[mocenigo]

But as those conditions never exist, you should not low pass first. Those conditions never exist because there are no 44.1kHz ADCs, I don't think there have ever been any. For at least 3 decades or so, ADCs convert using a few bits and sample rates well into the megahertz range. Even the Nyquist frequency (half the sample rate) is above 1mHz and a simple, cheap analogue filter (before the conversion) handles that easily. This converted (digital) signal then goes through a "decimation" filter to provide the chosen output sample rate and bit depth and obviously this decimation filter provides the necessary attenuation above the appropriate Nyquist freq. So there's no need to low pass first.

I know this. In that case, still, the post-processing would be done with care.

Edit: I'm not "knocking" dCS equipment, I've used some of your equipment professionally in the past.

Personally, I believe it is great stuff. It is just overengineered.

 

[gregorio]

I know this. In that case, still, the post-processing would be done with care.

Why?

Personally, I believe it is great stuff. It is just overengineered

Agreed.

G

 

[HeadUnit]

Randomize -120dB distortions? .LOL.

-120db distortions are with respect to sine waves or multitone sines

THIS is a key difficulty in audio, and why neither objectivists or subjectivists will ever win.
- Objectivists could be somewhat misquoted as saying "bits are bits and we can render them better than any human hearing, look at the measurements, if you can't measure it it doesn't count."
- Subjectivists counter that what matters "is the sound" which, well, how can you naysay that? Of course it can be affected by subjective things like mood, aesthetics of the equipment, psychological effects, the weather, and so on.
- And I do believe that we don't know how to measure everything, since pretty much all measurements are steady state. Even "impulse response" is calculated from steady state measurements.* Thus it becomes like trying to prove god doesn't exist. In theory a lot of work could be done into transient hearing and measurement techniques...in reality, nobody is going to spend the necessary time and money methinks.

*aside from DACs which I see tested with single sample pulses.

They do care about inaccuracy of the resistors, so they create multiple instances of the same resistor and a current source, opening only one of them a time in a pseudo-random manner. In this way they can decorrelate errors of individual resistors and also errors of current sources.

randomise errors on R2R ladder. It is actually done in some modern R2R implementations.

Would those DACs where they parallel a number of DAC chips to "average" them be an instance of what you mean? (To which I suppose dCS would say such systems are still time invariant, not randomly variant like a Ring. Heh, "one Ring to rule them all" ha ha.

 

[sajunky]

- And I do believe that we don't know how to measure everything, since pretty much all measurements are steady state.

Yes, but more important is a fact that test lab equipment do not interpret results in the same way as a human brain. It is why 'objectivist' leaves in the artificial world by negating results that human brain reports.

Would those DACs where they parallel a number of DAC chips to "average" them be an instance of what you mean? (To which I suppose dCS would say such systems are still time invariant, not randomly variant like a Ring. Heh, "one Ring to rule them all" ha ha.

Yip. Paralleling gives a time invariant averaging. dCS do both, I agree. It is not a joke.

 

[gregorio]

Subjectivists counter that what matters "is the sound" which, well, how can you naysay that?

Not really, because that’s not a “counter”, objectivists say that too. What subjectivists tend to counter with is something more along the lines that; some bit of gear affects the sound, to an extent that is actually audible.

Of course it can be affected by subjective things like mood, aesthetics of the equipment, psychological effects, the weather, and so on.

Our perception of sound can obviously be affected by subjective things like mood, etc., but of course the sound itself isn’t. This goes back to the previous point.

- And I do believe that we don't know how to measure everything, since pretty much all measurements are steady state.

Not sure what you mean by this? Off the top of my head, I can’t think of a single audio measurement that is steady state.

Even "impulse response" is calculated from steady state measurements.*

No, impulse response is measured over time and the response always varies over time. Do you mean a measurement is calculated from a sequence of discrete sample points? If so, that’s not steady state because that sequence of sample points represents a continuously varying signal.

Thus it becomes like trying to prove god doesn't exist.

How so?

In theory a lot of work could be done into transient hearing and measurement techniques...in reality, nobody is going to spend the necessary time and money methinks.

I’m not sure what reality you’re talking about here? In this reality, countless companies and organisations have spent vast amounts of time and money over a period of about 140 years researching transient hearing and measurement techniques. For example, speech is packed with transients, if no one had spent the time and money researching transients and how to measure them, we wouldn’t have a telecoms industry or it wouldn’t have advanced since the 1880’s when the telephone was first invented.

G

 

[HeadUnit]

@ replies below

Not really, because that’s not a “counter”, objectivists say that too. What subjectivists tend to counter with is something more along the lines that; some bit of gear affects the sound, to an extent that is actually audible.

