Phase Noise!

[Blumlein 88]

Amir, you're trying to convey that if you precisely measure phase noise in a certain test situation, using a certain method, that it's possible to translate that into a particular level of distortion, which by the book is inaudible - and that is perfectly OK: years ago I went through the exercise of working out precisely how much error it effectively created in amplitude if the DAC "reading" moment occurred a certain time interval away from the correct point - and amazingly, , it worked out just like the spec's said. Which said that the obsession with jitter back then was a nonsense, and I have never worried about it as a problem in itself. But that didn't stop me worrying about the sound not being as good, sometimes, as it should have been. And I have always been interested in some measurement regime that shows a change of behaviour in the DUT that correlates well with audible, subjective, performance characteristics. The fact that the numbers don't compute is irrelevant - what matters is that the numbers change in a way that corresponds to what one hears.

I seem to have missed where clocked devices sound better after 15 minutes, at the very worst by far at 1 hour, and then great one day or more later. Does that fit the subjective narrative?

 

[fas42]

I seem to have missed where clocked devices sound better after 15 minutes, at the very worst by far at 1 hour, and then great one day or more later. Does that fit the subjective narrative?

To a large degree, yes. The current NAD based setup fits that quality curve quite reasonably in its behaviour - on switch on it is quite pleasant, nothing particularly irritates, on the right material one would think it's in a good space - but it lacks detail, on recordings where the acoustic space is very important the subjective impression is of smallness of the picture. Then in the region of an hour or so after the cold start significantly more detail but there is an unpleasant harshness or edginess in 'testing' recordings - more can be heard, but it's uncomfortable listening to it. Beyond that point in time those negative aspects slowly fade away, and there is both detail and no sense of "offness" in the presentation.

This pattern repeats every time, which is why I used to run my gear 24/7 - not so fussy these days, I put up with it . Not saying it's all about an oscillator stabilising, it seems pretty generic to audio gear, of all varieties and persuasions.

I'm intrigued that this particular test, of one specific parameter, mirrored this behaviour cycle - could be a fluke of course, but certainly interesting to see.

 

[amirm]

And I have always been interested in some measurement regime that shows a change of behaviour in the DUT that correlates well with audible, subjective, performance characteristics. The fact that the numbers don't compute is irrelevant - what matters is that the numbers change in a way that corresponds to what one hears.

Pyschoacoustics and data I presented are derived from actual listening tests. They are completely based on what "one hears." Thresholds have been established and levels of distortions or noise well below them are simply not of audible type.

In the case of this test which you defended, they did not even measure what came out of the DAC! How can you say it corresponds to what one hears when nothing related to those waveforms was measured?

Leaps into audibility based on any piece of data is not logical, scientific, or valid. They are layman fantasies which cannot be catered to, lest you want to throw out every bit of science out of your everyday living. You think I can tell if my car tire went over a pin head on the ground???

 

[Cosmik]

What's amusing is that we may have a measurement technique here which correlates to when people say the sound is not up to scratch - yet the rush is on to insist that this can't possibly be audible ! What's the saying ... "You can lead a horse to water ... "

It fits perfectly into the narrative of systems sounding better as they warm up. Tell someone that this is true, and give them a reason for it and bingo, that is what they will hear. I think what goes on in our own ears and brains is far more likely to be the cause.

Just like walking into a live music concert, whenever I turn my system on and run it at the 'normal' volume setting, it sounds incredibly loud at first. My natural instinct is to turn the volume down a bit. This probably means that I am hearing the mid-range exaggerated relative to the bass and treble (=equal loudness contours). As time goes on, my hearing acclimatises and the volume goes up to something more like 'realistic'. At this point I will probably be able to appreciate a 'flat' response. It is only my hearing changing, not the system 'warming up'.

Over a longer period it is also probably the case that it is possible to become acclimatised to fairly gross problems in a system. Over several hours, one can become used to a lack of bass or other non-flat frequency response, for example. I would look here before assuming that minuscule changes in minuscule levels of jitter are responsible for changes in what I am 'hearing'.

 

[fas42]

Pyschoacoustics and data I presented are derived from actual listening tests. They are completely based on what "one hears." Thresholds have been established and levels of distortions or noise well below them are simply not of audible type.

Some listening tests have been done, and some criteria have been established. Everything I've experienced over the last 30 years has reinforced my belief that these standards are not adequate - otherwise, why do technically correct systems sound awful? I had my Steve William's WTF moment 30 years ago , and everything changed from that moment on - it was then obvious how much distortion, highly audible, is produced by just about all systems - and how the absence of such makes all the difference. If you're going to test for something then the design of that test has to be up to scratch - otherwise any conclusions are worthless.

In the case of this test which you defended, they did not even measure what came out of the DAC! How can you say it corresponds to what one hears when nothing related to those waveforms was measured?

Leaps into audibility based on any piece of data is not logical, scientific, or valid. They are layman fantasies which cannot be catered to, lest you want to throw out every bit of science out of your everyday living. You think I can tell if my car tire went over a pin head on the ground???

It could very well be that the test does show poor correlation in many cases - let's take a mediocre DAC and replace the clock in it with the highest quality temperature controlled unit; the phase noise of that single part in the DAC then shows superb stability with time. Does the DAC show variable, relatively poor subjective quality still? Or change in some audible fashion? That's the sort of thing that would be interesting to test ...

With audio it all starts with the hearing - does it sound good or doesn't it? If yes, we can put our feet up; if not, then time to get to work and find out why, and do something about it. That's the data I work with ... do you think that if you slipped into Steve's listening room and swapped his new cables back to the old ones, on the sly, that he would be none the wiser ... ?

 

[fas42]

It fits perfectly into the narrative of systems sounding better as they warm up. Tell someone that this is true, and give them a reason for it and bingo, that is what they will hear. I think what goes on in our own ears and brains is far more likely to be the cause.

Just like walking into a live music concert, whenever I turn my system on and run it at the 'normal' volume setting, it sounds incredibly loud at first. My natural instinct is to turn the volume down a bit. This probably means that I am hearing the mid-range exaggerated relative to the bass and treble (=equal loudness contours). As time goes on, my hearing acclimatises and the volume goes up to something more like 'realistic'. At this point I will probably be able to appreciate a 'flat' response. It is only my hearing changing, not the system 'warming up'.

Over a longer period it is also probably the case that it is possible to become acclimatised to fairly gross problems in a system. Over several hours, one can become used to a lack of bass or other non-flat frequency response, for example. I would look here before assuming that minuscule changes in minuscule levels of jitter are responsible for changes in what I am 'hearing'.

Fascinating that you ascribe the change to your hearing acclimatising rather than the system quality altering ... when I first succeeded in getting what I call competent sound from a system I was driven mad by the fact that this quality constantly deteriorated with time; it was an ongoing cycle of resetting the system, getting peak quality, and then hearing it slowly degrade until I couldn't stand it any more - it was Groundhog Day, all over again . I ended up abandoning audio all together for many years, the frustration of not having enough knowledge to control the behaviour wasn't worth the good bits ...

One can become acclimatised to many gross problems - say, someone playing a real piano and the rain's hammering down - your brain can adjust for the extra noise, and still recognise the quality of the sound of the instrument. This is what happens with competent audio replay - the ability to reject extraneous sound is as effective as for live sound - but if the artifacts are too disturbing then this doesn't happen; the sound just keeps being irritating, and only gets worse with time.