Slew rate and rise time

Sean, I think Herman is right: http://www.amplifier.cd/Tutorial/Slew_Rate/SlewRate.htm.
But I also understand your analogy, Sean. Is slew rate analogous to a car's acceleration speed and rise time to the time a car needs to go from 0 to 90 mph? The slew rate and rise time are a bit related to each other, but if plotted a device with a certain rise time can have another slew rate if compared to another device with the same rise time.

The term acceleration is not used correctly in Sean's analogy. The correct term would be velocity, but the analogy is still wrong. Velocity is how fast something is moving, how much distance you can travel in a given period of time. Acceleration is how fast the velocity is changing, you are moving but either speeding up or slowing down. Neither slew rate nor rise time have anything to do with speeding up or slowing down, only moving at a constant rate.

Velocity is a rate of change.
Acceleration is a changing rate of change.

If you want to use a speed analogy then slew rate is the velocity of the voltage. It is not related to the "volume" of the signal, at least I don't think it is because in 25 years I've never heard anyone talk about the volume of a signal except in terms of current.

These numbers won't tell you squat about how it sounds.

Herman: Iin the grander scheme of things, the hose analogy was not perfect and your comments pertaining to propogation delay were correct. I think that most people that lacked such understanding would get the basic idea though, or at least i think that they would. For sake of reference, i did try to explain things further when i said that rise time referred to the transition time from small to large signal flow. I'm glad that you pointed this out though for sake of clarity and better understanding.

Herman's clarification about propogation of delay from the beginning to the end of the circuit ( i referred to it as Td or Time Delay ) vs rise time also brings another matter to light. When trying to discuss technical matters in a non-technical manner, it is easy to make things more confusing to the lay person. As i think that most of you know, that is not my goal at all. It is quite evident that i'm not a professional teacher though, so my wording or ability to convey some ideas may not be the best that could have been chosen for any given subject.

As such, i would encourage questions, comments and clarification as one feels the need. I would rather make sure that everyone feels comfortable and has a grasp on what we've covered. While we can't expect to cover every aspect of operation in a simplistic forum like this, i don't want to gloss over what might be important details and leave one confused about the subject for life. As such, those having questions and / or corrections should PLEASE post them in a timely basis. The longer that someone believes "mis-information" to be correct, the harder it is to get them to unlearn it. On top of that, further clarification and / or correction will typically lead to an even wider coverage of the subject, furthering the educational value of this thread and the resultant questions asked.

I ran into this problem with my business partner many years ago. His college professor used an extremely poor analogy that caused him to stumble when trying to understand a certain part of circuit design & troubleshooting. This analogy, and therefore this stumbling block, has stuck with him for life. I have had a helluva hard time trying to get him to understand why it was wrong and a better way to look at things. The fact that i'm "self-educated" had made it hard for him to believe that i could know more about the subject or how to teach it than his college professor did. None the less, the only way that i found out about this analogy was because he couldn't figure out what was wrong with a circuit. As such, i tried to explain how to find the problem using a different analogy than what he had been taught, which is what caused us to get into the semantics of the analogy and why he couldn't track the problem.

With that in mind, i don't want to be the one that teaches you folks the wrong thing that you have to "unlearn" at a later date, so please ask questions / add comments as different subjects arise. I and the others that typically contribute to such threads will do our best to try and explain things in an easy to understand but correct manner. So long as we stay on course and avoid personal conflict, i think that this thread could be very enlightening. Sean
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I personally have read enough to understand Sean's analogy and even though "technically" it needed a "Slight" bit of refinement, I thought it was an excellent post allowing these parameters to be interpreted in an overall scheme. I also enjoyed Herman's post(s).
I would like to ask this, when looking at the effects of negative feedback in an amplifier, how does local feedback vs global feedback effect the overall musicality of the amp or overall performance (is there a compromise in here somewhere?)
I have seen a few amps that featured no global feedback but used local feedback and then, according to Charlie Hansen at Ayre, use no feedback, either local or global. Which type of feedback would be most audible or does it all equal up to about the samething?
I feel there is something to this feedback thing. Even though the no negative feedback amps do not offer up the "Slam" of feedback amps, they do seem to sound(for lack of a better description) more tube like. However, I can certainly see why someone might pass on the zero feedback amp if running it full range. The bass is a little light compared to some.
A really good example was when I compared the Parasound JC1's(39db of global feedback) to the 0 feedback Ayre V5xe amp (yes, I owned both and still have the Ayre.) Yes, the JC1 sounded more visceral but it also sounded more "Hi-fi-ish" overall. The mids and highs portrayed by the JC1 just didn't sound totally realistic. The Ayre was more liquid and harmonically rich. Also, the portrayal of the soundstaging cues seemed more fully developed through the Ayre (deeper stage cues vs a somewhat flatter stage presentation.)
I use subs, so the bottom end is not that much of a concern with me. Soundstaging, natural mids/highs and liquidity is.
Can this be directly related to the feedback or is it more of my personal preference to one sound over another or do I need to look at other parameters? I kinda would like to know why I hear what I hear or if it is truly just a personal thing and has nothing to do with design.
For general information, the amps were both broken in and used on 20 amp dedicated lines(2 in the case of the JC1.) I listened to both at around 85-90db or lower and my impressions stayed the same. I guess what I'm trying to say is the JC1 was kind of like a GTO, Camaro or whatever (lots of power but a touch short on refinement) where the Ayre was more BMW like(The Theta Dreadnaught also seemed this way-another zero feedback amp.)
BTW, this is not to disparage anyone who owns the JC1's but is related in context to design and its effects. This was my take over an extended period in my room with my equipment.