# QMS, QES, QTS, What makes up a speaker?



## audiophiledave (Nov 8, 2009)

I have read that when a driver has a higher qms rating, that it is tighter and shows more of a snappier sound and when the qms is lower that there is more dampening in the speaker giving it maybe more low end bass but not as fast as one with high qms. I am not sure if what I just stated is even correct or not. Also what does qes stand for in a speaker and I know that qts = qes*qms. Any comments very appreciated.


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## The Baron Groog (Mar 15, 2010)

Speakerplans.com


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## audiophiledave (Nov 8, 2009)

The Baron Groog said:


> Speakerplans.com


Thank you very much!


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## lycan (Dec 20, 2009)

While the speaker is operating in it's LINEAR range ... that is, coil still well within the gap ... *Qts* is all that matters. Yes, *Qms* and *Qes* both contribute to *Qts* (through a very simple relationship, but NOT the one in the first post of this thread) ... but in the end, the "total Q" (or *Qts*) is all that matters.

Why? A speaker in a closed box (including IB) is a 2nd order, high-pass system. This second-order system is COMPLETELY characterized by two parameters : *Qts* and *Fs* (strictly speaking, it's *Qtc* and *Fc* in the enclosure). These are all you need to describe the driver's frequency response, and time-domain transient response.

So ... will speakers with different *Qms* values "sound" different? It depends ... how different are the resulting *Qts* values? If the *Qms* values are different, but the *Qes* values _also_ differ in such a way that the resulting *Qts* values are the same ... then the speakers will have the same frequency response, and the same time-domain transient response.

And if two speakers have the _same_ frequency response, and the _same_ time-domain transient response ... what's the mechanism by which they can "sound" different?

Play around with some algebra, or your favorite modeling program  and there will be no need to rely on internet opinions about *tighter* response or *faster* bass


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