On 05/16/2013 10:16 AM, Ralf Mardorf wrote:
> On Wed, 2013-05-15 at 21:04 +0200, Jörn Nettingsmeier wrote:
>> iain, are you absolutely sure you need sample rates above 48k? i'd be
>> curious to hear more about your usecase.
>>
>> if you really do, e.g. for creating ultrasonics, then the only solution
>> that comes to mind is an rme hdspm plus a pricey converter for 96 or
>> even 192 khz, such as two adi-qs or an m16.
>
> Perhaps the noise floor at higher sample rates could be an issue for the
> OP.
<snip>
> FWIW, since my card still is within the warranty period I'm testing if
> everything does work on a Windows I installed to do the tests. I noticed
> that for sample rates from 32 KHz to 96 KHz nothing connected to the
> analog inputs of the card, the noise floor shown by TotalMix is at -110
> [1] and for sample rates from 128 KHz to 192 KHz it's at -54. If I
> connect an elCheapo no-name device, the noise floor for sample rates
> from 32 KHz to 96 KHz does raise to -87.
>
> Even if I would use sample rates higher than 48 KHz, it would be ok for
> my taste, but it's not what you want for professional usage.
> A Yamaha MT 44D, a 4-Track cassette recorder already has a better SNR
> [2].
>
> [1] From the user manual: "(SNR): 113 dB RMS unweighted, 116 dBA @ 44.1
> KHz", no information about the SNR for other sample rates.
> [2] From the service manual: "Signal-to-Noise Ratio (EIAJ) (Dolby OFF)
> 55 dB", "(Dolby C ON) 67 dB".
>
> So at least the card I'm using has got a noise floor for sample rates
>> 96 KHz, that perhaps isn't ok for the OPs needs.
sigh. ralf, the "noise floor" is a function of the bandwidth. if you
double the bandwidth, you will more or less double the total energy of
the noise.
incidentally, you will also double the energy of the signal.
and "measuring" a preamp/ad stage with open connectors says precisely
_nothing_ about the quality of the stage but a lot about the person
doing the measuring.
really, the amount of misinformation you are spreading here is
unbelievable. talking nonsense is ok every once in a while (says this
expert nonsense talker who's been wrong in public a thousand times). but
launching a steady stream of mails all the time in which almost every
single statement of fact is wrong, that's another matter. if you come
across an interesting question (like how come the apparent snr is so bad
for pro equipment at high sample rates), then post it as a _question_.
don't confuse other users with false statements.
oh, and maybe sometimes it is an option not to post at all.
-- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net _______________________________________________ Linux-audio-user mailing list Linux-audio-user@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-userReceived on Fri May 17 12:15:05 2013
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