Isolation for stereo guitar rig

[guitylerham]

Just a quick question as I'm re-designing my current pedalboard.

If I want to split my guitar signal and send it to two different signal chains on my pedalboard and then two different amps, I need to isolate one of the signals so it doesn't create a ground loop. My confusion is whether I need to separate and isolate the power supply of each signal chain or just the signal ground of each chain. Currently, everything on my board is powered by a common One-Spot. My plan is to build RG's "transformer coupled splitter". I have a more complex design in mind with more outputs and blending capabilities but I need to get this right in my head first.

Thanks!

[antonis]

My confusion is whether I need to separate and isolate the power supply of each signal chain or just the signal ground of each chain.

Are all power supplies dual..??

[bartimaeus]

Tbh I'd try it without isolation first and see if you have any issues. There's lot of stuff on forums about what you NEED to do, but most players get away not knowing it. How many people actually change their strings every week for example

I wouldn't bother isolating all of the pedals. Instead, I'd just add a transformer isolator to the last pedal in one of the two chains. As long as one of the amps is isolated from the other, you're very unlikely to notice any ground issues.

Consider this: even if your two pedal chains are plugged into different supplies, those supplies will be plugged into the same power strip. It's not like one of them will be plugged in on the other side of the room like an amp would be.

[guitylerham]

My confusion is whether I need to separate and isolate the power supply of each signal chain or just the signal ground of each chain.

Are all power supplies dual..??

Not sure I get what you're asking.

[guitylerham]

Tbh I'd try it without isolation first and see if you have any issues. There's lot of stuff on forums about what you NEED to do, but most players get away not knowing it. How many people actually change their strings every week for example

I wouldn't bother isolating all of the pedals. Instead, I'd just add a transformer isolator to the last pedal in one of the two chains. As long as one of the amps is isolated from the other, you're very unlikely to notice any ground issues.

Consider this: even if your two pedal chains are plugged into different supplies, those supplies will be plugged into the same power strip. It's not like one of them will be plugged in on the other side of the room like an amp would be.

I have a Boss OC5 that I've split and run to two different amps and definitely got a loud hum between the two so I'm gonna build this pedalboard to be more resilient than it currently is.

Agreed, with one of the two signal chains transformer-isolated, I should be good.

With two One-spots for example, plugged into a power strip, sure they'd both have a common ground but some power supplies are isolated and have discrete transformers or mosfets that claim to provide isolated power. 

[antonis]

Power supplies have a positive and a negative point..
For single supplies, negative and ground points coincide..
For dual supplies, they don't..

[guitylerham]

Power supplies have a positive and a negative point..
For single supplies, negative and ground points coincide..
For dual supplies, they don't..

Gotcha, like how a single supply can be referenced in the middle (instead of ground) for a bipolar supply.

[stallik]

I'm an advocate of RG's Hum Free ABY.
http://www.geofex.com/FX_images/TransformerSplitter.pdf
Does what it says on the label 

[bartimaeus]

I'm an advocate of RG's Hum Free ABY.
http://www.geofex.com/FX_images/TransformerSplitter.pdf
Does what it says on the label 

That one looks really solid! Similar to BYOC amp selector, which I also like a lot.

However, those devices will be useless if the pedals after the splitter/selector are connected in any way (including through the power supply). They only provide true isolation if they are put right in from of two amps (or other destinations).

That's why I recommend running the pedalboard as a single "stereo" board on one supply. Then add transformer isolators at the very end of the chains, instead of using "splitters".

A single channel of the RG's splitter would do the trick nicely.

[guitylerham]

Yep, the transformer out will be the last thing before the amp input.

My ultimate plan is to have some crazy complex flexible routing for the 3 different signals coming through my board but whatever I do, I'm not gonna go and undo it all by connecting the grounds together!! 

My next round of inquiry will be regarding a mixer circuit. Exciting!