THD is a key measurement when designing an electronic HiFi device, but I guess it is less important as soon as you connect a loudspeaker which has a distortion of about, hopefully, 1%... and then you listen to music in a room without "room correction" or another treatment to correct room modes and RT.I know about the Geddes-Lee metric.
somehow it didn't surprise me, I've given up distortion spectra used as an useful metric for audio quality long ago.
speaking of which. I think the subjectivists try to imply that the "meter readers" think low harmonics = good sound only because of frequency domain auditory masking.
well, I don't.
it's looks to me it's some sort of red herring. distortion spectra are a way of telling how close the output signal is to the input one. including in time-domain. I don't think any person capable valid opinions believes it's about auditory masking only.
well, yes, it's not necessarily the best metric in the context of human hearing. but it is too a metric of time-domain errors.
but to play devil's advocate again, I do believe that the relevant nonlinearities are somehow buried in distortion spectra plots.
So... it doesn't matter if it is a good metric or not, at least in the human hearing context,, because it isn't the only "distortion" in the game, and it isn't the most significative one 😱
It's far more complex to analize the full context, but - I guess - it is the only way to do that...
Distortion in the electrical domain is the most important element, IME. In the earlier post, of a grab bag of audio jargon, which I think most people can relate to, I can get a system which is suffering from the "bad" stuff to head over to the good side by doing absolutely zero about the room and the physical aspects of the speakers - all the solutions lie with parts involved in electrical behaviour.THD is a key measurement when designing an electronic HiFi device, but I guess it is less important as soon as you connect a loudspeaker which has a distortion of about, hopefully, 1%... and then you listen to music in a room without "room correction" or another treatment to correct room modes and RT.
Yes, the speaker may have high levels of distortion at certain, typically low, frequencies, but subjectively this doesn't stop the sound from "working" - it has been many years since I last tried a driver, relatively cheap, which had a definite, disturbing, distortion signature which wouldn't go away when fed with clean sound ...
You must see all the problem at once 😉Distortion in the electrical domain is the most important element, IME. In the earlier post, of a grab bag of audio jargon, which I think most people can relate to, I can get a system which is suffering from the "bad" stuff to head over to the good side by doing absolutely zero about the room and the physical aspects of the speakers - all the solutions lie with parts involved in electrical behaviour.
Electrical distortions IS important as an electrical parameter, but once it has been taken under 0.01% or even lower (just see D. Self designs), it becomes completely buried into the "distortion floor 😱" of loudspeakers and you should forget it for all uses and purposes.
Subjectively ... it stops nothing at all 😀Yes, the speaker may have high levels of distortion at certain, typically low, frequencies, but subjectively this doesn't stop the sound from "working" - it has been many years since I last tried a driver, relatively cheap, which had a definite, disturbing, distortion signature which wouldn't go away when fed with clean sound ...
Subjectively ... is just inside your brain, so nobody knows what you hear neither why you hear that way. The driver can be cheap or expensive, but what really matters is its distortion measurements and the effect of the environment surrounding it. After all, this is what you share (other than the music) if you are listening with a partner, because he/she isn't inside your head or inside your ears.
Perhaps we could talk about a couple of psycho effects which can take place in the group, but I guess it is a different story...
That thinking is why the audio industry is still a mess: 20 years ago I made a habit of visiting hifi dealers to see if anyone "got" how to achieve decent sound without going the extra yards required that I used. I got tired of rolling my eyes and listening to the dribble spouted by the sales chappie about how great the sound was, and gave up the exercise.You must see all the problem at once 😉
Electrical distortions IS important as an electrical parameter, but once it has been taken under 0.01% or even lower (just see D. Self designs), it becomes completely buried into the "distortion floor 😱" of loudspeakers and you should forget it for all uses and purposes.
The most recent hifi show demonstrated that significant movement forward has occurred: there were at least a few systems that weren't totally dreary and instantly forgettable. In each and every case the non acceptable sound was obviously due to poorly organised and tweaked electronics - the poor speakers just had to deal with the crud fed to them as best they could ...
