OK Clive (and anyone who's still interested). The LSB in a 24-bit PCM signal does indeed represent approximately -144dB wrt to full scale. However, in the real world, you have to allow some headroom in the recording to prevent (excessive) clipping, so the actual music you are listing to may well be (say) -20dB wrt full scale too. The LSB however, stays exactly where it is at -144dB wrt full scale, but only (say) -144dB minus -20dB down from the actual music volume - ie -124dB wrt the music
In addition, you are implementing a digital volume control, so you are reducing the music volume still further within the available PCM range, maybe by (say) 20-30dB. Once again the LSB stays where it is at -144dB wrt full scale, but now your actual music level is also (say) -40dB or -50dB below full scale. The difference between the actual music volume and the LSB rounding error is now -104dB or -94dB which is considerably less than the -144dB claimed elsewhere in this thread. Obviously the actual level of the rounding error wrt to the real music level will vary depending on the recording and the amount of volume control reduction used, but in the right circumstances - with a decent system and a decent recording, it is possible to hear the effect. It's not large, it's not 'night & day', but IME it does have an impact on the enjoyment of the music. -- Patrick Dixon www.at-tunes.co.uk ------------------------------------------------------------------------ Patrick Dixon's Profile: http://forums.slimdevices.com/member.php?userid=90 View this thread: http://forums.slimdevices.com/showthread.php?t=45736 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
