FXBus 1 Module 3 - a Tube Amp Style Tone/Volume Stack

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.