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Multi-Way Conventional loudspeakers with crossovers

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Old 25th November 2021, 05:51 PM   #11
Snickers-is is offline Snickers-is  Norway
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I agree with you on this @kipman725, but I had a couple of other points that are maybe not to clear from my previous post.

First of all, a passive crossover interacts with the impedance curve on the driver, both steady state and dynamic variations in the impedance will affect the crossover. This leads to dynamic modulation of the filter response, as well as some high Q EQ points that follows the peaks on the impedance curve. And, as we all (probably) know, this is also followed by phase distortion. One can EQ this, but it requires lots of components, and we need to be sure this does not change with any dynamic behavior.

About the subwoofer drivers, there are a few things that are not connected to their LF properties. Being a heavy moving mass/high excursion woofer with a relatively compact motor usually means it is a voice coil with a lot of mass. When using a significantly heavier motor, one can use less windings for the same force factor. This gives a lighter coil and lower inductance.

Drivers with high inductance will often have a significant portion of the impedance, AKA the load on the crossover, as pure inductance. Since the Bl(x) on a driver like this is not likely to be flat, it means moving the cone and coil means changing Bl, and then changing the impedance, which is the load on the crossover. That means the crossover point is changing with the coil position.

Using a stronger magnet circuit together with a lighter coil may affect the moving mass, but the moving mass can be kept the same using a heavier (and stronger) cone. But as probably also most of us are aware of, the efficiency at low frequencies is 100% determined by the box volume and tuning, given that the driver is voltage driven and capable of activating the box fundamental resonance.

So if they used a lower mass driver, it could be compensated by having a larger box. The frequency response can be the same, but with slightly higher efficiency.

And none of this have to affect the excursion limit, which in turn defines the capacity. But it would affect the inductance. A lighter coil would typically give lower inductance, and even if Bl(x) is not the flattest possible, it will affect the crossover less than if the inductance was higher.

So the impedance curve of the drivers, when playing, is probably the main issue that would make me think about different drivers.
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Old 25th November 2021, 07:01 PM   #12
David Morison is offline David Morison  Scotland
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Snickers-is, you do realise that the passive crossover in this design is only between the mid and high parts of the compression driver, and is not connected at all to the woofers, right?
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Old 25th November 2021, 11:00 PM   #13
Snickers-is is offline Snickers-is  Norway
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No David, I have to admit I did not read it that thoroughly.
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