pot taper to change volume sweep?

[dubkitty]

i have a couple of fuzzes (EQD Sound Shank and Tone Reaper) which have a metric fuckton of gain, and thus i have to set the volume quite low in order to have unity gain. it's really hard to set them, though, because the useable segment of the sweep is really small--like 5-6mm--and this makes it tough to adjust. would it be possible to alter this by swapping out the volume pot for one with a different taper? and what would i use?

[Bartimaeus]

A schematic I saw lists the tone reaper as using an A100K pot (audio/log). It could definitely be worth trying a B100K (linear) instead, but I believe it'll cause you to reach the higher volumes sooner, which is the opposite of what you want? You'll only get more control of low volume settings if the pedal has linear, and you swap in audio/log. But if you're never using the upper range of the volume knob, you could swap in something like an A50K or A25K. That'll limit the max volume, but give you greater control within the smaller range.

[crochambeau]

If the pot is linear you can try a resistor between wiper and ground (low on the pot) which will nudge taper toward LOG (audio) but will also reduce over-all pot value to whatever the resistor plus pot is in parallel.

When I do this I grab something in the 33 to 100% of original value range. An audio taper will ease in the low range stuff for sure, but be warned, if this pot has a lot of effect travel (ie: there's interesting shit going on over the rest of sweep as well) all the higher value stuff will get squished to the clockwise rotation creating the inverse of the problem you describe.

[crochambeau]

you could swap in something like an A50K or A25K. That'll limit the max volume, but give you greater control within the smaller range.

Without seeing a schematic I cannot be sure, but *most* of the time a pot is employed as a voltage divider. This means that the output (wiper position) of the pot is a ratio. Because of this, down scaling your pot value will not affect the apparent volume...

...it will affect the load the a preceding stage sees. Sometimes this will affect the output volume of a stage , but only when that stage is loaded down... and this will affect bandwidth and distortion characteristic as well. A lot of times the effect is so nuanced as to be considered non-existent, it really hinges on how much "work" the circuit is forced into.

Sorry about long winding it, I thought I was in DIY for a second.

[dubkitty]

i found a Tone Reaper schematic:



which does show a 100k audio taper pot for Level. so i guess i'm screwed there. can't find a Sound Shank schematic.

from the explanations i've been able to find online (i can sort of read schematics and data curves because i used to lay out data sheets for a semiconductor maker) it appears that audio taper is the best i can do.

[crochambeau]

If that's an A taper you can still employ the resistor trick to further squeeze it down.

Consider it may be a B taper on your build, schematics are often poor representations of reality.

[BetterOffShred]

If the pot is linear you can try a resistor between wiper and ground (low on the pot) which will nudge taper toward LOG (audio) but will also reduce over-all pot value to whatever the resistor plus pot is in parallel.

When I do this I grab something in the 33 to 100% of original value range. An audio taper will ease in the low range stuff for sure, but be warned, if this pot has a lot of effect travel (ie: there's interesting shit going on over the rest of sweep as well) all the higher value stuff will get squished to the clockwise rotation creating the inverse of the problem you describe.

From my experiences building classic circuits, as C points out, the audio taper pot will limit low end early in the sweep, which is why opamp big Muffs sound so legendary dimed. You could swap in a linear (B) or anti-log (C) taper with like 100k to ground from the wiper as C says and this will dump a bunch of the signal to ground (maybe not a bunch, but some) but they always change the characteristics of the sweep and the EQ dynamics of the volume level. It's pretty easy to tweak, but I'm guessing the pots are going to be board mounted so you may have to be invasive.. it might be daunting for someone who hasn't built pedals or gone fairly deep.

You could always turn down the amp a hair and dime the pedal..

[Bartimaeus]

you could swap in something like an A50K or A25K. That'll limit the max volume, but give you greater control within the smaller range.

Without seeing a schematic I cannot be sure, but *most* of the time a pot is employed as a voltage divider. This means that the output (wiper position) of the pot is a ratio. Because of this, down scaling your pot value will not affect the apparent volume...

...it will affect the load the a preceding stage sees. Sometimes this will affect the output volume of a stage , but only when that stage is loaded down... and this will affect bandwidth and distortion characteristic as well. A lot of times the effect is so nuanced as to be considered non-existent, it really hinges on how much "work" the circuit is forced into.

Sorry about long winding it, I thought I was in DIY for a second.

You're totally right, and in the case of the Tone Reaper you definitely can't limit the range by swapping the value. My bad! I knew that changing the value only works in some cases, and I really should have double-checked the schem first heh...

[drolo]

if you're swapping the pot anyway, you could try a reverse log pot (C) or in case you really are not going to use the max settings of the volume pot as it is, you could insert a 100k resistor before the volume pot, that way it will only go to half the maximum level but give you more control.