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DIY Stompboxes => Building your own stompbox => Topic started by: JohnM on December 10, 2003, 10:29:31 PM

Title: Substitute for 25k Audio Pot
Post by: JohnM on December 10, 2003, 10:29:31 PM
25K audio, 250k audio, etc.  What do people use?  Thanks.  -John
Title: Substitute for 25k Audio Pot
Post by: brett on December 10, 2003, 11:40:25 PM
Depends on what circuit and where.  If you give an example...
Title: Substitute for 25k Audio Pot
Post by: JohnM on December 10, 2003, 11:54:19 PM
How about the EA Tremolo for starters:

http://www.generalguitargadgets.com/v2/diagrams/eatrem2_sc.gif

Thanks!  -John
Title: Substitute for 25k Audio Pot
Post by: brett on December 11, 2003, 12:14:44 AM
Because the 25kA pot in the EA trem is used as a variable resistor rather than a potentiometer, my first alternative would be a 25k linear, then a 50kA, then a 50k linear.  Reason being that you don't want to lessen the range of the control (nor increase it by too much, presumably).  The difference between log and linear taper won't upset things, just give a slightly uneven response to turning (ie a bit "fast" from 7 o'clock to 12 o'clock, then a bit "slow" from 12 o'clock to 5 o'clock).

I hope that helps.
Title: Substitute for 25k Audio Pot
Post by: brett on December 11, 2003, 12:22:42 AM
Oops!  I just realised that the volume control in the EA tremolo is a 25kA too!  That one could have a wide range of pots substitute for the 25kA, but it'd be best to stay with "audio" taper. e.g. 10kA, 50kA, 100kA, 250kA.  The reason for being able to substitute so many different pots in this spot is that it is simply a voltage divider/reducer.  As long as it's not too small (e.g. 1kA) and therefore not loading the previous stage too much, then it's OK.

Cheers.
Title: Substitute for 25k Audio Pot
Post by: JohnM on December 11, 2003, 12:22:43 AM
That makes sense.  There are two 25k audio pots in that circuit.  Is what you said true for both?  Thanks, again.  -John

Edit:
OK.  Simultaneous posting!  You answered it!   :D
Title: Substitute for 25k Audio Pot
Post by: brett on December 11, 2003, 12:24:56 AM
I must have beaten your post by a couple of seconds!  So the answer appears before your question.
Title: Substitute for 25k Audio Pot
Post by: Samuel on December 11, 2003, 08:39:32 AM
Of course if you're really desperate for a 250K audio taper, You can get them from your local Guitar Center, since that's a standard size for Fender P Basses...It's 24mm, has a knurled shaft instead of the regular smooth one, and costs $5, but there you go...
Title: Substitute for 25k Audio Pot
Post by: PB Wilson on December 11, 2003, 09:16:55 AM
I mentioned this in an earlier post on EA Tremolos, but you can get 25K audio pots from http://www.stewmac.com

They are a pricey $6.95 each, are large sized and have a split shaft. They do work and I used them on my own EA Trem.