPERFLUX “L”-Single row of balance screws to accept impulses from string vibration over a narrow area to emphasize either treble or bass depending on location. 30 Hz-15,000 Hz. Standard impedance with long sustain due to high sensitivity.
• SUPERFLUX “M”-Single row of balance screws to accept impulses from string vibration over a narrow area to emphasize either treble or bass depending on location. Double the number of turns compared with the Hyperflux and Superflux, therefore it has double the output and double the impedance frequency response is slightly lower, 30 Hz-8,000 Hz tailing off.
• BIFLUX-Double wound parallel connected coils to reduce impedance while retaining long sustain due to high sensitivity. 30 Hz-20,000 Hz. Approximately half standard impedance.
• MAGNUM-Double row of balance screws to accept impulses from string vibration over a wide area. Double the number of turns compared with the Hyperflux and Superflux, therefore it has double the output and double the impedance. Frequency response is slightly lower, 30 Hz-8,000 Hz tailing off. This is the most powerful pickup ever made to really clobber the amplifier.
• MAGNUM “L”-Approximately half the impedance of Magnum to extend the frequency range to 15,000 Hz.
• MULTIFLUX-The most revolutionary pickup ever devised. It contains FOUR coils forming a STEREO unit within a standard case, all four ends of the coils being brought out to provide the maximum combinations. Two of these pickups when linked with the complex switching will give up to TWENTY-SIX different tones in Stereo, Mono, Anti-phase or QUADRAPHONIC. Such a range of effects is of infinite benefit for studio work where tonal changes can be made without changing over instruments. The number of combinations can be limited by individual requirements to avoid over-complication.

The guitars also featured unique switching options, having up to seven control knobs for a single neck guitar. With two Multiflux pickups, there are 22 switching options available, including stereo, in and out of phase, mono, and each pickup acting as a single unit.

The Multiflux pickups were the first commercially available pickups to use two humbucking pickups in one case. Dimarzio's Multibucker is a more recent take on this idea. The Multibucker has four side by side coils, as opposed to the Multiflux's two stacked coils. The Multiflux is a rather rare pickup, with not too many people having ordered it. It carried a higher price tag than the other pickups in the range and the switching options could become rather confusing.

If the Multiflux pickups did not offer enough flexibility, one could pay an extra £600 and get a guitar with removable pickups to offer an even greater range of tonal options. This was originally designed in collaboration with Tony Iommi for studio use.

John Diggins recalls the beginning of the interchangeable pickup system, "The interchangeable pick-up idea came from Tony . The pick-up routes went all the way through the body, with copper contact points along one edge of the pick-up route situated near the back of the instrument. The pick-ups were assembled on a plinth, pre adjusted for height. The pick-up surrounds were fitted to the front of the instrument so that when the modules were slotted in from the back they engaged into the surround at the correct height. The pick-ups were held in place with sprung loaded clips that located into a vee slot routed into the side of the pick-up cavity. When in place, the pick-up housing was flush with the back of the instrument. Contacts on the pick-ups were also sprung loaded and made contact with the adjacent copper points in the pick-up cavity."

In an interview, Tony Iommi was asked if he still had the patent to the interchangeable pickup system he helped to develop: "I did years ago, but I probably lost it now. That was about 28 years ago. I had just done it for my own interest. If it was successful I knew people would rip it off."

Several guitar manufacturers now make guitars with interchangeable pickup systems, such as Mercurio Guitars and Ramtrak Guitars.

There are only two John Birch interchangeable pickup guitars known to exist. One is the guitar originally built for Tony Iommi, the other is now owned by Nicky Panicci of David Bowie and USA Band S'cool Girls. The one in possession of Nicky Panicci is the one featured in the original John Birch catalog and is the rarest one to exist.