60 Cycle Hum in Outboard. Help please.

[lolzgreg]

OKAY

Well, I diagnosed the preamp noise. It is not the left channel of my FF800 (i.e, input 1 L) that is responsible for the noise. It is the first preamp in my SCA rack, which is coincidentally closest to the power transformer of the SCA rack! Transformer induced cyclical hum it is.

However, this has only solved a problem I don't know about. I need to try to figure out the larger issue.

 

[lolzgreg]

WELL, WE SORT OF GOT IT

It was a ground loop. I used two Ebtech Hum Eliminator XLRs in the signal path, and this was the result:

http://dl.dropbox.com/u/63792534/CLARIPHONIC HUM X XLR L+R.wav

Near dead silent, i.e., quiet enough for my tastes.

So, you ground-cutting gurus, can this ground issue be eliminated with cutting the ground on the cables?

If so, which end, the one going to the unit, or the one coming from the converter?

Also, on which cable: the input cable or the output cable?

I suppose the worst case scenario is I'm going to need to buy two 8 channel hum-8 rackmounts and put all my gear through there... that seems a little unnecessary...

Any other advice.

Thanks again everyone.

 

[Platinum Samples]

A patch bay is usually wired so that the grounds are only connected at the patch bay and not at the connectors to the gear... so try lifting the ground at the outboard (in & out).

Whatever works is usually the correct answer.

Rail

 

[lolzgreg]

Thanks everyone (especially Rail). I unsoldered the grounds on one side of the TRS cables heading from the converter to the outboard, and now I'm in business. This forum is still the best \m/