Yes, there is always the niggling thought that what you hear is not what others hear, and I'm certainly aware that people listen for certain types of sound elements in a track, so that they can rank the performance of a system. However, I now believe that many people really think their own system is "the one" - that's actually got the sound right - and what they're really listening for is a "better" version of exactly how the track sounds on their own gear; if it sounds significantly, or radically different then the unknown system is getting it "wrong", and will be marked down!Subjectively ... it stops nothing at all 😀
Subjectively ... is just inside your brain, so nobody knows what you hear neither why you hear that way. The driver can be cheap or expensive, but what really matters is its distortion measurementsand the effect of the environment surrounding it. After all, this is what you share (other than the music) if you are listening with a partner, because he/she isn't inside your head or inside your ears.
Perhaps we could talk about a couple of psycho effects which can take place in the group, but I guess it is a different story...
That said, I've gone through the experience too many times, with too many people, of having a system doing what I call "good" sound vs. "bad", and them being in agreement with my perceptions, to believe that I've got it totally wrong ...
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An interesting, other experience of what can happen when it comes together: My Experiences Building a Total Shunyata Zitron System--A Paradigm Shift. Now, this chap's done it by the throwing of expensive, pixie dust add-ons into the mix, so one has to just bypass that rhetoric; what counts is the outcome, which can come about, always, if one happens to get the right mix: key to the whole she-bang is the using of the Bryston components, these are technically good enough for the sound to fall into place once the disturbing distortions are quelled through a happy marriage of the other bits and pieces.
Essential to note that the big money is not necessary to get it to gell; knowledge and understanding are the most important ingredients, and successful sound can occur with cheap-as-chips setups if the right approach is taken ...
Essential to note that the big money is not necessary to get it to gell; knowledge and understanding are the most important ingredients, and successful sound can occur with cheap-as-chips setups if the right approach is taken ...
Geddes doesn't seem to think "transparent" audio electronics is hard to do, and good enough electronics can be had very cheaply
his Summa speakers were last sold for $6k each, he spent < 2% of a pair's price on his demo amp
it is hard for me to parse what fas42 is really saying - but to elevate elctronics over loudspeakers, directivity, diffraction, early reflection control, room influences is directly opposed to Geddes work - and many other with published peer reviewed studies - hard to understand how fas42 isn't peddling snake oil himself
his Summa speakers were last sold for $6k each, he spent < 2% of a pair's price on his demo amp
it is hard for me to parse what fas42 is really saying - but to elevate elctronics over loudspeakers, directivity, diffraction, early reflection control, room influences is directly opposed to Geddes work - and many other with published peer reviewed studies - hard to understand how fas42 isn't peddling snake oil himself
No hardly - I don't "favor it", but I was severly chastized for using it at RMAF when, in fact, no one really knew if it was any good or not. It works just fine as my measurements show. I would not use this amp for many applications, but it suited my point at the time, which was that loudspeakers account for 99% (well you could argue 98%, but you get my point) of the audio systems sound quality.
The amp is a Pioneer DSX-V912 - a receiver. The point is that it was on sale at Costco for $150.00. I bought several of them for home theater use. I used my test to measure the amps and they were quite good actually. Especially for chip amps. I was measuring a lot of chip amps (a survey of capability) and most were pretty bad. As a chip amp this unit deffinately stands out. It compared quite favorably to a very well engineered discrete amp that I also use.
I also tested several other receivers and they were almost universally bad.
Crossover distortion is a particularly insideous form of nonlinearity because it happens at all signal levels and there is no comparable mechanism in a loudspeaker to mask it. The question was asked if I have a way of identifying crossover distortion in an amplifier.
Yes, I do.
You see the situation with crossover distortion is that the % distortion increases with falling signal level. This is exactly why it is so audible since this is directly opposite to our hearing.
One could therefor ***** crossover distortion by looking at THD as the signal level goes lower, which is a typical measurement. The problem is that virtually all of these THD versus level measurements are THD + noise. When this is the case, the rise in THD at lower signal levels is actually the noise and NOT the distortion, but it is impossible to tell which is which. SO this test actually masks the real problem. One would have to track the individual harmonics of the waveform, but then the noise floor is still an issue.
Hence the measurement problem is one of noise floor and how to measure distortion products down below this floor.
