Originally Posted by
Kempy
in truth it is fs/2 (nyquist theorem)
With source DSD64 and target fs at 44.1kHz or 48kHz there is no need for a seperate lowpass filter as the signal is steep lowpassed at fs/2 in the SRC process.
For target fs 88.2kHz and above a steep lowpass filter starting at 30kHz in front of SRC is advisable. I did a little research and found above 26kHz you can't distinguish the music signal from the noise shaped noise, so I lowpassing at 26kHz with a steep filter min. 48dB/octave.
Advisable free lowpass filters are
- TDR Ultrasonic Filter (VST2 32 and 64 bit, alpha state but great working, parameters 25kHz, 100%, 100%)
- sox with: gain +6 sinc -L -26k, also good for SRC, -b 24 rate -v -a 88.2k dither (complete cmd: >source file< -b 24 <target file> gain +6 sinc -L -26k rate -v -a 88.2k dither)
If you don't want to burn a CD I would stay at 24bit. I'm usually doing DSD64 to PCM 24bit-88.2kHz.
Don't forget to dither to the final wordlength (16bit or 24bit) as final step.
G.