Re: [LAU] Rolling off high frequencies when mastering?

On Wednesday 21 April 2010 23:02:19 Arnold Krille wrote: I did some thinking... Attached is a small python script that generates some sinus data at 0.5, 0.49 and 0.25 the sampling rate, phase shifted pi/2 to the sampling clock. But the phase shift can be adapted in the first lines. Then it does fft on these. While the nyquist frequency shows up as amplitude 0 (for phase = pi/2) and 2 (for phase 0), the others remain at amplitude 1 no matter what the phase is. Sounds strange, especially when you see the perceived amplitude-modulation for f=0.49, but in the end its up to the analog filters to create a smaller than nyquist frequency sinus from the steps returned by the dac... It is also clear, why f=0.5, phase=0 shows an amplitude of 2: All the frequencies are endlessly mirrored to the left and right. And at f = 0.5*samplingrate, the mirror and the original are the same. So sorry for the fuss I tried to spread. Should have done this little exercise earlier. Have fun, Arnold