This is done by averaging. But normal averaging can only lower the noise floor so much - down to the noise power. But if I have a signal and I average this signal sychronously then I can raise the net signal to noise level. This too is common. But if the signal does not exactly fit the time base then I need to window it and the resultant spectral leakage makes this sychronous averaging less effective.
I use a signal that exactly fits into the time base of the A/D taking the data. This means that I don't have to use a window and I can sychronously average a signal to noise ratio that is about 20 dB better than a simpler test could achieve. This means for example that the input signal needs to be something like 976 Hz, not 1000 Hz, which doesn't exactly fit the window.
I actually had to generate the input wav file in FORTRAN using quad precision, special random number generators and rounding techniques, because the test signals needed to have a 120 dB dynamic range - very difficult with 16 bits.
I use a signal that starts out low and goes up in level. I plot out the results as the signal drops into the noise floor. This test shows vast differences in amps that measure identical with standard tests.
It also shows that my Pioneer amp - you know the "really crappy" one that I get crticized for using at RMAF - is an extremely good amplifier. As good as the best that I have tested with this technique.
I can appreciate that. It's an epiphany moment when one gets it, and until you experience and appreciate the quantum jump in subjective quality that occurs when the electronics function sufficiently well, then I would suppose it comes across as extremely fanciful. The simple answer why Geddes and others don't use this "measure" is because they've not experienced it themselves, the electronics they were using were not sufficiently competent -- in some ways it's like breaking the sound barrier, how many "experts" considered it was not appropriate to try to do this, because they had "calculated" that too many issues would occur ...?it is hard for me to parse what fas42 is really saying - but to elevate elctronics over loudspeakers, directivity, diffraction, early reflection control, room influences is directly opposed to Geddes work - and many other with published peer reviewed studies - hard to understand how fas42 isn't peddling snake oil himself
Once this level of quality is reached, then one automatically compares everything you listen to against that, to a large degree you can assess how sufficient the quality is in key areas, what extra is needed to able to go through the "barrier" -- how close to the speed of sound the system is currently running at ...
Edit: Didn't appreciate the quoted remarks of Geddes on first read -- that's fine, he's found a low cost amplifier that performs very well by a certain metric he's devised. Now, that doesn't guarantee that that it will easily perform to a sufficient standard - it does probably mean that it's running fairly close to what's required in raw form ...
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There's a simple "big picture" way of looking at what's going on:
1. The aim of enthusiast's audio playback is create a convincing illusion of a musical event
2. This has been done many times over the years so people know that it is possible
3. IME, key to this happening is that the subjective audibility of certain types of distortion generated by the playback mechanism is sufficiently low
4. The conventional, highly researched method of minimising this subjective audibility is to work with the speakers and their interaction with the listening space. A whole suite of finely crafted techniques have evolved, which if correctly implemented are very effective at doing this.
5. However, there is another technique: reduce the key distortion prior to it being fed to the speaker driver. If this is done adequately then the application of the conventional methods is not necessary; yes, they will enhance the illusion to some degree if also applied -- but, they are no longer a necessary condition ...
1. The aim of enthusiast's audio playback is create a convincing illusion of a musical event
2. This has been done many times over the years so people know that it is possible
3. IME, key to this happening is that the subjective audibility of certain types of distortion generated by the playback mechanism is sufficiently low
4. The conventional, highly researched method of minimising this subjective audibility is to work with the speakers and their interaction with the listening space. A whole suite of finely crafted techniques have evolved, which if correctly implemented are very effective at doing this.
5. However, there is another technique: reduce the key distortion prior to it being fed to the speaker driver. If this is done adequately then the application of the conventional methods is not necessary; yes, they will enhance the illusion to some degree if also applied -- but, they are no longer a necessary condition ...
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There's a simple "big picture" way of looking at what's going on:
1. The aim of enthusiast's audio playback is create a convincing illusion of a musical event
2. This has been done many times over the years so people know that it is possible
...
Yes, but this condition can be met by creating the illusion of a musical event, but not necessarily the one that was recorded.
