Reminder to myself. Fire up the spectrum analyzer software and post a screen shot showing how the CD rip of the Queens Greatest Hits album has a very obvious second harmonic component of the 50Hz British power line frequency near the beginning of the song Bohemian Rhapsody, down of course at about -70db (FS), but very obvious if you know how to look for it.
This may actually be important of course, because the experiments that I have been doing with FFT+DSP+sigma-delta seem to show that although low bit rate sigma-delta transcoding can suffer from noise bursts, as well as out of ban oscillations, which are characteristic of the convolutional nature of the algorithm, it does not seem to suffer from the so called "Cher effect" which MP3 suffers from at low bit rates, i.e., unwanted frequency shifting. This would of course be important to know about, when analyzing signals that might contain evidence of visco-elastic failure mode.
Note - that's visco-elastic failure, not DISCO-elastic! Sorry, I couldn't resist!