damping factor

Here's a link you may find useful, that relates directly to the matter of damping factor and matching the amp and the speaker for optimal operation:

http://www.atma-sphere.com/papers/paradigm_paper2.html

There is no speaker made that requires more than 20:1 for a damping factor, and there are speakers that prefer a damping factor of 1:10 (usually high efficiency full-range speakers). If a speaker is over-damped it will produce less bass and what bass there is will be tight and 'punchy', without much in the way of definition. When the speaker is properly damped not only will you have impact but you also get definition.

If the speaker is under-damped, many people assume that the loss of control by the amplifier is responsible for muddiness, but this is not true. What is really happening is that the amplifier has a high output impedance relative to the speaker, and is making excess distortion, which is interpreted as a loss of control.

The size of the woofer cone has absolutely no bearing on how well the amplifier will be able to damp the speaker. The idea that the cone size makes a difference is a common myth.

One other myth is the idea that the amplifier has to be able to 'stop' the speaker as well as get it started. It turns out that this issue is minor- if you look at any audio waveform, you will see that they don't require this of the amp and speaker to any great degree.

The only area where this really comes into play is 'overshoot'- the idea that the cone will move too far on transient peaks. But most cones will see a fair amount of mechanical damping coming from their own suspension on transients, and when an amplifier is reproducing a transient its damping factor will be higher than the that same amplifier's damping factor will be at rest; this is really not much of a problem!

05-27-11: Elizabeth
The damping factor is the 'control' the amp has of the woofer movement.
When the amp has a signal that moves the woofer and then the other way, the damping factor is the control the amp has to "HOLD" on to the cone and not allow it to continue going in the first direction, instead of obeying the amp and moving in the opposite immediately that the new signal wants. (sloppy explanation but it will do...

So "IF" your speakers have a BIG, 12" or maybe even a 10" sloppy woofer, the higher damping factor amp will 'control' it better, and that big sloppy woofer will behave better, giving a more solid punch, with less overhang and less woolly sound.
Where if you own a set of speakers with a single or pair of 'tight' 8" or 6" woofers, then the damping factor will not matter nearly as much, and other factors will overshadow the damping factor.
Generally it is said ANY solid state amp has enough damping factor to control any modern speaker system woofers. Only if you had some old speakers with giant woofers..
And the place where damping factor may be a little too small for some speakers is in a tube amp. Although the combo of a tube amp and big efficient speakers is usually heavenly, even if the bass is a little sloppy.
So all in all, you do not have to worry in any way about that particular spec called Damping factor. It is used to sell stuff, particularly amps which 'just by chance' have a particularly BIG damping factor, but it is a nearly meaningless spec.

there she goes again..............giving explanation on technical subjects she has no/little understanding!! Very similar situation to the "what is tube bias?" question posed not long ago by some other member.

Size of woofer cone has no bearing amp's ability to control woofer.

Hi Bombaywall,
Of course you are correct that woofer size has nothing to do with damping factor, but not everyone on Agon knows much about it, thats why this section says "learn". I still appreciate Elizabeth giving a very non technical breakdown of terms. I try to do the same, sometimes it is nearly impossible to explain technical terms in a non technical way. Normally she comes very close to getting it right and normally conveys the correct idea, which I think is what she is after. Overall I have always felt she does a good job and I'm sure people that didn't always get the technical explanations appreciated what she had to say.

Slew rate is just as important(the amps ability to recover after a hard bass note).

I believe that you're correct - slew rate can give the buyer/user an idea of the power amp's bandwidth.
What you wrote was re. transient decay (post event) but slew rate is equally important for transient attack. Thanks.