Custom 20/50 effects loop noise reduction strategies

[Dusty Chalk]

Update
When I put a loop in my send cable right near the input jack like this:

The noise in my effects loop is practically eliminated.
I don't understand why - it really bizarre...but it's been an awesome discovery...

Sounds like RF. You could try using shielded cables, perhaps?

 

[Beach Radio]

Sounds like RF. You could try using shielded cables, perhaps?

I am... I definitely am in a RF hot spot too

 

[Dusty Chalk]

Yeah, I have this fantasy wherein I make the entire room both sound proof and a Faraday cage, but that only eliminates outside noise -- you still need power, and the RF could be coming from any number of links in the chain.

 

[Kred]

If the loop noise sounds like 60/120 cycle hum, it's not RFI. RFI sounds like distortion or aliasing.

Is it 60 or 120 cycle hum? High voltage hum before the full wave rectifier will be 60 cycles (the power line frequency), high voltage hum after the full wave rectifier will be 120 cycles (the rectified frequency before the filter capacitors). This may help identify where the hum is coming from.

If loop noise is common with this design, it could be power transformer pickup (sensitive to cable movement) or a ground loop in the physical layout.

 

[Beach Radio]

If the loop noise sounds like 60/120 cycle hum, it's not RFI. RFI sounds like distortion or aliasing.

Is it 60 or 120 cycle hum? High voltage hum before the full wave rectifier will be 60 cycles (the power line frequency), high voltage hum after the full wave rectifier will be 120 cycles (the rectified frequency before the filter capacitors). This may help identify where the hum is coming from.

If loop noise is common with this design, it could be power transformer pickup (sensitive to cable movement) or a ground loop in the physical layout.

In my case, the RFI sounds like the local radio station. Moving the amp resolves that issue... Looping my send cable removes the hum.

 

[Ben]

Buy an Ebtech Hum Eliminator and run it with your pedals in the effect loop.