AB Switch hums only with LEDs

zelcanada

zelcanada

New member
I built an AB switcher for my board, so I can plug two guitars in, and switch between them on stage. The build works great. It is silent if I don't plug the pedal in. However, I wanted to switch between two LEDs, and when I plug the pedal in, there is a slight hum that isn't there when it's not plugged in.

I followed this schematic:
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And here's my build:

1000025773.jpg


1000025774.jpg

(The black electrical tape is to hold the LEDs in place. It was my first time using a step drill bit and I went a smidge too far!)

I know I can just leave it unplugged, but then I miss out on the cool factor of my daughter's artwork:

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Any advice would be appreciated!
 
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Or just remove the grounds to the OUT jacks
You don't need them as the amp with ground the cable. Though you would need to use either an isolated in or switch the outs isolated jacks
 
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jimilee said:
Turn that boy about 90 degrees and shorten those wires. Remove the grounds, as was previously suggested, and use a battery.
Click to expand...
I think they will still get a loop through the enclosure, especially if the pedalw and amps end up on different circuits at some point.
zelcanada said:
I'm not sure I understand what you mean (I'm fairly new to all this...). What do you mean by an "isolated" Jack?
Click to expand...
Jacks where there is no continuity between the "sleeve" connection and the barrel that attaches to the enclosure.
As it stands, the grounds of you amps, pedals and power supply are all connected. They're also connected via the actual ground at the wall. So. Ground loop.
 
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Instrument cables only *have* to be grounded once to shunt the shield to ground. Every amp *should* have its input sleeve grounded. So, your OUT jacks don't *need* a ground.
You can start by removing the ground to them. The input should have a ground, though it's likely grounded at the output of the previous device.
Beyond ditching the ground wires, I would swap the out jacks. It's quiet now when powered down because your getting rid of you current loop.
If this box is just to be used at home or whatnot, that's fine. If you are going to gig with it, you need isolated/insulated jacks. That, or carry and extension cable with your pedal board and always plug in your pedal board to the same power source. Reason being, if you plug your pedal board in to power at the front of the stage, amps into power at the back of the stage, then you could have big problems. All 3 could potentially be on 3 different circuits. You'll then have a ground loop from your pedal board through the wall to the circuit breaker, down another circuit to the amp and back to the pedal board through
🥁🥁🥁🥁
Your non-insulated jacks and metal enclosure.
Same could happen if the amps are on different circuits.
Another option is to add a lift switch in addition to the insulated jacks. Have it break the ground from the power ground to the insulated out jacks. You'll want that lifted most times UNLESS you end up plugging into something that doesn't have a grounded input jack. Again. I would only bother if you gig it.
Hope that helps.
 
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jwin615 said:
Instrument cables only *have* to be grounded once to shunt the shield to ground. Every amp *should* have its input sleeve grounded. So, your OUT jacks don't *need* a ground.
You can start by removing the ground to them. The input should have a ground, though it's likely grounded at the output of the previous device.
Beyond ditching the ground wires, I would swap the out jacks. It's quiet now when powered down because your getting rid of you current loop.
If this box is just to be used at home or whatnot, that's fine. If you are going to gig with it, you need isolated/insulated jacks. That, or carry and extension cable with your pedal board and always plug in your pedal board to the same power source. Reason being, if you plug your pedal board in to power at the front of the stage, amps into power at the back of the stage, then you could have big problems. All 3 could potentially be on 3 different circuits. You'll then have a ground loop from your pedal board through the wall to the circuit breaker, down another circuit to the amp and back to the pedal board through
🥁🥁🥁🥁
Your non-insulated jacks and metal enclosure.
Same could happen if the amps are on different circuits.
Another option is to add a lift switch in addition to the insulated jacks. Have it break the ground from the power ground to the insulated out jacks. You'll want that lifted most times UNLESS you end up plugging into something that doesn't have a grounded input jack. Again. I would only bother if you gig it.
Hope that helps.
Click to expand...
So I'm realizing how little I know about grounding...lol.
I'm also getting a bit lost because what's labeled as "input" on the diagram is my output, as I'm using it to switch between two guitars using the same amp.

Here's some background. I'm using a the Rockboard ISO Supply to power my pedals. I will gig with this, but my setup is such that I'm always plugging in my pedals to the same power bar as my amp.

Are you able to draw on the diagram what you mean about removing the grounds on the output?
 
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Okay. Cool.
That easier. Just replace your one out jack with an insulated one. Keep the ground wires except the one to the output.
Audio grounding is a bit different than general AC earth grounding.
 
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jwin615 said:
Okay. Cool.
That easier. Just replace your one out jack with an insulated one. Keep the ground wires except the one to the output.
Audio grounding is a bit different than general AC earth grounding.
Click to expand...
jwin615 said:
Okay. Cool.
That easier. Just replace your one out jack with an insulated one. Keep the ground wires except the one to the output.
Audio grounding is a bit different than general AC earth grounding.
Click to expand...
Like this?
1000025819.jpg
 
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