Back in the dark days of 1975, a talented 16 year-old DIY electronics freak by the name of Roy Gwinn designed himself a pretty great little LFO controlled VCA/VCF (tremolo/filter for the less synth-minded). He had it pubished as a project in Popular Electronics magazine under the somewhat uninspiring name of "Guitar Effects Pedal", and as such was sold in kit form by the publishers.
It would have probably disappeared into mists of time had it not been for another young, talented DIY electronics freak by the name of Chris Carter, who ordered himself a kit and (presumably not being much guitar-minded) boxed his up in a desktop enclosure and added rate and battery indicator LEDs. Perhaps more importantly, he also took the original design's internal set-and-forget volume and bias controls and promoted them to the enclosure's exterior (more on this later).
It so happened that Chris was a member of industrial music pioneers Throbbing Gristle. The "Guitar Effects Pedal" became the altogether sexier "Gristleizer" and went on to appear on many of that band's recordings. The Gristleizer has since attained an almost mythical status in the interim, so armed with a copy of that 1975 PE article, North Effects set out to re-create the legend and see what all the fuss is about.
We took the original circuit and redesigned it with convenience and reliability in mind. Starting with the power supply (the Gristleizer required bi-polar power provided by a pair of 9V batteries or modular synth supply), the Griskin features an on-board voltage converter that allows it to be powered by a single 9V battery, or a standard Boss-style 2.1mm DC jack (9V centre -ve, so it can be daisy-chained with your other fx). Modern low current-draw op-amps were use to extend battery life and reduce LFO feedthrough. Input impedance has been increased to a much more sensible level so that it will work well anywhere in your signal chain. A true bypass switch has been substituted in place of Carter's battery switch, giving you the option of switching the effect in and out of the loop without having to plug it out (which is obvoiusly less than ideal in a live setting). Throughout the re-design process, care was taken to ensure that the sonic characteristics were preserved and regular A/B comparisons with an original spec. circuit were made to keep us on-track.
The Griskin offers two seperate modes of modulation - VCA and VCF, with four different waveforms (ramp up, ramp down, triangular and square) as well as controls for rate, depth, bias and volume. The external bias control especially gives the Griskin the feel of an instrument rather than a mere effect, giving you the ability to add distortion, extra-deep modulation and greater versatility to the tones produced in VCF mode.
VCA mode offers a great sounding tremolo effect, with the different waveforms providing a repeat-percussion style sound in the ramped waveform settings. Triangular VCA gives a classic amp-style trem, whilst the square wave setting gives a more extreme on/off chop.
VCF mode adds a fantastically wobbly LFO controlled filter. The ramped shapes are brilliantly dub-spacey, triangle is fat and round sounding, and the square sounds very abrupt and "synthy" in a way that works great with bass.
There's a lot of output available on tap from the unit and we found it rarely necessary to go beyond 10 o'clock on the volume control. The rate goes high enough to get you into nasty faux ring mod territory and slow enough to let the differences between waveforms really shine. In all the Griskin is suitably appointed to make any tabletop noise maestro very happy indeed as he/she sets about the business of destroying your cochlea.