What am I doing wrong?

[j2dafo]

before I begin, please believe me when I say I have read and re-read nearly all the posts on this....

I am trying to interface my FMR RNC's and RNLA's with a balanced Neutrik patchbay. Experiencing some 60hz hum, unless I pull out the patch cables a tiny bit. While this is a plausible work around, it's pretty annoying, especially considering I spent good money on bulk wire and connectors to avoid having to do this. Making TRS-TS cables, I have attempted both tying the cold (ring) to ground, and also leaving it blank at the TS end. All cables have tested good with a meter, which I did obsessively every step of the way.

Any suggestions?

Also, having the same problem interfacing outs 3-8 on my relic, DIGI 001.

[roadsweeper]

I don't think you are doing anything wrong, I have the same problem with my Neutrik patchbays. We have 8 x 48 point Neutrik jack bays in the studio and at least 5 of the sockets have cables halfway out so as to stop this, however I usually just get nothing rather than hum but I assume it is the same problem. If it is worrying you, get a decent patchbay. I personally don't mind, I feel it adds a bit of romance to the studio!

[jeremy.c.]

Originally Posted by j2dafo

before I begin, please believe me when I say I have read and re-read nearly all the posts on this....

I am trying to interface my FMR RNC's and RNLA's with a balanced Neutrik patchbay. Experiencing some 60hz hum, unless I pull out the patch cables a tiny bit. While this is a plausible work around, it's pretty annoying, especially considering I spent good money on bulk wire and connectors to avoid having to do this. Making TRS-TS cables, I have attempted both tying the cold (ring) to ground, and also leaving it blank at the TS end. All cables have tested good with a meter, which I did obsessively every step of the way.

Any suggestions?

Also, having the same problem interfacing outs 3-8 on my relic, DIGI 001.

I had the same issues with my RNCs and RNLA with my Neutrik patchbay. I ended up using a TRS insert cable plugged into the insert point on the RNC/RNLA and then the two unbalanced ends as in/out into the patchbay. Not having any issues with hum and I don't have to seat the cables just right halfway in to get it work.

[j2dafo]

yes, very romantic, it really isn't the size of the plug that counts, but how far out you can pull to find "the spot"

i originally had it wired as mentioned above, with a TRS insert plug from the RNC/RNLA to 2 unbalanced plugs into the patchbay with no luck.

i thought neutrik was a decent patchbay. what's the next step up?

[JusSumguy]

If you're experiencing a 60 Hz. hum. Then it's prolly coming from the AC ground.

Try lifting the ground on the AC to the board. And all the other gear from there. ONE AT A TIME.

If that gets rid of it, then you got some decisions to make. It may be as easy as leaving the ground lift in place. And it may be as hard as installing an isolation transformer.


-

[j2dafo]

only experiencing the hum when something is patched thru the FMR boxes. no hum going straight to the board or to the converters or to some balanced outboard gear.

[u b k]

the rnc isn't balanced, but it does have a balanced connector on the trs input jacks that were designed to act as insert send/returns for one-cable connection to little consumer desks like mackies.

iow, you need to use unbalanced cables when interfacing to the unit via the input and output jacks.

my best guess: when you pull the cable out a little, you are essentially disengaging the 3rd connector in the jack, thereby achieving the same result as using an unbalanced cable.


gregoire
del
ubk
.

[j2dafo]

Not a noob. I know that the RNC is unbalanced, and the diff between the alternative, and what the trs input is designed to do. I have tried using straight unbalanced cables, which didn't work. So i made the recommended TRS-TS cables in the aforementioned ways. (R tied to ground, and also left blank on the TS end)

Has anyone tried using a TRS-TS cable as a patchcable? would this make any difference in the signal chain to/from the RNC?

Just a little frustrating because it seems I have followed steps others have taken to solve this....

Originally Posted by u b k

the rnc isn't balanced, but it does have a balanced connector on the trs input jacks that were designed to act as insert send/returns for one-cable connection to little consumer desks like mackies.

iow, you need to use unbalanced cables when interfacing to the unit via the input and output jacks.

my best guess: when you pull the cable out a little, you are essentially disengaging the 3rd connector in the jack, thereby achieving the same result as using an unbalanced cable.


gregoire
del
ubk
.

[j2dafo]

Originally Posted by j2dafo

Not a noob.

and to be clear, what i meant was... I'm not THAT much a noob

[imloggedin]

whatever you do, do NOT LEAVE the AC ground lifted from a box.

at any rate arent these powered by a wall wart? i think that changes the situation... if i were you id try to unscrewed the patch bay from the rack and see what happens. maybe your making some kind of weird loop through the chassis of the rack.

[j2dafo]

i'll try leaving the patchbay hanging/lying somewhere else, but as other gear wired to the same patchbay do not exhibit the symptom, i will keeps my hopes low. thanks for all the advice and suggestions.

[u b k]

Originally Posted by j2dafo

Just a little frustrating because it seems I have followed steps others have taken to solve this....

have you tried star grounding your rack? or a (good) power conditioner?


gregoire
del
ubk
.