Question about amplifier phase measurements

[JustJones]

In any case, the avenues explored are dwindling. This is not:
- An increase in THD+N, IMD of the audible upper frequencies, the cause of elimination: This increase is inaudible on Nuprimes STA-9 and Purifi)
- Phase variation, low-pass filter effect. Cause of elimination: The measurement of the Emotiva compared to the two Class D amplifiers tested.

From there, back to square one: the PWM signal slicing. Problem:
1/ 16-bit CDs are perfect for me...
2/ The analog input of Class D ICs is generally digitized, and this fatigue is also felt on these devices.

This suggests that the problem lies in the acquisition of an analog signal:
Either by digitization (documented quantization error)
Or by conversion to a PWM signal (Same quantization error, is this possible?)

The avenue you haven't explored is sighted bias which is where the problem usually lies.

 

[SIY]

This unexplained, repeated, and systematic observation can no longer be explained by auditory illusion, psychoacoustics, or any third-party factor (speakers, driver type, quality of power supply filtering, including poor impedance matching; this avenue has been explored at length).

Please elaborate on experimental setup, controls, and statistics, since this has been explored at length and (you claim) "auditory illusion, psychoacoustics, or any third-party factor" cannot explain it.

If it sounds like I think you haven't done any experimentation with the controls necessary to make extraordinary claims, well... I plead guilty.

 

[Jimbob54]

Oh dear . We know where this is likely to go.

 

[solderdude]

I therefore stick to the only observation shared by others, including my 16-year-old son, namely systematic auditory fatigue after one, two, or three hours of listening with a Class D amplifier and an entirely analog signal.

I'll ask again since you mention systematic observation.

When these observations are made is it clear what equipment is being used ? Meaning... when you get fatigued do you know which amp is being used ?

This unexplained, repeated, and systematic observation can no longer be explained by auditory illusion, psychoacoustics

Why not ? Was this phenomenon clearly and repeatably detected whenever such a problematic device was inserted/exchanged in the chain where you or any of the other observers did NOT know what was playing and these were also carefully level matched ?

If those conditions (not knowing, level matched, statistical relevant) were not met I would be very careful with the claim that it can no longer be explained by psychoacoustics simply because psychoacoustics would be the only logical explanation unless it has been ruled out using the described test conditions.

This suggests that the problem lies in the acquisition of an analog signal:
Either by digitization (documented quantization error) or by conversion to a PWM signal

Why would that be a logical conclusion ?

(Same quantization error, is this possible?)

Not likely and would be highly testable/provable with a valid test method.

 

[Thomas Savage]

Analog only

Attempts to describe subjective and personal feelings would only be consequences that we could then deduce if we "document" a constraint related to Class D.
It's also a way to find avenues to explore in the hope of finding an objective measurement that would shed light on this phenomenon. I agree, in this difficult-to-determine case, they lead to a waste of time.

I therefore stick to the only observation shared by others, including my 16-year-old son, namely systematic auditory fatigue after one, two, or three hours of listening with a Class D amplifier and an entirely analog signal.

A little history seems useful to me because this is an unexplained observation that I have made over several years, many hours of listening, and which is repeated every time I insert a Class D amplifier into one of my hi-fi systems.
However, it's long to write; I'll come back to it later, if it's really useful.

This unexplained, repeated, and systematic observation can no longer be explained by auditory illusion, psychoacoustics, or any third-party factor (speakers, driver type, quality of power supply filtering, including poor impedance matching; this avenue has been explored at length). Comparative listening (I have source and amp inverters) offers only subjective assessments and subtle differences. It's useless to demonstrate anything.

This fatigue is not observed with a USB connection on:
- Airpulse 80 (which I listen to every day),
- a Tangent amplifier, also Class D CI
- all other Class A/AB amplifiers (Kora Explorer 90SII CSC, Topping LA90, Topping LA90D, an old Sheerwood AVR, an 8W Class A amplifier from the 70s (DIY), and many others over nearly 20 years.

In any case, the avenues explored are dwindling. This is not:
- An increase in THD+N, IMD of the audible upper frequencies, the cause of elimination: This increase is inaudible on Nuprimes STA-9 and Purifi)
- Phase variation, low-pass filter effect. Cause of elimination: The measurement of the Emotiva compared to the two Class D amplifiers tested.

From there, back to square one: the PWM signal slicing. Problem:
1/ 16-bit CDs are perfect for me...
2/ The analog input of Class D ICs is generally digitized, and this fatigue is also felt on these devices.

This suggests that the problem lies in the acquisition of an analog signal:
Either by digitization (documented quantization error)
Or by conversion to a PWM signal (Same quantization error, is this possible?)

I absolutely understand the bugging interest a experience like this installs and the ' need ' to investigate it and find answers .

Along the same lines I used to be driven mad by the upsampling options on a esoteric CDP I had for awhile , couldn't understand why the native redbook would sound great to me but upsampling thin and terrible .

There's a difficulty inherent on all of us when trying to understand these phenomenon in discussions here. There's simply no reliable data to establish grounds for investigation, in fact in this case, theres probably a good deal of ' known ' understanding that would suggest human error , clever hans etc.

Its a very boring and rather frustrating fact that without adequate controls, the very origin of this perceived phenomenon is corrupted and of no use to us as a definite point of origin for research and exploration purposes.

Maddening I know.

 

[Melba59]

Oh dear . We know where this is likely to go.

What does your contribution add to the discussion?

Are you being questioned about the possible abuse of your moderator privileges?

Should we start the timer to close this discussion? Or would you allow me to respond to the other participants?

Edit: I'm being too kind, I forgot to mention my ban from the B200 conversation for a topic where even the sponsors apologized (it wasn't necessary on their part).
And especially the closing of our private message conversation!

 

[Jimbob54]

What does your contribution add to the discussion?

Are you being questioned about the possible abuse of your moderator privileges?

Should we start the timer to close this discussion? Or would you allow me to respond to the other participants?

Rather than replying to me you could have spent the time answering the question(s) you have been avoiding . So please , have at it .

 

[Jimbob54]

Edit: I'm being too kind, I forgot to mention my ban from the B200 conversation for a topic where even the sponsors apologized (it wasn't necessary on their part).
And especially the closing of our private message conversation!

Thanks for reminding me!

Goodbye .

 

[pkane]

Thanks for reminding me!

Goodbye .

<s>He was just about to reveal the details of his controlled testing methodology. Now we’ll never know… what a loss for science!</s>

 

[KL....]

<s>He was just about to reveal the details of his controlled testing methodology. Now we’ll never know… what a loss for science!</s>

This was never going to be a clear cut journey, was it?, until it was identifyed and measureable or not measureable, especially as at this stage it was only identifyed/noticeable by the observation (and variable hypothesis/s). Until pin pointed there is not much else one can do, is there?, except through the process of elimination (a Sherlock Holmes process) then what remains needs to be investigated/analysed/measured (if possible), which is a reasonable, isn't it?

 

[Miley_B]

It was slow, hard work but in another 300 or so pages of discussion and suggestions (with no rigorous testing in sight) he would have realised that the answer was 42.

 

[KL....]

It was slow, hard work but in another 300 or so pages of discussion and suggestions (with no rigorous testing in sight) he would have realised that the answer was 42.

Ah, Hitchhikers Guide to the Galaxy, number 42 is the answer after 7.5 million years of computing (via Deep Thought computer) the answer to the "Ultimate Question of Life, the Universe, and Everything".... bit harsh but humorous, if you know Hitchhikers Guide to the Galaxy :=)