Something like this, that fed with a suitable recording (of a violin probably!) can possibly create a plausible holographic 'sound field' in your living room by resonating just like a violin in your living room:
Violinspeaker - Product
Do we know that many audiophiles are not really attempting something half way similar with their open baffles and on? Trying to take a dry recording and boost their living room's ambience to the extent that it sounds like a performance in front of them. A neat trick, but really only good for girl-and-guitar type music, perhaps.
A player piano or fairground organ might also be set up to play back MIDI files for a similar lifelike illusion of a musical event!
Attachments
...and back to snake-oil! Do I also need a cello speaker, a flute-speaker, and a kettle-drum speaker? Do I need to tune my speakers before every "performance"?
Close to half of CD's dynamic range suffers from quantization distortion in excess of 1%
(Me) "It's the 'half' where distortion would be at about 100% on a vinyl LP. "
Low level LP distortion is in the hundredths or thousandths of a percent.
I suppose I should have said THD+N: the typical SNR of vinyl is supposedly 50dB.
So a signal at -48dB from peak ('half' of 16 bit dynamic range) on an LP is reputedly at a distortion level of hundredths of a percent... I dare say the same could be claimed for a signal broadcast over AM radio. But does that actually mean anything in amongst the noise, pops and clicks, and the inherent 'grain' of the analogue medium?
I suppose that it is possible to take any signal buried in any level of un-correlated interference and, if you integrate for long enough, find its average level of distortion. But you'll never actually hear the purity of the sine wave yourself, because at virtually no point will you ever hear the 'correct' level: it will always be subject to a massive random error.
The digitally sampled waveform cannot claim its 'noise' is un-correlated, but it can claim that the amplitude is low. (As you say, 1% on a signal already at -48dB). But then there's dither...
Well, should be no need for anyone to go into silliness to make sound, well, sound good ...Violinspeaker - Product
Do we know that many audiophiles are not really attempting something half way similar with their open baffles and on? Trying to take a dry recording and boost their living room's ambience to the extent that it sounds like a performance in front of them. A neat trick, but really only good for girl-and-guitar type music, perhaps.
The truth is, that there is no such such thing as a completely dry recording -- in spite of the best efforts of the sound engineers, the hallmark cues from subtle echos off the surroundings when recording are still picked up by the mic's. Unless they record in a 100% perfect anechoic chamber, with every surface of themselves and their instruments loaded up with sound absorbing material there will still be some reverberation occurring. Yes, very low level, subtle, but it is there. Which is why one should work hard, very hard to improve the "transparency" of the playback, because then those telltale clues will be clearly audible, and acoustically the sound as it emerges from the speaker drivers makes sense to your hearing mechanism - it sounds 'real'.
When a system works well every completely unknown recording is an adventure, you're drawn in to explore the acoustic space revealed: it may be huge, or have very small spaces around each sound element in the mix; but they're all interesting, and it's satisfying visiting the spaces in each recording ...
A good example of a fascinating soundscape is Michael Jackson's "Bad": the tracks on this demonstrate a vast labyrinth of sound that makes one feel you can crawl around for hours, exploring it all ... 🙂
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hmmm..... either your tastes are very different from mine, or you haven't heard any well implemented Open Baffles. Or maybe you're just guessing.A neat trick, but really only good for girl-and-guitar type music, perhaps.
Not all Open Baffle speakers are wimpy and defused.
A neat trick, but really only good for girl-and-guitar type music, perhaps.......either your tastes are very different from mine, or you haven't heard any well implemented Open Baffles.
Girl and guitar music is about the last thing I would feed my OB's. They prefer Pink Floyd, Depeche Mode and Metallica! Last night my neighbors got to listen to some dubstep.....
When the girl wants to play her guitar and sing, she prefers some full range horns and an SE tube amp.
I am one of those EE types. I build my own equipment, I measure it with the finest HP or Agilent equipment, then ignore the numbers. My cables....
Walmart! Due to the large population of thumpa-thumpa cars in South Florida you can get good 12 gauge speaker wire for $12 a roll. They have decent interconnects and even 1 Farad caps.
I work in a large electronics plant that had about 1000 engineers before the layoffs. There were about 5 of us who built audio stuff (a lot more back in the late 70's), and 3 of them were into the numbers. You know the ones on the front of that fancy Agilent stuff. The two of us who knew better both play guitar through tube amps.....coincidence????