@ Or maybe more precisely, the subjectivists believe/propone that a physical change has happened with the sound.
@ They are often incredibly wild-eyed resistant to even the mere possibility that the differences in sound are "in their head" due to psychological factors "I KNOW WHAT I HEAR!!!!!!!" er, OK, but that does NOT mean there is any physical difference.
@ However I have come to believe (with a total lack of hard evidence mind you) that if you could MRI the brains of those think the gear "sounds better now" you might well see actual differences. The perception is different even if the physical reality is not.

Off the top of my head, I can’t think of a single audio measurement that is steady state.

@ Maybe we're thinking of "steady state" differently
@ To me, frequency response, 32-tone, IMD...pretty much anything I see measured is measured not with bursts but with some kind of test tone which has reached a stable value and is thus easier to measure. Even like amp burst power runs multiple cycles.
@ I don't think anyone is for instance popping balloons any more to measure impulse response.
@ I'm not sure what you meant by "...impulse response is measured over time and the response always varies over time."
@ I was thinking for example of measuring a speaker with MLSSA or LMS back in the day. You could get an "impulse response" screen but that was not a direct measurement, it was a calculation of the impulse response from the frequency response.
@ DAC impulse response I've seen measured with a single full scale sample, that to me is indeed a transient measurement or as much as you can get in such systems.

 

[gregorio]

@ Or maybe more precisely, the subjectivists believe/propone that a physical change has happened with the sound.

Agreed, it’s typically nonsense of course because we can actually measure physical changes in sound.

@ They are often incredibly wild-eyed resistant to even the mere possibility that the differences in sound are "in their head" due to psychological factors "I KNOW WHAT I HEAR!!!!!!!" er, OK, but that does NOT mean there is any physical difference.

Put those audiophiles in a controlled test though and all those supposed physical differences magically disappear. Some audiophiles are genuinely shocked when they experience this but others are too far gone in their belief and dismiss controlled tests as broken or some trick designed to confuse them.

@ However I have come to believe (with a total lack of hard evidence mind you) that if you could MRI the brains of those think the gear "sounds better now" you might well see actual differences.

I’m sure it would be possible to detect differences in brain activity and there is some hard evidence to support this but as you say, that’s a difference in brain activity, not necessarily a difference in the sound entering their ears.

To me, frequency response, 32-tone, IMD...pretty much anything I see measured is measured not with bursts but with some kind of test tone which has reached a stable value and is thus easier to measure.

Ah, I see what you mean. Test signals are pretty much always of some known quantity, so we can identify any variation from that quantity in the output of a device. Even just a single sine wave is not “steady state” though, because the amplitude of a sine wave is constantly varying. A “stable value” makes more sense to me personally.

I'm not sure what you meant by "...impulse response is measured over time and the response always varies over time."

In the real world of analogue audio signals, sound pressure waves and the audio equipment which modifies or converts between them, there is always some deviation from a theoretically perfect impulse. We cannot make billions/trillions of electrons or air molecules be in two different places at the same instant in time, we obviously cannot make a speaker driver be in two different places at the same time and our ear drums obviously can’t be either. So, there must always be some transition time and virtually always there will be additional artefacts, driver overshoot or filter ringing for example, which deviate from the theoretically perfect impulse and occur over time.

DAC impulse response I've seen measured with a single full scale sample, that to me is indeed a transient measurement or as much as you can get in such systems.

Hmmm, that’s debatable. This type of impulse (often called a Dirac Impulse) is a theoretical/mathematical concept and cannot exist in any physical system, be that an electrical current or sound pressure waves (as mentioned above). To me therefore, this type of measurement is an impulse response measurement and NOT a “transient measurement” because there are no (and cannot be any) transients in music/sound with the properties of this impulse.

This impulse response measurement is potentially useful to see how a particular DAC/filter responds BEYOND any real/physical world limitations and potentially for comparison with other DACs/filter designs. Unfortunately though, it is often abused by audiophile marketers who falsely state/imply it’s actually a transient response measurement!

Having said all the above, I should also mention that while there can be no transient with the same properties as a (Dirac) impulse, there can, under specific circumstances, be a digital audio signal with similar enough properties to elicit a similar response. When a digital audio signal is clipped/heavily limited, under certain circumstances it can result in the filter ringing we see from an impulse response. However, even in heavily compressed recordings this response (filter ringing) occurs very rarely and even if it does occur, is of a far lower magnitude than we see with a Dirac impulse. Also, the majority of the energy in this ringing is at/near the Nyquist Frequency, so even if it were of a significant magnitude, still it would be outside the range of human hearing.

G