[linux-audio-user] External DAC for mastering use?

Mark Knecht mknecht at controlnet.com
Thu Mar 18 10:54:46 EST 2004

Jussi Laako wrote:
> On Thu, 2004-03-18 at 16:49, Mark Knecht wrote:
>>I think Steve's observation about clock quality is protentially very 
>>important. there can be more jitter in less expensive units, such as PC 
>>s/pdif implementations. That said, nothing stops you from hooking up 
>>your D/A that way today and then going to a better s/pdif environment 
>>later should you decide to.
> Clock is important, depending on D/A converter. Converter can also
> reclock the signal. My converter has jumper selectable reclocking.
> Other important thing on S/PDIF interfaces is that some soundcards can
> only output at some samplerate or do other nasty things before
> outputting the signal in digital format. Some cards use fixed internal
> samplerate of 48 kHz and then do samplerate conversion for other rates.
> Those may not be able to do direct 44.1 -> 44.1 output, but may rather
> do something like 44.1 -> 48 -> 44.1. Some examples are Aureal Vortex2
> and some Sound Blaster cards.

I stupidly ran into something like this on my system the other evening. 
I'm working right now with a lot of 96KHz material and I wanted to 
listen to it quickly on my Linux box before I moved it over to Windows 
for mixing. I just stupidly called up alsaplayer from my menu, listened, 
and hated what I heard. I moved the audio to Windows, it sounded great, 
so I cursed everything Linux.

Stupid me...

alsaplayer from my menu was going to the intel8x0 onboard chip instead 
of the AP2496. The 8x0 driver or the chip itself was mangling the audio, 
probably exactly as it was designed to do, but I'm pretty sure it wasn't 
playing it at 96KHz. I played it on the AP2496 and it was fine.

I praised Linux and then cursed myself...

Stupid me...

However, your point is really important. If Daniel wants to 'master', 
then he'd better be really sure of every single step in the process, 
from the player to Jamin to Jack to the driver to the onboard chipset to 
the clocks to the D/A to the speakers to the room. Anything wrong 
anywhere will absolutely make an impact.

BTW - Any comments? Would he be better to run Jamin *AND Jack and 
24-bits and then dither at the output of Jack? Or would he be better off 
to run Jack at 16-bits and dither at the output of Jamin? Or would this 
be dependent on his sound card and driver? I have no position on this.

- Mark

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