Re: [LAU] What audio interface to use for a Linux-powered surround preamp?

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To: Johan Herland <jherland@...>
Cc: <linux-audio-user@...>
Date: Monday, December 19, 2011 - 10:14 am

On 12/18/2011 03:28 PM, Johan Herland wrote:

>> out of curiousity, what is the benefit of upsampling? is there something

with these very simple and mostly linear operations, you will gain
nothing at all from upsampling. certainly nothing that would justify
doubling the cpu and throughput expense of your system.

preventing the full fidelity of material produced at 96k is another
issue, but such material is rare outside of studio workflows.

>> plus you will need to think about the clocking structure. usually

all digital gear in the signal chain must run from the same clock,
unless you insert a sample-rate converter.
in a studio, there is a common wordclock which is distributed to all
players, processors, and output DACs.
consumer equipment will generally not be able to deal with external
clocking, so your source will have to be the clock master. the clock is
then distributed embedded in the signal - hdmi audio, spdif and aes/ebu
are all self-clocking.

but this also means that if you switch from blue-ray player a to
blue-ray player b, your sound card must change its clocking source from
input a to input b. which might or might not cause an audible click or

as to "maximizing fidelity", this is digital pcm. it either works
perfectly or not at all. the only way to slightly degrade the signal is
to have a lossy codec in between (such as ac3 or dts), or when you're
forced to insert a SRC. but the latter should be pretty close to perfect
if it's a good one. no longer bit-transparent, obviously.

>>> - A suitable audio interface with at least 8 digital outputs.

i tend to agree on the 192k issue...
iirc, there is the rme hdsp 9636 which should fit your needs (2 adats).
or a hdsp hammerfall with the digiface break-out (3 adats). there might
be cheaper alternatives from other manufacturers, maybe others will
comment. m-audio used to be a linux-friendly choice...

> It really comes

haven't done a proper survey, but i'd use RME gear for this job. which
means the combination of adat card plus external AES/EBU bridge will be
more expensive and less elegant than the hdsp/aes card.

> When it comes to kernel compilation, I'm not too scared, as my

good :)

have fun,


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Messages in current thread:
Re: [LAU] What audio interface to use for a Linux-powered su..., Jörn Nettingsmeier, (Sun Dec 18, 11:30 am)
Re: [LAU] What audio interface to use for a Linux-powered su..., Jörn Nettingsmeier, (Mon Dec 19, 10:14 am)
Re: [LAU] , gene heskett, (Mon Dec 19, 11:19 pm)
Re: [LAU] , gene heskett, (Tue Dec 20, 11:24 pm)
Re: [LAU] , gene heskett, (Wed Dec 21, 3:52 am)
Re: [LAU] , gene heskett, (Wed Dec 21, 3:24 pm)