Hi all - I'm thinking of building a dedicated PC to use in field
recordings. Using the Shuttle SN41G2 SFF PC with two Endirol FA-101s
(Firewire audio interface, 10 in 10 out) would theoretically result in
a small unit with 16 analogue inputs...however, would such a system
actually be capable of recording that many tracks at the same time? Is
the Firewire throughput large enough, or would it depend on the
motherboard chipset in the Shuttle PC (North bridge-Nvidia nForce2,
South bridge-nVidia MCP-T)? There are two 6 pin firewire connectors on
the Shuttle, but I imagine these are both connected to the same
controller - perhaps I could use the PCI slot on the Shuttle for
another Firewire controller, and connect each FA-101 to each
controller?

If anyone has tried something similar or has an opinion on whether
this would work, please let me know!

thanks a lot,
Jamie

Jamie la Fey wrote:

Is
the Firewire throughput large enough

Theoretically, yes. 24-bit, 96kHz signals require 2.3mb/s per channel, so
disregarding overhead, Firewire's 400mb/s capacity is enough for 173
simultaneous channels of 24/96. I can't imagine the overhead is enough to
bring that number down to anywhere near your required capacity.

--
Mark.
http://tranchant.plus.com/

23 Mar 2004 04:45:06 -0800, suggested:
: Hi all - I'm thinking of building a dedicated PC to use in field
: recordings. Using the Shuttle SN41G2 SFF PC with two Endirol FA-101s
: (Firewire audio interface, 10 in 10 out) would theoretically result in
: a small unit with 16 analogue inputs...however, would such a system
: actually be capable of recording that many tracks at the same time? Is
: the Firewire throughput large enough, or would it depend on the
: motherboard chipset in the Shuttle PC (North bridge-Nvidia nForce2,
: South bridge-nVidia MCP-T)? There are two 6 pin firewire connectors on
: the Shuttle, but I imagine these are both connected to the same
: controller - perhaps I could use the PCI slot on the Shuttle for
: another Firewire controller, and connect each FA-101 to each
: controller?

Firewire's not going to be the bottleneck on this. CPU and memory (and
possibly disk performance) are most likely going to be the limiting
factors.

--
agreenbu @ nyx . net andrew michael greenburg

"Mark Tranchant" wrote in message
...
Theoretically, yes. 24-bit, 96kHz signals require 2.3mb/s per channel, so
disregarding overhead, Firewire's 400mb/s capacity is enough for 173
simultaneous channels of 24/96. I can't imagine the overhead is enough to
bring that number down to anywhere near your required capacity.

You mixed designations. 2.3 MB/s (bytes) is the required bandwidth for each
channel of 24/96 (I'm assuming you actually did the math) but Firewire is
400 Mb/s (bits) or 50 MB/s at absolute best theoretical speed (impossible to
achieve because Firewire likes to keep stay alives on the cables). On top
of that, there's a PCI limitation of 32 bit at 33 mHz which comes out to 133
MB/s transfer rate. So technically two Firewire units each running 8 inputs
would be enough throughput to get the data in, but with an internal 2.5"
hard drive running at 5400 rpm spindle rate, it's possible that there's not
enough throughput on the drive to store it properly.

The solution is to run something with 16 I/O on Firewire and then have an
external 3.5" 7200 rpm spindle rate drive on the other Firewire port. Now
whether there's a single converter set with 16 I/O and firewire, I don't
know. That's where the research starts.

--


Roger W. Norman
SirMusic Studio

Roger W. Norman wrote:

"Mark Tranchant" wrote in message
...

Theoretically, yes. 24-bit, 96kHz signals require 2.3mb/s per channel, so
disregarding overhead, Firewire's 400mb/s capacity is enough for 173
simultaneous channels of 24/96. I can't imagine the overhead is enough to
bring that number down to anywhere near your required capacity.


You mixed designations. 2.3 MB/s (bytes) is the required bandwidth for each
channel of 24/96 (I'm assuming you actually did the math) but Firewire is
400 Mb/s (bits) or 50 MB/s at absolute best theoretical speed (impossible to
achieve because Firewire likes to keep stay alives on the cables).

No I did not. 24 bits times 96,000 samples per second equals 2,304,000 bits
per second. Firewire capacity is 400,000,000 bits per second. Doing the
division gives 173.61 channels, assuming no overhead.

I used the "common computer" usage of m = 1000000, M = 1048576.

--
Mark.
http://tranchant.plus.com/

Tue, 23 Mar 2004 10:14:07 -0500, suggested:
: "Mark Tranchant" wrote in message
: ...
: Theoretically, yes. 24-bit, 96kHz signals require 2.3mb/s per channel, so
: disregarding overhead, Firewire's 400mb/s capacity is enough for 173
: simultaneous channels of 24/96. I can't imagine the overhead is enough to
: bring that number down to anywhere near your required capacity.
:
: You mixed designations. 2.3 MB/s (bytes) is the required bandwidth for each
: channel of 24/96 (I'm assuming you actually did the math) but Firewire is
: 400 Mb/s (bits) or 50 MB/s at absolute best theoretical speed (impossible to
: achieve because Firewire likes to keep stay alives on the cables). On top
: of that, there's a PCI limitation of 32 bit at 33 mHz which comes out to 133
: MB/s transfer rate. So technically two Firewire units each running 8 inputs
: would be enough throughput to get the data in, but with an internal 2.5"
: hard drive running at 5400 rpm spindle rate, it's possible that there's not
: enough throughput on the drive to store it properly.

24 bits * 96000 samples = 2.3 Mb/s. So, unless you're to have me believe
that there's nearly 2 megabytes per second of overhead per channel being
wasted, I think that you are mistaken. By your math, the most
16-bit/44.1kHz music that would fit on an audio CD is 9 and a half minutes.

: The solution is to run something with 16 I/O on Firewire and then have an
: external 3.5" 7200 rpm spindle rate drive on the other Firewire port. Now
: whether there's a single converter set with 16 I/O and firewire, I don't
: know. That's where the research starts.

I bet that I could pull a 7-year old 4 GB 5400 RPM hard drive out of one
of my deceased machines and it would still have enough performance for at
least 10 simultaneous channels of 24/96.

--
agreenbu @ nyx . net andrew michael greenburg

thanks everyone...guess I was seriously underestimating Firewire if it
could handle over 170 channels...!

that Shuttle PC can take a standard 3.5" 7200rpm hard drive so I don't
think there's a problem in that area...looks like it would work out
alright!

Jamie

"Jamie la Fey" wrote in message
om...
thanks everyone...guess I was seriously underestimating Firewire if it
could handle over 170 channels...!

that Shuttle PC can take a standard 3.5" 7200rpm hard drive so I don't
think there's a problem in that area...looks like it would work out
alright!

Don't count your chickens (or your channels) before they
are hatched. There are plenty of other bandwidth-limiters
to work through before you are home free.

In article writes:

thanks everyone...guess I was seriously underestimating Firewire if it
could handle over 170 channels...!

Don't count on more than 24 though. You know what they say about
"in theory" and "in practice." Besides, I'll bet you don't have 170
microphones.



--
I'm really Mike Rivers - )
However, until the spam goes away or Hell freezes over,
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and reach me he double-m-eleven-double-zero at yahoo