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MLXXX

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About MLXXX

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    Brisbane (ex-DTV Forum member)
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    Australia
  1. What would it take to change your view?

    How do files ripped from the burnt CDs compare with the original files? It appears either or both burning methods may be creating a difference compared to the originals. I know some burning software does an automatic dynamic compression; and/or an overall static level adjustment for each CD track, though either or both of these features may be able to be disabled.
  2. What would it take to change your view?

    If I strongly believed a player would play back a flac file the same as a wav file but I thought I heard a difference and then with the help of someone else I did a successful quick ABX test then my belief would be under strong attack. I'd probably try to load the flac and wav files into Audacity as soon as I had the opportunity, to test whether they were the same. If they were the same, I would then have to conclude that the player did indeed have a defect and indeed was not playing the flac file the same as the wav file. The next stage of my investigation would be to record the output of the player and see what was happening. For example it could be that the player was dropping the amplitude of the flac playback by 0.3dB relative to wav playback. That would be a benign change, although audible. On the other hand the player might be somehow boosting or cutting different frequency bands in different ways when playing back flac files. That would be a matter of great concern, and a definite defect! LHC, as a general statement, a DBT result would be strong prima facie evidence for me, but it's likely further checks would be needed (such as in the example above the checking that the files under comparison had identical audio content), before I'd fully accept an apparent DBT result. And I think any other person should also be slow to accept an apparent DBT outcome without being satisfied it was properly conducted. At the risk of straying too far off-topic for too long, if a DBT outcome shows no audible difference, chances are greater that you can rely on it than if the outcome shows some audible difference. This is because audiophile DBT experimental error tends to introduce differences rather than hide differences. Perhaps a discussion though for some other thread!
  3. What would it take to change your view?

    I suspected this type of comment might be made; and I almost fleshed out that paragraph you've quoted, a bit more! (For example to provide detail along the lines I had not told the Skipper, Gilligan, the Howells, Ginger, and Mary Ann which version I, as the professor (of course), had been playing.) I do agree that what seem to be "night and day" audible differences when sighted can turn out to have been self-generated illusions. The power of the illusion is revealed when one has only the sound to rely on, and what previously sounded like distinctly different versions become indistinguishable. On the other hand it is refreshing, and confidence-building, when a slight difference one thought one could hear in a sighted test, remains audible in a double blind test!
  4. Thanks for this, cwt. I was unaware of this development. It does surprise that such a long article can be so thin on technical detail. I have no idea from reading it as to what technological approach has been used. For example, does the screen require a viewer to wear passive glasses, or active glasses? And this paragraph makes a curious technical claim about resolution: “The existing 3D cinemas had to compromise between brightness and resolution. The screen is dark as if the viewers are wearing sunglasses in the theater. The brightness is already halved, and with the 3D glasses that audience must wear, it becomes a one-third level compared to other 2D films. The resolution is halved too. It is inevitable as the videos for the left and right eye are overlapped and reflected.” ” I've never before seen the claim that projecting Left and Right 3D images onto a screen halves the visible resolution. I don't think that claim is technically correct. Ah well, I guess it's an article primarily aimed at providing a "good news" marketing vibe. No doubt there will be other articles in due course with more specific technical detail. If the marketing claims are to be believed, this appears to be an exciting development.
  5. What would it take to change your view?

