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Woofer speed [message #16205] Mon, 08 March 2004 07:33 Go to next message
hurdy_gurdyman is currently offline  hurdy_gurdyman
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Registered: May 2009
Illuminati (1st Degree)
Anyone have any comments on this article about woofer speed?

http://www.adireaudio.com/tech_papers/woofer_speed.htm

I haven't heard about this viewpoint before and was wondering if this is this is the accepted view, or if other factors might be of greater import.

Dave


Re: Woofer speed [message #16206 is a reply to message #16205] Mon, 08 March 2004 10:10 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
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Registered: January 2001
Illuminati (33rd Degree)
The main point is that "speed" is a rather inaccurate term to use, since all speakers will move their diaphrams the same speed at a given frequency and a given excursion. But just like mass is only one property, so too is inductance. Each of these is a reactive property, and that's what is really importnat here. Some of the reactive components in a loudspeaker include the inductance of the motor, the mass of the diaphragm, and the stiffness of the suspension.

In a sealed cabinet, the list grows to include the added stiffness of the trapped air; In a bass-reflex cabinet, you must include the Helmholtz resonator. And in a horn you must include several resonant peaks starting at the flare frequency. None of these reactive properties are bad in themselves, but they do form a filter function. So each of these things is significant to the performance of the loudspeaker.

The speaker's motor exhibits inductance, its diaphragm has mass and its suspension has compliance. Most speakers use electrical damping to act as a sort of "motor braking" to control the cone, but its mechanical features are relevant too. Particularly with lower power amps like SET amps - In this case, the amplifier cannot be expected to electrically damp the cone as well as a high-power amp can. The output circuit doesn't have low enough impedance, and so it isn't particularly good as a current sink for back-EMF. So there is reason to examine the physical features of a woofer, especially if it is used with amplifiers that don't source and sink a lot of current.

Re: Woofer speed [message #16207 is a reply to message #16206] Mon, 08 March 2004 11:47 Go to previous message
hurdy_gurdyman is currently offline  hurdy_gurdyman
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Registered: May 2009
Illuminati (1st Degree)
Thanks Wayne. I kinda thought it was more complex then just inductance being all important. I don't think I'd buy a speaker just based on inductance.

Dave :^)

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