PRaT: "Pace Rhythm and Timing" or "PRetentious audiophile Trash"?

[mikewxyz]

Hi JKeny: I like how thorough your forum replies are. As a developer, you are far more knowledgable than I am. What I find difficult to understand from a system analysis perspective is the assertion that phase noise or jitter accounts for a significant portion of infidelity in playback.

The phase noise floor at 10 Hz in the graph seems to be significantly below the audible threshold and miles below the analog floor which many claim to be the gold standard.

Even if the the noise was in the audible range, Floyd Toole says phase problems are difficult to hear in music and are only noticeable using sine waves.

I think the PRaT designation is a catch-all phrase to describe something that people clearly hear but may have nothing to do with actual timing errors (as others have pointed out WRT analog playback).

 

[jkeny]

Hi JKeny: I like how thorough your forum replies are. As a developer, you are far more knowledgable than I am. What I find difficult to understand from a system analysis perspective is the assertion that phase noise or jitter accounts for a significant portion of infidelity in playback.

The phase noise floor at 10 Hz in the graph seems to be significantly below the audible threshold and miles below the analog floor which many claim to be the gold standard.

Even if the the noise was in the audible range, Floyd Toole says phase problems are difficult to hear in music and are only noticeable using sine waves.

I think the PRaT designation is a catch-all phrase to describe something that people clearly hear but may have nothing to do with actual timing errors (as others have pointed out WRT analog playback).

Thanks & I may be wrong. What I'm trying to do is explain some experiments I did where the only thing I changed in my DAC was a regular oscillator for one of these low phase noise oscillators.
What I perceived with this change was increased clarity & sound stage definition

So why do you stop at 10Hz when analysing the audibility level of phase noise? My premise is that the increasing phase noise below 1Hz could well be audible. What I'm surmising is that the spectral purity of frequencies in music is affected by this phase noise. I don't believe we perceive the notes themselves being affected rather the 2nd order effects of this on our auditory perception.

I've already stated why I believe it could well be a mistake to compare timing errors in analogue playback with timing errors in digital playback due to the differences in the underlying mechanisms at play between the two.

Have you got a link to Toole's reference to phase noise?

 

[microstrip]

IMO it can tell. There is a reason that even picoseconds can be detected. Evolution has fine tuned the system over a very long time where digital was nowhere to be found. Bits at the wrong time create small bits of cognitive dissonance that gives away the game that it's fake. Patterns matter more than individual bits and when the pattern doesn't quite fit then it is perceived as not really based on the imprint of real sounds you have heard since birth.

Now I think if you did a cruel experiment where you exposed a baby to only digitally synthesized sounds then perhaps that child would not be able to tell the difference because the digital pattern is being set as normal.

I would love to see this sentence properly quantified. Although it sounds nice, IMHO without proper numbers and experiments it is nice coffee talk - some people will want to write this sentence using nanoseconds, others with fentoseconds - six orders of magnitude divergence.

 

[microstrip]

Thanks & I may be wrong. What I'm trying to do is explain some experiments I did where the only thing I changed in my DAC was a regular oscillator for one of these low phase noise oscillators.
What I perceived with this change was increased clarity & sound stage definition

So why do you stop at 10Hz when analysing the audibility level of phase noise? My premise is that the increasing phase noise below 1Hz could well be audible. What I'm surmising is that the spectral purity of frequencies in music is affected by this phase noise. I don't believe we perceive the notes themselves being affected rather the 2nd order effects of this on our auditory perception.

I've already stated why I believe it could well be a mistake to compare timing errors in analogue playback with timing errors in digital playback due to the differences in the underlying mechanisms at play between the two.

Have you got a link to Toole's reference to phase noise?

Digital jitter being mixed with phase errors in crossovers?

And yes, John, it is a terrible mistake ...

 

[Joe Whip]

I know I am late to the discussion, but for me, prat is very simple for me. As I listen to tons of small combo jazz, if my feet don’t tap like they have mind if their own, it lacks prat. It simply pulls me in to the performance. If a system can’t do that, like a live performance does, my wallet stays closed. Of course, that is all very subjective. Of course, as always, YMMV. Cheers.

