JohnSwenson;571631 Wrote: > A predetermined random sequence can be devised (computer or real coin > flip or whatever). The tester sends an email to the "changer person" > who looks up the next state on the list and changes the setting in the > server. After sending the email the tester waits one minute then starts > listening again. There is no direct contact between the person changing > the setting and the tester and its only one way, there is no > communication at all between the person changing the setting and the > test subject. I think it need not be as complicated as requiring a partner to be involved during the test, getting them to change the SB Server streaming settings.
Just take a track you say exhibits an audible difference between FLAC and PCM, and store it on the SB Server in both FLAC and PCM formats. Then get someone to build a playlist containing these two versions at random. (Flipping a coin to decide each item is probably the simplest approach). Once the playlist is built and stored, your accomplice absents themselves from the remainder of the test so there can be no suggestion of influence. All you then have to do is play the playlist through the same system that has previously revealed the audible difference. Use a Controller to skip back and forth between tracks however you wish. For each item in the playlist, write down whether you believe you're hearing FLAC or PCM. After the test, check your results against the actual items in the playlist to see how well you've done. You are at liberty to train yourself by listening to the known FLAC and PCM versions as much as you like before the test. JohnSwenson;571631 Wrote: > Then the big question is how many tests to run. When others have done > other tests and only done 8 or 10 tests they have been beaten up by > some people saying that is way too small a number of tests, you need to > do several hundred to be scientifically valid. Whats the score on that? > Ten tests is not hard at all to do. 500 gets to be a little more > difficult. The guys over at Hydrogen Audio are probably the most fanatical about requiring statistically valid ABX tests to back up audibility claims, and they generally accept 20 trials as being sufficient. You don't have to face the prospect of 500. Incidentally - if you do find a provable audible difference, and are looking for an explanation, don't limit yourself to jitter. Isn't it also plausible that the RFI generated by the CPU in the Touch (which might be different when decoding FLAC and PCM) could influence the analogue circuitry? -- cliveb Transporter -> ATC SCM100A ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=71321 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
