Vocabulary question


What does it mean when people use the term "fast" for an amplifier?

thanks
longho68
I currently have the Pass x-250...and I heard that they are suppose to be fast..and that's why I wanted to know what fast really mean so that I can analyse how it sound. I had it for about 3 weeks...and currently driving the Sony SS-M9ED speakers. I don't have a preamp so I'm pluging my Shanling CD player directly into the x-250.

I'm thinking to get the Hovland HP100 as a pre to mate with the pass x-250...and eventually maybe upgrade the x-250 to the Hovland Sappire since it is so pretty....

Long
To me it means how quickly the output signal follows a changing input signal (which is the definition of slew rate). The "faster" the output rise means (generally) that transients and silences are more accurately depicted. The biggest impact, IMO, is that percussion instruments (pianos, cymbals, etc) are better defined with respect to the overall pace of the music.
Perhaps Peter Moncrief of IAR (Intern'l Audio Review) said it best during his reviewing a fast amp, perhaps the fastest in 1998. To paraphrase Moncrief's description of this fast amp:

"(This fast amp) effortlessly reveals layers of musical nuance, is more extended, with the rise and fall time on music's transient details such that each fast nuance is executed more individually, with better intertransient silence, yet at the same time each fast nuance sounds more delicate because it does not sluggishly linger at the peak or get clogged up there, as most amps do to varying degrees."

Mr. Moncrief goes on to say:
"Some amps try for musicality and delicacy by softening and defocusing the music, smudging and veiling everything. (This fast amp) doesn't need any such trickery as it can go for full articulation and sharp focus, yet still sound accurately musical and delicate, because it is so capably fast and transparent... and is so capable that it handles the entire spectrum, and all of music's demanding complexities, with the remarkable sense of relaxed ease that is the hallmark of a truly great audio component."

Moncrief then relates this sense of relaxed ease to Fred Astaire's dancing abilities which Fred seemed to do so effortlessly. Other dancers might come close to Fred but they sweated like pigs trying to do so. Thus the other dancer's straining and sweating were a distraction for the audience toward their performance. Where as, with Fred, the audience saw only the performance. Not the performer.

I think Michelle Kwan has much the same abilities in figure skating as Fred Astaire had with dancing.

-IMO
Does slew rate affect how fast an amp is?...My NAD S200 slew rate is 100v/us and my pass x-250 is only 50v/us?...

Which amp is better in this case?...I love my x-250 but I still think very highly of the S200. I still owned both amp.