To try and help the discussion around the volume bug, I got my SB2 in front of the analyser tonight and did some measurements.
I used the SPDIF o/p feeding the sound card in my PC (thereby eliminating the analogue element of the SB2) feeding the FFT analyser software with SPDIF volume adjustment enabled in Slimserver. I then installed Slismerver Version: 6.1.1 - 3774 - Windows XP - EN - cp1252 on my test PC, whilst the main music server ran SlimServer Version: 6.2.1 - 5252 - Windows XP - EN - cp1252. By connecting to each server in turn, I can swap between firmwares from 15 to the latest and back, then make some measurements. I played a 1kHz fs 44.1k, 16bit test file, then took THD measurements as the volume was lowered. Now remember the distortion produced by the rounding error isn't simply harmonic distortion (maybe THD+N would have been better) but none the less, it shows a difference. Below are the readings I made stepping volume from 39 (as indicated on the SB display) to 27. SB2 Vol OLD FW THD NEW FW THD 39 0.00034% 0.00034% 38 0.00029% 0.00036% 37 0.00034% 0.00034% 36 0.00031% 0.00037% 35 0.00031% 0.00050% 34 0.00044% 0.00064% 33 0.00032% 0.00050% 32 0.00038% 0.00104% 31 0.00034% 0.00118% 30 0.00039% 0.00126% 29 0.00035% 0.00119% 28 0.00040% 0.00177% 27 0.00031% 0.00164% Now the audibility doesn't bear much resemblance to those figures, but even so the degradation with the new firmware / volume law is clearly visible and repeatable. Hope this helps. Andy. -- Andrew L. Weekes ------------------------------------------------------------------------ Andrew L. Weekes's Profile: http://forums.slimdevices.com/member.php?userid=573 View this thread: http://forums.slimdevices.com/showthread.php?t=18439 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
