• Registered: 2013-08-17
  • Posts: 2

Topic: MADI Channels @ 96kHz

Hello RME community,

I've been looking for an answer at several places on the net, in shops and so on but noone seems to be able to answer my question.
If it has been answered, sorry for the hassle, please just point me to where to look.

Setup:
I am currently running an 32i/o interface via USB which also sports MADI i/o.
The drivers seem to be rather unstable with my mainboard to I plan on buying a RME card to hook it up via MADI.
All resources about MADI state that it can run up to 32 channels @ 96kHz i/o, but I don't understand whether a MADI channel can carry 32 channels in total (be it in OR out) or if it can carry 32 channels in AND 32 channels out at the same time.
My best guess would be that 32 channels are split up in both ways somehow.

My question is:
I never run my 32 channels at the same time, I just hate patchbays smile
If I buy say an HDSPe MADI with one MADI channel do I need to provision the channels to input and output or will MADI do that on it's own?
I mostly use 8 outputs (stereo mix + 3x monitor mix) and I never really need more than 24 inputs at the same time.

  • Jeff
  • Jeff
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  • From: USA
  • Registered: 2007-05-21
  • Posts: 4,684

Re: MADI Channels @ 96kHz

The devices you mentioned each have 1 MADI in and 1 MADI out per port. One cable only goes one direction (in or out), but you can use 64 in + 64 out at 48k or 32 in + 32 out at 96k, with bi-directional MADI cabling. You don't need to set up any special routings.

Regards,
Jeff Petersen
Synthax Inc.

Jeff's Website

  • From: Melbourne Australia
  • Registered: 2007-05-18
  • Posts: 70

Re: MADI Channels @ 96kHz

I can highly recommend the RME Madi cards (I use the older Madi PCI card) and as Jeff states, they can handle 32 channels in and out simultaneously at the 96KHz sampling rate. I use my converters at 44.1 KHz and therefore am able to carry 64 channels in and out simultaneously at this sampling rate. The other important benefit with the RME cards, in addition to the rock-solid driver reliability and low latency, is the fantastic TotalMix Matrix mixer and DigiCheck software. These are amazing additions to an already impressive feature set, and make setting up monitor/headphone mixes a breeze. Good luck.

Kind regards,
George

  • Registered: 2013-08-17
  • Posts: 2

Re: MADI Channels @ 96kHz

Thank you for the update.
I now am a proud owner of a HDSPe MADI.
Question is:
Do I (and if so how) clock the two devices.
AFAIK I have two and a half options.

a) Let the Antelope clock the RME
b) Let the RME clock the Antelope
c) Have MADI do the clocking (is this possible?)

I just wanted to ask, because I will be in the studio for the next couple of days and need to know whether to buy a BNC cable or not.

Thanks again in advance.

  • From: Melbourne Australia
  • Registered: 2007-05-18
  • Posts: 70

Re: MADI Channels @ 96kHz

Congratulation on your new Madi PCIe card. As regards clocking, whichever component of your system is doing the initial conversion from analogue to digital is the preferred unit to be the master-clock. Once this initial analogue to digital conversion (ADC) has happened, further transmission of this digital data will not generally be affected by (transmission) jitter unless it is so bad that the ones and zeroes in the digital data stream are corrupted and do not arrive correctly at the next unit. This is unlikely in any modern system with decent cabling and is usually the result of damaged cables. The initial conversion jitter is very different and much more important than any jitter in the transmission of your already converted digital data stream. Because your Antelope is converting your analog signals into a digital data stream, then it should be the master clock.

The internal crystal oscillator within any decent ADC will always outperform an external clock (due to the increased jitter inherent in using external cabling and the extra work required to recover the word-clock signal within the slave unit). The best that external clocking can hope for is to be equal to an internal clock (and that would only be because of a decent re-clocking implementation and good jitter removal and clock extraction within the slave unit). So in brief, your Antelope should be the clock master, and your RME Madi PCIe card should be the clock slave. Your RME Madi card will derive its clock from the Madi stream it receives from the Antelope.  As regards cabling, the RME Madi card should have no problems extracting the clock from your Antelope, using just the Madi optical fibre cable, however you could use a word-clock cable if you prefer.

Be aware that when using 96KHz sample rates, the Madi frame rate often needs to be set manually for each unit, as this is not always flagged correctly within the data stream. I believe that different brands handle this scenario differently, so it may be worth checking the manuals of both units to confirm how this is done. Hope that helps.

Kind regards,
George