Scratchy Wah

[Dave Eason]

Hi,

I have an old Jen crybaby wah, which used to sound terrible, but I cleaned it up and put a new pot in it (goin back a few years now of course) , and stuck in a DPDT switch to make it true bypass; it was sounding great for a while but it's gone back to its scratchy old ways now.  Any one have any ideas? If you rock the pedal slowly, it's fine, but when you vigorously rock it it's got a nasty scratchy effect at the top of the wah travel.  I suppose the most likely thing is the pot, but seeing as it's relatively new I couldn't imagine that was the problem.  Are there any other reasons to get thhis scratchy-ness apart from the pot.  I think it was one of those "hotpotz" pots or something like that, that went in there a few yeas back.  It's a fairly large sealed unit so you can't get switch cleaner in there (if that is a good idea..)

Dave

[alderbody]

it should be the pot, but maybe not because of the dust.

Maybe the rack - pinion system is too tightly connected, so it applies too much pressure on the pot's shaft.
Too much pressure + long and hard use could cause mechanical failure to the "innards" of the pot, hence the scratchiness...

If this is the reason, i think the damage is already done,
so you'd better get a new (decent) pot. (like a Fulltone, for instance...)

Try not to overtighten things in there.


...just a guess, ok?

good luck

[deadsnake]

Try incorporating a LED/LDR in it. This inteligent circuit can remove this issue because the resistance is applied to the pot which gradually lights up  as you turn the pot in consequence the LDR resistance raises thus creating the wah effect when used instead of the pot to create this resistance change. The LDR has no moving part so you never have to change it. And you are probably never going to change your pot unless it doesn't work at all.

[Dave Eason]

cheers guys,

Yeah, I'll give a new pot a go; otherwise I was considering some kind of optical system. 

Deadsnake: The only thing is with that idea is that you still have the pot in there! So I don't see how you've gained anything except added more parts!

Surely some kind of blade or something similar attached perpendicular to the pedal which will break the beamwhen the pedal is moved by varying amount, altering the amount of light hitting the LDR is a better idea?  And infra red too, so normal daylight and electric light doesn't make the thing wah on it's own (unless it was all cunningly sealed of course).

[Paul Marossy]

The only thing is with that idea is that you still have the pot in there! So I don't see how you've gained anything except added more parts!

Not exactly. With this arrangement, you loose the scratch because the pot is not directly in the audio path anymore. Well, let me restate that: the LDR makes it so the pot can not make a scratchy noise in the audio path.