Wah weirdness

[RogueWah]

Hi, I just joined and this is my first question.

Ok, was messing around at a friends house and starting banging around with the wah he just bought. Its a Rogue WP-101. Has a decent enough sweep but once you get toward the higher end of the spectrum there is a lot of crackling in the sweep.

Any ideas what could be causing this?

[RogueWah]

I did try lubing the pot up to see if that was the problem but it didn't help it much....

[Mark Hammer]

Wah pots take more abuse than the weatherman, more abuse than the woman at the airline counter, more abuse than the vice-principal at a high-end prep school, more abuse than.....well, you get the picture.

One of the things people often aren't aware of is that almost ANY pot works by friction. On the inside of the pot there is a resistive strip, like this:

The wiper that moves along that resistive strip only makes contact because it is pressing against the strip. You can see from the "tire tracks" on the strip that it rubs.

Now, the wiper that you see shown here: has no real end or "front" or back". But a great many DO, and they look a bit like the old "cow-catchers" you'd see on the front of locomotive engines. Depending on where the end of the wiper is pointing, you can find yourself grinding teeny tiny bits of resistive strip off and pushing them in one direction. So if the wiper is "facing" towards the clockwise end of rotation, then as you rotate it clockwise, whatever you are grinding off (and this really happens as microscopic levels) is "pushed" to that end of the pot. I also find that some pots seem to have more consistent thickness on the resistive strip along the middle 60%, than along the 20% at each end. The one in the picture looks like a better example to me, with fairly consistent thickness along the entire rotation.

While most people have a sense of pots getting dirty as a function of crap from the outside world finding its way into the pot, fewer people are aware that a pot can create its own crap buildup inside. What we hear as "noise" from the pot, is essentially a stream of very brief discontinuities in contact resulting from not only teeny tiny microscopic piles of crap built up on the resistive strip, but also small gaps created in the resistive strip when stuff is rubbed off. It's a bit like the noise you would hear while driving, if the street you were on was full of potholes and the chunks of asphalt that used to be in those potholes....except at a microscopic level.

When I think of the pricing of Rogue Wahs, it is hard for me to imagine that they use the sort of higher quality pots found in pricier wah pedals. Consequently, the odds are pretty good that what you are hearing is a result of the buildup of residue inside the pot at one extreme end of rotation.

That's my guess, and I'm stickin' to it.

[RogueWah]

Thanks!!

I kinda figured it might be cause his wah was kinda cheap.... Would you say that replacing the pot would help? It hasn't be used much so I got him to let me borrow it and I'm gonna just try using it a bit. I've heard tha tsome pots get better as they are 'broken' in....

RogueWah

[RogueWah]

Well, I took the thing apart and spun the pot manually and I can hear the scratching while I'm just spinning it with my fingers.. So It sounds exactly like what you said Mark...

Thanks!!!!!!!!

[Mark Hammer]

It IS possible to get in there and clean up the inside of the pot. You can pry up the tabs that hold that back cover on to the front part of the pot, exposing the resistive strip and wiper. Dab a Q-tip (cotton swab) in a bit of alcohol and twiddle the end so it can reach in smaller spaces and move it along the resistive strip as you rotate the shaft (normally, there will only be a small arc of the resistive strip exposed at any point), You should see the Q-tip get black as it picks up the eroded "resistance dust". Alternatively, you get yourself a spray can of contact cleaner and give a shpritz. Personally, I like the more direct approach because it doesn't leave you with spray all over everything, and there is nothing lift to wipe up.

In rehabilitating pots, I like to use some stuff called Stabilant (www.stabilant.com). It is a contact enhancer and provides a stable conductive layer on top of the cntact surface of your choice (which could be a pot, a switch, a jack, or even the gold pins of your favourite DS cartridge). The procedure I recommended above simply cleans up the stuff sitting on top of the resistive strip. If you recall the street analogy I used yesterday, there are the chunks of pavement sitting on the street, and the potholes created by removing those chunks from an otherwise smoothly paved street remain behind. As any driver can tell you, it's nice to take the crap away from on top of the street, but if there are potholes and cracks in the pavement, you'll still feel and hear it when you drive. The conductive layer that Stabilant provides fills in those potholes, making the pot behave as new. Keep in mind that in the world of electrons and wiper/strip contact, gaps of a micron may as well be gaps of 10ft, so even though the layer provided is thin, it does the trick nicely. As a nondrying liquid, however, the layer cannot be built up. So, obviously, if the pot is too worn, then the layer provided may not be sufficient to bridge the gap. The downside is that this stuff can be hard to get. They used to make little 50-cent 0.5ml sampler vials that I've found were enough to treat 30-40 pots, but have since discontinued making that size.

It may well be simpler, easier, and cheaper to just replace the pot with one of similar or better quality. Just note that "better" quality these days may well cost more than the actual wah did in the first place.

At the very least, though, give it a decent cleaning and see where that takes you.

[RogueWah]

I'm gonna try cleaning it.... But If the above doesn't work I've offered to build him another wah with the old case. He's agreed to pay for the parts and everything so no worries there.

[RogueWah]

Got another question. Does anyone know what value pots these pedals use??

[Mark Hammer]

usually 100k, but it would vary by manufacturer.

[Robmosis]

Not to sound like an ass or nothing, but you "usually" get what you pay for. I have bought many cheaper items and have been happy sometimes but usually not.
I have never had/tried any rogue products that were worth half of what was paid. They really are just junk. I do not think it would be worth even fixing. For you to offer to build a new one for your friend is awsome and maybe your best bet besides him buying a vox or crybaby.
I use crybaby and vox and besides the lack of true bypass(which I am looking for a mod for my mister crybaby super by the way) they are great pedals.
So please people no more rogue. they really just don't make good products(IMO at least).
Rob

[Mark Hammer]

Manufacturers cut corners so as to be able to undersell a competitor or to cover a niche which has been hitherto untapped. Some find ways to reduce production costs that do not detract from sonic quality, even if they sacrifice roadworthiness. It is fair to say that most buyers are not touring musicians, so pedals such as those made by Rogue, Danelectro, Behringer, and others, provide a valuable service to those who simply want to be able to produce certan sounds, and are not looking for something that is rugged.