What amp/ preamp has the fastest transients?

[caesar]

To my ear, fast transients are one of the most important factors that separates live music from a hifi system. My current winner is the VTL MB 750.

What components have you guys heard that do this the best?

 

[RogerD]

I always thought my VAC 140's do a solid accounting with fast transients. As far as SS amps my Agtron Platinum monoblocks with their dual toridial transformers are the best in my system. Just a thought how do the VTL's perform on producing natural decay, I think that is important too on reproducing live music.

 

[Jay_S]

I'm not sure what this means. What would be an example of a slow transient?

 

[caesar]

I'm not sure what this means. What would be an example of a slow transient?

To my ears, letting go of the disbelief of recorded vs. live music rests on the ability of the piece of gear to create these fast transients. For example, play a low powered tube amp on a demanding speaker and then play the same speakers fed by a quality, high powered SS amp. The transients will sound more realistic with the SS amp. (The decay and "other stuff" is another story...)

 

[caesar]

Just a thought how do the VTL's perform on producing natural decay, I think that is important too on reproducing live music.

I agree with you 100% percent and I think they do splendid. This natural decay is where the tube vs. SS stereotypes hold, and in a sense that decay and the texture of the music is why I and many other audiophiles own tubed amps.

The unusual thing about the VTL is how good it is at producing the transients. It sounds very "solid state" in that respect. It is faster than my Bryston and my 350 wpc CJ Premier 350.

 

[DonH50]

If an amp correctly reproduces transients, fast or slow, why would the decay be any different than the attack? Why would we even want that? As an aside, depending upon how the tubes are biased, and since most tube amps are single-ended (at least in the initial stages), I'd expect the decay to be a little faster than the rise.

I have a few theories (naturally) on the whole "how fast is fast" debate but in the interest of trying to stay on target, what about the Spectral amps?

Curious - Don (had and loved both tubes and SS)

 

[RogerD]

To my ears, letting go of the disbelief of recorded vs. live music rests on the ability of the piece of gear to create these fast transients. For example, play a low powered tube amp on a demanding speaker and then play the same speakers fed by a quality, high powered SS amp. The transients will sound more realistic with the SS amp. (The decay and "other stuff" is another story...)

Probably the hardest instrument to reproduce correctly is a piano. The piano gives you both ends of the spectrum. That's why I have both SS and tube amps. Both have their own qualities or the ability to reproduce the neccessary ques to draw you into the music.

Something as simple as a audience clapping can be a good indicator on whether it's "live" or is it memorex. The clapping part probably doesn't fit the category like a cymbal crash that startles you, but is one of the tells that I look for to measure where my system is. It does tell me if my system is well grounded though,but that's a whole different subject.

 

[Ron Party]

in the interest of trying to stay on target, what about the Spectral amps?

Curious - Don (had and loved both tubes and SS)

I was thinking Spectral as well.

 

[MylesBAstor]

To my ear, fast transients are one of the most important factors that separates live music from a hifi system. My current winner is the VTL MB 750.

What components have you guys heard that do this the best?

I don't think too many designers would agree that superfast transients make a great sounding amp. A couple have told me that in fact, they've made amps that were far faster sounding than their current products and they sounded awful. So I think that looking at this one particular aspect of performance is misleading since how this apparent circuit "speed" is achieved is more important.

 

[MylesBAstor]

If an amp correctly reproduces transients, fast or slow, why would the decay be any different than the attack? Why would we even want that? As an aside, depending upon how the tubes are biased, and since most tube amps are single-ended (at least in the initial stages), I'd expect the decay to be a little faster than the rise.

I have a few theories (naturally) on the whole "how fast is fast" debate but in the interest of trying to stay on target, what about the Spectral amps?

Curious - Don (had and loved both tubes and SS)

I think then one needs to then consider KOJ's thought on settling times.

 

[muralman1]

Amps can't do it alone. I found something as forgetful as the transport will make a big difference in speedy transients, decay, clear leading edges, and just plain musicality.

My H2O and Fire combo can do it all, but need direction from the proper source, and cables. Oh!, and the most important player in the mix, the speaker!

 

[DonH50]

Myles -- KOJ?

Faster transients require wider bandwidth, which in turn means more noise and potentially lower stability (more ringing). Anything carried to extremes can be bad.

Except chocolate.

 

[amirm]

Myles -- KOJ?

I believe he means Keith Johnson: http://www.spectralaudio.com/

 

[Mark (Basspig) Weiss]

If an amp correctly reproduces transients, fast or slow, why would the decay be any different than the attack? Why would we even want that? As an aside, depending upon how the tubes are biased, and since most tube amps are single-ended (at least in the initial stages), I'd expect the decay to be a little faster than the rise.

I have a few theories (naturally) on the whole "how fast is fast" debate but in the interest of trying to stay on target, what about the Spectral amps?

Curious - Don (had and loved both tubes and SS)

With vacuum tube amplifiers, the back EMF from a woofer that's coasting will feed energy back into the output transformer. Some of this enters the feedback loop and gets re-amplified. The result is a little extra ambience from this delayed signal.

Speed of preamps is inconsequential when the limiting factor is mechanical drivers. Any preamp is a high order of magnitude faster than any driver, excepting maybe a Plasma Tweeter.

The important thing to remember is to have the slowest slew rates in the earliest stages and each stage thereafter having a faster slew rate. About thirty years ago, I knew the formula for calculating the gain vs. slew rate product in order to design successive stages without running into slew rate limiting. This was back in the late 1970s when this was a hot topic.

 

[DonH50]

@Amir -- Thanks, I'll check it out.
@Mark -- I certainly agree with your points. I could look up (or derive) the formula for cascaded stages, but IIRC the basic version is based upon linear amplitude, gain and bandwidth so fails to provide the full picture when large- and small-signal bandwidths differ significantly. And, of course, the amplifier class of operation makes any simple formula useless in the real world, or even our (audiophile) world, unless it's class A. The forumlae get real ugly real quick after that...

FWIWFM - Don

 

[JackD201]

How big a part does cap storage capacity in an amp play in all this?

 

[c1ferrari]

FM Acoustics

is a contender in this arena.

 

[DonH50]

Jack, it depends on the caps and the signal levels, especially in power amps. Large electrolytics have fairly high series resistance (plus self-inductance) and thus are "slow" (though many if not most cut off above the audio band) so we (designers) add smaller, "faster" caps. How many, how good, and what size is a function of cost and how long they need to provide charge until the bigger caps "catch up". So, with no bypassing, transients will quickly get "snubbed" since big caps can't provide fast charge. With some smaller caps added, transients will fare much better but eventually charge must come from the larger caps (and then the wall).

I guess that's a long way of saying "it matters, but it's complicated".

Good question! - Don

 

[JackD201]

Yeah that WAS complicated!

 

[Nicholas Bedworth]

But a very good answer. Check out http://www.6moons.com/audioreviews/odyssey2/1.html for a review of mine (already decried as moronic "yammering" by another distinguised forum member ) description of the Odyssey Kismets transients. You could probably use them to pop fillings out of teeth, or arc-welding in an emergency. The reverberation is superb. Bandwidth is 2 to 500 kHz roughly. Spectral also is an enthusiast of very high current at very high bandwidth.