SOLVED Bass multi effect pedal board troubleshooting!!

ADAOCE

Well-known member
Hey folks so two things right up front.

1. How the F have I never built and used an audio probe before this?!?!
2. I’m never boxing then rocking ever again

That said I’m thinking this is not as bad as I initially thought. I’ve posted a video where I walk through what the main problem is but I’ll state it here too.

Using the audio probe with all the pedals bypassed the signal sounds fine maybe a tiny bit of noise but nothing I noticed at first. Once I engage any of the effects the ground noise is super bad. Also if I touch the audio probe to ground on the power distribution board I can hear the ground noise and the guitar signal coming through.

I tested the audio probe on a working pedal and when I touch the probe to ground it’s completely silent which is what I expect it should be.

Let me know what you guys think. I’m hesitant to say if there are other issues until I get this issue sorted. If I try to ignore the ground noise the wet signal actually sounds ok.

I realize this is a pretty complex build and I can post pictures or answer any questions on how things are coming in and out of the pedal.

For the power and ground distribution to each board (pedals, bypass boards, two leds, headphone amp) I have power from the dc Jack coming into a solderable breadboard from Adafruit which then goes out to everything effectively creating a common point so nothing is chained off one another it all ties back. For the two Aion pedals, the polarity protection diode and a power filtering cap are off board (it’s on the bypass board) so I used the breadboard to add those in. I’m thinking maybe the caps running to ground are causing the issue.

 

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It does sound as if you have something that isn't properly grounded. I think you need to test by isolation. Completely disconnect everything except 1 pedal. Have the power going to just one board and the inputs/outputs to that one board. Get it working and then add in the second one, etc
 
It does sound as if you have something that isn't properly grounded. I think you need to test by isolation. Completely disconnect everything except 1 pedal. Have the power going to just one board and the inputs/outputs to that one board. Get it working and then add in the second one, etc
I was thinking this is what I would likely have to do. Thank you. Do you think I could disconnect each pedals power connections and power it from a different isolated supply to see if having the pedal circuits power on a separate ground isolates the noise?
 
Ok so in my haste to put this thing together I forgot to connect the input Jack to ground. All the jacks were connected together but they’re all isolated from enclosure minus the input so that explains how if no effects touched the signal path it sounded fine. Threw a ground wire in there and bam it sounds perfect. I’ll post build report soon
 
I would think making patch cables would be a fun part of the process. Then again, I've never actually done that...yet...
Maybe it’s because I’m at the end of this whole thing but I’m finding it very tedious and monotonous. The Squareplugs I’m using are great but they’re real tight to work with so the leads are small and the tab holes are small too. Trade offs for super small profile plugs I guess.

I admit it will be fun to put all the cables in and zip tie it all down.
 
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