BMP, AMZ presence control question

[cam.man67]

Here's the board I'm looking at:

What I'm looking to do is add an AMZ-style mids-control. I kinda get the basic theory behind it, but I'm not sure where it goes in my particular circuit, nor am I 100% sure how it is supposed to look. Also, the 25k pot, how does that get wired in series? Does the 3.3k resistor attach to 2 ends of the pot, or what?

Help me out, please!

 

[Fuhgawz]

Excellent mod that makes the Muff more versatile! Look at this site for info: http://rkerkhof.ruhosting.nl/Taas/Mods/Big Muff.htm

You need to replace the 3n9 cap with a 22n cap. That would be the one green one beneath the middle pot, with "C9" and ".0039" written next to it.

Next, you need to replace the standard 22k resistor from the tone pot with a 3k3 resistor with a 10k or 25k pot in series. That's probably the R5 one there on the top right in between the pots, but I'm not entirely sure from this picture. You do this by taking out the resistor entirely. You now have two holes. One hole connects to the new 3k3 resistor. The other end of the new 3k3 resistor goes to one outer lug of the new mids pot. The other outer lug of the pot connects to the other hole. So it's:

hole 1 -> 3k3 resistor -> lug 1
hole 2 -> lug 3

You also need to connect the middle lug of the pot to either outer lug. Which one you choose (lug 1 or lug 3) controls which side the pot turns to, so either scooped mids to the full right OR scooped mids to the full left. Which one is actually which, I'm not sure at the moment. But it's an easy fix if you get it wrong, if it actually matters to you at all which side you need to turn. Good luck!

 

[cam.man67]

Awesome. That's exactly what I'm looking for. Thanks for the help!

 

[amz-fx]

Here is the original mod page for reference: http://www.muzique.com/lab/tone3.htm

-Jack