Take the cone resonance caused by the mass of the cone and the stiffness of the suspension. These factors react when a signal causes the cone to move, creating the resonance.
Now consider a reflection. The cone makes sound which travels away somewhere, and returns to combine with the direct sound. Now there are two separate sources of sound. The resonance is not intimately linked, it is a circumstantial combination of two sources with a delay between them.
Oh ok, so the subject has changed...
I was pretty sure, judging by the Spice simulation, that Allen started out talking about LC resonant circuits.
I was just trying to stay on topic...
How'd we get onto speaker cones and room modes?
You do understand that electronic circuits --like crossovers-- can also resonate... right?
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"These factors react when a signal causes the cone to move at a specific frequency, creating the resonance"
And, in case everyone missed it, the high impedance exhibited at that frequency is due to out of phase currents in the voice coil caused by the exaggerated motion of the cone and has nothing to do with acoustic reflections or time delays.
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We are in multiway speakers. So that is what it has been all along. Allen just did electrical sims for illustration purpose.
dave
Allen said nothing about speakers in that post.
So from now on I should consider the first post in a thread to be irrelevant?
Also, please note, that over the past few days, there have been some very intense conversations about electronics and crossovers and accidental resonances in this forum... were they off topic?
Really ... please help me understand...
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Plenty of people understand how it works...
Both room resonance and cone resonance are completely understood.
No, but you should pay attention to where you are. You went off on a tangent…
dave
Did I?
I saw an electronic --not mechanical-- example of resonance. The discussion posted was about electronic resonance and posited that a resonance could be used to fix a resonance ... no mention was made that he was talking about speaker cones or room modes or even time delays...
If he had said "now if we assume this circuit represents a speaker cone resonance" it would have made the world of difference.
Given that first message and it's illustrations, I'd be prone to think that you somehow got the wrong idea and thought it was about speaker cones...
Unless, of course, you guys were discussing this in private before launching the thread...
I've been thinking about this dilemma too, in layman level.
A loudspeaker driver suffers mostly about mechanical resonance/ringing, which can be seen as peak/dip in spl response/phase and in time domain (CSD) as prolonged decay.
A loudspeaker's motor is electromotoric device and also the electric circuit can have resonances between components L,C,R.
I don't believe that a mechanical resonance can be eliminated by electric circuit modification. Only the spl peak can be attenuated, but decay persits because it is mechanical by nature.
A loudspeaker driver suffers mostly about mechanical resonance/ringing, which can be seen as peak/dip in spl response/phase and in time domain (CSD) as prolonged decay.
A loudspeaker's motor is electromotoric device and also the electric circuit can have resonances between components L,C,R.
I don't believe that a mechanical resonance can be eliminated by electric circuit modification. Only the spl peak can be attenuated, but decay persits because it is mechanical by nature.
Yes, I can accept that.
but not this. In the second image of the first post, the two parts (red and green) vary symmetrically around the blue response. They are equal and opposite and the variations cancel.
One is electrical and one is mechanical, but the effect is the same nonetheless.
This has been discussed before, start here : Who makes the lowest distortion speaker drivers
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Great topic. This is the idea behind the Linkwitz filter. In school it was termed "inverting the plant" Where you take the transfer function of the "plant" in control system lingo, and make a filter that is the inverse then cascade a second filter that has the desired transfer function. It works well when the system is linear and relatively time invariant. Works well to compensate for low damping of woofer resonance when driven with transconductance amplifiers or with any speaker resonance that is predictable. If the total system, compensatiation filter and driver, have a flat response, I don't see how distortion would be increased.
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The discussion that scottjoplin linked is theoretical and simple. A typical loudspeaker resonance problem comes from the edge of the cone or surround resonating. That is a nonlinear distortion by nature. So a real challenge that also has wide directivity typically. Another easier one appears on the low end, and originates from coil/magnet motor and suspension.
https://www.klippel.de/fileadmin/kl...f Breakup Modes in Loudspeaker Diaphragms.pdf
https://www.klippel.de/fileadmin/kl...linearities_Causes,Parameters,Symptoms_06.pdf
more papers Papers
https://www.klippel.de/fileadmin/kl...f Breakup Modes in Loudspeaker Diaphragms.pdf
https://www.klippel.de/fileadmin/kl...linearities_Causes,Parameters,Symptoms_06.pdf
more papers Papers
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"That is a nonlinear distortion by nature. " The paper doesn't say that. "These resonances also present inconvenient directivity characteristics and can contribute to the nonlinearities if the local displacement is large enough [1]." Search the paper for "linear time invariant". If the pre-filter is used to reduce the displacement, the system should not become nonlinear. That's the point of using a compensation. The paper is based on a linear Finite Element structural model.