Buffalo II ultrasonic noise

[Bill Brown]

Can anyone describe the frequency spectrum of the ultrasonic noise generated by the ESS DAC chip and its implementation in The Buffalo II that requires filtering?

Is there the typical ~100kHz noise-shaping noise I have seen in the noise floor of graphs of other DAC's that must be addressed AND separate microprocessor noise that also needs managed? Is the frequency band for the latter known? Is it primarily related to the 100Mhz clock frequency or are there also lower or higher frequency components?

Thank you,

Bill

[barrows]

There was some discussion of this in the Legato I/V stage thread in relation to discussion of the analog filter circuits and appropriate values and corner frequencies. You might want to read that thread for more info. I suspect any other info on the ESS 9018 itself is to be found in the (undisclosed to the public) 9018 data sheet.
As I recall, Russ set the corner frequency in the original Legato design somewhere around 80-90 kHz, but many people are moving that filter higher and liking the results...

[Bill Brown]

That thread clearly will be a good place to look. Will check it out. The corner frequency data is also appreciated.

Perhaps like the people you alluded to, I am wondering about just focusing on the clock/microprocessor/etc spectrum (rather than that resulting from noise-shaping which I suspect would be significantly lower in frequency) and would love to know the distribution.

Thanks again,

Bill