 

[jkeny]

Digital jitter being mixed with phase errors in crossovers?

And yes, John, it is a terrible mistake ...

I'm not talking about phase differences in speakers/crossovers & that's why I was asking Mike for Toole's reference

I'm talking about clock jitter/phase noise in oscillators

As for my mistake can you expand on where you believe I'm wrong?

 

[microstrip]

I'm not talking about phase differences in speakers/crossovers & that's why I was asking Mike for Toole's reference

I'm talking about clock jitter/phase noise in oscillators

Yes, but it was what Toole addressed - he is a speaker scientist claiming all decently designed electrics sound similar - just see how out of the way this debate is coming.

As for my mistake can you expand on where you believe I'm wrong?

Timing errors in analog processes are either electrical or electro-mechanical they were well studied and documented, with a defined range of timing. They were deeply studied for analog tape recorders and speakers, less for the vinyl chain - it is why vinyl market is mainly driven by preference.

Timing errors in digital audio are of much smaller magnitude, but show indirectly with unforeseen structures bellow what we consider the thresholds of audibility. IMHO in the high-end we still do not have a "truth" about jitter - just some manufacturer claims that some of us are happy to endorse if we like them.

It seems I am agreeing with you, not disagreeing.

 

[jkeny]

Yes, but it was what Toole addressed - just see how out of the way this debate is coming.

Right that's what I thought & not what I was talking about, at all. So, yes, Mike's post is completely OT & confusing.

Timing errors in analog processes are either electrical or electro-mechanical they were well studied and documented, with a defined range of timing. They were deeply studied for analog tape recorders and speakers, less for the vinyl chain - it is why vinyl market is mainly driven by preference.

Timing errors in digital audio are of much smaller magnitude, but show indirectly with unforeseen structures bellow what we consider the thresholds of audibility. IMHO in the high-end we still do not have a "truth" about jitter - just some manufacturer claims that some of us are happy to endorse if we like them.

Yes, I agree with this & can't see how it makes what I said "a terrible mistake"? But maybe I'm picking you up wrong?

Ah, yes, your last sentence, added after I posted does agree with me, LOL

 

[mikewxyz]

JKeny: I’ve been reading Toole’s “Sound Reproduction” 3rd edition. The reference you want is top of page 93. He goes on to describe phase shift at low frequencies as a special case which may be of more interest to you.

The reason I stopped at 10Hz is that I don’t believe my Marantz CD player issues any signals below 20Hz and I know my speakers don’t make much noise below 40 Hz.

 

[jkeny]

JKeny: I’ve been reading Toole’s “Sound Reproduction” 3rd edition. The reference you want is top of page 93. He goes on to describe phase shift at low frequencies as a special case which may be of more interest to you.

The reason I stopped at 10Hz is that I don’t believe my Marantz CD player issues any signals below 20Hz and I know my speakers don’t make much noise below 40 Hz.

Thanks but as I said above - I'm not talking about phase shifts, group delay in speakers - that's a totally different & OT subject

 

[Al M.]

What does close-in phase noise mean? It means that if reproducing a 1KHz tone there are frequency fluctuations in this 1Khz tone - so at 1Hz away, these errors will result in a 1001Hz tone at about -85dB down; at .1Hz away from the tone these errors are only -55dB down & closer in -20dB down. So the tone is fluctuating about it's pure signal.

This is extremely interesting, John. It might explain why the usual low jitter figures don't necessarily correlate with what we hear. Engineers just don't measure what should be measured.

I guess that has been a problem in digital (as probably in every audio discipline) from the beginning: people just didn't measure the right thing. If I am not mistaken, the concept of jitter as a serious problem entered the broader engineering vocabulary only well after digital was introduced into the mainstream.

For the same reason we got excesses in negative feedback in the first or second generation of solid-state amplifiers, before engineers realized that there might actually be a problem.

 

[Al M.]

I know I am late to the discussion, but for me, prat is very simple for me. As I listen to tons of small combo jazz, if my feet don’t tap like they have mind if their own, it lacks prat. It simply pulls me in to the performance. If a system can’t do that, like a live performance does, my wallet stays closed. Of course, that is all very subjective. Of course, as always, YMMV. Cheers.

