What exactly is PRaT???

My perception at the time when the phrase first appeared was that it was an anti spec approach to SQ evaluation.

Back then perceived quality of all audio components was based on spec analysis. 

@richardbrand

Of course, the actual music does not really slow down, nor change in pitch, nor timing (unless stylus drag actually slows a turntable down!)..

But our perception of when the beat starts is affected by the arrival pattern in time of the first transients of a note. If the leading edge is sharp, not smeared in time, your brain will snap into recognising the start of something special. I am suggesting microseconds here! Get this right, and you’ll likely find your foot tapping ...

Seems plausible.

@calvinandhobbes

The type of music you’re listening to matters in term of whether PRaT is relevant.

 

Perhaps I simply don’t understand how you are defining PRaT or perhaps it’s the fact that how rhythms are presented by a system is vital to my engagement as a listener, but either way, I’m having difficulty grasping how any genre wouldn’t benefit from a system that presents PRaT well. . . unless one is solely listening to ambient music that "hovers" in space. 

Unfortunately it’s not a given that people understand or are receptive to “prat”
And that is not a criticism, hence why many folk are quite happy with Alexa music , car stereo music Blutooth speakers etc .
Naim equipment does it very well.

PR&T is simply an essential component in well reproduced music. We all strive for well reproduced music.  I often say ‘wow, listen to that tune, listen to that PR&T’. I also say ‘wow, that’s great music’.

@yoyoyaya "... The irony is that the ... LP12 of the mid eighties had dreadful micro timing stability due to the movement of the subchassis/armboard relative to the platter. Linn’s mantra was pitch and rhythm."

I lived in the UK before Linn, when speakers were regarded as the dominant factor in audio quality. Ivor’s argument was that distortions introduced at the start of the audio reproduction chain were also important.

His starting point was that any sloppiness between the cartridge and the record would be amplified by the cartridge. His engineering solution was to couple the cartridge to the platter as tightly as possible in the direction of the arm tube. The bearings that allowed the arm to track the groove, and the platter to rotate, had to have minimum play.

If different materials were used, which expanded at different rates, changes in temperature would open up gaps. So every mechanical connecting component was made of the same grade of stainless steel. The soft floating suspension allowed the entire platter, sub-chassis, arm, cartridge system to move as one, keeping the relationship between the cartridge and the record consistent.

The most obvious difference from competitive players was the response to transients, especially scratches in the record itself. Others exhibited lengthy mechanical ringing whereas scratches were much less obtrusive with Linn. Ivor the showman illustrated this through his casual handling of records in demonstrations, often throwing them around. Elsewhere I have tried to emphasize the importance of transients for our perception of PRaT.

My recollection is that specifications were notably absent from discussions of Naim products!  The same went for the specifications of Rolls Royce car engines, where the output was described as "sufficient".