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MLXXX

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About MLXXX

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    Brisbane (ex-DTV Forum member)
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  1. MLXXX

    Tubes vs solid state

    Thanks for your comments. Thanks for your detailed paragraphs in response to my post. Re the particular para of yours I've quoted above, I myself can't be definitive about the audiophile mentality, as over the last 50 years I've only been on the periphery of hi-fi. I do note however that fifty years ago coming up with a "blameless" amplifier was somewhat challenging. My impression as I recall it of that era was that you really did need to check specs and/or read reviews as some amplifiers had very high distortion figures, and some had a quite limited bass or treble response. You could not take these things for granted. You would accordingly read the technical paras of a review with interest. You could not afford to ignore these paragraphs. Later, the general standard became so high for frequency response and THD/IMD and SNR that it became routine for a review of a solid state amplifier to report a very wide power bandwidth, very low distortion, and very low noise. And so It became unnecessary for the average reader to bother to read the technical paragraphs, other than perhaps for the power output. There was little to no practical benefit for the reader.
  2. MLXXX

    Tubes vs solid state

    60 years ago it was not unusual to see published frequency response curves with large discrepancies from a flat response (within the audible range), and it was not unusual to see large figures for THD. The everyday audiophile of that era could be expected to have taken an interest in such matters. By perhaps 30 yeas ago, even entry level solid state audio amplifiers were typically able to provide a near ruler-flat frequency response over the range 20Hz to 20kHz, with quite low THD, and with a fairly high damping factor. By that time, Interest in perusing frequency response curves and distortion figures was waning. @Al.M , which particular types of "freq plots etc" are you referring to that you feel that 98% of SNA readers and audiophiles would not be able to interpret? What deficiencies might one expect to see revealed in these types of reported measurements, in today's amplifiers? And perhaps quite a difficult question, could you elucidate what you mean by "know[ing] how their own particular speaker would respond to an amp"? (I'd have thought that most audiophiles today would use speaker systems of a conventional design that did not present impedance variations outside those with which a modern amplifier would be designed to cope.)
  3. MLXXX

    Tubes vs solid state

    The 720p and 1080p versions selectable with the stream parser built into "4K video downloader" provided me with AAC audio averaging around 128kbps. However I could see webm versions using your second link. These would play on VLC media player but the audio codec and bitrate were not exposed in the VLC player playback statistics. How were you able to identify the bitrate of the Opus audio stream? If YouTube really are providing an option of 240kbps Opus stereo for recently uploaded videos, that would be quite important to know about and use, if seeking the best available audio quality! (Assuming of course that the uploader supplied the audio at a high quality...). _______________________________ I think there are two reasons YouTube AAC at 128kbps sounds good: 1. The sample rate is only 44.1kHz whereas AAC often is done at 48kHz. A slightly lower sample rate slightly reduces the bitrate requirement, other things being equal. 2. There are peaks of bitrate considerably higher than 128kbps. I referred to reason 2 last year in the thread Identifying the best AAC bitrate version of a YouTube title :-
  4. MLXXX

    Tubes vs solid state

    Yes, this thread is developing a strong off topic component! AAC is available in its original low complexity form, AAC LC, suited to higher bitrate encodings, and in a high efficiency form known as HE-AAC, developed for low bitrate encodings, typically used these days when the available stereo bitrate is under about 90kbps. For example, DAB+ broadcasts in Australia at a nominal 64kbps use HE-AAC v1, not AAC LC. At 64kbps, HE-AAC and Opus are both typically reported as much better sounding than MP3; and Opus is typicallly reported as somewhat better sounding than HE-AAC. See for example :http://opus-codec.org/comparison/
  5. MLXXX

