On Wed, January 23, 2013 8:17 am, Fons Adriaensen wrote: > On Wed, Jan 23, 2013 at 06:52:12AM -0800, Len Ovens wrote: > >> Just looking through TI's ADCs 96k and up. Any on chip audio circuitry >> (level controls etc.) seems to lower SNR (101 db typ.) which is no >> surprise. But what I did find interesting is that even 96k and 192k >> devices seem to optimized for 48k. So the spec of 112db SNR would be >> true >> for 48k, but by the time it gets to 96k that is down 3db (noise floor up >> 3db) and at 192k... not even listed. >> >> So 192k is snake oil anyway, I'm not concerned, though I will say the >> 192k >> device has better performance at 48K, much smoother frequency response. > > Noise in 24-bit ADC is all thermal noise in the analog parts, > not quantisation noise. If it is measured unweighted it increases > by 3 dB if the bandwidth is doubled. But for 96 kHz, half of it > is above 24 kHz, so the noise within the audio bandwidth remains > just the same. There is no degradation. > > The specs should tell you how exactly the SNR is measured. If the > A-weighted or 20 kHz BW noise increase at 96 at 192 kHz there is > something fishy. Unweighted in the specs. Thank you for pointing that out. -- Len Ovens www.OvenWerks.net _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
