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Don Hills

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  1. The decoder looks for a particular bit sequence that marks the beginning of a series. The series repeats at regular intervals. Editing a section out of an MQA file only breaks one instance of the series.
  2. An international cruise ship passenger (remember them?) visited a church in Australia. He noticed a payphone on the wall with a sign saying "Calls to God: $1000/minute". The next port on the cruise was in New Zealand. He visited a church there and again saw a payphone on the wall, with a sign: "Calls to God: $1/minute." Puzzled, he asked a passing cleric why the New Zealand rate was so much cheaper than in Australia. "Because," said the cleric, "it's a local call."
  3. 1 bit is enough. It's a bitstream, not a flag or switch. That is, all of the required info is encoded as a series of 1 or 0 bits which are stored in the LSB of successive samples.
  4. My interest is in advances in audio reproduction, especially the largest unsolved problem, the transduction of electric to acoustic energy. As such, I see little innovation in home audio. All the work is going on at the two ends of the field - PA and cell phones. For example, exotic fillers used in the back chamber of cell phone speakers to increase the apparent volume. Like the relationship of race cars to family autos, the technology is interesting and some of it will eventually filter down into home audio.
  5. How about this? Danley's J5-Caleb with the Matterhorn at 195 ft. There are other clips of that demo, including a bass sweep that broke a window in the adjoining building. Or this, which is the mid/top cab from the previous video? Tom's Synergy Horn You may call it a "clear transistor radio", but it's quite an engineering feat to achieve that clarity and SPL at that distance in the presence of wind gusts etc.
  6. The "better version" is the one you prefer, of course.
  7. Your ears are sensitive to pressure, not wave velocity. There's no requirement that a room be large enough for a full bass wavelength. You'd never get good bass in a car if this were the case, and well all know how that goes. ☺️ The problem with rooms is that resonances build up when the bass wavelength equals one or more of the room dimensions, like sloshing water back and forth in the bathtub. Headphones work well with bass because the space between the phone and ear is so small that there can be no bass resonances.
  8. Yes. See the equation in the OP... ☺️
  9. Yes, that makes sense. "True peak" meters do this to indicate intersample overs.
  10. If I recall correctly, the red in Audacity indicates where at least 3 consecutive samples are at the digital limit ("0dB"). This is usually real clipping, where the level of the signal being sampled at the sample moment is greater than that represented by the sample value. It is possible to have inter-sample overs where all of the sample values are valid (the sample value accurately represents the value of the input voltage at that moment). Try generating and filtering the white noise at a lower amplitude than 99%. Now normalise it. There should be no red, but there may be intersa
  11. Yes. In your example with an 11 KHz sine wave, clipping of the intersample peak will result in harmonic distortion. And those harmonics begin at 22 KHz... Edit: I think I can come up with special cases where there may be distortion products below 22 KHz. I'll see what I can do with Audacity.
  12. Personally, I don't spend much time worrying about them. By definition, an intersample over occurs between 2 samples. Therefore, its frequency content is above 22 KHz. Provided that the DAC clips cleanly and the ultrasonic content doesn't upset the following equipment, it should be inaudible. (Of course, in real life things are rarely that ideal.) But I'd still rather see them avoided at source than having to allow for them in playback.
  13. Thank you. I don't worry too much about intersample overs. I feel that music with aspirations to high fidelity won't have been pushed to the limit in mastering, and conversely music that has been pushed hard will likely already have more audible damage. As to audibility, it of course depends on the specific case. I could probably generate a test signal where it was quite audible, but I don't think it's a big problem in everyday music. It will also depend on your DAC's behaviour when processing intersample overs - some will handle them better than others. The
  14. I interpreted his meaning as being what you wrote in parentheses. Of course, for the effect to be audible it has to result in an audible change of the "main" signal, and therefore have caused a much higher level of distortion than -200dB.
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