What is the point of an impedance curve ??

[James Lehman]

Probably the most useful application of the impedance curve (of a woofer) is to determine the Theile Small Parameters.

You already mentioned that the peak of the curve is the free air resonance of the driver.

But, the hight and width of the curve determine the Q factors.

Also, if you add a known mass to the woofer cone and measure again, the sift in Fs will tell you the Vas and the mass of the moving parts of the woofer.

BTW, the derivative (slope) of the impedance curve is (very close to) the power phase angle.

Metal by James Lehman ~ Extra Stimulus Inc.

James.

 

[Illusus]

indeed, also the acoustic load will make some parameters change .
Everything is depending on other factors . The most important ones are under
the Q ( quality ). Moving mass , the motor ( Electrical Q ).
For speaker design, specially in DIY when you know which is driving which,
you can keep the design easy for your amplifier .
On the other hand, you can very skilled and aim for power & control, so you can manage to power a complex load such a 3-4 way loudspeaker with your 200 W amplifier which is stable under any load .

"Q", be it mechanical or electrical is the ratio of reactance to resistance, not quality.

 

[myhrrhleine]

what phase plot?
He only mentioned the impedance plot.

I don't think one can teach speaker design based on using an impedance plot.
I think the opener needs far more information thatn an impedance plot and far more knowledge than he is owning up to to design a speaker.

He can copy other speaker design/build articles/Threads.

hello,
the slope of the impedance curve shows the phase of the system.

 

[balerit]

Could anyone answer my questions please ? they were kind of precise I think

Thanks again in advance

They just look good on paper, and all you really see is the resonant peak as well as the peak impedance and the frequency that it occurs at. Here is a shot from my book The Lost Art Of Loudspeaker Design.

Mac

 

[aarvin2]

Probably the most useful application of the impedance curve (of a woofer) is to determine the Theile Small Parameters.

You already mentioned that the peak of the curve is the free air resonance of the driver.

But, the hight and width of the curve determine the Q factors.

Also, if you add a known mass to the woofer cone and measure again, the sift in Fs will tell you the Vas and the mass of the moving parts of the woofer.

BTW, the derivative (slope) of the impedance curve is (very close to) the power phase angle.

Metal by James Lehman ~ Extra Stimulus Inc.

James.

Thanks a lot mate , although it's not exactly replying to my question , u've shared some great practical information here thanks a bunch!

 

[James Lehman]

Excellent!

You're very welcome.

James.