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Don Hills

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  1. Don Hills

    MQA The Truth lies Somewhere in the Middle

    That's a very clever piece of misdirection by "Stuart and team." For the vast majority of the MQA content available, the sound heard in the studio was recorded through non-MQA ADCs, The sound that was approved for release by the artists, producers and label reps was auditioned through non-MQA DACs. Changing that sound post-approval moves it further away from the sound approved for release. As has been pointed out many times previously, making a music recording is a little like making sausages. You may like the result but you wouldn't like seeing them made so much. The raw sound as recorded is rarely as good as the processed sound that is released.
  2. Don Hills

    MQA vs HiRez: an apples-to-apples comparison

    Regarding filters in MQA: There is a filter in the encoder to split the signal into two parts (for example, 0-24 KHz and 24-48 KHz). The "low" part is stored in the top 15 bits of each 24-bit sample. The "high" part is encoded and stored in the lowest 8 bits of each sample. The decoder uses a matching but complementary filter to rejoin the decoded "high" part to the "low" part. In theory, the decoding filter should exactly reverse the effect of the encoding filter.
  3. Don Hills

    Cow Music

  4. Don Hills

    Cow Music

    Surprised no-one has mentioned this one:
  5. Don Hills

    Salute to Chris Connaker of Computer Audiophile

    Those answers and assertions from the "pro MQA" people in the audience deserve careful transcription and analysis. I gained the impression that they have put several shots in their own feet, or at least provided the ammunition.
  6. Don Hills


    You miss the point of the videos. They show very clearly that you can get sound that is closer to the original with a PA outdoors, even at extreme distances, than you get in a domestic room with presumably excellent speakers. For both examples (the Devore speakers and the Danley speaker) the source tracks are on Youtube. Cue them up and compare directly. See which one sounds more like the original, especially the Danley second video. (The time alignment is fine, there's just a bit more bass than the original.)
  7. Don Hills


    Big room.
  8. Don Hills


    I have a big complaint. There are shortcomings, but they're not the fault of the speakers. Using a dummy head is worse than, for example, a pair of cardioid microphones because it doesn't do what our auditory system does, filter out the majority of the reverberant / reflected sound in the room. The result doesn't sound like what it would sound like to be sitting in the room. If you must record the sound of the system, place it in an anechoic chamber or an open field. But conversely, don't judge it by listening to it live in such a situation. Most domestic speakers are designed to sound best in a room when listened to by ears.
  9. Don Hills


    The room is the elephant when it comes to recording a system in this way. Outside is much better:
  10. Don Hills


    Deleted - will post later.
  11. Don Hills

    PJ Harvey - Rid of me

    The performance on Jay Leno mentioned in the review: https://www.youtube.com/watch?v=tBtM0g-yZRU
  12. Don Hills

    Null test 88.2/24 and 44.1/16

    A couple of data points: - I use Adblock Plus and never see an ad before a video. I do see the ones that overlay the video as it's playing, but I'm generally OK with those, especially the ones at the end which suggest other videos - very useful if I'm just browsing. They're rare on the material I usually watch anyway. - I use "Youtube video and audio downloader". It allows selecting any of the available streams, including the choice of Opus or AAC audio at multiple bitrates. Note that not all formats are available for all videos - if it's new or not much viewed, it won't have as many options. For example, the audio-only download of the track listed by Kumakuma above is only available in AAC 128K and 38K. Old videos may have other audio bitrates, but they won't be offered as an audio-only download. Youtube videos used to be stored in one file as combined audio and video, but new videos and commonly watched older videos are stored as separate video and audio streams. (There are tools available to split a video into video and audio streams after downloading.) Also, note that some videos may say that the audio is AAC 192K, but Youtube now sets a maximum of 128K regardless of video resolution. So unless it's an old video that hasn't been converted, the best you can get is 128K AAC or 160K Opus.
  13. Don Hills

    What is this jitter of which you speak?

    In theory, capturing the jitter is simple - feed the DAC a signal, record (ADC) the output, subtract the input signal from the recorded signal, the residual is the error caused by the jitter (from whatever cause). In practice it's extremely difficult, as has been mentioned above. In any competent DAC the jitter is going to be down in the noise and distortion generated in the DAC. Accurately removing the original signal is also extremely different, as anyone who has used Diffmaker can attest. If I were to attempt this I'd take an indirect approach. Take a test signal, run it through the DAC, and use a spectrum analyzer to plot the jitter components and amplitudes. Then generate the components and apply them to the original signal at various amplitudes. It wouldn't be as accurate because it wouldn't preserve the phase of the "jittering" signal against the original signal, but it would be better than arbitrary signals if the goal is to hear what jitter sounds like for a given DAC. Maybe Yamamoto could be persuaded to add the capability to take a WAV file as the jittering signal instead of the built-in functions? This would allow choosing any desired jitter signal, for example jittering a music file with itself.
  14. Don Hills

    What is this jitter of which you speak?

    I'd like to be able to take two WAV files, one with a test signal / music and one with a "jitter" signal, and use the second file to apply jitter to the first. For example, if the second file contained random noise it would result in the same effect as Yamamoto's code. The current argument is that there are many mechanisms which can cause jitter in the DAC output. The resulting jitter may not resemble that artificially generated by simple noise or tones, for example jitter related to the actual signal being converted. But regardless of the actual cause, the effect on the output signal is measurable. If it's bad enough, it can even be separated from the original input and recorded as an error signal. It can then be applied in a tool such as I proposed above, at various amounts starting from grossly exaggerated and decreasing. You then A/B the result against the original, stepping through the decreasing amounts of "jitter" until you can't hear a difference any more. Provided the "jitter" at this point is well above the "real" jitter of the DAC, you can be confident that the DAC's performance is acceptable.