Damping factor..?????

[ThorstenL]

Hi,

Originally posted by emarald


Damping factor, in terms of impedance..ohms and output, what does a low dampening factor >200, give you versus a high dampening factor >5000

Emerald? As above so below? Who knows.

Oh, damping factor. A myth. No, not a myth, a marketing myth. Or more precise a marketing lie. The change from an amplifier with a damping factor of 10000 to a damping factor of 10 will result in a minimal measurable and audible difference, if the damping factor is reduced by adding series resistance.

Moreover, by the technical design of moving coil loudspeakers having a high damping factor means to maximise distortion and compression. Of course, modern speakers do not take kindly to really low damping factors like 0.1 or 0.01, even if they result in reduced distortion and compression.

But then, they where never designed to sound good, but measure well in the frequency domain, to work in small reflex enclosures and to be manufacturable at very low prices. I guess people do get what they ask for.... (small, low, cheap)

Sayonara

[phase_accurate]

Even though risking to get flamed I'd like to share my feelings (definitely subjective of course):
I think that more generously built amplifiers (big fat PSU, many paralleled output devices, high bias current) with reasonable feedback factors will show better control and bass precision than whimpy amps showing the same DF figures only due to the use of heavy feedback.

As long as the series resistance shows load- and frequency- independant behaviour one can live with quite low DF figures.
Even if the DF is decreasing with frequency it isn't tragic either as long as it isn't too extreme.

Regards

Charles

[traderbam]

There is sometimes a presumption that something that sounds soft or not tightly controlled is caused by too low a damping factor, or more directly too high an output resistance of the amp.

This is logical. I'm sure if we put 10-ohm resistors in series with our speakers we would hear a softening effect, particularly in the bass.

But there are other reasons why something will sound soft or muddled that are nothing to do with output resistance. In my experience these other factors are usually dominant and this is why pursuing damping factors >>10 may not be worthwhile.

Nelson, why do you think the bigger-the-better? Do you have a specific reason for this or is it an observation?

[gpapag]

[QUOTE]Originally posted by phase_accurate
[B]"Even though risking to get flamed I'd like to share my feelings (definitely subjective of course):"
--------------------------------------------------------------------------------
Flaming for being subjective, should not be considered a danger here. I think that what drives us toward buillding and modifying audio gear, is music, the perception of which, is almost by definition, subjective.

I agree with phase accurate. Traderbam also, touches the issue of subjectivism from an other perspective. Two amplifiers do sound different, but this can be attributed to too many reasons.
Even in the proccess of being more objective, we start comparing two identical amps with the same load (speaker), but with one of them having each parameter that affects output resistance changed one at a time, who will confirm that the results will be objective? At first it has to be clarified what is the acoustically optimum against which we crosscheck. I am affraid that it is non existent. If electrical measurements were relating to acoustical opinions, it would be ok. But they are not, to a certain extend at least. And then as damping factor (D.F.) effects are concerned, an amplifier can not be seen in isolation. Cables, x-over, drive units, box, all are part of the chain. Can anyone define clearly the position of the amp output in this chain? I believe that defining it as the place where the output transistors are, is a compromise, serving the economy of the analysis certainly, but serving not the economy of the problem's solution.

I have built amps which if i will accept the proper D.F. definition, have D.Fs ranging from less than 1 to about 10000. Now, if i will tell you that with some particular speakers and some particular kind of music, i preffered the sound of the "less than one", how would you judge my words? (And how much different are they from the words of a "forrmal" proffessional review?)

But if i have to act positive and give a constructive (and not a chaotic) opinion, i would say that the D.F. issue is not at all different from the "voltage feed, or current feed " dilemma.
Regards
George

[emarald]

Thanks guys, appreciate the information, one more thing, is there a relationship betw the amp stability, ie 2ohm stable or 1ohm stable and dampening factor, aka would the dampening factor decrease the lower the resistence of the load ie 5000@4ohm, 500@2ohm and 50@1ohm, assuming a 2ohm stable amp, or am i barking up the wrong tree

[janneman]

Well, since the damping factor is the ratio of load impedance to the amp output impedance, everytime you halve the load, you halve the damping factor.

This assumes that the output impedance is independent of the load impedance, which may not be 100% true, but to a first order, yes, the damping factor decreases with a decrease in load.

Jan Didden