1 (edited by ramses 2020-01-18 14:57:53)

Topic: MADI: information about optical cabling and standards

See also MADI info center on archived webserver: https://archiv.rme-audio.de/en/products … lossar.php

The different optical cable plugs, SC/LC

The SFP (Small Form-factor Pluggable, colloquially also "Mini-GBIC") has a smaller form factor with LC plugs.
SC are the bigger plugs that you know from former RME products like Octamic XTC, etc.

There are OM3 / OM4 multimode patch cables available for all plug combinations that you might require:
- SC/SC (to connect devices with the bigger plug to other devices or patch panel with the same bigger plug)
- LC/LC (same as above, but only for SFP with the smaller plugs on both sides)
- LC/SC (to connect smaller SFP plugs to devices or patch panels with bigger SC plugs)

https://www.it-budget.de/media/image/product/7807/md/lwl-patchkabel-50-125-lm-om4-faser-sc-duplex-stecker-lc-duplex-stecker-violett-1-m.jpg

Cables are available as single or double cable (simplex vs duplex), but you can make 2 simplex out of one duplex cable by removing the plastic connector between the two cable plugs:

https://img-en.fs.com/images/ckfinder/ftp_images/tutorial/simplex-vs-duplex-stecker.jpg

Here the differences between the different cable standards (multi mode / single mode):
http://www.krakovic.de/wp-content/uploads/2013/02/Screen_2013.02.14__00297__021.png

Multimode cables and their color codes

The different cables have a color code, it makes it easier to distinguish them:
http://blog.leviton.com/sites/blogs.leviton.com/files/fiber-colorsb.jpg

RME MADI products

Former RME products with built-in MADI adapters were shipped per default with support for multimode supporting distances up to 2km. That is what most people require.
On special order you could also get a "single mode" variant supporting higher distances up to 10km without repeater.

Advantages of the newly introduced SFPs

It custs down the basic cost of the unit. If the customer needs optical, then he simply needs to order a SFP where he has the freedom to order a multimode or single-mode SFP as he requires.

For distances up to 2km between units you simply need a multi-mode SFP.
Single mode uses laser technology supporting distances over 2km up to 10km without repeater.

Compatibility of multimode cable

You can only mix cables of the same diameter, so you can mix OM3+OM4 but not OM1 with OM3 or OM4.
Some customer prefer to have the same type of cable, either OM3 or OM4.
Makes it maybe easier to predict the max supported cable length depending on the transfer speed being used.

Price Difference OM3 / OM4

You need to look and compare, LWL prices differ much from vendor to vendor.

OM3: Lightwin LC/SC, MM, 1m: €4,95
LSP-50 LC-SC1OM3 Simplex LWL Patchkabel, MM OM3, LC - SC, 1,0 m
https://www.reichelt.de/simplex-lwl-pat … &nbc=1

OM4: Lightwin LC/SC, MM, 1m: €5,95
LSP-50 LC-SC1OM4 Simplex LWL Patchkabel, MM OM4, LC - SC, 1,0 m
https://www.reichelt.de/simplex-lwl-pat … &nbc=1

Summary

  • You can connect RME MADI devices with SC and LC plugs by choosing an OM3 or OM4 LC/SC multimode patch cable.

  • "Patch cables" are usually available up to 30m length, for longer distances you need "fiber optic interior installation cable".

  • You can choose between OM3 and OM4 multimode cable.

  • OM4 is the more modern standard allowing longer distances (only a little bit more expensive)

I would use OM4 cable if you also use OM4 cables in the network or have structured OM4 cabling.

BR
Ramses
X10SRi-F, E5-1650v4, Win10 Pro 20H2, Cubase 11.0 Pro, UFX+, XTC, 12Mic, ADI-2 Pro FS R BE