General board power wiring questions

Hi all,

I’m still having trouble with midi bleeding into audio, even after giving every midi enabled pedal an individual isolated power supply. While that has helped a lot, the midi is still audible and varies in severity between different routings I’ve set up in the ML10X’s. I’ll admit I’m a beginner and this is the first proper board I’m setting up, I feel like it’s getting messy with all my adjustments so I’m going to start from scratch.

I have 16 pedals or devices for 12 isolated outputs from the power supply so some daisy chaining will be necessary. I was under the impression that daisy chaining pedals was fine if their overall power draw was under the 500mA supplied by each output, but obviously it’s a bit more nuanced than that. So my questions are -

  1. Does the bleeding occur just between audio/midi devices like the pedals or the ML10X? Does it happen on the device itself or does it bleed through the power cable?
  2. I figure I have 3 types of pedals/devices, audio with no midi, audio with midi, and midi controllers/exp pedals with no audio. Would I be best to give each audio/midi device its own power output and chain audio-only devices together, and midi-only devices together?

Hope that makes sense!
I’ll start a new topic for my other question.

I’m not an expert in the electronics of this, but I can tell from experience that daisy chaining is generally a bad idea, especially if you use a lot of digital devices. So my guess would be that you already put down about 3k for your board, my advice would be to spend 100 more to get a second power supply.

Thanks GuitarWolf, seems like the best advice but I’d need a whole new board to be able to fit another power supply. And I’m no expert either but it seems like overkill to provide an individual output of 500mA for just a footswitch or Midi box that only needs 20mA. So I’m going to try daisy chaining my non-audio devices together (MC8, Midi box, footswitches, exp pedals), and a few analog non-midi pedals together, then all the rest can have their own output. Will see how it goes I guess :slight_smile:

Won’t hurt to try it. If possible I’d consider to power some pedals with batteries.

Which pedalboard do you have and what is your current power supply unit?

I built the board myself, the power supply is a Fender Engine Room Lvl 12, with 12 isolated 500mA outputs.

Do you have a photo of it? There are lots of new power supplies that could meet your power requirements that may mean minor adjustments and not a complete rebuild. Unless that’s what you want?

Just working for a couple more hours but will post some pics soon

Ok, I’m a little embarrassed of this mess, especially after seeing some of the beautiful boards here haha. But this is my work in progress. I am planning a completely new build at some point in the future, just want to be a bit more certain of exactly what I want first. And when I designed this I didn’t even know about the brilliance of the ML10X let alone that I would want two of them. So it’s not completely perfect for what I have now but doing the job ok!

So I’m sure you can see why some rewiring will be necessary anyway. Consider these the ‘before’ pics now I’m going to learn to solder…

You could probably fit One big Strymon power supply and at least one of the smaller supplies in the same space as the Fender Engine Room.

What you could also do is multiple CIOK’s power supplies.

I’d strongly recommend avoiding running power and audio cables next to each other and daisy chaining power to pedals.

Have you tried removing effects from the chain one at a time until the noise problem goes away? Or start with none and add them in one at a time until the noise problem starts, at which point maybe swap the last one or two for something else and see if that makes any difference. Or just temporarily remove all the MIDI cables to see if that makes any difference.

In other words, some methodical experimentation to see if the problem is with certain specific pedals.

Regarding daisy-chaining power, it’s “usually” okay for analogue pedals. But I always run digital pedals on their own isolated power outlet.


I owe you one @nnnnnn, your comment came at the perfect time as I was getting carried away learning to solder and experiencing the joys of perfectly aligning bespoke cabling lol, forgetting to test everything as I went. In fact I was just planning on testing the pedals anyway but thought it couldn’t hurt to check just the midi setup.

And the culprit is the Rockboard Mod 2. It has 4 trs thru ports and 2 midi thru, and not great isolation apparently. The Asabi has been exonerated hahaha. Have it and the Beetronics Zzombee plugged in so far and not a whisper of midi noise.

Thanks everyone for the tips!

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I would definitely get ride of those solderless patch cables. Or at least check them with an ohm meter. I’ve never had any success with the solderless cables.

@mthompson - I have both Disaster Area EVO and Evidence Audio SIS solderless patch cables on my guitar pedalboard, and EVO on my bass pedalboard. No problems of any kind with either product after several years of use.

I had Midi noise too, funny enough I had the same Expression Pedal (Lehle) on my board, when I removed it the noise was gone.