PRaT: Real? Measurable? Or just BS?

[fas42]

I've heard systems which subjectively do seem to possess an hard to describe 'driven' character. The sound frequently, though probably inaccurately, just seems to lock into a propulsive groove. This can be an highly satisfying effect with rock, pop, R&B, etc.

The effect appears to be an mid-bass focused phenomena, but is not necessarily an obviously bass prominent sound. In addition, the sound character can feature an coherence, for lack of a better term, across the entire audio spectrum, not just the mid-bass. I suspect there isn't a single metric that quantifies this effect, it likely being due to some confluence of multiple system parameters, maybe including room acoustics.

Ummm ... I tend to call this competent playback - I'm not sure why you call it "probably inaccurately". Yes, the bass lines have an urgency and bite to them, just like the "real thing" - there is a live recording of Cream doing Crossroads, where Jack Bruce's bass guitar drives the song forward with almost a manic intensity; Baker and Clapton are dragged along, seemingly gasping to keep up - if ever a track can be said to be able to test a rig's PRaT this one does ...

 

[Cosmik]

I have come across systems which subjectively feel like they're dragging the beat; one registers that the musicians are just going through the motions, and are ready to head to bed ... it's how our hearing is reacting to a type of distortion in the replay; fix that distortion and the sound "springs back to life".

Doesn't that contradict your oft-made assertion that old recordings shine through despite their poor frequency response, distortion, noise?

Why would evolution and our life's experience cause us to register distortion as an indication that people are feeling tired and want to go to bed?

 

[fas42]

Doesn't that contradict your oft-made assertion that old recordings shine through despite their poor frequency response, distortion, noise?

Why would evolution and our life's experience cause us to register distortion as an indication that people are feeling tired and want to go to bed?

The problem is in the replay chain, not in the distortion, etc, of the old recordings.

Again, it's the nature of the distortion that's key, not the level of it - if I was forced to try and analyse it, off the cuff, I would probably say that the quality of the transients has been degraded - if someone has lost motivation in doing something, then they're not as energetic, impulsive in the way they use their body and the "tools" they are holding, and we are quite capable of registering that lack of interest, by the loss of "sharpness" in what our senses pick up.

 

[Ken Newton]

Ummm ... I tend to call this competent playback - I'm not sure why you call it "probably inaccurately". Yes, the bass lines have an urgency and bite to them, just like the "real thing" - there is a live recording of Cream doing Crossroads, where Jack Bruce's bass guitar drives the song forward with almost a manic intensity; Baker and Clapton are dragged along, seemingly gasping to keep up - if ever a track can be said to be able to test a rig's PRaT this one does ...

I say, probably inaccurate, because the effect is rather consistent across most program content, giving a decidedly propulsive quality to everything. As such, it seems likely an coloration, although a pleasant one. As far as live music, some of it exhibits this driven quality, while much doesn't. I don't uniformly experience such an effect live.

 

[watchnerd]

I've heard systems which subjectively do seem to possess an hard to describe 'driven' character. The sound frequently, though probably inaccurately, just seems to lock into a propulsive groove. This can be an highly satisfying effect with rock, pop, R&B, etc.

I've had this happen with vinyl and I'm pretty sure it has to do with beat resonances being picked up and amplified by the cartridge in time with the music.

Interestingly, I've experienced it more with cheaper TT's than with higher quality ones.

 

[Frank Dernie]

By a considerable margin the biggest disappointment I remember in my hifi listening/buying life was hearing Spendor BC1 speakers.
Everybody in the UK hifi world was raving over them so I saved up some money and, consistent with previous experience of needing to listen to stuff myself rather than rely on reviews, asked Spendor for the location of my nearest dealer, which turned out to be in Bath, a beautiful town.
I duly set up an appointment and showed up with some favourite LPs, this would probably be the mid to late 1970s.
Demonstrated on BBC radio 4 broadcast the speech was very impressive, but on music, at a higher level, they were flat and lifeless - I wouldn't have taken them home if they were free.
The thing that was completely absent was any drive or feeling of dynamics. I guessed at the time that they were not only inefficient but had low power handling, so any reasonable volume level took them way past their thermal linear range. I wasn't in any position to measure them, and I haven't heard a pair since.
I would say they were subjectively the antithesis of the Yamaha NS1000s I got some years later and still own and like.

 

[Cosmik]

By a considerable margin the biggest disappointment I remember in my hifi listening/buying life was hearing Spendor BC1 speakers.
Everybody in the UK hifi world was raving over them so I saved up some money and, consistent with previous experience of needing to listen to stuff myself rather than rely on reviews, asked Spendor for the location of my nearest dealer, which turned out to be in Bath, a beautiful town.
I duly set up an appointment and showed up with some favourite LPs, this would probably be the mid to late 1970s.
Demonstrated on BBC radio 4 broadcast the speech was very impressive, but on music, at a higher level, they were flat and lifeless - I wouldn't have taken them home if they were free.
The thing that was completely absent was any drive or feeling of dynamics. I guessed at the time that they were not only inefficient but had low power handling, so any reasonable volume level took them way past their thermal linear range. I wasn't in any position to measure them, and I haven't heard a pair since.
I would say they were subjectively the antithesis of the Yamaha NS1000s I got some years later and still own and like.

I have had similar experiences. Was it psychological, the room, or are some people just not hearing the same thing? I was at a hi-fi show recently where one of the exhibitors was chuckling about how a visitor had spotted that the speakers were wired out of phase. He took this as an indication that the visitor had golden ears.

