Akashic Guitar effects circuit lookup
LOADFUZZBIASTONEBODYVOLUME

1590B · 6 knobs

Tagboard Effects

MI Audio GI FuzzVerified

Based on the MI Audio GI Fuzz· 2 other boards clone it

Category
Fuzz
Controls
Load · Fuzz · Bias · Tone · Body · Volume
Build
Vero· 19×11· 17 cuts, 5 links
Layout
Verified · Tagboard Effects marks it as built and working
Tags
Fuzz, MI Audio

From the post

6 knobs plus a Bright switch, and still needs an onboard trimmer. I will be extremely impressed with anyone getting this in a 1590B! Basically it's a modded silicon Tonebender MkII and it must be one of the most tweakable ones out there so I'm sure it would be a great addition to many peoples collections.

Info from MI Audio about their original:

The GI Fuzz is a high gain fuzz design, featuring a trio of ultra low noise, high gain silicon transistors. This is not a fuzz for the faint hearted. It has about 20db more gain than a Fuzz Face, so you can think of the gain achievable as being equivalent to a a Fuzz Face at full tilt being driven by a booster! This is military spec fuzz, complete with a camouflage green aluminium enclosure and stencil script. The GI Fuzz is not a clone of anything out there.

MI Audio settled on a design which makes the GI Fuzz one of the most versatile fuzz pedals out there. At last, the fuzz pedal has joined the 21st century! No longer the 2 knob, unstable, radio receiver of yesteryear. You get 6 knobs, an internal trimmer, a 3 position switch, and the ability to create anything from fat bluesy tones, to traditional fuzz, to all-out sustain, to gated, synth-like bleeps.

High Gain silicon fuzz.

Fuzz generated by a trio of high gain silicon transistors

Ultimate flexibility with the following 8 controls (1 internal):

● Fuzz - from nothing to all out fuzz ● Load - input impedance control ● Bias - controls the bias of the 2 transistors ● Body - midrange control ● Tone - balancing control for controlling highs and lows ● Volume ● Bright switch ● Internal Gain trimmer.

Professionally powder-coated and silk-screened enclosure, measuring only 4.3" x 2.2"

IN DEPTH CONTROL DETAILS FROM MI AUDIO:

A huge gain range, from nothing to sustain-for-days

It can be used as a low gain device (for a fat bluesy bite), which is fairly unique for a fuzz pedal, since fuzz pedals tend to have a very narrow range of gain.

To tame this pedal, there's an internal gain trimmer to wind things back (which I recommend)

Load control, which is a variable input impedance. This can be used to match the GI Fuzz to humbuckers as well as single coils (Fuzz pedals tend to have low input impedance which is a better match for single coils. Now you can also use humbuckers without any problems). You can also use it to go from a tradition fuzz sound (low input impedance) to a more articulate sound with detailed highs (high impedance)

A bias control to set up the operating point of the transistors, from a fat symmetrical fuzz, to an asymmetrical 'mosquito' buzz, and beyond, to a gated synth-like sound (almost sounds like your amp is about to die!)

Body control, which full range mid range control. The mids, of course, are the most important frequencies for determining how your guitar tone sits in with the rest of the band.

Tone control, which controls both lows and highs, as opposed to simply a high cut filter. This is like bass and

Schematic

This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Tagboard Effects. No KiCad fragment has been drawn for this circuit yet.

Parts list 27 rows

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RefValueNormalizedTypeNotes
Resistors 8
×34K74.7kread from the layout by eye
×22K22.2kread from the layout by eye
×2100K100kread from the layout by eye
×222K22kread from the layout by eye
×11M1Mread from the layout by eye
×11K1kread from the layout by eye
×1470R470read from the layout by eye
×110K10kread from the layout by eye
Capacitors 7
×31u1udrawn as film caps; read from the layout by eye
×11u1uelectrolytic; read from the layout by eye
×3100u100uelectrolytic; read from the layout by eye
×222n22nread from the layout by eye
×1220p220pread from the layout by eye
×13n93.9non the bright switch; read from the layout by eye
×11n21.2non the bright switch; read from the layout by eye
Diodes 1
D11N40011N4001read from the layout by eye
Transistors 3
Q1BC549CBC549Cread from the layout by eye
Q2BC549CBC549Cread from the layout by eye
Q3BC549CBC549Cread from the layout by eye
Potentiometers 6
LoadA100KA100kPotentiometerread from the layout by eye
FuzzB10KB10kPotentiometerread from the layout by eye
BiasB2KB2kPotentiometerread from the layout by eye
ToneB100KB100kPotentiometerread from the layout by eye
BodyA20KA20kPotentiometerread from the layout by eye
VolumeA100KA100kPotentiometerread from the layout by eye
Trimmers 1
Gain1K1kread from the layout by eye
Switches 1
BrightDPDT on/off/onDPDT ON/OFF/ONtoggle, 3 position; read from the layout by eye

Other boards based on the MI Audio GI Fuzz