When designing a vented enclosure, there are 2 impedance peaks. I am just playing with WinISD.
I am trying to learn what those 2 impedance peaks mean. Given a fixed box size, if I tweak the port frequency until the two peaks are equal in height, I found that the port gain curve has the most even smooth shape. (And I suppose the overall gain curve is the smoothest in the same way.) Is this what I am supposed to be aiming for? Excuse me for this kind of newbie question.
I am trying to learn what those 2 impedance peaks mean. Given a fixed box size, if I tweak the port frequency until the two peaks are equal in height, I found that the port gain curve has the most even smooth shape. (And I suppose the overall gain curve is the smoothest in the same way.) Is this what I am supposed to be aiming for? Excuse me for this kind of newbie question.
In the classical theory, the box is the Hegelian antithesis of the driver at resonance. So equal bumps is natural and means at the box tuning is right on the money. But the output is not "symmetrical" in that the basis falls away fast below the resonance and you (and lots of manufacturers) may not care for that result.
But what sounds bests at your seat is a complicated mix of driver, box, room, and your taste in bass sound since the odd reinforcements and cuts the box produces in the bass band is its own colouration.
Something similar could be said about all driver housings to some degree but the BR box is complicated and has a tuning.
B.
But what sounds bests at your seat is a complicated mix of driver, box, room, and your taste in bass sound since the odd reinforcements and cuts the box produces in the bass band is its own colouration.
Something similar could be said about all driver housings to some degree but the BR box is complicated and has a tuning.
B.
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OP needs more help than a BR sceptic like me can provide.
The peaks do correctly reflect the motion of the cone. But like other features of BR boxes, it does not reflect the speaker sound output. For that reason, you can shift the box tuning about to get different FR results and that causes the peaks to shift about.
It may be that the Hegelian tuning does provide the best damping and for BR sceptics, that may be more important than the FR which can be tweaked with EQ. Of course, BR sceptics do not build BR boxes.
BTW, Altec departed from the Hegelian equal-height impedance model well more than 50 years ago and we all thought they were smart to do so back then, at least given their commercial purposes (movie theatres) and constraints.
B.
The peaks do correctly reflect the motion of the cone. But like other features of BR boxes, it does not reflect the speaker sound output. For that reason, you can shift the box tuning about to get different FR results and that causes the peaks to shift about.
It may be that the Hegelian tuning does provide the best damping and for BR sceptics, that may be more important than the FR which can be tweaked with EQ. Of course, BR sceptics do not build BR boxes.
BTW, Altec departed from the Hegelian equal-height impedance model well more than 50 years ago and we all thought they were smart to do so back then, at least given their commercial purposes (movie theatres) and constraints.
B.
For a vented enclosure, you get two impedance peaks because there are two tuned elements, the woofer and the port. For a sealed enclosure you get just one and for a 6th order bandpass enclosure you get three peaks.
The box (interior air volume and plug of port air acting together) is tuned to counter-act the driver resonance. The impedance curve reflects the motion of the voice coil as a reading of back-EMF of the coil in motion in the magnetic gap.
What we see is the driver resonance motion with a big counter-action usually right in the middle. That's really one resonance that got squished.
And as everybody knows, for a BR box, the sound output is related to cone motion in a complex (and some would say, regrettable) way.
B.
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Maybe this helps.... vented graphs are towards the bottom of the article...
Speaker impedance curve explained with examples - Audio Judgement
Speaker impedance curve explained with examples - Audio Judgement
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