There are many factors that affect a system's PRaT, it is not restricted to the transport and DAC. I'd say that both components are equally important, as is the amplification and cabling (and pretty much everything else in the audio chain). |
prat is misunderstood. if you play a cd on two stereo systems, and both cd players are spinning the cd at the same speed, the elapsed time will be the same for each stereo system. thus, the pace must be the same as well as the timing. if one perceives that one stereo system seems "faster" or another "slower", it's in the mind, not the music.
what is it in the presentation that creates the psychoacoustic effect of speed ? |
Hello, in theory Mrtennis is right,
however in practice, your 10 yrs old Accuphase transport might
need re-calibration. The main crystal is aging, because of that it could change transport's main clock frequency.
If this change is more than +/-200ppm the rhytm and tempo of music will change. After all sampling frequency (44.1Khz) derived from main clock. |
Ahh, Mr. Tennis. You don't understand PRaT, and probably never will until you hear a system that does it well. It is not a matter the speed of a disk, it is a matter of how an entire system reproduces music in a manner that gives a sensation of rythmic tightness, or "pace". It is a very real thing.
Mind you it does come at a cost. Systems that do PRaT well (Naim, Linn) do so somewhat at the expense of other aspects of music reprodution that others may find more important. But to say that there is no such thing because records/CDs spin at the same rate is to completely miss the point. It is even more over simplified (and in error) than saying there is no difference in the sound of cables because they all are transfering the same electronic information from one component to the next. |
PRaT and cables all in one message. Next we will have past life regressions and crystal power. Spend your money on something real like room treatments and speakers. |
if you listen to live unamplified music, the playing exhibits a tempo, and within that structure the individual notes may vary. for example, in 4/4 time, there are 8th notes, quarter notes, etc.
if a composition takes 10 minutes, there is a sense of pace based upon the markings. thus, for example, adagio, presto, etc. .
musicians play can play fast or slow. once it is recorded the tempo is set and the timing is set. if you play a recording on 5 stereo systems, the tempo is still the same and the elapsed time is also the same.
if you are talking about perception, that depends upon the listener.
i think the concept is a construct used by audiophiles but has no value as to communication.
i would like to hear a demonstration of this concept. any suggestions ? |
PRAT has to do with both frequency response and transient response. Without reasonable tonal balance, you can't have PRAT. Without reasonable transient response, you can't have PRAT. With lesser degrees of either tonal balance and / or transient response, you get correspondingly lesser degrees of PRAT.
What we hear is SYSTEM dependent, so one has to look at the system as a whole. Having said that, one small leak can sink a large ship if unattended to, so you have to find where the leaks are and attend to them individually. One might find that they have one giant leak or they might have a bunch of smaller leaks spread throughout the entire system.
The question here is, did these two components as you are using them now ever deliver "PRAT" when combined with the other parts of your system in the past? Sean
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Newmanoc: I think that you hit the nail on the head. Mrtennis doesn't understand and / or hasn't experienced what PRAT really is, hence his thinking that consistency of playing speed ( live or recorded )is all that "timing" ( part of PRAT ) is about. Sean
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It's hard to nail it down to one component - but if I had to choose between the transport or the DAC - I'd say the DAC.
I came from an all Linn Aktiv system which was nothing but PRaT. I enjoyed it but have since moved on to a mostly non-linn system.
Regardless - I found that as I inserted more and more Linn components in the chain the system always got better (in terms of PRT). So to sum it up - PRT is really a function of synergy between components. |
as i understand, prat is an acronym--pace, rhythm and timing.
these words are metrics, they can be measured.
i have listened to 100's of stereo systems at ces. i have not been aware of prat on any of them.
sean, if you were with me, you could have pointed out at least one instance of this.
perhaps you could explain the terms in such a way that i could understand them.
it is easy to define the individual words, but i suspect there may be a conotation that i am missing. it is also possible that this phenomenon is irrelevant to me, i.e., i may experience it but pay no attention since i am listening for other attributes, such as spectral balance and a pleasing sound. |
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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DAC and transport equally important: bad transport could make an otherwise good dac slow and mudded, while a good transport could be "slowed down" by a bad dac. Still, I think, the most important thing is the amp-loudspeaker relationship. Unfortunately, as very wisely was written above by Sean, many system unable to give back the roughness and inmediacy of live music. None the less, they are voiced to give back some of the elements of musical experience through coloration and exaggarion of certain elements of music, which may trigger emotional involvement and/or pleasure of enjoyment (this is what we call in our poor language "transparent", "neutral", "warm", "bass", "airy", "open", "musical" etc.). To PRAT one really need to find the right speaker with the right amplification. My experience is that, firstly, active speaker, and secondy, very efficient speaker is the way to go. And than comes the issue of source. |
sean, i proably ignore this aspect of recorded music, as i tend to concentradte on timbre and tonal balance.
