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In the Forum: Off Air Audio
In the Thread: How many Bits needed for FM, the Accuphase T1000 dilemma.
Post Subject: How many Bits needed for FM, the Accuphase T1000 dilemma.Posted by Romy the Cat on: 3/11/2009
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I wrote before about the Accuphase T-1000 and about my interest about it. Since I record FM it is supers beneficial to me that Accuphase has digitalized multiplex decoder with digital out before the output DA converters. This would allow sucking out of tuner a row digital stream bypassing the habitual output stage and a separate A/D converter. The benefits are unquestionable and the only concern that I had if the Accuphase T-1000 might be the tuner to do the job.

The Accuphase T-1000 is 4 varactors design that is very much not the same as a number of well implemented LC section but for the urban environments where I can fry a chicken on antenna it might do. Let parented that whatever they did in the Accuphase is fine and then the subject of my “dilemma” become clear. Here is the key.

The Accuphase T-1000 runs after a detector A/D processing into 24/192. Then the multiplexing done at digital domain with understandable bits lost during DSP processing. The T-1000 outputs 16/48 to it’s SPIDIF.  The 48kHz is 1X for 192 kHz which is fine. I presume that 48kHz sampling is sufficient to care the 16khz restricted signal. My primary concern is about the 16 bit rate. A played a lot with A/D conversion and I know that the 16 bit is the last bit rate that I would use. I have a number of good A/D processors (Lavry AD122 and Pacific) and with both of then I get way better results at 20 bit then at 16 (Pacific works much better at 16 bit then Lavry). So, to me in my recording endeavor the 16 bit is a big no-no…

So, lately I had an opportunity to have access to Accuphase T-1000 and to try it. However, learning about the fact that it sends out just 16 bit I made the decisions do not even exercise this opportunity. Come on who the hell need a devised with output stream of 16 bit?

However a couple of days back I have a conversation with people I know who advised me that my judgments about the inferiority of 16bit of Accuphase’s out was idiotic. According to them that 96dB of 16bit’s dymick range is more then enough to cover the limited by nature FM dymick range. Furthermore FM own noise always cover the younger bits with noise (or the natural dithering), so if the youngest 16 bit are already in nose then what the purpose to add more bits? To have more dynamic range of noise?

It sound very reasonable and from the argument above it very much might be that 16bit of raw and not processed after recording stream very much might be sufficient for FM. Honestly, I do not have an opinion at this point.

Rgs, Romy the Cat

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