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DIY Stompboxes => Building your own stompbox => Topic started by: zener on December 09, 2003, 09:36:18 PM

Title: Reverse log pot for Dist +
Post by: zener on December 09, 2003, 09:36:18 PM
I'm planning to build the Dist+. I can't find a reverse log here. :x . Is there any substitute to it? How about three resistors values to be used in a three-way toggle that will let me switch from no (or low) gain, medium and full?

Thanks for any help :wink:
Title: Reverse log pot for Dist +
Post by: Ansil on December 09, 2003, 09:39:13 PM
i have never used the reverese log pot i always used a 1meg pot.  no  problems with it sofar
Title: Reverse log pot for Dist +
Post by: gtrmac on December 10, 2003, 12:13:01 AM
Get it from Small Bear Electronics. He ships via the Postal Service so the shipping cost will be pretty low. I get stuff from him sent to Japan regularly.
Title: Reverse log pot for Dist +
Post by: Mark Hammer on December 10, 2003, 10:26:37 AM
I have no idea why it would be necessary to use a reverse-log pot for the Dist+.  Unless there is some very specific degree of distortion you need to dial in, there is absolutely nothing gained by using one taper over another.  The circuit certainly does not need any particular taper to function.

All that pot tapers do is provide a particular degree of resistance change per unit of rotation.  In some instances, if the audible change  is such that the ear detects it as nonlinear, or if the user needs to have a certain amount of "rotation arc" reserved for a particular range of change that they want to be picky about, then taper can become important.  But other than that taper is less magical than most think it is.

The few cases where pot taper is truely important seem to be:
1) Anything where you are controlling the volume.  Log taper provides smoother volume changes because of how the ear works.

2) Anything where there is a defined "middle", such as balance controls, or EQ cut/boost controls, where it is important that the midpoint of rotation (or sliding) be very close to half the max resistance.

3) Anything where you continuously move the pot with your foot, such as a wah or expression pedal.  In these instances, the pot taper is actually compensating for the degree to which foot movements of different angles can be articulated.  You can provide fine gradations of movement when pushing forward with the ball of your foot, but only much coarser movements when rocking back on your heel.