Ernie Ball Volume Pedal...replacing pot...reverse log/audio taper

[modsquad]

I am thinking about replacing the pot in my EB Jr volume pedal with a reverse audio/log pot of 250k...good or bad idea...is it even feasible.   I just don't like the sweep it has right now.  YOu really have to use a lot of "throw" to get changes at normal volume.   Now if you crank everything up then its a moot point.   I was thinking of changing the taper to have more effect on volume in the early range of pressing down on the pot.

[petemoore]

  Outside is easier maybe, inside if you can fit the small clips on the potlugs.
  Clip>resistor>wire>clip works pretty good but you can substitute pot where resistor.
  That and try different pots, experimenting with anything in the pedal, and comparing that to what can you get going on the bench...using the meter or running a signal through it and trying out the travel/sweep.
  I don't like 0 volume on anything because it makes anything seem broken, and absolute 0 is available at the next volume pot [in the guitar], I like the sound of the pot near open [or with treble bleed capacitor across the SP lugs over about 100k, depending]...so I use the stop resistor regularly on volume pots, leave at least a little something coming through so I'll look at the volume pot.
  This can have the effect of spreading the values desired across a larger portion of the potwafer = finer control / greater treadle travel = fine tunable control over the volumes I want control over.

[modsquad]

Pete, sorry, but I am not quite getting what you are saying.  The schematic shows a 220k resistor from the taper to the volume pot.   What I am really looking at is "flipping" the volume curve from a log curve where you get an exponential increase in volume the farther down the pedal is pressed to getting a reverse log curve where you get exponential increase early and flattening out later.   I do like the idea of removing "absolute" zero on the volume.   The only issue for me would be that I use my volume pedal to kill my signal sometimes while changing guitars, etc.   I guess I could just put a switch inline instead.

[zombiwoof]

Pete, sorry, but I am not quite getting what you are saying.  The schematic shows a 220k resistor from the taper to the volume pot.   What I am really looking at is "flipping" the volume curve from a log curve where you get an exponential increase in volume the farther down the pedal is pressed to getting a reverse log curve where you get exponential increase early and flattening out later.   I do like the idea of removing "absolute" zero on the volume.   The only issue for me would be that I use my volume pedal to kill my signal sometimes while changing guitars, etc.   I guess I could just put a switch inline instead.

I think what PeteMoore was suggesting was using tapering resistors between the lugs of the pot to change the taper of the pot, instead of actually changing the pot out.  There is a calculator (I think it's linked to in the FAQ section here) which allows you to calculate what resistors you need to change the taper.  You would have to probably put resistors between the 1 and 2 lugs and the 2 and 3 lugs to do this.  Usually you start with a linear pot to do this, but I think you could do it with the audio pot you have.  Attach alligator-clip leads between the lugs and try different resistor values until you get the taper you want.  It may also change the overall resistance reading of the pot, and this may or may not be desirable.

I'm not sure what you mean by "a 220k resistor from the taper to the volume pot".  How can you have a resistor from the "taper"?.  Did you mean to say something else?.

Al

[modsquad]

I was looking at the wrong schematic.  I get what you are refering to.   Something like the option on this schematic, where they have a taper switch.

http://www.ernieball.com/products/volume_pedal/pdf/po6180_vpjr_mono_250k_with_taper_switch_2003-02-10.pdf

[modsquad]

Actually thinking about it, why could't you add a pot to allow you to control the taper on the pot and dial in what you wanted.

[joegagan]

this thread just made me think of something. why not put your 'more than zero' pot in series with the main pot, but on a clickswitch pot so you can have either one depending on the situation? ( the clickswitch lets you take the extra resistance out of signal path when not needed)

seems that most users nowadays have a low impedence buffered signal before the vol pedal, so the 25k ernie balls aren't too bad. the only people who seem to really need 500k or 1 meg pots are the players with nothing else between their guitar and the amp.

but almost everyone has a tuner, no?
the buffer on the boss TU2 adds a little brightness when a/b'd to the straight guitar signal ( short cord test so cable capacatance difference was minimal).

[joegagan]

stan, to get back to your original question - i agree with zombi, you might be able to custom build your own taper by going larger, like you said and playing with trimpots on both sides. i have built one meg volume pedals with dual 1 meg trimmers on either side, works well. don't be surprised if you end up with a very lopsided set of tapering resistors.

as mentioned, the signal ahead of the pedal will make a lot of difference how the vol pedal reacts. what is in your signal chain ahead of the ernie ball?

[modsquad]

I have been using it as the first pedal in the chain.   Some interesting ideas and things to play with.    Never thought such a simple device could be so versatile and "modable".   You guys are evil....

[joegagan]

also, a volume pedal can be an awesome dirt controller as well. if you have a nice OD or fuzz pedal that cleans up, you can do full bore power chords by maxing your guitar volume but bringing your level to rhythm part levels with the vol control. actually, in my perfect world, i would have a volped at the front of the chain and one at the end.

[modsquad]

Its interesting you mention the location.   I have been reading some debates about putting it after the distortion.   These things are pretty cheap used.   I might pick one up and do that.   I will try it out.   That is after I experiment with changing the taper of the one I have.