    Tubes vs solid state

    On this side topic of YouTube sound quality:- I've noticed that the 128kbps (approx) AAC that YouTube provides these days sounds remarkably good for 128kbs. My Panasonic DMC-G7 camera's AAC encoding at 128kbps sounds poorer. The way I tested (in July last year) was by recording an uncompressed wav file to my camera (using its mic input socket) and uploading the same wav file to Youtube. Playing back, I could hear codec effects in the camera's AAC that I couldn't hear in the Youtube version. I didn't investigate the audio frequency upper limits. I had been all set to complain to Youtube that 128kbps is an inadequate bitrate for stereo AAC (they used to provide a higher bitrate), but I had to abandon that based on the evidence of my ears. (However, perhaps I should have complained to Panasonic!)
  6. MLXXX

    Tubes vs solid state

    [I'm aware some of the older AAC encodings still have higher bitrates.] Yes, I'm afraid that seems distinctly possible, @Eggcup The Daft. I shouldn't have assumed the YouTube clips were valid. My apologies to forum members. For example, testing a moment ago I find that the audio for the following YouTube clip at the highest available video quality (1080p) cuts out at about 15.5kHz:-
  7. MLXXX

    Tubes vs solid state

    I think the tangent developed from statements about the audibiility of amplifier high frequency roll-off . For example, this was said:
  8. MLXXX

    Tubes vs solid state

    It's important that the playback equipment doesn't produce spurious frequencies. Checking a moment ago I find that highest available quality versions of the four YouTube clips provide the following (at a 44.1kHz sample rate, encoded with AAC at around 125kbps): speech, plus an 8kHz sine wave at -9.6dB a sine wave at 12kHz and -3dB (with fade in and fade out) a sine wave at 15kHz and -1.9dB (continuous, no fades) nothing other than a click at around .036 seconds, at -3dB. The click is only about one cycle (with some possible pre and post ringing), and could well be at the 17.4kHz rate it is supposed to be. With the last YouTube clip, did you hear the click as a short duration tone? (If I slow down the audio of that last file by 90%, using Audacity, it provides the audible effect of a short "plop" with a distinct pitch.) _________ If in doubt you could use Audacity to generate some sine wave tones. That would give you the ability to pause and repeat very easily, and to set the amplitude easily (taking care to avoid dangerousy high amplitudes). When I was 17, I could hear the 15.625kHz horizontal scan rate of PAL analogue CRT TV set if I stood in a room where the set was operating. The horizontal deflection yoke of the CRT would vibrate sufficiently to make an audible sound. I recall that this was a sound even young adults typically could not hear. It was a bit too faint and a bit too high pitched. Today in my 60s I am dimly aware if a 15.625kHz sine wave test tone is played on my stereo system at high volume. It is not so much "hearing" as just being aware of a mild sensation (a slight irritation in my ears). I don't hear a pitch. These days for me to hear a distinct pitch the frequency needs to be around 10kHz or less.
  9. MLXXX

    Tubes vs solid state

    I don't know what caused you to hear a 27kHz alarm. That's certainly well above the usual upper limit for human hearing, even for high sound pressure levels. I note that a reference to a young adult's hearing possibly extending to 20kHz is a reference to a loud test stimulus, not just a conversational level of volume. You can see an indication of the level of sound intensity required by referring to the graph already provided in this thread. (The vertical axis shows the intensity.) I note that a 40 year old is most unlikely to be able to hear 20kHz even at a high sound pressure level. Below is a set of tests. It would be as well to set the playing volume for the 8kHz at a loud but not overly loud level to avoid potential speaker overload from the higher frequency tones: [from https://www.sandiegohearing.com/high-frequency-hearing-loss/ ] What sounds should you be able to hear? (click the links below) 8,000 Hz should be easily heard by everyone with normal hearing 12,000 Hz is hard for anyone over 50 years of age to hear 15,000 Hz is difficult for anyone over the age of 40 to hear 17,400 Hz is a frequency that only teenagers can hear. Here is a YouTube video that provides a greater range of high test frequencies:
  10. MLXXX

    High Definition Vinyl

    Yes, it isn't a new idea.
  11. MLXXX

    High Definition Vinyl

    If re-engineering the production of vinyl discs in this manner, it might also make sense to use laser technology to read the grooves. However, the further you went in that direction the closer you would get to... a CD!
  12. MLXXX

    4K Quality Questions.

