PRAT, in my mind, must be the dumbest term adopted by Audiophiles. I personally think it's dumb for the following reasons:
1. The term is borrowed from Physiology and was not as previously thought, one dedicated to reproduced music.
2. Pace, Rythm AND Timing. Kokopyahin man, hindi pa linubos. Ang iniwan pa yung talagang may saysay. A should not be AND. It should be ATTACK.
So why dumb again? Pace, Rythm and Timing are not steady states in musical reproduction. They are an essential part in music YES but not in the reproduction. Why do I say so? Regardless of what you got plugged into your wall socket or hooked up to your batteries, PRT is dictated by playback at the proper speed. Nothing more. Be it 30ips,15ips, 331/3, 45, or whatever that crystal inside the DAC says to play at.
Every system has PRAT and as Einstein said in the greatest cop out and scientific theory of modern history...."It's all Relative, Baby". Okay I added the "Baby".
So ironically it's on the now missing A. A for Attack. It is this and not P,R and T that remains constant relative (
) to the playback gear that gets the toe tapping.
Wanna know what determines the missing A? Okay I'll give it a shot since I looked all over Google and haven't found anybody who actually tried to explain it. I'll try to give it my best. We'll have to divide the playback chain in two for now and sew it all back together. Electronics on one side and Electromagnetics on the other. So digital players, amplification on one side and cartridges and speakers on the other.
Electronics. Good attack comes from high rise times or available current on demand. Dynamic headroom is a big plus for the feeling of speedy attack. That's why traditionally Class A/AB , AB and Class D (with big power supplies) have excelled. Brute power is not the determinant rather the ability to accelerate when called for. Think a 2000bhp Earthmover vs a 140bhp Sport Bike. Even preamps and analog stages in source components, in ML speak, make "copies" of the input signal. This is only half the story though because we have to look at WHAT is being accelerated.
The loudspeaker. Good attack comes from loudspeakers whose diaphragms are light, have powerful magnetic fields and high impedance. Look familiar? looks like the requirements for any high sensitivity design doesn't it? Well yes and no because again, sensitivity is relative. Thank you Mr. Einstein. Given enough juice even low sensitivity speakers can give tremendous attacks. Geez I wish I had some waveforms of a snare vs an electric bass to show or better yet a bass vs a kickdrum vs a bass and kickdrum together. Zach, can you provide some screen captures?
Sewing it all together. Lets add an "s" to Attack to make it "Attacks" because it is the series of individual "Attacks" that psychoacoustically trigger the toe tapping, fight or run for your life mode. If you have a combination of a even reasonably tonally balanced source, an amp and speaker combination that can reproduce what they put out at a level that can mentally and physically affect you, then there you have it. PRAT.
So are we done yet? Ummmm. No. Because depending on how you look at things there are ways to either "enhance" or "cheat". Electronic designers and speaker designers don't just have tone or voicing contours in their arsenal. If one can use dips to enhance vocal intelligability (<---paano ba spelling niyan?) and humps to enhance bass, there are tricks to subjectively make a component or speaker seem to have more Attack or dynamic punch. This is done many ways in electronics like emphasizing the frequencies that make up the leading transients of percussion instruments but more commonly be voicing it so the levels of the sustain and decay of the envelope fall off just that much more quickly or a combination of both. Think of a drummer hitting a cymbal quickly. If he doesn't damp it it will sound like a long "Shhhhhhhhhhhhhh" as opposed to doing it when "pinched" (HELP ME ZACH!!!!) and you get practically all attack with very little sustain or decay. Speaker designers have their own tricks too. Some do exactly the same thing with their crossover designs as electronics designers do while some do their trickery with driver construction. Midrange drivers that use very stiff surrounds almost always have faster decay times. The latter makes a speaker sound more punchy. Do it right and the adjectives used are often "tight", "tuneful" and even "dry bass" but go too far and the adjectives often used are "stiff", "boxy" and/or "over-damped".
Okay so that's about as well as I can put things for now. I skipped dynamics on purpose because I think that side of things is already very well understood. I have a headache now. I hope this helps somewhat.