For the most part, it doesn't really matter what chips they're using. Most of the factors that will determine the sound of the converter happen in the clock section of the converter, and the analog electronics of the converter... the actual chip will only come into play if the analog section of the converter is very well designed, and the clock exceptionally stable... other than that most converters [like with the DigiDesign stuff], are so poorly designed that you never really get to hearing the actual chip.

Interesting, Fletcher. When you say poorly designed - what do you mean? Are you just making a general statement or talking about PCB layout considerations, part selections, matching aspects, would be nice to hear your opinion? But I guess you're right, there is too much talk about parts when design and especially groundig philosphy is probably the most vital aspects of a good analog design.

By the way I emailed EMU support and they gave me the following answer:

The converters in the EMU DAS range are as follows:

1820M
A/D Convertors: AK5394A
D/A Convertors: Cirrus Logic CS4398

1820
A/D Convertors: Texas Instruments PCM1804
D/A Convertors: Cirrus Logic CS4392

1212M
Same A/D and D/A converters as the 1820M.

All Op-Amps are NJM 2068.

The reason of my question is because I have "reversed-engineered" my own M-Audio Firewire 410, and I was intereseted in a comparison with high-end stuff.

phulden,

I have to disagree somewhat with Fletcher's assessment. It's not that the chips are poorly designed...it's that, since the advent of oversampling, the need for super-high precision filtering & track-&-hold components has been eliminated. Prior to oversampling, Nyquist rate conversion placed an extremely high demand on component accuracy. Oversampling (in conjunction w/ noise shaping) allows precision signal quality to be achieved without as close a tolerance (by allowing anti-aliasing & reconstruction filters to be realized w/o as steep a cut-off slope...reducing phase linearity & ripple problems in the passband & all that.)

I agree with the (often overlooked) importance of a quality analog front end, but...on the clock thing, if you look at the block diagram of a good quality sigma-delta A/D chip (for example, your AK5394), the system timing & control are integrated within the chip, right...tied into the mod, the comb filter, the FIR & the serial interface, right?

So I would think overall chip quality is important, right?

Correct me if I'm off base here.

Thanks,

mark4man

BTW - Can't go wrong with AKM