Copyright 2000 R.G. Keen. All rights reserved.
Module 3 is just a tube amp tone/volume stack with all the non-pot components on the module board, the pots on a wiring pigtail from the top of the card. This illustrates one way to get around the one-pot-per-module built into FXBus1 - if the pots are always particular to the module, as they are in this case, just connect the pots to the module itself.
Here's how it's laid out:
Here are a few examples of what you can make this thing do:
(caps in uF unless noted; pots are audio taper unless noted)
| Circuit | Ct | Cb | Cm | R | Treble | Bass | Mid | Vol. | Wiring Notes |
| Bassman 5F6 tone control | 250pf | 0.02 | 0.02 | 56K | 250K | 1M | 25K | 1M | Pad 3 connects only to wiper of Mid; Bass "cold" and Mid "hot" lugs remain connected. |
| Fender Twin AB763 | 250pf | 0.1 | 0.05 | 100K | 250K | 250K | 10K | 1M | Pad 3 connects only to wiper of Mid; Bass "cold" and Mid "hot" lugs remain connected. |
| Vox AC-30 Top Boost | 50pF | 0.022 | 0.022 | 100K | 1M | 1M | 10K fixed | 1M | See http://www.voxamps.co.uk/support/circuits/tbmod.jpg for wiring diagram - it's a bit non-standard |
| Marshall 1987X | 470pF | 0.022 | 0.022 | 33K | 220K | 1M | 22K linear | 1M | Pad 3 connects only to wiper of Mid; Bass "cold" and Mid "hot" lugs remain connected. |
And how it's wired:
It's easiest to understand by separating it into input options, biasing options, and output options.
