Lookiong for solution for DIY bass preamp dilemma

[wolfman_645]

Great site.  Glad I found it!

Quick question for you guys.  I'm trying to build my own DIY bass preamp which will do a 3 band boost/cut on 3 center detent pots.  I think I have most of it figured out except one part.

• I need the pots to be 25K in the center position. According to my analysis this circuit will be flat at 25K (at least I hope).
• 0 K is supposed to be "wide open" (fully clockwise) and therefore provide full boost at the desired frequency
• 500K (or even higher) will provide enough resistance for the cut (fully counterclockwise), but the higher the resistance, the bigger the cut.
  

My problem is nobody makes a 500K pot with 25K resistance in the center detent position. Do you think I should try this using  a ganged/blend pot?  If using a ganged control (say 500K), how can I get this happening, or can you think of some other way to get the desired result (namely Fully CCW 500K, center 25K, fully CW 0K)

Thank you in advance

[twabelljr]

Read this article by R.G. Keen: http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

I have not done the math to see if it is possible to get what you need, but everything you need to know about pots can be found there.
Good luck!

[Eric H]

It sounds like you are re-inventing the wheel.
There are any number of schemes floating around for Baxandall boost/cut eq's that use standard center-detent linear pots.

To directly answer your question, though: I've never seen a pot with that configuration. Any pot manufacturer will make them for you, but you'll have to order thousands.

-Eric