opaqueice;194762 Wrote: > I'm a bit skeptical about counting those extra 30 dB below the noise... With suitable dither, it's also possible to hear signal below the noise floor of a digital signal, of course.
opaqueice;194762 Wrote: > So we can say it like this - if we assume the bandwidth of an LP is > 30kHz * 2 channels, we would need 71 dB of S/N to match CD quality. > > However we're still being pretty generous here, since presumably people > can only hear up to 20kHz or so. If we restrict to the audible range, > it becomes very simple - the LP would simply need 96dB S/N to match CD. The top-end frequency limit of LP is often debated. Vinyl supporters often cite the 35kHz signals (or was it 34kHz? - my memory is a little hazy) that were pressed into CD4 quad LPs. But those ultrasonic signals were destroyed in very short order unless the LP was played with a suitable cartridge with Shibata stylus. Back in the real world, any signal above about 18kHz that comes off an LP is almost entirely noise and distortion. Indeed, nearly all LP cutting lathes had low pass filters to prevent high frequencies causing a resonance in the cutter head. One very commonly used cutter head (Westrex, IIRC) had its low pass filter set at 16kHz. As for the noise floor of LPs: a commonly quoted RMS figure for LPs is around the -45dB to -55dB area. But the majority of this is low frequency "vinyl hash" and rumble. If you high pass filter at about 100Hz and re-measure, good condition LPs typically have an RMS noise floor around the -70dB mark. So my estimate of the "effective bitrate" of typical LPs in good condition is about 400kbps. -- cliveb Performers -> dozens of mixers and effects -> clipped/hypercompressed mastering -> you think a few extra ps of jitter matters? ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=34379 _______________________________________________ audiophiles mailing list [EMAIL PROTECTED] http://lists.slimdevices.com/lists/listinfo/audiophiles
