Copyright 2000 R.G. Keen. All rights reserved.
Module 9 is a Big Muff Style feedback diode clipper - that is, it does distortion by putting diodes around the feedback path of an single transistor rather than a diode. This is very similar in principle to the clipping stage of Ibanez' Tube Screamer series. For a detailed discussion of the workings of a feedback diode clipper, see "The Technology of the Tube Screamer".
Here's the schematic and layout:
Here's the parts list and what each part does (Note - caps in uF unless noted; pots are audio taper unless noted):
| Part | Value | Notes |
| R1 | 8.2K | |
| R2 | 150K | |
| R3 | 470K | |
| R4 | 10K to 15K | |
| R5 | 100 - 150 | |
| D1, D2 | See Text | Usually 1N914/1N4148 silicon, may sub other types for special clipping needs. |
| C1 | 1uF, see text | |
| C2 | 470pF | |
| C3 | 1uF, see text | |
| C4 | 1uF, see text | |
| Q1 | 2N5088 | High gain silicon NPN; 2N5088 recommended, but actual type number doesn't matter much. |