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A cone driver consists of a coil of wire (inductor) attached to a cone and located within a static magnetic gap.
An amplifier sends alternating current (AC) to this inductor, which creates a magnetic field.
The magnetic field created by the inductor reacts with the static magnetic field of the permanent magnet attached to the driver's frame.
Many people think heavy woofers are slow and light woofers are fast -- so they recommend small diameter woofers, or multiple small diameter woofers, over large diameter woofers.
They may know the old high school physics formula:
Force = Mass x Acceleration
... but may have no idea how it applies to cone speakers.
First of all, the mass of a cone is related to its resonant frequency.
A tweeter may have low mass, but can't play 30Hz..
A subwoofer driver may have high mass, but also has a much lower resonant frequency that will allows it to play 30Hz.
As a rough approximation, a cone woofer in a sealed enclosure will roll off at 12dB/octave starting about 1/2 octave above its resonant frequency.
A subwoofer cone with a 20Hz. FS, for one example, will probably have bass roll-off below 30Hz. (starting about 1/2 octave above the FS) when used in a sealed enclosure.
Adding a port can create a +5 to +7dB Helmholtz Resonance at the port tuning frequency, that will extend the bass response roughly 1/2 octave to the FS of 20 Hz. That means a higher FS lighter cone can be used with a port for the same bass extension as a lower FS heavier cone used in s sealed enclosure. The sound produced by a port does not accelerate or decay as fast as the sound produced by a cone -- so that's a trade off from using a port. But back to the fast driver story:
The mass of a cone is closely related to the bass extension.
A lower mass cone can be used with a port to equal the bass extension of a higher mass lower FS cone used in a sealed enclosure.
Whatever design you chose, driver manufacturers are not deliberately making their cones heavier than they need to be for the required frequency range -- extra weight reduces efficiency, lowers FS, requires a more expensive "motor", and extra cone material costs money
F = MA
For a cone speaker, F is the Motor Force Factor (BL) x Current (C)
The BL is a constant for any driver, except at high excursions where BL fades for most designs
A = acceleration = transient response
The primary factor in A is electrical, not mass or BL
A voice coil is an inductor on the end of a cone.
Inductors resist changes in the AC current flowing through them.
Music IS changes in AC current from the amplifier!
That means the lower the inductance of a cone driver, the less the driver will resist AC current changes, and the faster the cone will react to changes in AC current from the amplifier.
The most important attribute determining whether a woofer is "fast woofer" within its intended frequency range, is low inductance of the driver = faster transient response = faster woofer.
Of course a driver that measures and sounds fast in an anechoic chamber, can sound very slow after room resonances do their thing inside a real room.
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Richard BassNut Greene
"I know what I hear" is often an audio fantasyland
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