Wombat wrote: > I don't know how you create these pics. If you do it with DAC output you > should make sure no further resampling is done and for comparison it > should be nice to see both results with SoX, one with dither and one > without. Maybe this hints to something. Sorry if that makes you busy > only because i have a wild speculation. > edit: didn't see your edited post, was typing to long on my pad...
The pics are snapped from real-time FFT done from the direct RCA capture of the DAC output through the E-MU 0404USB at 24/96. No resampling or DSP engaged... Just spectrum analysis of what's coming in. Tonight, as I look into this, I realized just how complicated it's getting and how hard it would be to show the pictures unless this was one of my long blog posts! Bottom line: It really depends a lot on the resampling algorithm and obviously hardware! It looks like *both* integer resampling and dynamic headroom have a part to play in the square wave tests at 0dB. IN SOFTWARE: If you do integer resampling on 0dBFS like 44kHz --> 88 --> 176, Adobe Audition, and dBPowerAmp maintains the clean harmonics. SOX for some reason is not giving me the same result! Not sure if it's because Audition and dBPowerAmp are anticipating and upsampling with a small amount of volume overhead adjustment. IN HARDWARE: Using the TEAC UD-501, integer resampling is not a problem - for example 48kHz --> 192kHz results in a nice spectrum. Likewise the ASUS Essence One "symmetric upsampling" was not a problem. However non-integer 44kHz --> 192kHz results in the additional harmonics I showed last night with the Teac; presumably similar to the DAC1 pictures from Ken Rockwell. Now as for volume headroom - YES, this does result in cleaner harmonics including SOX even with non-integer upsampling from what I see using SOX, Audition, and dBPowerAmp. Therefore, Darren / Benchmark is right to allow headroom while upsampling - avoidance from clipping is never a bad thing! I couldn't see a difference with dithering since this was upsampling from 16 --> 24-bit which is logical when I tried SOX (both dithered and undithered looked nasty going from 44 --> 192)... In any case, as you can see, the situation looks complicated and it'd be tough to put together images of the combinations I tested. Bottom line, and I think the *only graph* that would be of benefit for Benchmark DAC1 owners is one where a -3dB 1.00227kHz square wave is passed through the DAC1 and there's demonstration of a clean 1kHz primary with the appropriate clean 3/5/7/9...kHz harmonics to show that the volume reduction helps. Based on my TEAC UD-501, it should look like this: -3dB Square: 14796 -3dB Square upsampled to 24/192 by Teac: 14797 Nice and clean with minimal even order harmonics... +-------------------------------------------------------------------+ |Filename: -3dB_Square_Upsampled.jpg | |Download: http://forums.slimdevices.com/attachment.php?attachmentid=14797| +-------------------------------------------------------------------+ ------------------------------------------------------------------------ Archimago's Profile: http://forums.slimdevices.com/member.php?userid=2207 View this thread: http://forums.slimdevices.com/showthread.php?t=98661 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
