I got the Dunlop MC-404 wah back at the beginning of March, and after a few months it started to make a weird high pitch humming sound when I had the pots adjusted a certain way, so I thought it was broken and sent it to SweetWater where I bought it from, they told me it was defective and would send me a new one. and with the new one I am getting the same annoying sound with it. So I called sweetwater and the guy didn't know anything about the pedal so he said he would call dunlop and try to find a solution and here's what I got in a email, "There are usually two things that cause the wah pedal to squeal. First is if the cables are plugged in backwards. Second if the q is set too narrow and the gain is too high the pedal can feedback. " the first one I thought wtf the cables plugged in backwards? and the second one I'm not to sure what they mean. so anyone know what I can do? this is getting really frustrating so I'm thinking about asking sweetwater to let me switch it for something else but everywhere I look people say this is the best wah.
Gibson Les Paul Studio Pro
ESP: H-1001
Eleven rack
Fender blues Jr III
Digitech DT Whammy
Ibanez Sweeping Demon
Earthquake Bit Commander
Tone Mob Model 001 Fuzz Generator
DOD Bone Shaker
Stomp Under Foot Sonic Warfare
Daredevil 77 IC Op-Amp Fuzz
Basically, by setting the Q too narrow and boosting gain you're getting feedback on a certain frequency; and it sounds awful.

When you say "when I had the pots adjusted a certain way" what do you mean? There are internal pots for gain and Q. Q adjusts the width of the frequency band effected. Are you playing with these? Basically, experiment with them until you get the sound you want. Can you get a good sound from it?
Not all combinations of settings will be pleasant - you can say the same for any piece of gear.

Regarding using the cables backwards - with most wahs, if you plug the guitar into the output of the pedal and the input to the amp, you get squeal.
Quote by fly135
Just because one has tone suck it doesn't mean one's tone sucks.