Re: [Alsa-user] M-audio, RME, Hercules -> what hardware should I

[Giuliano P. <po...@sh...>]

On 21-Nov-2005 Roman Katzer wrote:
> On 20/11/05, Giuliano Pochini <po...@sh...> wrote:
>> IMHO some chips provide data which is very good. For instance, the AK5385
>> samples sound at 6.144MHz.
>
> Pleeease... that would most likely be a sigma-delta ADC.  And
> sigma-deltas operate at these frequencies. That doesn't mean you could
> actually sample frequencies up to 3 MHz.  Also, show me a perfect
> decimation filter...

The chip can. It allows you to (actually you must) use a simple
analog lowpass filter (eg. a 30dB/decade filter centered at 100KHz
has about -140dB response at 3MHz).

But this is not the point. I meant to say that with a lot of
chips you don't gain anything in terms of accuracy by using 192KHz
sampling rate because those chips halve the number of sampling
points in the decimation filter in order to double the sampling
rate. IOW I do agree with fons adriaensen. And no, I do not know
what hardware achieves 192KHz without compromises :).


--
Giuliano.