Re: [MLUG - DISCUSSION] "optical digital sound cards" OR "what's the best way to play MP3 files on stereo system?"

[Mike Miller <EMAIL:PROTECTED>]

On Sat, 1 Sep 2007, Mark Rages wrote:

> It's easy to hear the difference at 128kbps mp3.  Try a single 
> instrument like solo piano or acoustic guitar.

How about a cymbal?  I think that is even easier.  They say that the kind 
of sound where you hear it most is in random noise, and that applause 
gives a good example of that kind of randomness.


> To address the original question, the bitrate of the optical out is 
> uncompressed digital data.  As an example, an mp3 ripped from CD will 
> uncompress to 44.1kHz * 16 bits * stereo = 1411200 bits per second.

I'm a little confused about the difference between kHz and kbps in this 
context.  I guess "stereo" in your equation equals 2.  Where does the 16 
come from?  Why doesn't the bit rate figure into this?

When looking for info about cards, I was seeing things such as this...

http://www0.epinions.com/Sound_Cards--reviews--1_x_optical_digital_output

...that imply that some cards max out at 192 kHz (or less), but I'm not 
sure of the implication of that number.


> The important question is, does your computer or receiver have a better 
> DAC?  Analog technology like DACs are one area where the best technology 
> is an order of magnitude more expensive.  Just don't walk into the 
> golden-ear audiophile store and tell them you're buying an $800 DAC to 
> listen to MP3's!

I think I'm getting the idea here.  So a DAC is a digital-to-analog 
converter and if the computer (or is it the sound card?) is good at 
conversion, I can do the conversion there, and use the usual auxiliary 
analog inputs on the amplifier.  But if the amplifier has the better DAC, 
the conversion can be done there.  This does make me a little clearer on 
what the issue is.  I'll always need to do digital-to-analog conversion to 
go from MP3 to speaker -- it's just a question of where that step occurs 
and what kind of data is being transmitted between the different 
processing points along the way: HDD, CPU, sound card, amplifier, speaker. 
Apparently, the DAC is usually in the sound card.

By the way, audio-store salesmen know that the name of the game is to 
manipulate the customer by pretending that a really good audiophile can 
detect all sorts of things that no human can actually hear, and get the 
customer to buy a bunch of things that he really can't use.  Would they 
sell me an $800 DAC that I didn't need?  Yes!

Mike

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