1 Topic by explodingPSYCH (edited by explodingPSYCH 2022-11-02 21:42:02)

  • Registered: 2017-12-26
  • Posts: 49

Topic: Using I/O for FX Send and Return

Are there any special considerations I need to make to ensure proper audio grounding when using the output of an RME device as a send to a TS line level device and returning back from that device into the input of an RME device?


I am attempting to do this, via a Redco 96pt patchbay (with programmable grounding) and I cannot find a grounding option that isn't introducing much more noise than taking the original signal source and going direct into the effect.

The noise is only introduced in external devices that are making an audio loop (have an input and output connect to RME units). External devices with only outputs connected do not have the noise.


-I have attempted moving my computer to other circuits.
    (when on a different circuit, noise is mostly hum. When on same circuit noise is mostly digital "hash")
-I use a Linear Power Conditioner for all studio gear.
-I have tried all grounding options on patch bay (Bus, Isolated, Vert Strapped. Best is using Isolated when coming from RME and Bus when going back).
-Reamps seem to help, as they seem to decouple the RME from the device, but the audio is then much too quiet (no longer line level).

2 Reply by MC

  • MC
  • MC
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  • Registered: 2007-04-06
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Re: Using I/O for FX Send and Return

Connecting unbalanced devices in a bigger setup is always a challenge. It also depends if that unbalanced unit is connected to PE/ground or not. Sometimes the easiest solution is to run it galavanically isolated via DI boxes.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2017-12-26
  • Posts: 49

Re: Using I/O for FX Send and Return

Definitely curious about my options here. It seems like what might be happening is that I creating some kind of ground loop in the shield part of the TS cables.

Could you elaborate on what you mean by running it "galvanically isolated via DI"?

Would I need a DI for every return path then? I have 15+ devices, many of which are stereo return.

This doesn't happen with my console, just the RMEs. It makes me wonder if there's something on the computer/USB end as opposed to every send and/or return.

RME set up:
UFX+         (Master, connected via USB3 to computer)
UFX+         (connected to master via ADAT I/O)
M32pro AD (connected to master via MADI)
M32DA       (connected to master via MADI)

4 Reply by MC

  • MC
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Re: Using I/O for FX Send and Return

You have 15+ unbalanced devices?

I don't know the exact grounding options of the patchbay, but one permanent solution might be to use the RME balanced inputs without ground. For that the TS shield is connected to XLR pin 3 or TRS R. Pin 1/sleeve stays free. Try it with one or two channels. If that works you could mod all cables going back to the RME inputs.

Otherwise I would suggest to get an electrical trained guy to check all your grounds and connections for other solutions or workarounds.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2017-12-26
  • Posts: 49

Re: Using I/O for FX Send and Return

I have 15+ devices, many TS, many XLR or TRS.

Options on the patchbay are Bus, Isolated and Vertically Strapped. Sometimes having Isolated on the sends to the devices and Bussed on the returns helps with the noise, but not in all cases.

I'm already looking into professional options, though I'm trying to make sure I'm not overlooking any obvious variables. In this case I want to make sure I'm using the RME's as designed and suggested.

I was under the impression they would (under normal circumstances) work correctly with unmodified TS connections. I'm starting to wonder if this assumption might not cover units that both send to and return from the RME units.