DeVerm;352213 Wrote: > Same here, sorry Phil. Will start a separate thread next time and stop > off-topic posts here. > > Actually, I have been thinking about your problem. My observation from > your photo's is that the tops from the 5th-7th harmonics are clearly > missing from the square wave. As the fundamental was 1 kHz, this is the > harmonics at 5, 7 and 9 kHz. I also read that you checked at different > amplitude levels and frequencies and that the pictures were the same. I > would propose this: > > 1. check those pictures for the different frequencies again or may be > you remember this detail clearly still. If that 5th-7th harmonic is > still the missing, it is not frequency related but algorithm related. > If it's also the same for lower amplitudes, we can assume that it's a > core-bug in the algorithm and not just an amplitude-related artifact of > overflow etc. > > 2. I am still curious on the TACT picture of a pure sine 21 kHz signal > because it will show what the TACT does with signals at the limits of > the 44 kHz sample rate. I mean, it will up-sample it, after which it > isn't close to the limit anymore. The question is if distortion appears > before, during or after the up-sampling. If we see any distortion here, > it would point to a bug before or during up-sampling. > > 3. test with a 21 kHz sine but in a 48 kHz sample-rate file. Again for > 96 kHz rate. Just to make sure it isn't a frequency limit. > > 4. Did you do the 1 kHz squarewave with 48 and 96 kHz files? I assume > the TACT up-samples to 96 kHz? And I assume it doesn't up-sample if the > input is 96 kHz already because I wouldn't know how that would be done. > This will show several things: > > The middle of the squarewave isn't the 5th-7th harmonics anymore > because we go beyond the 11f harmonic for the higher sample-rates. So, > if it's still missing the "center" tops instead of the 5th-7th tops, > the error is independent from input-signal > > If the 5th-7th harmonic is still missing (the flattened part moves left > of center square-top), we must re-evaluate our thinking ;-) > > A final set of test-signals would be a 10 and a 12 kHz squarewave as 44 > kHz sample-rate. The 10 should show one big valley between two tops and > the 12 kHz should show... a sine? See if there still is that same > distortion. > > cheers, > Nick.
Nick - you are a star! - this will take me some time to organise but I WILL do it as you suggest. Might have to wait until Friday afternoon or the weekend though. I need the brains of this forum (you, Mr O and all "the guys in the band") to help me with this because I am well out of my depth here. Analogue - yes ...digital - No! -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...SB3+Stontronics PSU - Altmann JISCO/UPCI - 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, Kimber & Chord cables Outdoors: Boombox+Creative Sub (If I remember to turn it on...) ------------------------------------------------------------------------ Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=53345 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
