Slew Rate

Sean, That was educational reading. What current production amps do this very well? Thanks.

Sean, i can always count on you for one hell of an answer! Thanks!

Yup, I say Sean slew that dragon, allright!

My understanding is that slew rate needs to be faster as the amount of negative feedback goes up. Even Nelson Pass has said that anything over 50v/microsecond is not describing anything happening in audio or even low RF on a low feedback design. And this is for a power amplifier; a preamp needs even less.

That being said, what is even more important than Slew rate, but seldom if ever mentioned, is "settling time" the time it takes the amp to settle down to its quiescent conditon. Lots of 70's amps had fast "attacks" but took forever to settle down; in a crude way one can say the amp described the leading edge of the waveform well but not the back side (or decay side).

That being said companies like Spectral have 700 to 1000 volt/microsecond slew and nano-second settling times. It sounds good, but does that make it the best preamp? No, not really (it is my favorite, but that is not the point). There are just too many other important qualities that matter to the sound. Sure, it is nice that an amp or preamp can describe a color TV signal perfectly, but that has nothing to do with audio.

Sean, I once heard that Sunfire amps have very low slew rates, (part of what gives them a "tubey" sound). I can't find any specs though. I know that you're a fan of these amps (and in fact, I just ordered one). Do you think that your comment above regarding low slew rates,

"...can sound quite "musical" but typically tend to be far less resolving, not nearly as transparent and tend to get "hard, nasty and gritty" with a less cohesive presentation as they are pushed harder."

applies to their amps? I always thought sunfire was known for standing up well under tough loads. Just curious. Thanks for the great explanation above.