Electronics experts help please - some sort of earth hum

[Guest Jecklin]

This is driving me mad.

My set up is not conventional so I'm aware this may be a little off the radar for most.

Here we go....

I run two condenser microphones clipped onto my Contrabassoon into a little beringher mixer (providing phantom power) through my effects chain (EHX freeze and pitch fork) into a philjones double4.
Great.
And I get an earth hum. If I touch any metal in the chain the hum reduces massively.
If I run a line out from the mixer into my audio interface to record I get no hum on that channel.
If I remove the pedals the hum is still there.
If I plug a bass into the double 4 instead, there is no hum.

So... There is some interaction between the double4. I used to use one microphone and a Joe meek Q3 and got hum from that as well.

The double4 runs on a wall wart so too the Joe meek and the mixer.

Would you imagine that there is not adequate earthing?
Is there a way to add earthing short of clipping Some wire from metal onto me?

Any help gladly received.

Cheers
Thomas

[Guest Jecklin]

Ok it seems this problem is widely reported from double 4 users.

I need the newer 3prong UK earthed power supply.
Time to give synergie a shout