This is a difficult term to put into understanding because our universal musical vocabulary is so limited. Quite honestly, you really do have to hear something like this to better understand it. Once you've experienced it, you'll understand what you've been missing in music reproduction for so long.
A system that exhibits a high level of "PRAT" is a system that not only draws you into the music i.e. gets and holds your attention due to the rhythmic pulses that ebb and flow, but also makes you aware of just how subtle dynamics and timing shifts seem to be reproduced in an effortless manner. You become emotionally involved with the music, forgetting about the system and your surroundings.
While doing all of this with great ease, the harmonic structure is preserved, giving the music not only greater weight, but also a much richer and vivid texture. Not only is the presentation delivered harmonically rich i.e. full of overtones, but also with the right timing of delivery due to reduced signal loss and smearing. That is, the overtones retain the proper pitch and are delivered in step with that of the primary notes i.e. sound is produced in a cohesive manner across the audible spectrum.
The "speed" of such a system seems to be "just right", as dynamics are properly weighted and delivered in a timely basis. Upon initial listening, it may seem to reproduce the music at an increased tempo i.e. faster than normal, as most systems don't have the drawing power to lift your heart and soul and soar with the music. The music is not being reproduced at a more rapid pace though, as notes maintain the proper duration and decay naturally as they should.
While i'm quite certain that i didn't do the definition of PRAT much justice, i hope that i've at least given you some idea of what we are talking about. Mind you, i did not mention anything about spatial characteristics, imaging, soundstage, etc.. at all in this description, as those are seperate entities and not necessarily PRAT related.
Other than that, most systems at audio shows are pretty terrible in my experience, with most of them demonstrating how NOT to set up a system. Like many other systems, they sound sterile and lack any form of emotion. Music plods along, stripped of the life, speed, immediacy and dynamics that one normally encounters in the real world. If you're basing how things should sound using big name high dollar systems as assembled at shows as a point of reference, i can see how you've never experienced "PRAT" or know what it is. In that respect, i can fully understand your comment of "i have listened to 100's of stereo systems at ces. i have not been aware of prat on any of them".
The two worst sounding exhibits i've heard in terms of PRAT came from systems by Linn and Naim. Both of these companies are known for high levels of PRAT.
I went so far as to tell those exhibiting the Linn system that it was the worst i had heard at the show. It sounded SOOOO "mechanical" in reproduction and stripped of life / natural properties that the majority of people left within the first two minutes of the demonstration. The funny thing was that this system was probably close to $100,000 or so at the retail level, using all of their latest and greatest products. The Naim system sounded like elevator music at best.
The two best sounding systems that i've heard at a show were produced by Atma-Sphere and Legend ( now called Von Gaylord Audio ), but for completely different reasons. The Atma system had phenomenal PRAT.
With the Atma-Sphere demo, it sounded so good that when Ralph first started the demo, the room was relatively vacant. Once the music started playing, people came into the room and filled it up ( PRAT literally DREW the people into the room via the sound being reproduced in the hallway ). At the end of the presentation, which simply consisted of Ralph & crew playing a wide assortment of vinyl without any fanfare or marketing, the consumers in the room actually stood up and clapped. In other words, the consumers were so satisfied with what they heard, that they felt the need to emotionally show their appreciation for a job well done. Much like the emotion that one experiences at a truly rousing live performance.
As for the Legend room, the sound was so delicately airy, warm, detailed and relaxed, that it made all of the stress of the day disappear. One was simply able to melt into the music and absorb the phenomenally spacious tranquility. This made us forget about all of the hustle and bustle taking place in every other room and passageway and simply let us enjoy the music. The presentation itself was done quite well, adding to the enjoyment of the system and what we heard.
These four demo's were what stood out in my mind from that show, as they were the polar opposites of each other in terms of emotional involvement and sonic reproduction. The problem is, more of the rooms were closer to the Linn / Naim systems than to the Atma-Sphere & Legend / Von Gaylord systems. Sean
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