Re: [LAU] RME Multiface and an extra 8 output channels

On Mon, 13 May 2013, Iain Mott wrote:

> I have an RME Multiface I/HDSP PCI card. This gives 8 balanced audio
> outputs. However I require an extra 8 outputs for a specific project.

I've also looked at my options for expanding beyond 8 analog i/o's on my
Multiface II....

> One option is to sync two Multiface/HDSP PIC card together. Although
> not exactly necessary, I understand the extra hdsp card is needed if i
> wish to use sampling rates higher than 48k which i do. There are some
> other set up benefits too I gather.

Something to be aware of is that although you can have up to 3
Hammerfall cards in a single computer, they cannot share any kind of bus
for monitoring or headphones in TotalMix (or its Linux clone,
hdspmixer). You will end up with separate headphone lines, which you
may be able to merge with cabling yourself at the expense of a couple of
inputs, but that's messy.

Alternatives to getting a second Hammerfall card include:

* Taking advantage of the digital i/o's that you already have... I've
had some trouble finding the exact specs of the Multiface I, but on the
II, there is an SPDIF digital i/o (2ch. in, 2ch. out), and an ADAT port
(8ch. in, 8ch. out). The analogs, the SPDIF, and the ADAT can all be
used at the same time, but the catch is that because ADAT itself has a
48kHz limit, there's no way to use the ADAT's at 96kHz unless you bind
the 8 i/o's together as 4 virtual i/o's that each combine two channels
to get double speed (called SMUX).
         Since I've seen that the Multiface's analog converters don't
really sound right (probably due to filter design) unless you run it at
96kHz, and since it's not possible to run the analog i/o's at 96kHz
while you run the digitals at another speed, the net effect of all this
boils down to that you're going to want to run at 96kHz, and if you're
using the ADAT ports at that speed, you will have to use SMUX even
though that will cut you down to 4 ADAT i/o's instead of 8.
         And the net effect of all that totally is that you have the
potential for up to 14 i/o's if you put all the analogs,
SMUX'ed-together ADAT's, and the SPDIF l/r pair together and use them
all, from one Hammerfall card. Not quite the 16 analog i/o's you'd get
from having two Hammerfall's, but at least it all ends up in one unified
TotalMix/hdspmixer session with one headphone monitor.
         There is one further complication: There aren't a lot of
8-channel standalone ADAT AD/DA's out there that I've seen that aren't
either rediculous expensive or suspiciously cheap. It's amazing how
much you might end up paying for those 4 SMUX'ed i/o's if you go this
route. RME themselves make one, but it's one of the expensive ones, and
oddly, it costs way more than getting a whole second
Hammerfall/Multiface setup even though it does far less. (But again, if
you get that second Hammerfall, it will have its own separate busses in
TotalMix.)

* You can go with RME MADI, which is MADIly expensive, but has an insane
channel count. Sadly, as far as I know, there's no support in Linux for
TotalMix or anything like it if you go this route, though it is driver
compatible with Alsa and Jack. You just won't have any GUI mixer like
hdspmixer, which would kind of stink, especially on such pro-grade
hardware.

* You could get someone else's audio hardware, perhaps taking adventage
of FFADO to get it done by firewire...but then you'd lose the stability
and it-just-works experience that you get from the RME Multiface on
Linux. Or you could take a chance on USB, which is becoming more and
more popular despite that it reminds me of trying to use a Volkswagon
Bug for an Antarctic polar expedition.

All of the above is why, for the moment, I'm just living with my 8
analog i/o's and dealing with it. :-/ At least the analog i/o's the
one Multiface comes with just work, and splendidly.

-- 
+ Brent A. Busby	 + "We've all heard that a million monkeys
+ Sr. UNIX Systems Admin +  banging on a million typewriters will
+ University of Chicago	 +  eventually reproduce the entire works of
+ James Franck Institute +  Shakespeare.  Now, thanks to the Internet,
+ Materials Research Ctr +  we know this is not true." -Robert Wilensky
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