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Re: OT - PCI vs external sound cards for professional audio (was Re: What professional PCIe audio cards do work with Linux?)

On Tue, 13 Nov 2012 09:59:42 +0000
Jon Dowland <jmtd@debian.org> wrote:

> On Mon, Nov 12, 2012 at 11:25:51AM -0500, Rob Owens wrote:
> > I use an M-Audio Delta 1010LT on Debian Squeeze.
> Interesting stuff, thanks for sharing!
> I have an M-Audio Audiophile 2496 which I use for some very amateur
> messing around. I occasionally hook an Alesis Micron up to it, both
> MIDI and the headphone-out into the M-Audio's line-in.
> I've read/heard some folks suggest that for "serious" audio work,
> one should use an external sound "card" (e.g. via USB - such as the
> old SB Extigy's), because all PCI cards suffer from some noise due
> to their nature (close proximity to the HDD, signal interference on
> the mainboard etc.) -- is this basically horseshit? 

No, they are good reasons, and I've never seen an on-board or standard
plug-in audio board do better than about 42dB S/N ratio, with most at
35-40dB. I can get about 48dB with a SB USB board, with careful
earthing, which is just about acceptable for recording vinyl sources
for domestic listening, if you clip the 'silences' off at each end. I'm
not prepared to pay a lot of money for my relatively small amount of

These are utterly laughable noise figures when compared with
purpose-built sound equipment, even domestic stuff, and I can remember
being horrified by my SB AWE16 ISA card all those years ago. I assume
that expensive PCI boards can do a bit better, but I'd be surprised if
it's very much better. The inside of a PC is an extremely hostile
environment for audio.

Even a USB device would have to be very carefully designed to begin to
approach the 90dB+ S/N ratio that 16-bit PCM should be capable of, and
it cannot escape being electrically connected to the PC. You really want
to start with a well-designed standalone A/D converter optically coupled
to the recording gear, with a purely analogue power supply and with
mains transients heavily filtered. You'd be surprised how much rubbish a
fridge or freezer thermostat can bash into the mains wiring.


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