[mythtv-users] "Do you really need a discrete audio card ?"

[James Courtier-Dutton]

On 26 November 2010 08:04, Andre <mythtv-list at dinkum.org.uk> wrote:
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> Not so much at line level, it's also quite likely that the audio you are receiving has already been over some long analog line level cables, especially if we are talking about live sports it's very common to use analog because AES digital doesn't work well enough over 500m to 1km.
>
> When we use analog at home it's usually those awful phono connections, high impedance (so the noise is kept at high level ;-) and unbalanced co-axial so any interference is retained! The balanced 600 ohm +10dBm (often 10 ohm drive impedance) lines that outside broadcast people use are amazingly good up to a km or two. The drive electronics are too expensive for domestic hifi and deemed irrelevant over a 1m cable.
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> I am amazed that the monstrously expensive esoteric hifi people haven't latched on to proper balanced line level XLR interconnects, to me this demonstrates that they are selling snake oil and don't really know how to do things properly. I have never seen a recording studio where "oxygen free directional" cables were used, usually standard FST everywhere except the mic cables. I think some esoteric hifi nuts would throw a wobbly if they saw the cabling most studios use to create the sound they are so carefully trying to preserve ;-)
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>> </dreaming on>
>> But the perfect word would be: several speakers with onboard DAC and amp all plugged to the mains and get their audio from them. Probably a sync problem has to be solved but well it sounds doable.
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> No sync problem if you use a simple digital format, like AES which is almost exactly spdif with some optional extra resolution. To use these for a home surround system you would need a surround decoder which can convert AC3, DTS etc to 3xPCM spdif, probably better to have 6x spdif.
>

I don't know why consumer stuff does AC3 and DTS decoding in the AMP.
ADAT has been around for ages, provides 8 channels of PCM over the
same cabling as SPDIF. The PC could then have done the decoding,
making the AMP a lot cheaper.
Probably for the same reason consumer stuff does not use XLR (balanced)
If consumer applications started using professional connectors, all
the pro stuff would fall in price drastically.
Another reason is that one cannot fit XLR connectors on a PCI card,
one has to use external breakout boxes like EMU use.
http://www.emu.com/products/category.asp?category=505

This is why I favour digital out of the PCI card, because digital
optical connectors are small but retain quality.
Then some external device doing the ADC.