What exactly is PRaT???


Ok, it’s like this thing and is associated with “toe tapping” and such.  I confess, I don’t get it.  Apparently companies like Linn and Naim get it, and I don’t and find it a bit frustrating.  What am I missing?  I’m a drummer and am as sensitive as anyone to timing and beats, so why don’t I perceive this PRaT thing that many of you obviously do and prize as it occurs in stereo systems?  When I read many Brit reviews a lot of attention goes to “rhythm” and “timing” and it’s useless to me and I just don’t get it.  If someone can give me a concrete example of what the hell I’m not getting I’d sincerely be most appreciative.  To be clear, enough people I greatly respect consider it a thing so objectively speaking it’s either something I can’t hear or maybe just don’t care about — or both.  Can someone finally define this “thing” for me cause I seriously wanna learn something I clearly don’t know or understand.  

soix

That Chris Rea song is garbage. Hard to find PRaT in garbage. It’s got everything that made music suck in the 80s. Bombino is a better example. It still seems like no one can come up with a definition but plenty of examples of what they think it is. Seems like it’s more a quality of the song and whether the system can reproduce those qualities. If that’s the case then shouldn’t there be some way to quantify what makes the system do that? Whether it’s transients or decay or midrange quality or phase coherent drivers or even room treatments.  Basically something like if you want a system that can reproduce PRaT then it needs these n number of qualities.

@bolong

Master of PRAT ie."swing"

You might check out this analysis, exploring how Little Wing in fact incorporates both straight time and swing, which is why it’s deceptively difficult to get right:

https://www.youtube.com/watch?v=0uGDYs__ZP8

 

PRaT is experiential, and as such takes some experience to hear - or not hear. It's pretty clear it does not exist in any one domain, like frequency, or phase, per se. The Large Advent is great example - beautifully voiced, extended well controlled bass, but PRaT? Not so much. My explanation is hysteresis - the delay between input and output. Hysteresis may vary due to a lot of factors, amplifier damping, a function of output series resistance, including the amp, speaker cabling, crossover series inductor (one reason internally amplified speakers tend to sound 'quicker') and overall speaker alignment. Acoustic suspension speakers rely on compreesion of trapped cabinet air for damping, and are as a result inherently slower and less linear to stop, resulting in a smear that doesn't show up in frequency response graphs. By comparison, full range drivers, for all their other limitations and freed from those driver control constraints tend to have that ineffable 'liveness' that they are known for.

Likewise, much of the difference between MM, MI, and MC phono carts can be attributed to their inductance, with MM carts having 10X the series inductance - and resulting hysteresis - of most MC carts, with MI like Grado and Soundsmith falling in between. 

As for amplifiers, the ability to control and dissipate the woofers back EMF (the 'brakes') is likely their major contribution to PRaT. 

Overall, I believe PRaT is fundamentally about controlling and minimizing stored energy within a system. It is the release of that stored energy that smears the sound, robbing the music of PRaT.