JohnSwenson wrote: > Let me see if I understand your first question. As long as the highest > frequency of the audio data is small relative to the sample rate (say > 40KHz maximum signal frequency for a 192 sample rate) you do not need > much if any filtering. There are going to be very little aliasing and > its going to be above the audio range. The big problem comes with 44.1 > where the audio data is right next to the aliases. > But then you've got all these high frequencies still in there on the analog side. Isn't the biggest problem with the high frequencies that power amps (especially ones filtering through intermediate frequencies like "Class D" amps) tend to create artifacts if you have signal in multiples of the audible range?
> > By a complex filter I mean multiple filters cascaded together > (especially different types of filters) rather than one filter (even if > it has a large number of taps). All of the DAC chips with filters have > at least three (some 4) different digital filters cascaded together. > They do this because the individual filters can be a fairly small number > of taps. To implement the same amount of alias suppression with a simple > single filter would take a lot more hardware. > > Again I have no idea why the complex filters cause sonic issues, but it > does seem like they do. Every time I have replaced a complex filter with > a simple filter the resulting music sounds much better. > What kind of filters do they use? I do know that kind of stuff for analog filters where both the reason for their use and the negative impact are quite obvious. But then... like for the windowed sinc filter you mentioned even digital filters are not perfectly discrete if you need finite impulse response and linear phase so it makes sense that they will also flatten the frequencies within your filter/below your cutoff frequency. But isn't that the same for your interpolation filter in sox? Of course, the interpolation filter doesn't window so it keeps all the harmonics in there (and creates some arbitrary new ones) but why is that better than leaving the simple harmonics of the 44.1 kHz samples in? What kind of filters does sox use? --- learn more about iPeng, the iPhone and iPad remote for the Squeezebox and *New: Logitech UE Smart Radio* as well as iPeng Party, the free Party-App, at penguinlovesmusic.com ------------------------------------------------------------------------ pippin's Profile: http://forums.slimdevices.com/member.php?userid=13777 View this thread: http://forums.slimdevices.com/showthread.php?t=99088 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
