Audibility thresholds of amp and DAC measurements

[xr100]

Interesting. Has that been demonstrated?

Not sure if you were looking for more information/references or were querying the validity of the assertion.

However, as a more general point, I hope we can all treat JJ with the respect he deserves. No-one is God but the guy _really_ knows what he's talking about, and it's a great blessing to have his input and participation.

 

[Krunok]

Well, yes, how do you think I know that?

Because you also said this "At very low frequencies, even less may be the case, but I'm unaware of anyone actually creating a signal to demonstrate that. " so I was wondering if that was maybe the same case. In any case, no offense meant.

 

[Krunok]

Not sure if you were looking for more information/references or were querying the validity of the assertion.

However, as a more general point, I hope we can all treat JJ with the respect he deserves. No-one is God but the guy _really_ knows what he's talking about, and it's a great blessing to have his input and participation.

I don't think he needs you to solicite for him - we have Savage (pun intended) for that if and when necessary.
Btw, sticking your head in someone's ass is not really a good way to show respect - asking a competent question is a much better way to do that.

 

[DonH56]

Curious...

@j_j : I would expect phase-shift detection, outside of extreme examples, to correlate to time shifts that can cause "smearing" and similar audible artifacts. That is, I would expect the amount of phase shift that is detectable to vary with frequency. Is that true? And if so, would a better metric be time shift (delay, whatever)? Or is the detectable phase shift unrelated to time (e.g. group delay -- does non-constant group delay matter)?

Chances are I'm oversimplifying, natch.

I know the answer for a radar or ultrasound system, not sure about audio and our ears (brain, etc.)

 

[Krunok]

And if so, would a better metric be time shift (delay, whatever)? Or is the detectable phase shift unrelated to time (e.g. group delay)?

I was thinking the same. Maybe Group delay?

 

[xr100]

Btw, sticking your head in someone's ass

I haven't a clue what you mean but the tone of your post hardly makes for a friendly dialogue so that we can understand each other better.

Just in case you haven't noticed, I've been trying to go through some of the questions that I thought this thread posed systematically and carefully. I think I've put in quite a bit of effort so far to do so. I'm not here to grind axes or troll.

 

[Thomas savage]

I'm pumping iron at the moment, don't make me come in here all barbell enraged .

Be nice.

 

[Krunok]

I'm pumping iron at the moment, don't make me come in here all barbell enraged .

Be nice.

LOL You know I couldn't resist it. But ok, I'll just put him on ignore list.

 

[xr100]

OK, thought I was being polite but moving on...

 

[amirm]

I don't think he needs you to solicite for him - we have Savage (pun intended) for that if and when necessary.
Btw, sticking your head in someone's ass is not really a good way to show respect - asking a competent question is a much better way to do that.

You best clean up your tone or you won't have the opportunity to raise any questions here. Read the forum mission statement above if you are confused about any of it.

 

[Krunok]

You best clean up your tone or you won't have the opportunity to raise any questions here. Read the forum mission statement above if you are confused about any of it.

Did it occur to you that guy accused me for something I haven't remotely done? Not to mention he's not a Mod so it's definitely not his job to do policing on the forum.

And now my tone is more problematic than those 2 simple facts? You have interesting sense of justice.

 

[xr100]

Or is the detectable phase shift unrelated to time (e.g. group delay -- does non-constant group delay matter)?

Whilst we're on the subject of "group delay," I know the textbook definition perfectly well but I never did quite understand why its derivation is important and why on Earth it's called "group" delay?

 

[DonH56]

Whilst we're on the subject of "group delay," I know the textbook definition perfectly well but I never did quite understand why its derivation is important and why on Earth it's called "group" delay?

Linear phase means constant group delay (*) which in turn means every frequency is delayed equally (all frequencies as a "group"). If you have something like a step or pulse waveform that contains wideband frequency content (like, say, music ) then constant group delay means the signal arrives at the endpoint (listener) just as it left the source (speaker), only delayed in time. Some call a system not having constant group delay as exhibiting time distortion since different frequencies arrive at different times.

Constant group delay, and thus pulse waveform integrity, is critical in things like radar systems and medical ultrasound scanners that rely on pulses or pulse trains to decipher the picture. AFAIK it's criticalness to audio has been debated over the years, partly because music is semi-random in nature and thus any time-smearing is lost in the noise (err, music). Until it gets extreme, of course.

HTH - Don

(*) For those who do not know, group delay = -(change in phase/change in frequency). If the phase changes with frequency the same amount for each frequency step, it is just a straight (linear) line, and it's slope is a constant so group delay is constant. If the line curves, then slope is not constant, and neither is group delay. Since different frequencies arrive at different times for the latter case, a step waveform (for example) input would be "smeared" in time when it arrives at the listener.

 

[xr100]

Linear phase means constant group delay (*) which in turn means every frequency is delayed equally (all frequencies as a "group"). If you have something like a step or pulse waveform that contains wideband frequency content (like, say, music ) then constant group delay means the signal arrives at the endpoint (listener) just as it left the source (speaker), only delayed in time. Some call a system not having constant group delay as exhibiting time distortion since different frequencies arrive at different times. [...]

Thanks Don, your post has helped straighten things out in my head.

 

[Serge Smirnoff]

It can be seen that the behaviour of the two processes is very different.

... but the result (according to df-metric) is very similar with this m-signal. Can you tell them apart by listening? In df-metric there is no need to look inside a DUT as it is a black box.

