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RE: TESTS: Round-up of Windows and Mac Audio Players.

Hi,

You are way off track. As you are already looking at an FFT you need to SUBTRACT (not add) process gain.

As the EMU0404 actually has around 113dBA SNR (see the measurements). Note that this is A-weighted so we need to reduce this a lot, around 10dB (estimate)to get linear noise.

So the AD conversion in the EMU0404 has around -103dB real noise. If you use the common formulas you find that for 17 bits you expects -104...

As the noise with signal in the FFT generally stays well above around -140dBFS, lets call it -138dBFS and run with it. The process gain for FFT pretty much bottoms out at around 33-36dB for normal FFT window sizes, so lets subtract 33dB from 138db and we get 105dB.

This is within 2dB of 103dB estimated above from the A-Weighted SNR, either way we are somewhere in the vicinity of 17 Bit's actual performance.

Incidentally, this "back of envelope math" also matches comparisons of using RMAA with known performance Audio Cards (I use a EMU1616M with RMAA Pro - the paid for version), you can find the loop-back results here (AD + DA that is):

http://audio.rightmark.org/test/EMU1616m.htm

Bottom line - Archimago's measurements may be adequate for CD Audio, they are meaningless for any other format. If he concludes "no difference" it simply means "no difference observable with inadequate test equipment and software".

QED.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

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