"William Krick" wrote in message
oups.com

I have a friend who has a home studio. He's enlisted my
help in
building a new PC to use for recording.

He needs to record 12 or more _analog_ channels
simultaneously
on a PC at 192KHz/24-bit.

Need? More likely *wants*.

I've been researching the current PC based recording
hardware
technology and I'm not sure that this is even possible.

12 x 23/192 doesn't seem beyond reason. It's the same basic
problem as 48 channels of 24/48. I've done about half that
with an entirely conventional setup.

12+ analog channels at 192/24 produces a huge volume of
data.

I get just under 7 megabytes a second, which is not all that
much by modern standards. See below.

This data has to come into the PC over the PCI bus, and at
the
same time, be moved stored on the hard drive.

The common 32 bit PCI bus is easily good for at least 132
megabytes per second. 33 MHz * 4 bytes.

Modern PCs can have more than one PCI bus per motherboard,
and they put a number of what may seem to be PCI devices on
other independent data paths.

Check out the illustration of an Athlon-64 motherboard at
for example

http://techreport.com/reviews/2004q2...o/index.x?pg=1

Note that the PCI bus has a private path to the south bridge
chip that is independent of the hard drives, independent of
the USB interface(s), independent of the graphics board,
independent of any PCI express devices, etc.

Now, lets talk a second about the capacity of the current
PCI bus standards:

http://www.techfest.com/hardware/bus/pci.htm

"PCI implements a 32-bit multiplexed Address and Data bus
(AD[31:0]). It architects a means of supporting a 64-bit
data bus through a longer connector slot, but most of
today's personal computers support only 32-bit data
transfers through the base 32-bit PCI connector. At 33 MHz,
a 32-bit slot supports a maximum data transfer rate of 132
MBytes/sec, and a 64-bit slot supports 264 MBytes/sec."

It seems to me
that the PCI bus and/or the IDE bus would present an
insurmountable bottleneck.

As they say, do the math. ;-)

Is anyone out there doing this? If so, what exact
hardware
are you using, both PC hardware and recording hardware.
I'd
really like to know.

I've done 24 channels of 24/48 with 3 M-Audio Delta 1010
cards and regular IDE drives. I did not perceive that I was
anywhere near the practical limit. I should try 24 24/96
channels with this setup some time just for grins and
giggles.

I'm confused about external A/D converter units (like the
FireFace) vs. internal units like the Hammerfall series.
Which are people using, and why?

Interal A/Ds have the advantage of eliminating the cost of
another data bus. The converters have a direct path to the
PCI bus.

Are people using Windows XP?

Sure, why not?

What actual recording/editing software is up to this task?

I was using Audition. Audition supports streaming data to 2
logical hard drives at one time. With a simple cheap RAID
IDE subsystem (striping), there are up to 2 physical drives
implementating each logical drive, for a total of 4 drives.
That's only 1.75 megabyte per second per drive which is
almost idling for a modern hard drive.

7 megabytes per second is easily within the performance
envelope of a single larger IDE drive.