Well, you have an easy time talking, Joe . Like me, you own the Yggdrasil DAC which simply excels in rhythm & timing...

Like for you, PRAT is among the top items of the list of what my system should do.

"It don't mean a thing if it ain't got that swing."

 

[Pb Blimp]

Thanks & I may be wrong. What I'm trying to do is explain some experiments I did where the only thing I changed in my DAC was a regular oscillator for one of these low phase noise oscillators.
What I perceived with this change was increased clarity & sound stage definition

So why do you stop at 10Hz when analysing the audibility level of phase noise? My premise is that the increasing phase noise below 1Hz could well be audible. What I'm surmising is that the spectral purity of frequencies in music is affected by this phase noise. I don't believe we perceive the notes themselves being affected rather the 2nd order effects of this on our auditory perception.

I've already stated why I believe it could well be a mistake to compare timing errors in analogue playback with timing errors in digital playback due to the differences in the underlying mechanisms at play between the two.

Have you got a link to Toole's reference to phase noise?

Similar to what happens when you take an MSB DAC and replace nothing in the entire system except the clock. Go from a Femto 140 to a 33 and the gatekeeper in the brain passes more to the limbic system and less to the cortex. You get more emotion and less fatigue, all else held constant. And no this has nothing to do whatsoever with what happens with changes in speed in analog. I can make fairly large changes to TT speed which will constitute an change in the character of the music but will have no change in the degree of emotional engagement versus fatigue.

 

[dcathro]

Agree there. Noise shaping in many modern DACs to get the perceived perfect lab report, that has killed music for years IMO. They seem to have more and more complex filtering and circuits designs but 25 years on many DACs just don't do it for me, no PRaT, in fact pretty lifeless. But hey, we have a nice lab report.

In digital, half of the enjoyment is the timing and music pace / sway / foot tapping. And to enjoy that I think we have to have zero noise and digital hash in the sound, along with dynamics and drive of course.

Why do we 'accept' tape hiss and still enjoy the music? My many early years on cassette tapes attest to that. Why do we accept pops and clicks in a TT replay system? It seems those things in our brains we have no problem with, put it to the back and not analyse it. Maybe like wind noise or a distant bird or something.

But digital noise or hash, especially inconsistent noise, speaking for myself, I find it gets my attention (unwanted attention). It seems like a piece of plastic in a field, stands out right away, ruins the view (the sound). Bit like a mobile phone going off at the other end of a concert hall, it bugs me and ruins the illusion, reminds me I am listing to a 'digital' device.

It may be the DACs at fault here, but some of the blame is also IMO squarely at the original studio where it was recorded / mastered. Adele for example, terribly recorded masters and over the top processing to get her voice to sound more pitchy. Why did they do that? Totally unnecessary, her voice sounds amazing without it. Interestingly there is a big forum where studio engineers post a lot, and Adel is on the 'bad' list, along with Metallica Death Magnetic, many other modern studio disastrous recordings.

So I think there is noise and noise. Some noise we perceive as a 'natural' element we are ok with, no problem, it isn't bothering me. Other noise we perceive as unnatural, we have an issue with.... and right there we have even coined a phrase for it - 'digital sound'. Oh my.....

My current DAC is the best and most natural sound I have heard in digital to date.

Thoughts?

Hi Astrostar,

I find your post to be very thoughtful!

I have heard both analog and digital systems that have or lack PRaT, but certainly digital seems to be at a disadvantage. I have never heard a file or streaming based system that has any sense of rhythm or drive.

I am sure that your DAC has PRaT - A friend of mine, who works with Martin Colloms at HifiCritic, told me that the top Audio Note 4 box CD player is the best source he has heard next to master tape.

As far as music goes, I find most modern recordings/masterings to be poor. Fortunately, I got introduced to the world of CD "first pressings" on the Steve Hoffman and have put together a collection of music all manufactured in the early 80's with no noise reduction, limiting, false EQ, or digital processing. This is fine for me, as my tastes are oriented towards the 50s, 60s, and 70's.

