damping factor

From the wiki on damping:
Note the 'curve' for 0.7, which is critically dampened. Desireable in a loudspeaker.

http://en.wikipedia.org/wiki/File:2nd_Order_Damping_Ratios.svg

Please read the section on QTC

http://www.members.shaw.ca/loudspeakerbuilder.ca/thiele-small.html

The connection of speaker and damping factor is simple. IF a speaker system has a high QTC (Q of the Total System) than no amount of damping (electrical) will keep it from sounding a little full and maybe have bass bloom. This is worst case scenario, I hope.

On most speakers I've seen measurments for, the resonant frequency is also an impedance minima. They go together. Read the text for the B&W speaker tested by Stereophile.
http://www.stereophile.com/content/bampw-800-diamond-loudspeaker-measurements

I'm not big into damping factor. It's just my opin that any competently designed SS amp which is operated within its electrical limits will have enough damping for a compatible speaker. Some of the audible problems may be due to speaker amp mismatch or simply the design of the speaker. I just don't think a wacky high DF will fix those speakers. Also, don't forget that many of the very HIGHEST DF amps also employ lots of Negative Feedback....yet another can of worms! I won't touch this on a BET!

It may be noted as an aside that when measuring a bare woofer, a resistance can be put in series with the driver and the voltage measured and considered proportional to the drivers impedance. This using a sweep frequency signal generator / amp and not clipped. I understand there are other methods for making this measure, but this is the one many pre-computer DIY persons use.

Sorry guys, had family over last night, just picked up on the thread. Here is my attempt to explain Q in easy terms. A driver has 3 Q ratings, QMS, QES and QTS.
QMS is a drivers Quality Mechanical Speaker... It is the mechanical resistance that particular driver gives or how much mechanical loss that driver has, QES is the drivers Quality Electrical Speaker, it tells us how the driver electrically generates its strength from the magnet and voice coil assembly. These two measurements combined tell us a driver QTS (the summed total of the two) FS, the drivers resonance, QTS, a drivers summed Q and VAS, the Equivalent air volume tell us what type a box a driver needs to be in. QTC mentioned above is typically used to describe a sealed box design. It does tell us how a woofer is damped in a sealed box. .707 is a perfectly flat curve rolling off at its maximum 3db downpoint and is what we think of as being perfectly damped.
I'll leave it at that for now, if someone wants more post it in the speaker forum. Tim

05-27-11: Elizabeth
I guess guys in Bombay don't like chicks in there forums...

we do like women (I won't use "chicks" ...ahem!) in our forums Elizabeth (& those women do spell correctly too. Sorry that aspect was begging to be addressed. LOL! :-)) & they are always welcome but we'd like them to educate the public correctly on technical matters because in this particular case the subject matter is well-defined & documented & has a science-based explanation. Continuing to spread old wives tales keeps people uneducated which is never a good thing.
No major beef with you - you've been on this forum for as long (& maybe longer) than I have....