    My relevant beliefs: I believe that, apart from rare exceptions that might arise from time to time, lossless rips intended to be bit-for-bit accurate will be bit-for bit accurate; as it would be so trivial to show they are not and yet we don't hear reports about such problems. [Also I've had no issues with the transcoding I've done with selected codecs.] I believe that lossless rips will play back the same unless there is an unusual player defect. (The processing load to decode compressed sound files is not high, and if there were problems with playback we could expect to have been alerted to this by now. Also, I haven't heard any differences when playing back a flac version of a file compared with a linear PCM version.) Process to check the above beliefs for a particular CD or player: With the current example Sir Sanders has given us, if the ripped file could be converted back to the CD PCM format and be found to be bit for bit identical, I'd then proceed to use an audio interface (such as I use to record music performances) to record the output of the player under three scenarios: wav, FLAC and Apple Lossless. I'd perhaps make two recordings of each. I'd then compare the 6 recordings with each other using say the freeware Audacity. That ought to show up if the Apple Lossless playback had an apparent problem compared with the wav and FLAC playback. If that were shown up I could then progress to subjective hearing tests to determine whether the difference was obvious enough for myself, my partner, or others to hear. ______ I am not averse to a quick subjective sighted test to start off with. I assume in this instance that FLAC and Apple Lossless versions would almost certainly sound the same. If they sounded obviously different, I'd first check to see that the files appeared to have been correctly converted. If they did, then suspicion would fall on the player and exhaustive testing could be concentrated there. (Perhaps a problem with a corrupt codec, if a software player.) ___ So there you have it, LHC. I guess if I were stranded on a tropical island like Gilligan's Island, without access to test equipment, and with only a player, I could only do blind tests to pass away the time. It wouldn't totally satisfy me if no one could reliably hear differences that the files were really playing back exactly the same, as human hearing has limitations, but the converse would be persuasive: if statistically significant DBT results came back that the Apple Lossless was slightly audibly different, then that would be a usable result. But I am also not averse to using subjective results only, in a case where the audible result is extremely, extremely obvious. If all of the people on my alternate Gilligan's Island were immediately revolted when the Apple Lossless version was played, but not with the other versions, then I hardly think I'd bother with a DBT! Of course this would imply a really serious defect in the player, or in the ripping. Summary: To be persuaded my beliefs are ill-founded I'd need to see a well written article outlining the sort of investigation I've described above and concluding that a widely used rip algorithm was defective, so much so that the defect was audible for people with healthy hearing; or that a widely used player had an audible software or hardware fault when attempting to play particular formats, a fault that had remained undiagnosed and untreated for a significant period of time. I'm not sure why I would abandon the predominantly technical approach outlined above if investigating myself. The only exception I can think of is a highly audible ripping quality failure, or highly audible playback quality failure. However those things would be picked up by so many consumers so quickly one would think that the device would be recalled, or a firmware or software update issued, as a matter of urgency. Impact of a report about a defective codec I think if a persuasive article emerged that explained in detail that a particular ostensibly lossless compression codec that had been in use for a long time would under rare circumstances be triggered into an unstable mode that resulted in a brief interlude of audibly impaired sound, that would be a very big deal for audiophile forums like this one.
  6. What would it take to change your view?

    I am still relatively new here and was not aware of that "typical" usage you have pointed out to me. I was using the word broadly simply to mean a person who firmly holds an opinion, irrespective of the extent of evidence, subjective or objective, that may have led them to be of that opinion.
  7. What would it take to change your view?

    I'm struggling to understand your point. There are in fact people who believe that different types of lossless rips give different results. How much proof they have that led them to hold that belief I wouldn't know. It might well be the way the rips have sounded to them. It could be something adverse they read about a particular codec. However they may have arrived at their belief, Sir Sanders is asking what would it take to change their view.
  8. What would it take to change your view?

    In his example, he is referring to people who do not believe that rips are truly lossless, or do not believe that truly lossless rips necessarily play back correctly, or audibly the same. To my mind these people are non-believers in the use of lossless rips (or at least in certain varieties of lossless rips, and at least with some equipment). Yes, you can express the same idea by saying these people believe in an audible difference existing between different types of lossless rips (at least on some occasions, and at least with some equipment).
  9. What would it take to change your view?

    Thanks for providing a specific example. It appears to me to involve two quite different aspects: 1. Whether the non-believer is of the opinion that the supposedly lossless encoding algorithms available for ripping their CDs are not all bit perfect. 2. Whether the the non-believer is of the opinion that the player they use will, when presented with alternative bit-perfect FLAC, Apple Lossless, or other lossless compressed formats, not be capable of decoding them all of them in a bit-perfect manner, and playing them all smoothly and correctly. I'd imagine it would be much easier to change a non-believer's mind about 1 than 2, but I'll leave it to any non-believers among us to have their say!
  10. What would it take to change your view?

    I'm having a bit of trouble understanding what precise question you are asking here, Sir Sanders. I presume you mean identical audio information presented in different file formats, such as 96kHz 24 bit linear PCM packaged uncompressed as wav or packaged compressed without loss to FLAC, Dolby TrueHD, or DTS-HD Master Audio. An initial question would be: "Has the conversion been carried out so that the converted version can be verified to be bit- for-bit identical with the original version"? That question could be answered by running an approved decoding algorithm and then running a bit-for-bit file comparison. If this were not feasible one could use a listening test but that would only be revealing if there were significant discrepancies. A further question would be: "Is the device under test defective in relation to its ability to decode and play different formats?". It appears to me that your question could relate to: a belief that mastering processes can or do result in a lossless compressed format not having the same audio content as an uncompressed format, or other lossless format; or, a belief that playback devices can or do fail to decode and play different formats properly. something else I haven't thought of! The first two dot points are quite different! In summary, 1. By different file formats do you mean identical audio ostensibly (supposedly) packaged into different formats without loss so that they are bit-for-bit identical? 2. By audible difference between file formats do you mean a difference brought about by faulty or different mastering such that the files created are not in fact actually identical bit-for-bit in their content ? 3. Alternatively by audible difference between file formats do you mean a difference brought about by a defect in the player when attempting to play a file in a particular format that it can only play correctly if supplied in another format? For simplicity, I am excluding SACDs and their DSD format as the DSD format is not one that can be converted on a bit-for-bit identical basis to the usual range of lossless compressed formats.
  11. What would it take to change your view?

