active volume pedal circuit

[1878]

Hello Peeps

I would like to put a simple lpb-1 into a volume pedal. Is there a way of setting a MIN & MAX volume for each end of the sweep ?? Also, would these changes be shared out equally along the normal sweep of the pedal or would the sweep change with each adjustment of the MIN & MAX controls ??

I hope that makes sense.

Thanks.

[R.G.]

There are simple ways that aren't too good, and good ways that aren't too simple.

The simple but not too good way is to use a pair of pots, one for min and one for max that just add their resistance to the end resistance of the actual volume pot.  This is going to have problems with how well the output tracks a volume/log curve with varying min/max settings.

The good but not too simple way is to (1) buffer the input signal and drive it into a series pair of pots, these being the min (bottom) and max(top) pots stacked. The wipers of these pots should really be buffered, and then the actual volume pot goes across the wipers. The output of the volume pot then can only go between the min and max voltages, and you can't get max below min as you could with some schemes I've seen. The output of the volume pedal should really be buffered.

There are other schemes, but they get a little harder to understand.

Tapers are going to be an issue with this. Best thing to do is probably to try it and see how bad it is.

[1878]

Best thing to do is probably to try it and see how bad it is.

Hahahahaha !!

This started off as a wah/volume pedal in one enclosure problem which has developed into an 'ultimate volume' problem. I had an idea this wasn't gonna be as easy as it 'should' be. I only ever use the volume pedal for violin effects or killing the signal rather than controlling gain etc, so the taper may not be too much of a problem. Hmmm.

[ashcat_lt]

Keep in mind that most wah pots and the gear mechanisms attached to them are designed to not actually go all the way to either extreme to begin with.  You can usually mess with it and get it to hit one extreme or another, but the difference comes off the other end (you change both min and max at the same time and in the same direction), and this is on purpose to protect the pot itself from the unreasonable amount of torque that the treadle/gearing will help you apply to the shaft.  So, your sweep is already limited.  You can obviously add gain to make up for a maximum less than unity, but you can't really get it to go all the way off if the pot wiper doesn't actually hit ground.

[1878]

The original wah/vol project was gonna be housed in an old Coloursound wah enclosure. These things have a HUGE throw compared to a Crybaby, plus they have a completely different way of rotating the pot. I'm pretty sure it doesn't cover the full rotation of the pot though.

The original idea was to switch between the wah & volume circuits with the 3PDT using a stereo pot (you can use any type in the Coloursound) but I gave up on the idea as no one could really solve the problem of having both a usable wah & volume circuit. I tinkered, I gave up.

[Keppy]

Dunlop already has a wah/volume combo pedal, the Mr. Crybaby. You can find the schematic online.

[joegagan]

true, there  was a wah /volume combo from dunlop.

two totally different versions , in fact.

both with the designation EW-95V.  the first version, early 90s, carried a JEN Italy type or sourced red fasel,  - old style not the weird reissue red fasel, printed with ' licensed by JEN italy ' on the bottom plate, and a single 100k pot with the cap to ground off inductor to actuate the wah or vol function just like BG2 boomerangs and many other 60s and 70s wah - vols.

the 2nd version EW-95v used a specially sourced dual gang pot and may have been mid 90s to late 90s? perhaps dunlop found the weirdness of the wah circuit being part of the volume pedal worth redesigning.

somewhat related to above - dunlop and dunlop made vox volume pedals ( not the new modern dunlop volume but the ones in wah shell. ) can be adjusted to go full silent by finessing the nut on the pot to assure the pot is hitting the internal stop.