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Don Hills

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About Don Hills

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  1. Yes, that makes sense. "True peak" meters do this to indicate intersample overs.
  2. 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
  3. 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.
  4. 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.
  5. 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
  6. 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.
  7. The time precision quoted does not depend on a "steady state". As I pointed out in my previous post, it is just as valid for a transient. You'll need to provide some proof of the "ringing" getting worse for each iteration. In Monty's video, as well as showing the effect of moving a transient event between sample times, he showed that once the signal has been filtered during the ADC - DAC process, it can be run through the chain again and the "ringing" does not change. For there to be "ringing" at the output of the filter there has to be signal presented to the filter that is outsid
  8. It came from JJ. It is the math describing the effect. A transient might occur between sample times. When you (correctly) low pass filter the transient before sampling, the filtering spreads the transient energy over a period of time. The sample times before and after the time of the transient then capture the energy. If you move the transient occurrence to a different time between samples, the values sampled will change. To detect that the transient has "moved", at least one digital sample value has to change. The formula describes how far the transient has to "move" to change at least o
  9. The actual amplifier stages are Class A. They do get hot: 350 watts at idle, likely more when outputting signal. They use switch mode power supplies instead of LPS for compact size and low weight, though 30 kg (about 67 lb) is not exactly featherweight.
  10. Last time I looked into Youtube's processing of uploaded videos (a couple of years ago), uploaded videos were originally made available in their uploaded format. A background process would then convert them to the "Youtube standard" formats, prioritised on the video's watch count. I don't know if this is still the case. I'll take a look.
  11. That could work. The problem is the significant amount of work required by the distributors to determine the best settings for each item. Could they make a profit from it? Another option would be a crowd-sourced online database of decoder options, indexed by media catalogue numbers. In the simplest form, you would look up the catalogue number of your CD etc and apply the provided settings. Refinements could include the decoder doing the database lookup itself. This could work the way the Freedb database works for ripping CDs, or the Dynamic Range database.
  12. We don't get the choice in this country... non-reusable plastic bags have been banned since last year. Some places offer paper bags but the supermarkets require you to use your own bags or purchase new reusable totes.
  13. Look after yourself before the decoder, John. Especially in these times. We don't want to see obituaries here.
  14. Using a LPS to replace the SMPS in a computer seems to be a popular mod. But it ignores the elephant in the room - the SMPSes on the motherboard that supply the CPU and peripheral chips. They're much more intimately coupled to the internal circuitry. (I agree that a LPS for the main supply can reduce noise fed back into the mains, although a good line filter will do that too.)
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