 

[xr100]

... but the result (according to df-metric) is very similar with this m-signal. Can you tell them apart by listening?

I think so, but I know that won't suffice so I guess it's ABX test time. :-( foobar is playing up, so I'll try the "ABX Comparator" facility in DeltaWave.

Hmm, first few trials didn't go too well but... selecting "X" (even with "Restart on switch" deselected) seems to result in the file starting from the beginning again (hmm... why?) placing too much dependency on short-term memory. OK, so removing the first 1.6 seconds of the file and starting again...

Trial 1, user: B actual: B 1/1
Trial 2, user: A actual: B 1/2
Trial 3, user: A actual: A 2/3
Trial 4, user: A actual: A 3/4
Trial 5, user: A actual: A 4/5
Trial 6, user: B actual: B 5/6
Probability of guessing: 10.9%
A=Reference,B=Comparison
Test type: ABX

Where:

Reference: Softube Trident A-Range - Remove First 1.6s.flac[?] 3942540 samples 44100Hz 24bits, ch=0, MD5=00
Comparison: Soft Clip Test - Remove First 1.6s.flac[?] 3942540 samples 44100Hz 24bits, ch=0, MD5=00


ABX tests are no fun, and I'm only using my "desktop" speakers. (Bose Computer MusicMonitor.) I can't be bothered to do any more trials right now.

I would also prefer if the software allowed one to depress keys "A," "B" and "X" on the keyboard, and not stop playback almost as soon as the ("mouse"--actually trackball in my case) pointer is moved off the "A," "B" and "X" buttons.

In df-metric there is no need to look inside a DUT as it is a black box.

In attempting to test the validity, or at least use, of "DF Metric" scores, what's going on inside the "DUT"--or at least some idea of its "transfer function"--would seem to be very much of concern.

A soft clipper would be expected to act more on percussive transients, etc.--in which case it's acting more on "inharmonic" components (that can cope with a lot of IMD--"smashing" snares is done in production, after all) and it would tend to make these perceptually louder, giving an increased sense of dynamics and energy. These transients would also tend to mask the "harmonic" content underneath, thus the effect of the clipper on "harmonic" components underneath too is masked. OTOH, the "Softube Trident A-Range" (with the setting used) would add some colouration to everything; it still modifies the signal below ~4dBFS, and, as shown, THD exists at considerably lower levels.

And that, BTW, is why I selected those processes in the first place--where the "error" may well be similar but the psychoacoustic effect, if audible, to all intents and purposes, must be different. I'm rather surprised that it turns out that the scores (that you obtained for them) are so very similar!

With the "DF Metric" results that I obtained for dithered vs. truncated versions of my reference file, the score was "worse" for the dithered versions; and when truncating to 4-bits, the signal is full of highly audible quantization distortion. So, that's another area that I think is worth exploring further.

 

[pkane]

I think so, but I know that won't suffice so I guess it's ABX test time. :-( foobar is playing up, so I'll try the "ABX Comparator" in DeltaWave.

Hmm, first few trials didn't go too well but... selecting "X" (even with "Restart on switch" deselected) seems to result in the file starting from the beginning again (hmm... why?) placing too much dependency on short-term memory.

You can adjust the portion of the file that's repeated by using the sliders below:

 

[xr100]

You can adjust the portion of the file that's repeated by using the sliders below:

Thank you, I'll give that a try.

I think as much removal of short-term memory dependency as possible is needed. That means instant, "gapless" and "glitchless" switching between A, B and X and not changing position when moving to X.

Human short-term memory, at least according to what I know of, say, cognitive psychology, not to put too fine a point on it, really sucks.

 

[pkane]

Thank you, I'll give that a try.

I think as much removal of short-term memory dependency as possible is needed. That means instant, "gapless" and "glitchless" switching from A to B to X and not changing position when moving to X.

Human short-term memory, at least according to what I know of, say, cognitive psychology, not to put fine a point on it, really sucks.

I can probably improve the "glitchless" part if I spend more time on it, for now it mutes the audio when switching A/B/X and this can result in a short pause in between (about a second).

Back to your test, I think you need to a lot more than 6 tries. Try a couple of tests, each with 10 guesses and rest in between.

 

[xr100]

Back to your test, I think you need to a lot more than 6 tries. Try a couple of tests, each with 10 guesses and rest in between.

Sure, I'll do that when I get the chance.

I would prefer to use headphones for this test but I really don't use them anymore as they are all too easily the fast track to hearing loss, so haven't really got any decent pairs nor way of using them (and I broke my IEM's a couple of years ago... ) I've do have Sony MDR-7506's in a cupboard somewhere which I suppose would might work OK with my motherboard's on-board TI op-amp headphone amplifier (ESS 9023P DAC.)

EDIT:

That being said:

Trial 1, user: A actual: A 1/1
Trial 2, user: B actual: B 2/2
Trial 3, user: B actual: B 3/3
Trial 4, user: A actual: A 4/4
Trial 5, user: B actual: A 4/5
Trial 6, user: B actual: B 5/6
Trial 7, user: B actual: B 6/7
Trial 8, user: A actual: A 7/8
Trial 9, user: B actual: B 8/9
Trial 10, user: A actual: A 9/10
Probability of guessing: 1.1%
A=Reference,B=Comparison
Test type: ABX

I'll do another set (if I must, LOL) tomorrow.