Re-amping Electric DI Problem

[MikeTrahearn]

Last night I tried to re-voice a recorded electric DI part out of my 002 and into a Line 6 Pedal Board to take advantage of the variax amp simulation. The I took two lines from the pedal board (L+R) output back into the 002 to re-record it since the original performance wasn't bad and would save the guitar player doing it all over some other time.

The trouble was, that when I hit record enable, when the guitar wasn't playing, I got horrendous computer noise on the two return lines. The noise went away when I disconnected the input to the Line 6, and even when an actual guitar was plugged into it instead of the 002. Strange. I tried all the outputs, each the same computer noise - I could hear data noise when I moved the mouse. Pretty bad. My monitor speakers don't do that. Hmm I couldn't figure it out.

I try to use balanced cables wherever possible.
I remember having this problem before when I used an outboard digital reverb (clocked to the 002) the amount of noise present in the signal path was destroying. Unplugging the 002 from the outboard's input removed the noise. Never got to the bottom of it. Is there something fundamental I'm doing that could be the cuplrit?

Any ideas?

Mike

[dubhausdisco1]

I am not that familiar with the line 6 stuff, but I would guess that it is either some sort of ground loop problem(possibly caused by using balanced cables in unbalanced jacks)...don't quote me, though!

[philwinkle]

Did you use a DI box from your 002 out to your amp? This fixed a similar problem (data noise) when re-tracking from my mBox2. The only outputs are XLR balanced anyhow - but using a DI instead of an XLR to 1/4" fixed my grounding problem.

[randyT]

You will probably need to use an isolation transformer to ellimintae the ground loop. I have several in my setup to elliminate exactly the kind of noise you are describing. The Ebtech hum elliminators and line level shifters work well for me.

randy

[MikeTrahearn]

Thanks Guys!

I did contemplate using a DI box to electrically isolate the output from the 002 (the DI track to be re-amped) and the line-6 input, which would normally take the guitar lead. However, I couldn't figure out how to wire it up since the line-6 only has unbalanced in, and the DI's I have are all active, so you can't wire them up backwards like you can with the passive sort.
I thought that all the TRS outputs from the 002 are balanced?

The other option is to DI the returns from the line-6 before going back into the 002? But if the noise eminates before the Line-6, then I'll have to come up with another idea.

Here's what I'm trying to do:

DI track ---> 002 out 8 ----> AmpSim ----> In 1 ---> New Audio Track

I think the problem is here ^ but I tried both balanced and unbalanced cables. But I didn't use a DI at this stage.

I'll give it another go and see how it goes.

Mike

[philwinkle]

Try the DI. With the active sort you may need phantom power - so connect the XLR output end to the 002. You're not actually going to use the returned signal, just get power from the 002. Use the TRS balanced cable in one of the parallel inputs and run back out of the other into your Line 6. It's a convoluted way to do it and would certainly be much easier with a passive dual-direction DI.

YMMV.