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  1. Thanks for confirming. Is it fair to say that all the MQA-CD does is carry the original sampling rate of the PCM master + the preferred upsampling filter to be used by the MQA-enabled renderer/DAC?
  2. So is there any truth in Bob Stuart's statements regarding B (i.e. 22...44 kHz or 24...48 kHz out-of-band spectral content) "estimates" in 16-bit MQA-CD audio of recent Warner & Uni Japan releases?..
  3. How about these passages from Bob's post: The Green signal is completely removed by MQA decoders; but it is there so that we can hear more of the music when playback is limited to a 16-bit stream. The coder for B uses an approximation (prediction) + a touch-up signal to make it lossless. The estimates of B1’ and B2’ can be buried within or below the green line (at the choice of the mastering engineer). The next step is to fold this information into a small 48kHz 24-bit PCM file that you can hear wherever you play music today. If we don’t have a decoder this still sounds better than CD. This MQA file is low data rate – it is easy to stream and small to download. This encoded MQA file can also be previewed in the studio. We can play it on a Hi-Fi, a smartphone, a portable player, in the car, in a PC, on a Wi-Fi speaker or Bluetooth headphone. This signal can be passed over a digital output to a downstream decoder. Decoders can unwrap the Music to give us as much quality as the playback platform can support. The same file supports Studio quality playback and a smartphone! Sometimes we might want to listen to MQA music on equipment that doesn’t support 24 bits – maybe only 16? Rather than throw away all the buried information, MQA carries a small data channel (shown in Green) which can contain the ‘B’ estimates, enabling significantly improved playback quality on, e.g. a CD, over ‘Airplay’, in-car, to certain WiFi speakers and similar scenarios. If the target is a CD then specific coding is used to optimize the time-frequency balance and minimize the audibility of channel noise. Of course, if your system handles 24 bits then the full file and dynamic range can be decoded. The MQA ‘Core’ contains and protects all the music information in the Triangle – and more besides. It also contains region C and additional information – buried as noise, in noise, far below audibility. A ‘Core’ decoder can unwrap back to this stage. In case the subsequent converters don’t go any faster, the MQA decoder has prepared this music for analogue replay. We can enjoy our music in 96 kHz 24-bit quality. However, there is something special here. We can pass this 24-bit MQA Core signal on to another MQA device over USB, Lightning, S/PDIF, etc – and it is completely understood by a downstream MQA Decoder or MQA Renderer. An MQA Decoder will continue to unfold as shown. Region C is reconstructed using buried instructions, which may have been pre-determined by the studio mastering engineer. At this step, the MQA decoder also handles compensation and filtering of the following D/A converter, which, depending on the model, may contain a cascade of signal processing, upsamplers or other forms of conversion and filtering. This step in the decode process will be different for every product, in order to make the resulting analogue conform closely to the hierarchical target and to most accurately replicate what was approved in the studio. The rendering stage can, on certain platforms, use cross-family rate conversion to maximise quality and minimize analogue blur. Showing the full system (analogue-to-analogue) average transmission kernel for the different decoding options shown in the previous two images. Olive is the full decoded result. When the transmission channel is limited to 16 bits, the decoder maintains good temporal performance, as the comparison between the olive and black curves show. Audio below 20 kHz is maintained at full resolution, while some precision is lost in the next octave. If the final conversion to analogue is not using an MQA converter, the signals are preconditioned for a typical chip converter. The orange curve illustrates the input to the final converter if there is no decoder (‘Legacy mode’). Blue shows the output of the ‘first unfold’ Core decoder at 2x speed. The orange and blue curves show the input to a DAC, not the analogue output. Shows the Fourier transforms of the kernel responses in the previous image.
  4. Can you debunk his statements regarding out-of-band spectral content of MQA CD audio?
  5. Are you saying that the above mentioned Bob Stuart's posts are entirely false?
  6. Can anyone comment on contents of Bob's recent posts specifically in regard to MQA CDs? http://www.bobtalks.co.uk/2018/09/
  7. Oops, forgot to reset my Audacity setting of 16-bit sample precision to 32-bit float...
  8. What you posted is a spectrogram, not spectrum...
  9. Post the spectrum of your null-test delta signal for comparison.
  10. Shouldn't the spectrum of null-test delta look something like that (well, mine does)?..
  11. The waveform delta of of my loosely aligned analogue capture 1 & 2 excerpts is not great, admittedly... The excerpts spectral delta, however, shows no substantial difference in spectrum within audible range, so regardless of small differences around 400Hz noted by others, they will be extremely hard to discern when the actual track excerpts are played back (not their refined null-test result produced by DiffMaker), IMHO...
  12. Here you go: - Delta closeup (frequency range 20...20000Hz; logarithmic scale):
  13. No, just lined up samples the best I could on time axis (almost impossible to do with all the HF noise present), plotted their spectra & then calculated spectral delta.
  14. Not sure... Digital captures 1 & 2 are identical. Analogue captures are very close spectrally (especially in 20...20000Hz audible range), but not quite the same.
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