Signal noise- any ideas?

[bassbiscuits]

So I play acoustic guitar, which usually goes straight into my little PA (a little Allen and Heath desk and two Mackie SRM350 powered speakers).

 

The only pedals I use are a Korg Pitchblack tuner, and occasionally a Boss GE7 Eq pedal and a EBS compressor. 
 

However I’ve noticed at a couple of gigs (mainly the ones where you’re running a lot off one socket/extension) that whenever I add my pedals into the chain there’s a massive buzz thru the PA.

 

I’ve swapped out each pedal, each guitar, two different power supplies and plugged them into to different extensions etc but still it happens. Even one single pedal and one single adaptor is enough to do it, so it’s not any individual pedal or the adaptor trying to draw too much power.

 

The only way around it has been to stick with just a tuner running off batteries, which is perfectly silent. 
 

What am I missing here? Is this problem with venue wiring, nearby lighting, my leads (swapped them out too), my PA, or something else? 
 

It’s doing my head in. 

[BigRedX]

Do your pedal mains adaptors have a plastic earth pin on the plug? Have you tried running them off batteries?

[bassbiscuits]

One of them has a plastic earth pin (a One Spot) the other doesn’t (a Mooer). I tried both and gave up. I ended up using just a tuner running off battery and the hum disappeared. 

[BigRedX]

It will be an earthing problem due to the PSUs for your pedals not having the same earth reference as the rest of the signal chain. I suspect that the metal earth pin on the Mooer PSU isn't actually connected to anything and is there simply because it's more robust (the plastic pin on the One Spot is notorious for breaking off). How are you connecting to the mixer?

Edited yesterday at 09:45 by BigRedX

[bassbiscuits]

Just guitar lead from acoustic to tuner and then tuner to 3/4 inch jack channel input on mixer. 

[BigRedX]

Is the jack input expecting a balanced line using a TSR jack plug?

[bassbiscuits]

Not as far as I know. I’ve not got the mixer to hand at the moment but it’s always just worked with normal guitar leads. It’s only when effects which are connected to power supplies are involved that the noise starts. 

[bassbiscuits]

Aha. The manual points out that: “Guitarists will be pleased to know that two of ZEDi-10FX's mono channels feature Guitar DI high impedance inputs, allowing guitars to be plugged straight into the mixer without the hassle and expense of carrying separate DI boxes.”

 

Theres a push button with a pic of a guitar on it on the channels Im using. If I don’t press it you cant hear enough signal to use. If I do press it you get this massive hum. 
 

I’ll try using my DI pedal in the chain and not using the “guitar button.” Also wondered if 3/4 from tuner into XLR of mixer channel would get around it. 
 

hmm.