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runoffgroove Mockman

runoffgroove.com has been churning out great great designs for years. And the Mockman

is one of my favorites. This opamp distortion pedal is billed as getting close to the 80's

Rockman type sound. Distortion is mainly achieved by overdriving the opamps as opposed

to diode clipping, but the circuit includes a switchable set of red LED clippers for an even

more distorted/compressed sound. The result is a great project. For more info, check out

http://www.runoffgroove.com/mockman.html.

beavis board project

A100K

Volume

in

out

Mods!Try different dual opamps to find the sound you like the best.

C3 and C5 are low value capacitors in the feedback loop of the opamps. Their

primary purpose is to tame any oscillations but they also shape the sound. Try

different value caps here.

R3 sets the gain for the first opamp stage, R5 for the second stage. Try replacing

one of these fixed resistors with a 500K linear (B500K) pot and experiment with

gain settings.

Red LEDs are specified for the switchable clippers, but be sure to try other diode

types.

10uf+

C1

10nF

5

6

8

7

4

+

-

U1a

TL072Input

9 volts +

R122KΩ

R3470KΩ

R210KΩ

C3

100pF

3

2 1

+

-

U1b

TL072

C4

10nF

R422KΩ

R5470KΩ

C5

100pF

C6

10nF

OutputVR1

A100K(volume)

C2

10uF

SW1

SPST D1/D2

red

LEDs

TL072

10nf

22KΩ

10KΩ

10nf

22KΩ

10nf

100pF

470KΩ

100pF

470KΩ

sw

sw

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revision: 1.0 28 may 2008 © 2008 beavis audio research