daisy chaining interfaces; how many theoretical channels.?

[timizere]

hi. i have a location recording session coming up rather soon and i'm going to need a fair bit of multitracking beef.
So my questions are; how many channels can i get into my DAW using an 828mk3 as the primary interface, taking into consideration daisychaining via f/w and both channels of ADAT.
Also, how many channels of audio are theoretically possible over a 400mbit/s firewire line? any figures based on 44.1khz 24 bit would be great.
How much of what i am trying to do is based on the power of the host pc? i am guessing not a great deal as my laptop has a 7200 rpm drive which would easily outperform the firewire transfer speed.

thanks guys, tim.

[TheRealRoach]

There are limitations to the daisy chain capacity. The manual states that up to 4 firewire MOTU's can be linked, and usually up to a max sample rate of 48khz (the higher sample rates are sacrificed for quantity of channels. Regardless, I would do an extreme amount of testing on the system prior to the recording if you haven't run multiple MOTU's before. It can be a real pain. Do some searching around here for "multiple", "daisy chained", "sync", "squeal", "dropouts" and you'll see what I mean.

For a test, I would run a sine-wave test tone into all channels that you intend on using and recording for about an hour paying close attention that there aren't any dropouts in the recording or playback.

[timizere]

thanks for the response! i have had no trouble running an 828mk2 via f/w daisychain.. but you're right, and i would definately stress test the system before the session. By what you've said about the MOTU spec i could run a theoretical 56 channel system (40 through daisy chained F/W and 16 via the host 828's ADAT.) i wonder if it is possible to use the 16 channels of ADAT on each daisychained device.. this is cleary going to put huge stress on the f/w bus but if it can handle it the track count would be 104! hence my question how many channels is it theoretically possible to run over firewire?

[TheRealRoach]

I really doubt that you could run all of the onboard channels plus the ADAT as well. You can only squeeze so much through a pipe. The manual for your MOTU unit should tell you exactly how many channels you can run in various configurations. Good luck.