Akashic Guitar effects circuit lookup
DISTORTIONFILTERVOLUME

Enclosure not stated · 3 knobs

Revolution Deux

ProCo The Rat (early version, 1986 trace)

Based on the ProCo RAT· 41 other boards clone it

Category
Distortion
Controls
Distortion · Filter · Volume
Price
see vendor
Read the post at Revolution Deux Schematic imagetonepad.com RAT project

From the vendor

A schematic of an early ProCo RAT traced in 1986 from an actual unit: an LM308 op-amp gain stage with hard-clipping 1N4148 diodes to ground, a passive Filter control and a 2N5458 JFET output buffer. Part of a post on building Kurt Cobain's Nevermind-era pedalboard; the author prefers the RAT to the DS-1 for its more open, less nasal tone.

The clipping diodes are a big part of the RAT sound: the 1N4148s can be swapped for almost anything (the author likes red LEDs; MOSFETs wired as diodes also sound good). For the Nirvana tone keep the 1N4148s.

Schematic

The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.

Parts list 33 rows

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RefValueNormalizedTypeNotes
Resistors 12
R14747read from the schematic by eye
R21M1Mread from the schematic by eye
R3100K100kread from the schematic by eye
R4100K100kread from the schematic by eye
R51M1Mread from the schematic by eye
R61K1kread from the schematic by eye
R7560560read from the schematic by eye
R84747read from the schematic by eye
R91K1kread from the schematic by eye
R101.5K1.5kread from the schematic by eye
R111M1Mread from the schematic by eye
R1210K10kread from the schematic by eye
Capacitors 13
C12100u100uelectrolytic; read from the schematic by eye
C1310n10nread from the schematic by eye
C122n22nread from the schematic by eye
C21u1uread from the schematic by eye
C31n1nread from the schematic by eye
C6100p100pceramic; read from the schematic by eye
C730p30pceramic; read from the schematic by eye
C44.7u4.7uread from the schematic by eye
C52.2u2.2uread from the schematic by eye
C84.7u4.7uelectrolytic; read from the schematic by eye
C93.3n3.3nread from the schematic by eye
C1022n22nread from the schematic by eye
C111u1uelectrolytic; read from the schematic by eye
Diodes 3
D31N40011N4001read from the schematic by eye
D11N41481N4148read from the schematic by eye
D21N41481N4148read from the schematic by eye
Transistors 1
Q12N54582N5458read from the schematic by eye
ICs 1
IC1LM308NLM308Nread from the schematic by eye
Potentiometers 3
DistortionA100KA100kPotentiometerP1; read from the schematic by eye
FilterA100KA100kPotentiometerP2; read from the schematic by eye
VolumeA100KA100kPotentiometerP3; read from the schematic by eye

Other boards based on the ProCo RAT