Is SP/DIF an additional I/O on MBox?

[studioJ]

Can the digital input be used simultaneously with the analog inputs on the Mbox? Is there a direct patch through mode for the digital input?

Thanks.

[Mightypudge]

If you are trying to use the SPDIF inputs along with the analog inputs to record more than 2 tracks at a time, it won't work. Due to USB bandwidth limitations, the Mbox can only record 2 tracks simultaneously.

[studioJ]

I just want to be able to monitor the SPDIF input while recording the analog inputs. I don't need to monitor anything through FX. Possible?

thanks.

[SoundWrangler]

Due to USB bandwidth limitations, the Mbox can only record 2 tracks simultaneously.

<font size="2" face="Verdana, Arial">Actually, there are USB audio interfaces (incl. the Tascam US428 & others) that can stream four channels of input audio (yes, 24-bit up to 48K) into the computer via the USB connection. (True, way back when the USB spec was introduced, the wisdom was that they certified only two channels of audio I/O.)

The more interesting question is whether the current 2-chan I/O on the Mbox is a permanent design limitation of the unit itself, or merely reflects the way the MBox hardware is currently handled by the PT software? (Let's recall that for quite some time the Audiomedia card was also only 2-chan I/O, then Digi eventually allowed PT to use both its analog & digital I/O independently & simultaneously - long after other MIDI sequencer SW had already been doing precisely that with this card.)

[The Electric Trombone]

Perhaps I'm ignorant of some factor but 10-12 meg per second can only handle two channels of audio ?

I think USB is more than capable of more than two audio channels.

I belive its the PTLE software that won't allow both analogue and digital inputs to be used concurrently, or perhaps the MBOX itself. I would hope however that its the software, that way DIGI can throw you guys a bone later with a software upgrade.

[studioJ]

So the answer is no monitoring of digital inputs while recording analog inputs? I don't need to pass it all via USB, I just need to hear it. i don't actually have an MBox but I have a customer who wants a small mixerless setup for his powerbook and wants to use ProTools. He has a single synth with digital outputs. Too bad the 002 isn't coming out tomorrow.

[where02190]

M-box allows either the analog or the spdif inputs to be used, but not at the same time.
The short answer is no.

[vf124]

Why can?t I use the analog and digital inputs independent of one another? I could do this with my Audiomedia III card. Why can?t I turn off S/PDIF mirroring?

The USB spec only allows for a certain amount of Data to pass in either direction at any given time, and there is simply not enough bandwidth to handle the load presented by 4 discrete audio streams. Audiomedia III uses the PCI bus for throughput, which is not limited in this way.

<font size="2" face="Verdana, Arial">This is taken directly fm Digi's Mbox FAQ...

[clutch]

But once again, the Tascam US428 is capable of handling SPDIF i/o and audio i/o and Midi i/o at the same time through the USB bus.
What's the big limitation? [img]images/icons/confused.gif[/img]

[vf124]

What's the big limitation? [img]images/icons/confused.gif[/img]

<font size="2" face="Verdana, Arial">My guess, the "special edition" of Pro Tools LE used w/ the Mbox...