What does 'Fast mean?

Two points to answer:

"Fast is nonsense.... Same applies to PRAT."

No, Porziob, this statement is nonsense, at least to me. It is beyond me why people who have never experienced systems that do PRAT well insist that it doesn't exist. It most certainly does exist. Whether these systems are your preference is another matter entirely.

"Fast usually means the sound is thin and without body/weight making it seem faster! That is what I have found when auditioning "fast" gear."

Now I do not think this statement is nonsense, Grannyring. While I wouldn't put the matter in such pejorative terms, I think there is truth here. As far as I can tell the subjective experience elicited by systems that we say are fast or do PRAT well does seem to come at a cost of reducing the fullness of the sound, creating at least some degree of leanness in the music. What one gets in return is a musical tightness - a rhythmic coherence - that many of us find captivating and involving. Too much of this leanness can be as dissatisfying to some ears as bloated tube gear is to mine. (I don’t find all tube gear unpleasant - just the soft, mushy-mouthed stuff.) We all have our preferences.

"BTW, "pratt" (lovely stuff from Linn's marketing) can be achieved in systems by slightly emphasising the lower mid-range/upper bass"

Gregm:
I own Linn gear, though I have never heard the term "PRAT" from the mouth of any of the three Linn dealers I have worked with in the past two years. But I am too young in the hobby to know the marketing history behind these terms. I actually assumed the term was Naim's coinage.

I don't understand the distinction you are drawing between the terms "PRAT" and "fast." At least I have been using them interchangeably, perhaps in ignorance. Could you explain what you mean? Certainly increasing midbass doesn't lead to the phenomenon Seantaylor is describing above.

In my experience, such as it is, the excitement, immediacy and rhythmic coherence of music clearly varies from system to system (most dramatically between some tube gear and good solid state). I am sure midbass can give you the “thump - thump” of a dance club, but I doubt that is what you mean. It is certainly not what I mean when I use the term “PRAT.”

John (jafox):
Of course they all mean the same thing. I have never met anyone who has been able to describe any meaningful differences between the constituents of this acronym, nor do I expect to. I use it simply because it is recognizable and seems to have found its way into the audio argot, not because I defend its origins, semantics or anything else. Perhaps I should just use "fast" or "well paced" in the future, because that is all I mean.

Chris

Gregm:
Thank you - your post was very informative and very helpful. Your description of systems designed for "PRaT" slightly emphasizing frequencies across the core of the audible frequency range makes sense to me. This is perhaps what people mean when they talk about "smearing" of sound from these systems (a term that strikes me as a little harsh). It does seem that systems that have this "crispy" sound do so at the cost of sacrificing things that others value more, such as the frequency extensions and low level detail (if I understand this latter term correctly). I suppose what to one man sounds like musical coherence to another sounds like sonic oversimplification. I think this "PRaTy" emphasis sounds less “audiophile” and more like live music. But my ears are not everyone’s ears, nor my tastes their tastes. Thanks again for your helpful post.