Schallfeldwebel wrote on Mon, 30 October 2006 16:20 |
My Lake-People AD converters have the AKM AK5393 AD converterchips on board. Because an upgrade was made in this system from AK5392 (only 44-48k)to AK5393 (96k) it was not possible to have both 44-48k and 88-96k switchable for the oversampling. 64x for 96 and 128x for 48k. The change of oversampling is done within the software of the chip I understood. Therefore my unit runs always on 64x, even when it is set to 44,1 mode. This effects the signal to noise ratio with about 3 dB less good values at 44,1K. Are there other consequences ? Less precision ? Erik Sikkema |
Schallfeldwebel wrote on Mon, 30 October 2006 19:36 |
Maybe I have been unclear, but my question is, what happens if a chip which is designed to run 128x oversampling for 44,1K is set to 64x oversmpling at 44,1k? Just to accomodate the possibility of recording 96K. At 96K the chip runs on a 64x oversampling. /E |
Schallfeldwebel wrote on Tue, 31 October 2006 18:54 |
Dan, you write:"The answer to your question may be IC specific, but as a rule, I would expect the front end of an AD (the modulator) to operate at some fixed high frequency. In your case, the rate for 44.1KHz is 5.644MHz, and for 48KHz it is 6.144MHz. That coresponds to 128fs." The manufacturer of my AD converter told me, instead of 128xfs, it runs on 64xfs at 44,1K, although it is designed to run 128x at 44,1K. Is that possible, and what are the consequences? Does it mean that the modulator runs on half the speed? 2.822Mhz? How could they change the modulator speed? If I understand you well, and the modulators run fixed 5.644Mhz, and the fs is set to 44,1 you always run 128x oversampling. The older IC's which ran indeed 64x at 44,1, did their modulator ran on 2.822Mhz. What is the trade off for 2.822Mhz? /E |