HELP! HX stomp and JHS colourbox BUZZZZ! problem

[LukeFRC]

Help

I have a colourbox that I love, and had a HX stomp and was getting noise from the both. so sold the stomp.
Two years on I rebuy a HX stomp.... .... and the first time I take it to church to play and it sounds great...

Until the main lights in the room go on (LED spotlights) and it goes Buzz really loudly - like about 1/3 of the signal of the bass. This happens even when the bass is muted. 

It seems to be a combination of the venue lights, the HX stomp and the colourbox just don't work together... but why? 

Isolated power supplies, 
Lights on a different mains ring from switchboard 
Turn hx off, no buzz
or turn Colourbox off and use it as a passive DI, no buzz
turn lights off, no buzz - but apparently not an acceptable solution!

What's going on here and how do I avoid it? 

I made a diagram of things I've tried so far...

 

[0175westwood29]

have you tried lifting the ground on the Xlr from the colour box? is that something they could do at the pa?

[LukeFRC]

4 hours ago, 0175westwood29 said:

have you tried lifting the ground on the Xlr from the colour box? is that something they could do at the pa?

No - because it doesn’t have ground lift! Neither does the stomp - other people have had this issue it seems https://line6.com/support/topic/60123-ground-loop-hum-from-a-pa-system/

 

balls

[SumOne]

Yeah, my guess is a ground loop issue.  A bit slack of HX Stomp and Colourbox not to have ground lift, there is good reason most preamp pedals have one. 

 

There are things like https://www.thegigrig.com/humdinger

[LukeFRC]

7 minutes ago, SumOne said:

Yeah, my guess is a ground loop issue.  A bit slack of HX Stomp and Colourbox not to have ground lift, there is good reason most preamp pedals have one. 

 

There are things like https://www.thegigrig.com/humdinger

in-between HX and colourbox? 
I'm guessing it's some kind of 1:1 transformer in there

[SumOne]

13 minutes ago, LukeFRC said:

in-between HX and colourbox? 
I'm guessing it's some kind of 1:1 transformer in there

 

I'm no expert, but I think the issue is that each pedal needs their own direct earth path or the interference from things like lighting can get caught in a ground loop. The solutions seem to be: isolated power supplies, balanced cables, or add a ground lift (I assume the ground lift would need to be between the pedals, but I'm not sure). 

 

Although the Cioks is sold as 'isolated' I did have an issue with another power supply that was advertised as 'isolated' but had ground loop issues, this was what a pedal maker told me: 

 

"some power supplies advertised 'isolated' but they only have separate regulators, filters and over current protection for each of the DC output positive terminals but the output negative (ground) terminals are still bonded together - which is not a true isolated supply. You can test this using a digital ohm meter by measuring the resistance between the centre pins (negatives) between two outputs, testing  without the power supply energized should show infinite resistance between the two of the centre pins if the supply has truly isolated outputs). "

[LukeFRC]

just tested the outputs of the Cioks DC7 with my multimeter - they are isolated from one another

[Jakester]

I found one of the problems I was having with ground loop hums (despite having a ground lift on my preamp) was to do with daisy chaining pedals. 

 

I had a fully isolated Cioks PSU but even so, I ended up with a lot of noise in the signal chain. 

 

I've ended up trying to make sure that only pedals that don't contribute to the signal chain (such as a tuner driven from a separate tuner out, MIDI switcher pedal, A/B switch etc) are daisy chained. 

 

Can you reconfigure your 'other pedals' if they're daisy chained?

[LukeFRC]

no daisy chaining- I'll go and try again and unplug things but when I had it before it was just stomp and colourbox and Cioks being used. (before my pedal phase started) 

[Jakester]

12 minutes ago, LukeFRC said:

no daisy chaining- I'll go and try again and unplug things but when I had it before it was just stomp and colourbox and Cioks being used. (before my pedal phase started) 

 

Hmm, what a pain! I did get one of these but never got round to trying it - might be worth a crack on each pedal to try and sort it?

 

https://www.thomann.co.uk/joyo_zgp_noise_blocker.htm

 

 

[LukeFRC]

9 minutes ago, Jakester said:

 

Hmm, what a pain! I did get one of these but never got round to trying it - might be worth a crack on each pedal to try and sort it?

 

https://www.thomann.co.uk/joyo_zgp_noise_blocker.htm

 

 

If it's the noise from lights being picked up by stomp is it the power or the signal ground I need to try and sort? 

[tauzero]

How about disconnecting the shield at one end of the jack-jack cable connecting Stomp and JHS? Should be the equivalent of a ground lift.

[lukea]

I'm definitely not an expert, and am happy to be proven wrong, but since the colour box has two transformers in it, I'd be surprised if the ground loop was coming from after the colour box (I.e. a ground loop created between the mixing desk and your pedalboard), but to check that you could try using a cable with an integrated ground lift like this one:

https://www.thomann.co.uk/sommer_cable_sghxu.htm

 

What I'd suggest though is trying one of these:

https://www.thomann.co.uk/harley_benton_groundbox.htm

Its a fairly cheap solution, and could hopefully fix the grounding issue within your board (or whatever the heck it is that's going on!). But if it doesn't work, you wouldn't have wasted that much money on it!

[JPJ]

Just a silly thought, and despite not owning either of the pedals in question, could it be that there’s not enough power going to both pedals from your power supply as I’ve heard that both of these pedals are quite power hungry? 

[LukeFRC]

1 hour ago, JPJ said:

Just a silly thought, and despite not owning either of the pedals in question, could it be that there’s not enough power going to both pedals from your power supply as I’ve heard that both of these pedals are quite power hungry? 

I don't think so - if it was I don't know why the main room lights switching on and off would turn the noise on or off.

[JPJ]

3 minutes ago, LukeFRC said:

I don't think so - if it was I don't know why the main room lights switching on and off would turn the noise on or off.

I know that power transformers do strange things if the are underpowered - an electrical engineer once told me, something about THD or harmonic distortion or something like that. It all got a bit technical and I might have glazed over.