ABY splitter hum issues

tennisdude · February 05, 2006, 02:11:07 PM

Hey guys,

I know alot of you have built the geofex ABY splitter. Mine's up and running, not in an enclosure yet. However, with the gain cranked up on one of my amps, there is a definately noticable added hum coming from the splitter. Here's what i think my options could be:

1. live with it.
2. box it up-- should help the hum.
3. help fix the hum by adding to/modding the pedal.

Any thoughts?

John

R.G. · February 05, 2006, 03:45:42 PM

With all hum problems, a lot depends on the exact details of construction.

What's yours look like?

tennisdude · February 05, 2006, 03:59:39 PM

I'm using the exact layout at general guitar gadgets:
http://www.generalguitargadgets.com/pdf/ggg_amp_aby.pdf

no crossed wires, and i dont think any shorts (because the pedal itself is working flawlessly).

thanks

R.G. · February 05, 2006, 05:21:51 PM

Which output causes hum?

tennisdude · February 05, 2006, 06:04:27 PM

I'll get back to you on that. I'm pretty sure its both, but it might only be the left output (A?). What I mean by left is, if your looking at the component side of the PCB, the one to the left.

thanks

tennisdude · February 06, 2006, 10:58:22 PM

both outputs hum if connected to a high gain amplifier. I know there's a similiar thread going right now, I don't want to draw attention away from it, but i think we both have the same issue.

theundeadelvis · February 06, 2006, 11:07:05 PM

I fixed the LED problem by running a ground from the leds to the ground. I was told that it was accidently left out on GGGs layout.

theundeadelvis · February 07, 2006, 03:10:23 PM

I just installed an on/off/on (spdt?) toggle with the center pole going to chasis ground, one pole going to one of the output jacks and the other pole going to both outputs. I can switch between total output isolation, 1, or none. It seems to work pretty and gives me options for other amp and enviroment interactions. Hope this helps!

mydementia · February 08, 2006, 09:38:22 AM

I thought I'd chime in here...
I've been fighting hum on this circuit for a couple months now and was excited to see theundeadelvis' solution. I tried it out last night and found that the on-off-on switch does help reduce hum in my setup (Peavey XXX) but not enough to be usable. For folks with lower gain amps, this might work just fine...but for those of us with gain-monsters - keep looking.

Mike

EDIT: Oddly enough, I've had very good (=quiet) luck using the Fulltone passive AB switch...

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ABY splitter hum issues