Ground Loop Noise? Unbalanced ground lift possible?

[Uladyne]

So I was trying to record some guitars direct while monitoring through my amp, and I've been getting this annoying whiny noise.

Normally for direct guitars I'd just record the unprocessed output from my Podxt pro since I was using the Pod for the processed tone as well. Now that I have a real amp I want to monitor my performance through it instead of the pod partially for accuracy (The sound I hear when playing influences how I play) and also just because it sounds way better.

So on my first attempt I split the signal with a boss LS-2 line selector (not the problem, I already eliminated it and the rest of my pedals to no effect) and sent one out to my amp and one into the Pod as a sort of over-priced DI box. Annoying noise. Tried the ground lift switch on the pod. No effect.

On my second attempt I tried using one of the instrument inputs on my Firepod, splitting the signal the same way as before. Still annoying noise.

So I finally said fuck it and grabbed my old behringer DI and plugged my guitar into the input, ran the "link" to my amp, and plugged the output into my firpod. Still noise, and no dry output. Hit the ground lift switch on the DI and bam, no more noise, but the damn DI box is fucked. It just puts out really low farty noises. Paper weight.

Assuming I'm suffering from ground loop noise, is there any way to make some sort of ground lift device that will work on an unbalanced signal? Like between one of the outputs of the LS-2 and the instrument input on the firepod? I'm assuming there isn't, as there isn't really a ground lead to "break", but I remain hopeful that I will find a cheap (free?) solution to this annoying problem.

I don't have any other power circuits to use (my studio is a converted laundry room, not many options) and the noise isn't only present coming from the amp, but is also present in the DI tracks I made with the Pod and firepod instrument input. Whenever I disconnect the cable from whatever I'm using for the DI, the noise instantly vanishes.

Can I wire something up that will still get my DI signal to the DAW without the ground and without fucking anything up? I'm hoping I can get a decent DI box for my burfday, but thats months from now.

 

[Metaltastic]

What you're looking for is an isolation transformer, which doesn't lift the ground but rather isolates it (safer) - normally, they go in the signal path, but the Ebtech Hum X goes at the end of the amp's power cord instead; I bought one when I had AWFUL ground loop noises while reamping, and it solved the problem 100%!

 

[Uladyne]

I may have to look into that. I've been scanning the "prepping your tracks for reamping" thread and it seems like the instrument input on my firepod should work well as a DI, so if I can get that noise eliminated I should be good to go!

 

[Ermz]

What you're looking for is an isolation transformer, which doesn't lift the ground but rather isolates it (safer) - normally, they go in the signal path, but the Ebtech Hum X goes at the end of the amp's power cord instead; I bought one when I had AWFUL ground loop noises while reamping, and it solved the problem 100%!

Yes, ground hum problems are the bane of my damned existence. You'll ALWAYS run into one at some point if you're interfacing a lot of gear in a studio. I have it here at home, and had an insane amount at a local studio. Thankfully, for home purposes the LL Red Eye's 'ground lift' switch takes care of all my issues.

 

[Uladyne]

Damn I'm a fucking boner. I forgot the Behringer DI can work off phantom power. For some reason it doesn't like batteries but seems to be working fine powered by phantom power. I'd still like to be able to use the Firepod instrument input but this will work till I get that figured out. Thanks guys!

Edit: I just "Rediscovered" the "preamp outputs" on the back of the Firepod. When I get my reamp box up and running, according to the manual I should be able to plug my guitar straight into one of the instrument inputs on the firepod, and run a TRS from the preamp out into my reamp box and into the amp for monitoring/recording. That will kick ass. Unless plugging a cable into that output makes the firepod look for a "return" signal, which I won't be providing. I dunno I'm gonna have to do some tests.

 

[Wolfeman]

Yeah I think the outs on the back of the FP are tip send / ring receive or something of that nature... Have you thought of just adding a DI into your reamp box??? Make it somewhat of a Redeye? it's not that hard to accomplish...

 

[Wolfeman]

Oh yeah and I wanted to add, when it comes to ground loops, doing things like 'lifting' is only transferring the ground noise to a different path. Only way to truly get rid of it is to fix it at the source, or isolate it with a transformer as already stated. I recommend buying a few Palmer isolators, they are more pricey but work in many different situations and you'll never need another again...

 

[Uladyne]

Yeah I think the outs on the back of the FP are tip send / ring receive or something of that nature... Have you thought of just adding a DI into your reamp box??? Make it somewhat of a Redeye? it's not that hard to accomplish...

According to the firepod manual the preamp outs act like an effects loop send and the line inputs next to them act as returns, but I'm just not sure if it behaves like a parallel or series effects loop. When I get to messing around with it again I'll just monitor the dry input of the guitar in the instrument input and see if it cuts out when I stick a trs jack in the preamp out or not. Maybe plug the other end into the line in on the pod to pretend its my reamp box and amp and see what happens.

I actually did think about putting DI capabilities into the nydave box, as there is certainly room, but I didn't forsee these issues popping up when I ordered all the parts. If I'm able to use the Firepod as a DI it will probably be fine for my purposes. If not, I'll more than likely be modding my reamp box.