    Whilst it can be shown that a FLAC file encoded with appropriate parameters* from a PCM original can be converted back to a file that is bit for bit identical with the PCM original, that doesn't mean that any player will successfully do an on-the-fly conversion from FLAC to PCM and then process the result in exactly the same manner as if it were reading and playing the original PCM file. So the actual player could -- well theoretically -- make a difference. If people are truly hearing differences, this aspect could bear scrutiny. Edit: Using the standard ABX player foobar2000 would I think obviate the issue of different playback performance; but it could be said to represent a departure from the playback conditions under which the claimant would likely have developed their view that lossless FLAC sounds different to linear PCM. * When converting from PCM to FLAC there can be the option to change the sample rate and/or the bit depth. Such a FLAC version would be inappropriate to use in the type of test under discussion.
  12. Annoying earth hum issue using USB

    Your 2014 iMac uses a three pin IEC power connector at the back and would be earthed. The suggestion to connect the Line magnetic DAC power plug and the iMac power plug to the same power board was a good one but you must have tried that by now and must have found it didn't solve your hum problem. That suggests to me that the nominal ground the iMac uses for its USB output socket is not at exactly the same potential as the power cord earth the iMac uses. That situation is more likely to arise with a full size computer with its higher power consumption and larger physical layout, than it is with a laptop. (Also with a laptop you can temporarily operate it solely with its own battery power, and avoid any earth connection!) Apple themselves recognize an earth loop issue can arise and provide a number of suggestions: https://support.apple.com/en-au/HT201781 However the suggestions don't specifically cover USB cables. @125dBmonster's suggestion of an isolation transformer for the iMac but maintaining the earth connection might work, but the fact the earth connection to the iMac would be maintained suggests to me it is very possible it would not solve your hum problem. It would still be possible for the iMac's USB socket nominal ground potential to differ from the mains power plug ground potential. Can you tell us what model Line magnetic DAC you use? If it has a healthy buffer size and well-designed reclocking I'd have thought it could sanitize an incoming optical feed very effectively! Of course another approach would be to get your hands again on a laptop set up with USB drivers and do careful A B comparisons between it and your iMac with optical. Unless the laptop delivered noticeably better sound there would seem to be no reason not to continue using your existing iMac optical interface! Edit: If you are really determined to use your iMac USB interface then you could consider a so-called USB isolator, intended for stereo audio and hum reduction. I see that has already been suggested to you, earlier in this thread, but I think care would be needed to choose an appropriate model. [I haven't researched this in any depth but the HiFimeDIY isolator looks promising.]
  13. Trump

    This is to a large extent I'd say an opinion piece, but it does read very plausibly: https://www.vox.com/policy-and-politics/2018/2/13/17004108/trump-aides-legal-fees-firing-resignations (Vox: Why there’s so much chaos in the Trump administration. Dysfunction at the top, inexperience below: the White House’s management crisis, explained.)
  14. Annoying earth hum issue using USB

    @125dBmonster, if you have such a device it would not meet traditional Australian safety standards. Australian safety standards have classified the neutral as a live conductor (even though under normal operation it should remain at near earth potential). The safety guidelines about connecting the power plug neutral to exposed metal parts of a consumer appliance may be less stringent in certain overseas countries. The below is extracted from an older version of Australian standards known informally as "test and tag" and used extensively for workplace safety inspections. I would be surprised if the requirements had been relaxed in the updated version of it, AS/NZS 3760:2010 In-service safety inspection and testing of electrical equipment. I suggest you look into whether your equipment that connects its power plug neutral to an exposed metal part of the equipment is approved for use in Australia. If it is, then that represents a relaxation in Australian safety standards of which I am unaware. Edit: One reason for the traditional safety requirement of not allowing the power point neutral to be exposed to a human test finger is that in the event that the connection of the power point neutral back to the switchboard failed, the neutral would be able to float up to near full mains potential if some device was plugged in to one of the affected power points and switched on.
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