modified crybaby humming????

[AC30Dirty]

Hey guys, here's my dilema.... I have a GCB95 that i modded. I true bypassed it with a 3PDT swith and I removed the input buffer. I moved the gain bass resistor down to 390ohm and replaced the 33K resistor for the vocal mod with a 100K. I also replace the fasel it came with with a Fulltone inductor I had .Thats it!!!! I love the way it sounds except i noticed that i'm getting a humming sound now. When I tried the pedal stock the humming wasn't there. its pretty loud also. I don't know what it could be. Maybe it was removing the buffer that did it but i'm not sure. Here's what my pedal board consists of.... guitar to Ernie Ball VP jr., GCB95, fulldrive 2, Fulltone '69, voodoo lad tremolo, EHX Small Stone, Fulltone Choralflange, EHX Deluxe Memoryman, to amp. Could it be where its located in the signal chain? I'm also powering the wah, tremolo, phaser, and chorus with a 1Spot. Could that be doing it?

[Papa_lazerous]

Ok I think before we start to worry about what you may have done wrong with your mods it would be a very good idea to eliminate any other causes.

Connect your guitar and play straight into your amp, no hum?  then continue

Plug guitar into Wah and wah into amp, nothing else in chain.  Also use a battery or simplicity.

Play through it if you get a hum then you know you have done something wrong.  If you dont add things one at a time to see where it comes in that will help you track it done.

If it is the Wah you will have to give us some more to go on.  Maybe some pics or voltage readings, that'd be a very good idea.  Also double check everything dont assume that something is right because its so simple that it could never be wrong thats often where the mistake is!

Hope thats a start

[AC30Dirty]

well' i took the wah off my board and tried it out by itself with my little practice amp. Just guitar----wah----amp.... it still makes the same humm. only when the wah is engaged. I tried it with the 1 spot and a battery and it does it with both.  I've modded many wahs and this is the first time anything like this happens. I'm really stumped!!!!!

[R.G.]

There are only a few ways to make something hum.

- open signal ground
- open high impedance input
- pickup coil/loop
- leaking AC power

Which of these is yours?

[Paul Marossy]

Wah inductors are generally pretty sensitive to EMI. Were you close to any wall warts while you were doing your testing? Have you tried doing your testing in a different location?

[AC30Dirty]

OK.... I'm thinking its a grounding problem. I used the info on this web page http://www.stinkfoot.se/andreas/diy/mods/dunlop.htm. Is connecting the switch to R14 sufficent ground? Something tells me its not.

[AC30Dirty]

what have you guys who have modded your own wah used as a grounding point for the pedal. I'm thinking maybe the humm is supposed to be there. I've just never noticed it. Its really loud with distortion and not with clean, which makes sense. I can only really hear it when the wah is engaged and is closer to the toe position. What do you think?

[alfafalfa]

You could try to see if the 220 uf electrolytic and the 100 nf cap are okay !
Change them to see if it makes a difference.
I have never had any trouble with hum in a wah unless I used a single coil guitar but that's obvious.

[AC30Dirty]

Well, I replaced the fulltone inductor I had in the wah with the stock Fasel inductor that came with the wah and it made no difference. It's also not a grounding problem with the switch either. I'm really stumped!!!! Could it be the high gain transistors in conjunction with the 390 ohm resistor casing too much gain? Other than this I really don't see what could be causing it.

[Paul Marossy]

My vote is for EMI. Have you tried different physical locations, not different rooms in the same bldg, but a whole different location?

[AC30Dirty]

Hey Paul, I actually have tried it in 3 different locations. Here at home and at 2 different location i regularly play at on the weekends. I really think it might be a grounding thing but, who knows. Like I said earlier in this thread it only does it when its on and is most noticeable in the toe down position. It sounds like when you got a distortion pedal on and your not playing; your hear a buzz or hiss because there is a lot of gain. Also, the thing is that I can't really hear it on a clean channel. This leads me to think that the pedal is fine and that its just going to do that.

[Paul Marossy]

OK, just making sure it's not a location thing. If you're using really high gain pedals, it will amplify the heck out of any hum being picked up by the inductor that you wouldn't otherwise normally be able to hear. That is just something you have to live with. 

[AC30Dirty]

Thanks Paul. I guess I will have to live with this. But, if you have any more ideas as to what it might be or any other way I can troubleshoot this i'd appreciate it.