    Could you provide links to two or three examples of YouTube 4K video you consider illustrate your point, that is 4K video of almost jaw-dropping clarity? That might assist readers of this thread to comment. Sometimes apparent clarity is achieved simply by increasing the contrast or using a sharpening algorithm. I myself find 4K video quality on Netflix a little variable from scene to scene: some scenes can be sharper than others. A show that is generally of a very good standard is Grace and Frankie. It doesn't use HDR but the colour is rich and the detail can be exceptional.
  13. MLXXX

    Trump

    Thanks. Trump never ceases to amaze me. The aggressive and uninformed way he bad-mouthed Amazon, in front of cameras and microphones, reminds me of a bogan talking to his mates at the pub. I don't think an Australian prime minister could get away with such remarks. I think he/she would be torn apart by the media and public opinion, and would likely face legal action.
  14. MLXXX

    Trump

    Sometimes even a media outlet that generally supports the 45th POTUS can call out an apparent whopper. I refer in this instance to Fox News and Trump's claim about Amazon costing the U.S. post office billions of dollars a year. I don't usually like to link to videos (as distinct from text) but this one (from the David Pakman show) strikes me as being particularly effective. It starts with actual video of the POTUS making claims that Amazon's delivery costs are being heavily subsidized by the US government. And then shows a well known news anchor on Fox News presenting what appears to be a devastating demolition of the president's "alternative reality". I wonder whether Amazon might have grounds to sue for injurious falsehood. Its stock price plummeted as a result of the president's, apparently unfounded, trenchant criticisms. Anyway here is the report on the David Pakman show: EDIT: There is also a potential violation of American law with respect to reckless false statements that would affect stock prices, as discussed in this article: http://www.cbc.ca/radio/day6/episode-384-trump-takes-on-amazon-canadian-hip-hop-a-bitcoin-mining-boom-nafta-vs-bar-bands-and-more-1.4605296/trump-s-attacks-on-amazon-might-have-broken-the-law-says-former-white-house-ethics-lawyer-1.4605298 It has been suggested this matter heightens the prospects for impeachment proceedings against the president. See for example the articles at https://www.politicususa.com/2018/03/29/amazon-shares-fall-after-report-trump-wants-to-curb-its-power.html , https://www.bloomberg.com/view/articles/2018-04-04/trump-s-baseless-amazon-attacks-can-t-be-ignored , and https://www.rawstory.com/2018/03/wall-street-journal-warns-trumps-political-attacks-amazon-jeff-bezos-lead-impeachment/ .
  15. I am very sceptical about claims about audibility of smearing, ringing, etc.. There is a big difference between being able to display a waveform on an oscilloscope and point to imperfections, and proving that the hearing given to us by evolution (or creation if you prefer) can detect such differences at all (let alone find them significant in the overall experience of listening to reproduced music). MQA was developed a few years ago (circa 2014) at a time when: it was still assumed by many (without carefully conducted human trials to support the assumption) that sample rates above 48kHz actually provide an audible difference and improvement in a distribution format streaming rates for audio over the internet using high sample rates and high bit-depth without compression would have seemed very high (e.g. uncompressed 192kHz 24-bit stereo requires a little over 9Mbps). [pulpit] Currently, we live in a world where the benefits of high sample rates (e.g. higher than 48kHz) in distribution of audio remain unproven in formal human trials, and where lossless compression is available for 48kHz 24-bit material (notably FLAC). Audiophile consumers would generally have more than enough internet bandwidth to handle that. In these circumstances, as has often been noted, MQA appears to be the proverbial solution looking for a problem. Various manufacturers and distributors have caved in to audiophile consumer interest in making the feature available [or have tried to create and foster consumer interest!]. And so there have been development costs, and licencing fees. We do see the format on offer as source content, and we do see audiophile equipment that is able to decode it. However, what has audiophile history shown? SACD (much lauded at the turn of the millennium for alleged audible superiority even with two-channel material) has been a niche format that has never come close to supplanting ordinary CDs. I would be very surprised if MQA were any more successful in dominating the audiophile market than SACD has been. [/pulpit]
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