>Please elaborate on the inductance. I've heard that low inductance is a Good Thing, but I'm ignernt as to why.
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"Inductance is that property of an electrical circuit which tends to prevent a change in current", or so says the textbook. Anyway, it causes the impedance to rise and the FR to rise to a point where the mass of the driver combined with the rising impedance causes a roll off of its HF response.
If you look at Rodd's FR plot, you'll see that it looks nothing like what WINISD predicts, except the box controlled 6dB/octave (0.5 Qtc) roll off below F3 of course. Since impedance is rising, the FR tracks it till it reaches its mass corner (2*(Fs/Qes)), then instead of flattening out it falls because the continued impedance rise keeps the motor from efficiently using the power available. With a much lower inductance, the FR is much flatter so the roll off is much more gradual on both sides of the mass corner, extending its effective BW and maximizing its transient response potential.
It does have the advantage of increased efficiency over a narrow BW compared to a lower inductance motor, but the tradeoff is increased harmonic distortion, so whatever transient response gains you get from a low Q alignment gets somewhat negated.
WRT getting a flat in-room response, theoretical room gain curves (which unfortunately are just 'pipe dreams' for most of the rooms I've measured) don't sum very flat with a typical medium-high inductance sub driver.
This of course doesn't mean it won't have enough output for the app. or sound obviously bad, just don't be surprised if you have to use considerable EQ to get a measured flat in-room response, and that if distortion measurements are made that they aren't what a 0.5Qtc implies.
GM
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"Inductance is that property of an electrical circuit which tends to prevent a change in current", or so says the textbook. Anyway, it causes the impedance to rise and the FR to rise to a point where the mass of the driver combined with the rising impedance causes a roll off of its HF response.
If you look at Rodd's FR plot, you'll see that it looks nothing like what WINISD predicts, except the box controlled 6dB/octave (0.5 Qtc) roll off below F3 of course. Since impedance is rising, the FR tracks it till it reaches its mass corner (2*(Fs/Qes)), then instead of flattening out it falls because the continued impedance rise keeps the motor from efficiently using the power available. With a much lower inductance, the FR is much flatter so the roll off is much more gradual on both sides of the mass corner, extending its effective BW and maximizing its transient response potential.
It does have the advantage of increased efficiency over a narrow BW compared to a lower inductance motor, but the tradeoff is increased harmonic distortion, so whatever transient response gains you get from a low Q alignment gets somewhat negated.
WRT getting a flat in-room response, theoretical room gain curves (which unfortunately are just 'pipe dreams' for most of the rooms I've measured) don't sum very flat with a typical medium-high inductance sub driver.
This of course doesn't mean it won't have enough output for the app. or sound obviously bad, just don't be surprised if you have to use considerable EQ to get a measured flat in-room response, and that if distortion measurements are made that they aren't what a 0.5Qtc implies.
GM