Qts Qes Qms WTF?

[scampo77]

im new to this and i am having a hard time understanding Qts Qms Qes. it seems to be the mecahanical and electrical damping of a speaker. can someone please explain very slowly to me what this means?

i am used to seeing damping used in electrical engineering diagrams on paper, solved using differential equations. im not sure if this is even the same kind of damping. ex: over/under/critical damping

if someone could put some real world words to this it would help me a lot.

[Ron E]

Originally Posted by scampo77

i am used to seeing damping used in electrical engineering diagrams on paper, solved using differential equations. im not sure if this is even the same kind of damping. ex: over/under/critical damping

All that really matters for designing sealed speaker enclosures is Qts
Qtc=Qts*sqrt(Vas/Vb+1)
Fc=Fs*Qtc/Qts
Transfer function: H(s)=sn^2/(sn^2+sn/Qtc+1) : sn=normalized frequency
Qtc=0.5 is critically damped....

For anything else, go to wikipedia, or go to The Subwoofer DIY Page - applicable to more than just subwoofers..

[scampo77]

thanks for the response but you told me almost nothing. what im looking for is someone who understands this topic enough to be able to explain electrical/mechanical damping in REAL words or possibly an analogy.

[Trevor White]

Originally Posted by scampo77

im new to this and i am having a hard time understanding Qts Qms Qes. it seems to be the mecahanical and electrical damping of a speaker. can someone please explain very slowly to me what this means?

i am used to seeing damping used in electrical engineering diagrams on paper, solved using differential equations. im not sure if this is even the same kind of damping. ex: over/under/critical damping

if someone could put some real world words to this it would help me a lot.

The Qms is a measure of the damping caused by the mechanical damping of the diaphragm suspension. A higher Qms means less mechanical damping.

The Qes is a measure of the electromechanical damping caused by voice coil resistance and the interaction of the voice coil in the magnetic gap. A higher Qes means less electromechanical damping or a smaller magnet.

The Qts is the total damping which is the combination of mechanical and electromechanical damping.

Qms is always much larger than Qes because the electromechanical damping always dominates.

[Cal Weldon]

Qts: the higher the number = the drivers inability to come to rest after the electrical signal has ceased. a rating of 0.707 is just right for a lot of folks. If you like drier bass, around 0.5 - 0.6 is better. if you like speakers from the 70's, a little higher 0.8 - 1.0 will make your ears happy.

[ashok]

Will "Loudspeaker Cook book" by Vance Dickason be helpful ?

[scampo77]

probably if it helps explain TS parameters a bit better

[Ron E]

Originally Posted by scampo77

thanks for the response but you told me almost nothing. what im looking for is someone who understands this topic enough to be able to explain electrical/mechanical damping in REAL words or possibly an analogy.

No, you want to be spoon fed an answer, but I'm not your caregiver.

Here's your analogy.
mechanical damping = shock absorber
a velocity dependent force dissipating the energy in the suspension and cone mass.

electrical damping = motor back emf try spinning a small DC electric motor with and without the power terminals shorted. also velocity dependent and dissipative, but sourced from the motion of the coil in a magnetic field, acting through the resistance of the coil + wires + amplifier output impedance. Ever heard of Lenz's law?

Good luck.

[HK26147]

A good portion of this title can be previewed ( Google Books )...
Loudspeakers: for music recording and reproduction By Philip Newell, Philip Richard Newell, Keith Holland
Chapter 1 : What is a Loudspeaker?
On page 14 ( fig 1.7 ) is an equivalent circuit.

( This might help - Syd )

[scampo77]

so from what you guys are saying it seems like it is the mechanical and electrical drag or inefficiencies in the speaker? or the speakers "run on" after the music stops

i read the Qts dominates the box volume if this is true why would a speakers inefficiency determine box size?

ive some across lenz's law in school but never more then just touched on it in class. i can see how this would add to the speaker "stopping itself unnecessarily and all of these answers seem to be clearing things up for me, thanks everyone