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DIY Stompboxes => Building your own stompbox => Topic started by: Arn C. on June 10, 2004, 03:15:16 PM

Title: Need 20KA Pot......
Post by: Arn C. on June 10, 2004, 03:15:16 PM
Howdy!
    I built a Fender Jazz Bass Preamp, but it calls for a 20K Log taper pot for the level control.  I have only a 50KA , will this be okay?  I also have some 10KA, could they be made into a 20KA Pot?
   I also have a 20KLinear Taper 3 Turns.  Help........
If anyone can hep, please do....
Thanks!
Arn C.
Title: Need 20KA Pot......
Post by: john1056 on June 10, 2004, 04:32:33 PM
http://www.tpub.com/neets/book1/chapter3/1-26.htm

1/Req = 1/R1 + 1/R2

1/20k = 1/50k + 1/R2

R2 = ~ 33K

I think you can just solder R2 across the outer lugs (1 and 3).  Maybe a guru can confirm this, or explain why it wouldn't work :)
Title: Need 20KA Pot......
Post by: Arn C. on June 11, 2004, 08:10:41 AM
Thanks John!
    Does anyone else have any other suggestions ?

Thanks!
Arn C.
Title: Need 20KA Pot......
Post by: cd on June 11, 2004, 10:55:11 AM
50k will work fine, it may sound a bit brighter and your output impedance may be increase a bit, but really there will be hardly any difference.

Soldering the resistor across the lugs will work, but the taper of the pot will be messed up.  That formula only takes into account when the pot is at max (i.e 0k on one side, 50k on the other side).
Title: Need 20KA Pot......
Post by: Arn C. on June 11, 2004, 10:55:35 AM
John,
    I did what you said and it worked great!!!
Thanks a Bunch!!!!
Arn C.