Subject: RE: [linux-audio-user] USB Quattro and Jack questions
From: Brian Redfern (bredfern_AT_calarts.edu)
Date: Tue May 27 2003 - 23:52:45 EEST
The quattro only does two outputs at 24bit 96khz, with two outs at
44100khz at 16 bit I get really nice, loud, clean output that works really
well with terminatorX (after adding an extra buffer to its settings), and
works great with pd in a default install.
On Tue, 27 May 2003, Mark Knecht wrote:
> >
> > Another thing about the quattro is that even the windows drivers will
> > not allow you to record and playback on all 4 channels at one time.
> >
> > You can use
> >
> > 4 in, 2 out 48khz 24 bit
> > 2 in, 4 out
> > 2 in, 2 out 94 khz 24 bit
> >
> > I think I am running up against this with my latest attempts. It may be
> > that the quattro cannot do all 8 channels because of a hardware switch
> > maybe for power consumption or something. They do run awfully hot and I
> > can imagine that it would be possible to melt something if their is too
> > much power running through them.
> >
>
> USB 1.0/1.1 is built on a 12Mb/Sec physical layer.
>
> 96000 * 24-bits * 4-channels = 9.216Mb/S if I did the calculations
> correctly.
>
> I think that's probably more than USB can really handle. When I worked for a
> company that did USB hardware, we found in many PCs (at that time -
> 1996-1999) that most USB implementations would really do much more than
> about 2Mb/Sec reliably. The newer implementations are much better, but these
> numbers bring you up to 75% bus efficiency. Even 1394 doesn't get much
> beyond that and it uses much larger packet sizes to get some of that.
>
>
>
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