A lot of people seem to be under the perception that the early CDs were poor, but I find them to be equivalent to an excellent vinyl pressing, with good dynamic range and natural frequency response. They certainly work well on a Non Oversampling CD player.

In terms of what gives good PRaT, or what destroys it, I would not like to get too intellectual (as others currently are), but I would say that what was mentioned earlier in the thread in a quote from Martin Colloms, that it is very fragile, and that digital processing seems to be more destructive that analog processing.

I know that systems I tend to enjoy, have been very thoughtfully put together, and have a simplicity about them. The PRaT has to be in the music, and has to be preserved by the source component, and the following system, which includes the room. I was once told by a designer that it takes thousands of careful steps to make something great, and just one bad one to destroy it.

Cheers

David

 

[dcathro]

I know I am late to the discussion, but for me, prat is very simple for me. As I listen to tons of small combo jazz, if my feet don’t tap like they have mind if their own, it lacks prat. It simply pulls me in to the performance. If a system can’t do that, like a live performance does, my wallet stays closed. Of course, that is all very subjective. Of course, as always, YMMV. Cheers.

Hi Joe,

I think that you described it perfectly. PRaT makes you want to move. Many systems are good for insomnia .

Cheers

David

 

[LL21]

Hi Astrostar,

I find your post to be very thoughtful!

I have heard both analog and digital systems that have or lack PRaT, but certainly digital seems to be at a disadvantage. I have never heard a file or streaming based system that has any sense of rhythm or drive.

I am sure that your DAC has PRaT - A friend of mine, who works with Martin Colloms at HifiCritic, told me that the top Audio Note 4 box CD player is the best source he has heard next to master tape.

As far as music goes, I find most modern recordings/masterings to be poor. Fortunately, I got introduced to the world of CD "first pressings" on the Steve Hoffman and have put together a collection of music all manufactured in the early 80's with no noise reduction, limiting, false EQ, or digital processing. This is fine for me, as my tastes are oriented towards the 50s, 60s, and 70's.

A lot of people seem to be under the perception that the early CDs were poor, but I find them to be equivalent to an excellent vinyl pressing, with good dynamic range and natural frequency response. They certainly work well on a Non Oversampling CD player.

In terms of what gives good PRaT, or what destroys it, I would not like to get too intellectual (as others currently are), but I would say that what was mentioned earlier in the thread in a quote from Martin Colloms, that it is very fragile, and that digital processing seems to be more destructive that analog processing.

I know that systems I tend to enjoy, have been very thoughtfully put together, and have a simplicity about them. The PRaT has to be in the music, and has to be preserved by the source component, and the following system, which includes the room. I was once told by a designer that it takes thousands of careful steps to make something great, and just one bad one to destroy it.

Cheers

David

Very interesting reading. A few questions:

1. I too have enjoyed reading MC over the many years, and in fact have sought his direct guidance on a number of occasions which he has graciously and generously provided. Do you mean the Audio Note DAC 5th Element? That is definitely one which MC liked a lot, and by his rankings, is far and away his highest ranking digital where he (like you) suggested that Redbook could sit side by side with vinyl with the AN DAC 5th Element

2. What do you think of the FIM, MFSL and Esoteric Remasterings...as well as newer Harmonia Mundi, Channel Classics? I too have a number of Steve Hoffman masterings, but i also enjoy these other mastering labels as well.

3. Just as a note regarding your 'thousand steps to make something great...and just one bad one to destroy it.' i was told the same thing by a director once...he called it his 'sh-t soup theory'. The way to make **** soup is to use the best of the best ingredients, marinate and spend time perfecting the mixture of ingredients...let it simmer to the perfect temperature...then add 1 piece of sh-t...

4. You mention NOS digital...any particular you like?

5. Any other digital equipment you have heard you like?

 

[dcathro]

Very interesting reading. A few questions:

1. I too have enjoyed reading MC over the many years, and in fact have sought his direct guidance on a number of occasions which he has graciously and generously provided. Do you mean the Audio Note DAC 5th Element? That is definitely one which MC liked a lot, and by his rankings, is far and away his highest ranking digital where he (like you) suggested that Redbook could sit side by side with vinyl with the AN DAC 5th Element

Yes that is the one I meant. You never know with reviews just how good something is, so I asked very specifically if this was as good as the very finest most expensive analog replay, and I was told yes.

