Tapering resistor: How to install

[Navigator]

I am trying to convert a CryBaby wah into a volume pedal. I did the conversion and used the original crybaby pot adding a 100 pf cap between the tip terminals on the pot. It works but the volume goes from silent to loud to very loud. I would like a more even and gradual transition from silent to very loud. I read that a tapering resistor may help do that. I am not sure where the tapering resistor goes and how many ohms it should be.

Does the tapering resistor go between the input tip and the pot terminal?

Or does it go between the input ring and the pot terminal? Or elsewhere?

And how many ohms should the resistor be?

Thanks in advance for help on this.

[tjk3052]

Here's the obligatory link whenever someone asks about pots.
http://www.geofex.com/article_folder...s/potscret.htm

[Navigator]

yes I read that. That is where I learned what "taper" means in regard to pots. But that article is more theoretical than "how to". It was so full of technical jargon that it was rather difficult to understand. I am going to read it again to see how much more I can get from it.

[fatsound77]

You need to change the pot to a log with a value of 250-500K if you want to use it as a passive volume pedal. The crybaby's pot taper is not what you want to use. As for tapering resistors to pull the curve "up" put the resistor between the in and out and to pull it "down" put the resistor between the out and ground. I would not recommend using capacitors as they will just create a RC filter that affects frequency response that changes exponentially as you move the wiper.

[Navigator]

Thank you fatsound77 that is a helpful reply. I think I want to bring the curve down. So as I understand it to bring the curve "down" means to make it so that as the wiper turns the volume goes up slowly at first but them more quickly or to a very loud volume more toward the end of the pedal's throw? Is that correct?

To see if I understand this .... A capacitor would pull the curve "up": Is that correct? Is that what you mean by "affects frequency response that changes exponentially as you move the wiper." The volume goes up quickly and to a very loud level with very little pedal movement?

[fatsound77]

You are correct with the resistor and taper. The cap doesn't effect the taper really. The value of the cap acts as treble bypass cap allowing treble to not be lost as you roll off the volume as it does normal. The whole subject deals with resonate frequency and RC networks, but to keep it simple you just want to mess with resistors. Caps in this situation are used for say, a treble bleed on your guitars volume, allowing you to roll off your volume and not lot lose the top end... but the treble bypass will change your corner frequency more as you roll the volume back. Giving you what?... more treble the lower your volume vs what would be nice a consistant tone at all volumes. This is why you see treble bleed kits with resistors tied with the cap. You can counter balance it a bit, but theres no perfect system with a passive design. This ultimately jacks your guitars tone up imo and in your situation I would recommend no capacitors.

[Navigator]

fatsound77:

I finished the wah to volume pedal mod last night. I put a 100k resistor b/w (I tried a 47k resistor but I didn't seem to get any volume at all) the out and ground. And it pulled the curve down some. Now it is : silent - not too loud --- loud --- almost very loud (doesn't go to the max of the amp). This is workable and helpful for adjusting volume to useful levels without having to go to the amp. From reading about it I knew it wasn't going to be like a real volume pedal with a smooth even transition between silent and max. But it is good enough for a $20.00 wah pedal.

Thanks for the help. I learned something on this project.