The thing is, to get your sound right, and then add the ability to go as loud as you'll ever likely want to go, for a peak transient, just as cleanly. At one stage I was thinking 120dB, but this has evolved: I would be aiming now for the ability to hit 132dB as a transient SPL. Your ears can handle this sort of thing, because they're doing it all the time in everday living, when there's a sudden impact sound ...
hmmm..... either your tastes are very different from mine, or you haven't heard any well implemented Open Baffles. Or maybe you're just guessing.
Not all Open Baffle speakers are wimpy and defused.
I wasn't suggesting specifically that open baffles are wimpy, more that they (and others I have seen with rear- and side-firing drivers..?) are harnessing the ambience of the room more than a conventional box design. I was thinking along the lines that if the room's ambience dominates over the recording's, it might help in creating the illusion of a musical performance in your living room, but that the choice of material would be important in how strong the illusion is.
My only experience of these unconventional speakers has been at a show where I wasn't impressed: the 'phasiness' made me feel a little queasy. As always, they were playing girl-and-guitar, jazz, or Dave Brubeck's Take Five. The one exception was a room where they were playing some orchestral waltz music, and this didn't work for me at all.
Reading about these unconventional speakers in general, a common sentiment seems to be that placement is critical - which I automatically interpret as meaning there is no "critical" best position, merely several positions that sound better or worse with this recording or that recording (I think there's a common audiophile belief that there is always a perfect setup that will be best with all music if only it can be found). I see the speaker-and-room interaction as being one with many dimensions, and for which it is highly likely that there is no perfect solution; merely several not-too-bad compromises. Compared to box speakers, the open baffle/rear-firing drivers type of thing increases the number of dimensions in the problem does it not?
The thing is, to get your sound right, and then add the ability to go as loud as you'll ever likely want to go, for a peak transient, just as cleanly. At one stage I was thinking 120dB, but this has evolved: I would be aiming now for the ability to hit 132dB as a transient SPL. Your ears can handle this sort of thing, because they're doing it all the time in everday living, when there's a sudden impact sound ...
Frank,
You will never achieve this with the garbage you hack.
...I would be aiming now for the ability to hit 132dB as a transient SPL. Your ears can handle this sort of thing, because they're doing it all the time in everday living, when there's a sudden impact sound ...
The levels I use when listening would never expose my ears to 132dB, and nor would I want it to. Can't think of anything in my everyday living that would be that loud either. 😕
Obviously it can't be done with normal equipment, the maximum I can do currently is about 106dB. But it is a worthy goal, because then compression at any stage is never an issue. Remember, the intent is never to overload the hearing mechanism on a sustained or ongoing basis, merely to have the capacity to reach that sound level for a split second, so that completely realistic sound can be reproduced.
In terms of everyday living, if one solid object hits another at reasonably high speed, at the precise moment of the initial impact the extremely short pulse of impact sound can reach those sorts of levels - this is why serious microphones are typically spec'd to handle volumes with these sorts of numbers.
Normal music recordings are somewhat compressed, so it would be silly to run them such that the peak of 132dB is reached several times. However, if one were to have a uncompressed recording of a natural event where true peaks at this level occurred, then one could faithfully reproduce the experience.
It's highly unlikely at the moment that I would actually assemble such a system, but it would be an interesting technical challenge to do this at a moderate cost, while retaining the quality of reproduction. Large studio monitors and more substantial PA systems can do this without much difficulty, but they cost a bit or the quality's not too brilliant ...
In terms of everyday living, if one solid object hits another at reasonably high speed, at the precise moment of the initial impact the extremely short pulse of impact sound can reach those sorts of levels - this is why serious microphones are typically spec'd to handle volumes with these sorts of numbers.
Normal music recordings are somewhat compressed, so it would be silly to run them such that the peak of 132dB is reached several times. However, if one were to have a uncompressed recording of a natural event where true peaks at this level occurred, then one could faithfully reproduce the experience.
It's highly unlikely at the moment that I would actually assemble such a system, but it would be an interesting technical challenge to do this at a moderate cost, while retaining the quality of reproduction. Large studio monitors and more substantial PA systems can do this without much difficulty, but they cost a bit or the quality's not too brilliant ...
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