Fast/Slow Speaker Article

[solacedagony]

http://www.adireaudio.com/Files/TechPap ... rSpeed.pdf

[GlassWolf]

While that article goes into more of the physics of why, this topic has been brought up numerous times here in the past. It more or less boils down to motor control more tahn moving mass or speaker diameter that determines a speaker's responsiveness.

[solacedagony]

So would the inductance be affecting motor control than?

Edit: I guess what I'm asking is what determines motor control. BL would be the strength, but there must be more to it than just the strength.

[GlassWolf]

I think I covered that in the amplifier fundamentals paper, under damping factor.
if not, I can go over it later. let me know.

[solacedagony]

Ok, will go read it.

[solacedagony]

So the damping factor is basically the internal resistance in the amplifier. Thus, good transient response has most to do with damping factor than the speaker itself?

[GlassWolf]

this is easier than me typing it all out:
http://www.epanorama.net/documents/audi ... dance.html

that should help

[geolemon]

So would the inductance be affecting motor control than?

Edit: I guess what I'm asking is what determines motor control. BL would be the strength, but there must be more to it than just the strength.

One argument in that whitepaper is that inductance is what determines the high-speed motion limit of the cone, and NOT mass, and NOT BL (or BL^2/Re).

(BTW... BL isn't motor strength - you have to factor in impedence, as per Ohms law impedence is what determines how much current is drawn when connected to a voltage source such as an amplifier, and of course if you multiply current times voltage you end up with power - the magnetic flux field strength in the gap , the length of windings in the voice coil [L], AND the amount of power sent from the amplifier are what matter - SO if you use "BL^2/Re" instead of "BL", THEN you have a motor strength number you can use to compare between subs, even those of different impedences. ]

Think of it this way - a voice coil is a coil of magnet wire. An inductor is a coil of magnet wire. Therefore, a voice coil inherently has inductance, because a voice coil inherently IS an inductor.

A passive crossover is built from capacitors and inductors. In simplest form, the basic 6dB/octave crossover, you can build a HP filter using just a single capacitor (not a bad cheap way to implement "bass blockers" into front speakers that are choking on bass )...
...and you can build a simple LP filter using just a single inductor.
And what that does, of course, is attenuate off (or 'block', but at some rate) the high frequencies, so your subwoofer only gets the low frequencies.

And the low frequencies cycle SLOWER than high frequencies, correct?
50hz being "50 cycles per second", 200hz being "200 cycles per second", 10kHz being "10,000 cycles per second", etc.

So the voice coil inductance itself IS a LP filter, and the subwoofer itself blocks it's ability to play higher frequencies at some point - or in other words, that is what controls how fast the subwoofer cone can cycle.

And in reality, it's not just how fast it can "cycle" - the inductor is an interesting piece, in that electrons sent through that magnet wire generate a magnetic field affecting the speed of the other electrons travelling through the wire, inherently slowing them, preventing an AC signal from changing frequency quickly, or from cycling quickly.
So it does block transient, or instantanious-impulse speed, as well as limiting high frequency capability.

And "high frequency capability " IS "woofer speed", that's the crux of it.

[geolemon]

So the damping factor is basically the internal resistance in the amplifier. Thus, good transient response has most to do with damping factor than the speaker itself?

No, damping factor in an amplifier goes to the crapper the moment you hook up a speaker wire to it... much less an actual speaker itself - and you really can't consider the damping factor of the amplifier alone, since it's the function of the whole circuit that matters.

[GlassWolf]

thanks. after (during) 3 days in the hospital, I wasn't in the mood to type even half of that stuff.