2. What do you think of the FIM, MFSL and Esoteric Remasterings...as well as newer Harmonia Mundi, Channel Classics? I too have a number of Steve Hoffman masterings, but i also enjoy these other mastering labels as well.

My first preference is for the very first CDs made in Japan & West Germany in the early 80's, later releases are almost always worse. As far as audiophile releases such as DCC, MFSL, etc, Some of the releases are not to my taste, whilst others can be good - you have to compare against an original release CD from the early 80's. Again, I have a number of classical XRCDs as well as some later FIMs, and I like those. I didn't like the XRCD jazz/pop releases which seemed to be EQed.

3. Just as a note regarding your 'thousand steps to make something great...and just one bad one to destroy it.' i was told the same thing by a director once...he called it his 'sh-t soup theory'. The way to make **** soup is to use the best of the best ingredients, marinate and spend time perfecting the mixture of ingredients...let it simmer to the perfect temperature...then add 1 piece of sh-t...

4. You mention NOS digital...any particular you like?

I am using a single box machine which is based on the Philips tda1541a dac and CDM4 transport. It was designed by Chris Bryant who has been designing CD players since the mid 80's. I am very happy with the machine, as it is extremely analog and has great drive and dynamics.

Edit - I just noticed you have the Zanden NOS player, which is interesting, because it was the inspiration for Chris to develop his player, whilst The Fifth element player has had him working hard to improve it.

5. Any other digital equipment you have heard you like?

I have heard the usual suspect such as the MSB and DCS dacs. I quite like the MSB sound, but not the price, whilst I have never liked DCS gear. I have not heard the Audio Note Fifth Element myself.

Cheers

David

 

[bach_king]

“Pace, rhythm and timing ” has shown in the audiophile narrative decades ago in a defined context to illustrate the subjective characteristics of some systems when compared to another school of stereo sound reproduction. Those who lived at that time and listened to such equipment will perfectly understand what it can mean - it is surely related to preference. Probably reading those old debates people with some experience can understand what PRAT addressed. But I do not expect that anyone will change his mind just reading some posts a few lines long in audioforums.



Those interested can google "PRAT" "Martim colloms" or "PRAT" "Paul Messenger" - there are tens of good references on it and great debates against and pro PRAT. But the more recent articles on PRAT are published in HifCritic, a subscription paid magazine.

I have a pragmatic approach to high-end - if a concept is useful for communicating in audio with others and can helps me building my audio system and enjoying my music I try to understand it and those who express around it. But I would never use the word PRAT in the DIYaudio forum ...

I think that the term PRaT originated in the 1970’s when the Linn Sondek LP12 was emerging. In those days two of it biggest supporters were Messrs Collins and Messenger. It was, I recall one of the LP12’s great points of difference. However whichever way you cut it a PRaT’s a PRaT!

Kind regards

David

 

[mikewxyz]

Ok, Jkeny gave a reasonable explanation of how a better oscillator could improve PRaT on a DAC. Yet, we see this phrase used to describe non source equipment like amplifiers. (Robert S. Youman reviewing the Pass Labs INT-60 in Positive Feedback Issue 79.) How does this make sense?

 

[Robh3606]

It might be interesting to contemplate the underlying differences in timing & how we are perceiving them

In my example where I have used the wrong clock & achieved the exact same slowing down or speeding up lets calculate the differences
Using a 22.5792MHz clock to play back a 44.1Hz audio file results in 22.67us timing of each sample
If a 24.576MHz clock is used instead then we get 20.83uS timing of each sample

So what is being perceived is the result of a 1.84uS difference in timing or am I being too simplistic in my logic here?

If that is all that is affected then the gross difference you hear is the result of this 1.84uS difference in samples - interesting?

Well would it be the cumulative effect or 44.1K times the 1.84??

Rob