Klon & EM-Drive/Paramount 2-in-1 high-pitched hum issue

[Ncuab]

So I've built a Klon (with TBP) and a EM-Drive 2-in-1 Dual overdrive pedal and the EM-Drive side has slight high-pitched hum to it.  I've also built a Klon (with buffered bypass) and a Paramount 2-in-1 dual overdrive pedal and the Paramount has a slight high-pitched hum to it.  Both sides of both pedals works great, except for the EM-Drive & Paramount sides which humming.  Anyone else have this issue?

[Ncuab]

I just built another 2-in-1 pedal with a TS-808 with a charge pump and Super Hard-On and I'm getting the same issue.  I think it's because of the charge pumps.  I've tried grounding the non-charge pump sides and its seems like nothing is working.

[Beaker]

Dual pedals often present problems like this, and it's not always easy to track it down.

Firstly, are you using battery or wall wart for your power? Sometimes you get hum or squeal when wall wart powered, but not when using a battery, so see if this is the case first.

If battery is ok, but you get squeal with a power supply, then the power supply is the cause of your noise.

Secondly, how is your cable management inside the enclosure? If your wiring is too long or messy, with power wires running alongside signal wires, this can induce squeal.

Try re-arranging your wires to keep power and signal wires as well seperated as possible.
If this helps, but does not cure the problem entirely, use grounded wire.

I use this stuff:

http://www.ebay.co.uk/itm/Van-Damme-Pro-Grade-Classic-XKE-1-Pair-Install-Cable-BY-THE-METRE-10-Colours-/181308920422?var=&hash=item2a36da9266

I always use grounded cable on all my twin pedal builds - it makes a big difference!