i believe it is a term which applies only to recorded music.
i tend to think in terms of live music and try to relate to recorded music as if it were live. |
Even a "somewhat poor" transport can be band-aided with a good DAC that re-clocks the incoming signal. This is not to say that there aren't differences between transports, but that a well designed DAC can somewhat alleviate those differences. Sean
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Sean 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 Sean what you are saying is the system exhibits linear phase and has reasonably extended frequency response (esp. preserving mid to high freq integrity) -- and, not least, excellent midbass. In particular, when you note, "sound (i.e. music) is (re)produced in a cohesive manner across the audible spectrum". I would agree. Although across the audible spectrum is asking for too much; lets say 45-18kHz? Also, the speakers are well set up. No:)? Cheers |
Sean and Gregm, in my experience PRaT can also be enhanced by slightly raising the midrange/midbass output. I have also a weird experience that after I inserted my very simple DIY unshielded S/PDIF digital interlink (that has an impedance that is far from the specified 75 Ohms I guess), there seems to be more PRaT and midrange fullness. I'm starting to believe that jitter also can improve PRaT (which is actually a contradictio in terminis)!
Chris |
Chris sez: in my experience PRaT can also be enhanced by slightly raising the midrange/midbass output In mine too. Also Linn's. And Naim's to a certain extent. But it has to be "clear" rather than "muddy" sounding. Cheers |
As Judge Potter Stewart said of pornography, "I shall not today attempt further to define the kinds of material I understand to be embraced . . . but I know it when I see it . . . "
PRAT is pretty much in this same elusive category. It's also a kind of holy grail that's only revealed once a number of problems have been resolved through both additive and subtractive effects. Once other problems are resolved, the most stubborn gating factor for most systems is probably the DAC/transport clock. Nuances of timing, pitch, and timbre are revealed in the reduction of treble smear and bass wooliness caused by even low levels of jitter. It's much easier to get PRAT from a vinyl source. I've had four different clocks in my CDP, as well as many other mods, and only the best clock will get your foot tapping.
Dave |
Gregm: Yes, i would venture to say that phase linearity is a good portion of what contributes to "PRAT". As Dazzdax also added, an added bit of "warmth" can sometimes help this out too. As Dgarretson also pointed out, when things are right, your toes are tapping. The system is singing and you can't help but get into the groove. This is a natural reaction to music, whether it is live or recorded.
In that respect, i have to ask Mrtennis how often he finds himself wanting to tap his toes, bang on drums or play air guitar when listening to various systems / components? After all, the more intensely that the music draws you in, the more of the "you are there" effect you experience. You are no longer just hearing recorded notes, but jamming tunes to the extent thatyou can easily visual and share in the energy of the performers playing their hearts out. Sean
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my reaction to music in the home is more dependent upon how i feel and how much i like the music. it is much less dependent upon the sound of a stereo system.
i own an acoustic guitar and when listening to the raio, i would sometime try to play along with the melody.
it's about the music and the person more thanm about the stereo.
if you want to enjoy your stereo, relax, rid your mind of extraneous thoughts and overlook flaws in the stereo system. |
Mrtennis sez i tend to concentradte on timbre and tonal balance.
Ideally, in a well set up system, you would NOT have to concentrate on anything -- but the music. Of course, even in such a well set up system I believe there is an individual "minimum resolution" level which allows to concentrate on music rather than be distracted by reproduction anomalies and artefacts. It's that dividing line that must be crossed by system performance level and set-up level -- and we can enjoy the music: this level obviously differs from one to another. Also the preference points differ; you express your focus points as timbre and tonal balance. I am very partial to "dynamics" (i.e. changes in amplitude) and linear phase & resolution: for me, the thin dividing line between listening to a musical artifact and listening to music is there. |
FWIW, in my limited experience I have come to believe that the sense of PRAT has more to do with any components ability the recreate the initial or leading edge of the note, get the rise time right and you've got half of the battle won. Then get the decay time right and you've got the ability to sense PRAT, assuming its on the recording in the first place.
Now, get that signal thru all your stuff undistorted (perfectly resolved, without hyped detail common to much that is called 'resolved') and you've got great imaging (potential) as well. Every thing in the system contributes to this effect but probably the last place I would think to look for loss of PRAT otherwise available would be in a CDP/Transport-Dac unless it had tubes. JMHO. |
