GMP Germanium MOSFET Preamp/Distortion

GMP Germanium MOSFET Preamp/Distortion


The Damnation Audio Germanium MOSFET Preamp or “GMP” started out as a simple idea to build myself a different pedal that uses the same style of distortion available in the MBD-1 but with a focus on lower gain and more midrange.  Then a few friends got a hold of one and demanded more gain and less gain and more mids and less mids and more lows and less lows, etc.

So I cherry-picked a few of the requests and after some revisions have worked out the version I have here.  The hi/lo switch goes between the low gain version (that I originally built) and the high gain version (that my friends requested).  The mid is a passive midrange control that slowly adds mids back to the circuit that are cut by the distortion stages.  The tone control is centered in a familiar place for those who love old tube amps and the last final concession is that I lowered the pregain bass boost that I held onto so tightly (the same thing that makes the MBD-1 so massive in the low-end).  Lowering this was the last piece of the puzzle that gives the GMP its own identity.  Anyone who has played an original may be surprised by the latest mod which tightens up the low-end fantastically.


Gain: Controls the amount of input gain.

Level: Controls the output level.

Tone: Tilt-style tone control centered around 450Hz.

Mid: Restores midrange frequencies.

Hi/Lo: Switches from low gain preamp mode to high gain distortion mode.


Use only 9VDC 2.1mm center negative (boss-style) power adapters.  Isolated pedal specific power supplies are highly recommended.  Damnation Audio pedals are designed for maximum headroom and ideal performance with a 9V supply.  Going above 9VDC will damage your pedal and void any warranties.  Damnation Audio pedals do not accept 9V batteries.

In the interest of continuous improvement, all specifications are subject to change without notice.

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