Topic: Why is each MADI channel duplicated in this setup?

We've been using a fibre optic patch bay at a local studio to connect 2 x Octamic XTC to a MADIface and for some reason each preamp channel is duplicated in the MADI stream so preamp 1 is coming into TotalMix on channels 1 and 2, preamp 2 on 3 and 4 and so on.

Changing the sample rate doesn't affect this behaviour.  Have I set up the wrong routing in TotalMix, or is this a side effect of the fibre optic infrastructure having the wrong spec (e.g. single mode)?

The wall connectors are ST, so we've been using ST->SC cables, but other than that everything seems normal.

Eastwood Records
www.eastwoodrecords.co.uk

2 (edited by ramses 2019-02-05 20:40:40)

Re: Why is each MADI channel duplicated in this setup?

Single and multimode can not work together, completely different thing.
https://www.multicominc.com/training/te … tic-cable/
Single mode = laser beam over pure glass fibre cable.

All RME MADI devices use multimode unless especially ordered to be equipped to support single mode for longer distances.

BR Ramses
UFX+, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1650v4, Win10Pro22H2, Cub12Pro

3 (edited by ramses 2019-02-05 21:00:09)

Re: Why is each MADI channel duplicated in this setup?

You should not mix Multimode standards and need to stick to one standard, i.e. OM3 or OM4.
This you should do to avoid dampening of the signal, see this article here: https://www.flukenetworks.com/blog/cabl … iber-types

Maybe it helps you to distinguish the cables:
"Jacket color is sometimes used to distinguish multi-mode cables from single-mode ones. The standard TIA-598C recommends, for non-military applications, the use of a yellow jacket for single-mode fiber, and orange or aqua for multi-mode fiber, depending on type. Some vendors use violet to distinguish higher performance OM4 communications fiber from other types."

http://www.rme-audio.de/en/products/mad … =605%22%27

I personally recommend to choose OM4 (or even OM5) cables because this is a cable standard which is also being used for data networks to support highest distances to connect servers high speed, see chapter comparison: https://en.wikipedia.org/wiki/Multi-mode_optical_fiber

EDIT: root cause see Jeffs posting. Maybe my posting gives you ideas what to look for, not to dampen the signals too much.

BR Ramses
UFX+, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1650v4, Win10Pro22H2, Cub12Pro

Re: Why is each MADI channel duplicated in this setup?

ST and SC are just plug types.

From the report it seems an issue of clock, it looks like the Octamic units work at double speed (96k) while the card works at single speed (48k).

Regards,
Jeff Petersen
Synthax Inc.