 

[Wombat]

By a considerable margin the biggest disappointment I remember in my hifi listening/buying life was hearing Spendor BC1 speakers.
Everybody in the UK hifi world was raving over them so I saved up some money and, consistent with previous experience of needing to listen to stuff myself rather than rely on reviews, asked Spendor for the location of my nearest dealer, which turned out to be in Bath, a beautiful town.
I duly set up an appointment and showed up with some favourite LPs, this would probably be the mid to late 1970s.
Demonstrated on BBC radio 4 broadcast the speech was very impressive, but on music, at a higher level, they were flat and lifeless - I wouldn't have taken them home if they were free.
The thing that was completely absent was any drive or feeling of dynamics. I guessed at the time that they were not only inefficient but had low power handling, so any reasonable volume level took them way past their thermal linear range. I wasn't in any position to measure them, and I haven't heard a pair since.
I would say they were subjectively the antithesis of the Yamaha NS1000s I got some years later and still own and like.

The BC1 is closely related to the BBC LS3/6 outdoor broadcast monitor for OB studio vans(near-field speakers). BBC broadcast monitors tended to focus on speech quality for radio or TV transmission.

https://www.markhennessy.co.uk/rogers/others.htm

The LS3/6 is not included here but the numerical classification for intended BBC monitor use is noted. https://www.markhennessy.co.uk/rogers/bbc_txt.htm

BBC monitor design: http://www.bbc.co.uk/rd/publications/rdreport_1988_14

BBC monitors: http://www.bbc.co.uk/rd/search?query=monitor+loudspeaker+ls3/6&submit=

 

[Jakob1863]

So, in your mind, PRaT is real....but is it measurable or unmeasurable?

First point should be to define what is meant by "measurable/unmeasurable".
Any term like "PRaT" is an attempt to describe an internal process, an impression based on a multidimensional experience and although i´d agree with tomelex that group delay can play a role, it does not mean that there is a single measurable parameter describing the effect.

 

[Frank Dernie]

The BC1 is closely related to the BBC LS3/6 outdoor broadcast monitor for OB studio vans(near-field speakers). BBC broadcast monitors tended to focus on speech quality for radio or TV transmission.

https://www.markhennessy.co.uk/rogers/others.htm

The LS3/6 is not included here but the numerical classification for intended BBC monitor use is noted. https://www.markhennessy.co.uk/rogers/bbc_txt.htm

BBC monitor design: http://www.bbc.co.uk/rd/publications/rdreport_1988_14

BBC monitors: http://www.bbc.co.uk/rd/search?query=monitor+loudspeaker+ls3/6&submit=

I have owned LS3/5a and now have the similar Harbeth P3ES-2, I also have KEF LS50s which are not physically similar at all but followed a similar but updated engineering approach to minimising colouration as was taken decades ago for the LS3/5a.
I also have some Harbeth Monitor 40 Actives here, which I have tried but can't get the bass into control in my room so I am just storing them for the owner now.
Both times I have heard the LS5/8 it had the same problem of bloated very low bass. I guess the BBC control rooms have better bass traps than I have.

 

[TBone]

arghh ... the term PRAT was coined well before digital, generally used to describe the affect of a turntable speed inaccuracy in relation to inherited noise. A loose example; added compliance between drive & platter can often lead to loss of speed stability, blurring hard hit transients. Even a slight speed increase or decrease can have a major affect on sound reproduction quality. Worse yet, inconsistent speed-deviations caused by ...
(huge f`n sigh)

 

[Cosmik]

arghh ... the term PRAT was coined well before digital, generally used to describe the affect of a turntable speed inaccuracy in relation to inherited noise. A loose example; added compliance between drive & platter can often lead to loss of speed stability, blurring hard hit transients. Even a slight speed increase or decrease can have a major affect on sound reproduction quality. Worse yet, inconsistent speed-deviations caused by ...
(huge f`n sigh)

Why not just measure the wow and flutter (and other speed & pitch-related statistics)?

If not, don't these factors also affect "emotion", "solidity", "authority", "purity", "joie de vivre", "competence", "musicality", etc. Why not coin some terms including these also?

 

[Thomas savage]

arghh ... the term PRAT was coined well before digital, generally used to describe the affect of a turntable speed inaccuracy in relation to inherited noise. A loose example; added compliance between drive & platter can often lead to loss of speed stability, blurring hard hit transients. Even a slight speed increase or decrease can have a major affect on sound reproduction quality. Worse yet, inconsistent speed-deviations caused by ...
(huge f`n sigh)

Nice to see you

 

[TBone]

Hi Thomas, hope things are well in the land of Tempest and Spitfires.

 

[TBone]

Why not coin some terms including these also?

rube: a term coined for those who consistently pretend without any actual hands on experience or knowledge.

 

[Cosmik]

rube: a term coined for those who consistently pretend without any actual hands on experience or knowledge.

Experience and knowledge of what? Prats? PRaT??

I have in the past owned a vinyl gramophone.

 

[TBone]

I have in the past owned a vinyl gramophone.

ah, the past, such fleeting moments ...

 

[Cosmik]

I have also owned several cassette decks, reel-to-reel machines, video recorders and once made a hand-operated foil cylinder recorder - not great wow and flutter but very 'dynamic' pace, rhythm and timing.

 

[Thomas savage]

Hi Thomas, hope things are well in the land of Tempest and Spitfires.

 

[TBone]

Thomas, don`t remember seeing the Talking Heads live ... but what the bleep do I know ... few months ago I was invited to attend a local Martin Barre concert ... and embarrassingly ... I asked (probably with Locomotive Breath) ... who is Martin Barre.