• Registered: 2008-01-28
  • Posts: 37

Topic: FF800 Slaved via ADAT into FF-UFX

Up until now, my main audio interface has been a Fireface 800 and it has served me admirably. I could not want for better sound quality. Now that I have recently acquired a Fireface UFX, my plan is to setup my FF800 to run standalone and slave it via ADAT into my UFX, in order to add 8 more AD and 8 more DA channels to the UFX.

I am trying to figure out if the round trip latency through the FF800 AD + DA and ADAT in addition to the FF-UFX USB safety buffer will be an issue. If I am adding things up correctly, at 44.1 KHz sample rate, the H/W RTL of the FF800 analog and UFX USB would be .98 msec FF800 AD + .63 msec FF800 DA + .725 msec FF-UFX USB = 2.34 msec H/W latency. Are there any other H/W delays that come into play when using the FF800 as an ADAT unit?

How does the 2.34 msec H/W latency of the FF800 used as an ADAT unit compare to other ADAT converter interfaces like the ADI-8 DS Mk III? I could not find any specs on the ADI-8 DS Mk III for RTL other than the RME product page says "Low latency conversion: less than 12 samples delay". I'm not clear if that is 12 samples delay each on the AD and the DA or total, but anyway it is apparently less than the FF800 used as an ADAT unit.

For quite a long time, I have been using an analog mixer paralleled with my inputs to my audio interface to create monitor mixes here in my studio. Now that I have the UFX, my plan is to get rid of the analog mixer and generate all of my monitor mixes using the UFX.

I'm interested in hearing comments from people here on this forum as to how much would the H/W latency of the digital mixers (FF800 and FF-UFX) affect the monitoring mix in the setup I have planned?

2 Reply by MC

  • MC
  • MC
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  • From: Germany/Thailand
  • Registered: 2007-04-06
  • Posts: 24,847

Re: FF800 Slaved via ADAT into FF-UFX

That confuses me. You want to compare the delays of AD and DA conversion between inside the UFX and outside (the FF 800)? All values are listed in the manuals, also in the one of the ADI-8. The safety buffer is irrelevant as it affects both in the same way. The UFX ADAT I/O adds three samples to the combined AD/DA value of the FF 800, same does the ADAT I/O of the FF 800.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2008-01-28
  • Posts: 37

Re: FF800 Slaved via ADAT into FF-UFX

Ok that's good information Matthias -- thanks.

So, if connecting the FF800 as an ADAT slave unit to the UFX adds 6 samples to the FF800 2.34 msec RTL latency => 2.48 msec.Then adding the 32 sample safety buffer in the UFX (.726 msec), totals to 3.2 msec RTL at 44.1 KHz.

That is compared to .9 AD + DA + .726 msec saftey buffer = 1.6 msec total for analog I/O only in the UFX.

I guess I was trying to figure out if using a higher performance ADAT converter (eg ADI-8 DS Mk III) would give any significant improvement over the 3.2 msec I would get using the FF800 for that purpose. If it is only 1 or 2 msec faster then maybe it's not worth pursuing.