OD Pot Taper question ??

[HOTTUBES]

This Tube Screamer build calls for a W20K tone pot , but i do not have any of those on hand
at the moment , But ... I do have A20K  and  B20K pots , will these work in place of the W20K?
If so , what taper would be better ?




Thanks for any help !

[HOTTUBES]

I have read that some long time builder's like the 5k B taper pot instead in this case ....
Did i understand that correct ?

[armdnrdy]

Check out reply #14 on out. It seems as if the 5K works fine.


http://www.diystompboxes.com/smfforum/index.php?topic=86988.0

[HOTTUBES]

Hey Cool !

Thanks for the link !

[zombiwoof]

Small Bear sells that exact W-taper pot for your pedal.

Al

[pappasmurfsharem]

Mammoth also has them in various forms for $1.09

http://www.mammothelectronics.com/SearchResults.asp?Search=W20K

[armdnrdy]

Tayda also stock them but...I think he was looking for something he had on hand.

http://www.taydaelectronics.com/potentiometer-variable-resistors/rotary-potentiometer/w-taper.html

[Mark Hammer]

If you want to make something with the goal of being absolutely unassailably on-spec, then get a W-taper pot.  However, the TS tone control is highly amenable to mods, many of which you can read about here: http://www.muzique.com/lab/tstone.htm  and a great many of which form the basis of the hundreds of TS variants you see for sale by boutique makers.

Stock, the control is intended to provide reciprocal action: two consequences, where producing more of one automatically results in less of the other.  Butr there is absolutely no requirement why that has to be the case.  A personal could use two pots instead to vary treble rolloff and mid-high boost. 

For instance, instead of using a single .22uf cap and a shared 20k pot, consider using a 220R resistor, 1k-5k linear pot, and .22uf cap in series, as the ground leg from the inverting ("-") pin of the tone stage.  With a 1k feedback resistor, and a ground leg that could vary from 220R to 1220R (assuming a 1k pot), the gain of that stage could vary from 1.8x to 5.4x, with bass cut (and a perceived mid/treble boost) starting around 3.3khz (with max gain) and 590hz (at min gain).

That boost can applied on top of the variable "smoothing" treble cut.  As Jack's document illustrates, the stock tone control applies a treble boost at one extreme, and a treble cut at the other.  Without any additional treble cutting, the 1k/.22uf network after the clipping stage produces a rolloff starting around 720hz.....but it doesn't HAVE to.  If a person replaced the .22uf cap with a .1uf cap, that stock rolloff now becomes around 1.6khz.  Stick a .33ufcap and a 5k pot in series, and place THAT in parallel with the aforementioned .1uf cap to ground, and you'll now have a variable treble cut control to complement the variable treble boost.  Since neither of these are the exact mirror image of each other, combinations of their adjustment can get you a wider variety of tones than the stock single control.