In Reply to: RE: Something seems very wrong here posted by Jim Austin on June 5, 2017 at 18:08:50:
Thanks for posting this second file. It provides some good clues to help understand what is going on. There are still a lot of variables remaining, so it is difficult to draw any conclusions at this point. However we can say that:
1) Apparently it is possible to create an MQA file of a 44.1 kHz track that doesn't have a marked notch centered at Fs/2. Currently it is unclear if this is due to the settings during the MQA encoding or possibly some differences in settings on the playback DAC you used.
2) They cyan trace is presumably that of the CD. I have *never* seen the spectrum from any CD that did not have a sharp drop-off at Fs/2 due to the anti-aliasing filter in the A/D converter. This trace does not. Even if there were *no* filter in the playback D/A converter (ie, a "non-oversampling" design), the spectrum should *not* look like this at all. What D/A converter did you use to capture this spectrum, and how was it configured?
Thanks!
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Follow Ups
- Hmmm... - Charles Hansen 19:31:32 06/05/17 (11)
- RE: Hmmm... - Jim Austin 19:37:30 06/05/17 (10)
- Something still seems wrong here - Charles Hansen 22:40:21 06/05/17 (9)
- Let's go back to Beyonce - Jim Austin 07:47:16 06/06/17 (8)
- OK, now we are on the same page - it is aliasing *and* it is a bug. - Charles Hansen 13:47:03 06/06/17 (7)
- On a different, yet related topic - Charles Hansen 14:54:02 06/06/17 (0)
- RE: OK, now we are on the same page - it is aliasing *and* it is a bug. - Jim Austin 14:34:09 06/06/17 (5)
- Aha! - Charles Hansen 19:01:41 06/06/17 (4)
- Interesting - Jim Austin 19:22:14 06/06/17 (3)
- Agreed - very interesting! - Charles Hansen 22:08:13 06/06/17 (2)
- RE: Agreed - very interesting! - Jim Austin 04:50:06 06/07/17 (1)
- Thanks - Charles Hansen 12:42:23 06/07/17 (0)