pounce;540472 Wrote: > Ok. I'll give it a go. > > > When you see a difference how do you know it's actually audible and not > something that's masked by the content? > > The test approach would be to baseline with whatever AD you have > regardless of quality? I struggle with this a bit since you probably > want to have as high of resolution as possible in theory to make this > work well. > > wrt SPDIF I think the testing would want to look for Jitter which > would/could impact the DAC on the receiving end and result in audible > differences. I don't think this software is going to help at all with > jitter testing.
1) (on analogue) there are two sorts of "differences" you encounter - white noise at very low level - probably inaudible - and residual traces of the music... potentially audible unless very low level. Based on my experience, anything below -80dB (as reported on ADM for 16-bit material) is almost certainly inaudible in practice. 2) wrt jitter testing - it does help IF you record the analogue output from the DAC - because that is where the effects of any jitter actually manifest themselves. Recording the spdif is something you do once to prove to yourself it works... The only meaningful way to record spdif is to lock the soundcard sample rate clock to the incoming stream. Looking for jitter prior to a DAC is like looking for a needle in a haystack... 3) The resolution of the AD (in my case 24/96) does not really matter as you are looking for deltas between 2 (theoretically) steady state conditions. Provided that the AD res is equal to or higher than the source material... it works. Once you have a difference file, you need to listen to it and study it with a spectrum analyser/plotter. Usually the difference will need to be amplified a lot (e.g. +50dB of gain). You soon get the hang of it. -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... Touch(wired/XP) - TACT 2.2X (Linear PSU) + Good Vibrations S/W - MF Triplethreat(Audiocom full mods) - Linn 5103 - Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Townsend Supertweeters, Blue Jeans Digital,Kimber Speaker & Chord Interconnect cables Kitchen Boom, Outdoors: SB Radio ------------------------------------------------------------------------ Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=77908 _______________________________________________ Touch mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/touch
