FX8 direct to Amp Hum

F

fstrat76

Member
I've searched all the hum threads here and a bunch of other places, and still can't figure this one out. (Thanks X-Mann for the conversation and suggestions).

I purchased a PRS MT-15, hooked it up to the FX8 - very loud hum. Guitar direct into MT-15, there is no hum. There is no hum when the FX8 is connected to my Orange RV50 MKIII direct or 4CM.

Tracking down the hum, its connected like this (using different cables also, but not humbusters):

With or without guitar input
FX8 and MT-15 plugged into the same circuit.
FX8 out pre direct into MT-15

This connection results in a terrible hum.

Here's the thing, the FX8 can be OFF and the hum persists.

I added a ABY switch between the FX8 out pre and the amp, and used the ground lift switch. Hum gone.

This sure smells like a ground loop, but its in the same AC outlet. Makes no sense to me and this all works with other amps. I've ordered fractal humbusters, and might try the ebtech, but technically I'm not understanding why this occurs.

Any other ideas or suggestions?

Thanks!
 
Ok.....This is the original thread that started it all for me & my Hum issue.

I had used the FX8 w/ a Friedman Runt w/ Humbuster cables and no isssues at all.

I get a Carvin Legacy-3 w/ an all metal chassis (just like the PRS MT15) & no ground switch.....& Hum too loud to use the FX8 with it.....

https://forum.fractalaudio.com/threads/for-the-love-of-god-legacy-help.124756/

This eventually ended up being an actual ground loop & a great learning lesson for me. It was never the FX8 creating any of the Hum/Noise.....It was a loop that’s very commonly caused by the 4cm method.

I wish you nothing but luck.....& my main amp is the MT15 w/ the FX8.....& I have no buzz/Hum. The difference between our set-ups could be many things.....& or....your amp could have an issue. I use the Humbuster Cables & the Ebtech Hum-X in the Power Cord of the amp.....Plus my FX8 presets are dialed in with a pre-noise Gate & one after the FX loop of the MT15.

Hopefully someone smarter than me will come in and help w/ some new advice. Having said that, I’ve had the same issue w/ a different amp, own what you have now & don’t have this issue.

Peace! X
 
Last edited:
Thanks X-Mann. I have a couple things to try yet, humbusters and maybe the ebtech.

I'm looking for the technical reason this occurs - for knowledge so to prevent any future damage from reaching my studio/other equipment.

The metal chassis is an interesting theory though the other thread indicates another metal chassis amp doesn't have the issue.
 
You must log in or register to reply here.
Back
Top Bottom