Stompbox help....

[tylereot]

Hey, guys...

I built a very simple A/B box from a kit from General Guitar Gadgets.
I've double and triple checked the wiring with the layout http://www.generalguitargadgets.com/pdf/ggg_sw_ab_lo.pdf?phpMyAdmin=4a28f86a515b7883e7bc35a68d4e7b6d&phpMyAdmin=78482479fd7e7fc3768044a841b3e85a.

My issue is that while the box works as it should, there's a high pitched whine it seems to introduce.  It's not loud, and since I'm playing with mostly single coils, I'm pretty used to EMI hum.  But it's distinctly there, and doesn't change with either output.  It's a much higher frequency than pickup hum.
:icon_scratch:
Thanks for all your help!

 

[Cagey]

There's nothing in there that can create noise, so it must be picking it up. Is it a metal box? If so, are the input/output jacks grounded to it? I know that sounds like a silly question, but there are a lot of isolated 1/4" jacks out there. Might be worth trying different cables as well.

 

[tylereot]

I guess I'm wondering if a cold solder joint might do that.  I'm still pretty new with a soldering iron, but they all seemed pretty straight forward to me.

 

[Cagey]

It's unlikely. Cold solder joints tend to either present an intermittent, high-resistance or open (infinite resistance) connection. In the first instance the signal would come and go. In the second, the signal would be reduced. In the third, there'd be no signal at all. Often, a cold solder joint will progress through all three of those stages over time, perhaps even starting off perfectly fine. How much time depends on how bad the joint is.

In any event, it doesn't inject signal. If you're hearing a high-pitched signal that wasn't there before, it's being picked up from somewhere. That's why I asked if the box was grounded. You should be able to read continuity between the box's housing and your amp's chassis, as well as the bridge on your guitar.

 

[line6man]

There's nothing in there that can create noise

Technically there is. The resistance of the wire increases the thermal noise. But obviously that is not to say it is significant. We're talking fractions of an Ohm with a high (-ish) impedance signal.

 

[crash]

That is not uncommon with a/b boxes.  All of that unshielded wiring can be a source of noise.  That is why you see a lot of buffered a/b boxes now.

 

[mayfly]

That is not uncommon with a/b boxes.  All of that unshielded wiring can be a source of noise.  That is why you see a lot of buffered a/b boxes now.

er, not if you just put the whole thing into a metal box and ground that.  What's inside the box does not matter because it's very low amplitude.

 

[tylereot]

Yeah, and this isn't hum like you get with pickups and guitar wiring.  Much higher frequency.
I'll drop the Guitar Gadgets guys a note, and see if they know what it is.
It's really unusable this way. 
I also got an overdrive box from them, but I'm thinking I'm out of my depth with this stuff.  I should probably send it back. 

 

[leo12.]

If your using 2 guitars to 1 amp, is it a low quality lead you had lying around?
If its 1 guitar into 2 amps it could be a ground loop problem.  here's a link hope it helps;
http://www.tdpri.com/forum/amp-central-station/161892-b-y-box.html

 

[tylereot]

Grounded the box.
Problem esolved.  :doh:

Thanks guys!  Works great.