Was just reading about the Infinity Kappa Perfect 12d VQ sub and it says it has variable Q thru the use of pole piece inserts ......... what do you guys think of it? anyone ever try it?
I guess it's good if you're not sure the type of sound you're gonna want/need/get and want to experiment.... but once you're set - will u ever change it again? how many people switch sub boxes? how often? hmm
Variable Q is a cool thing... But it's something you can do on ANY dual voice coil sub, without violating your subwoofer's virginity. :blush: I'm very much unsure how the pole piece inserts would vary the Q (or how you'd get them in there), since you'd expect the size/shape of the gap to change to effect such a change... You can purchase a dual voice coil sub, wiring only one voice coil to the amplifier, simply wiring a potentiometer across the other voice coil. That allows you to vary the Q of the woofer, with the potentiometer. That is called "Resistively Damped Operation". B) That one I can explain... Just like an electric motor also works as a generator, a voice coil can make the cone move, or the windings can generate electricity as they are moved in and out of the magnetic field. Same deal. When you move a "dead" set of coils through the magnetic field, the resistance of the load attached to the coils determines how much resistance that set of coils moving through the gap presents against to the actual physical movement through the coils... Just like a strong demand on your alternator requires a bit more grunt to turn it. So, your turning the potentiometer on the empty coil presents resistance against movement. Check out Adire's tech document on operating a subwoofer this way: http://www.adireaudio.com/tech_papers/rdo_...o_operation.htm It's interesting, and fun to play with, if you get a chance! Rather opens up your subwoofer selection, also, doesn't it?
I believe it does it by controling the pole piece saturation. Without a plug, the pole is saturated, as you add a larger plug, this allows more flux to flow through. I know this would increase BL, but wouldn't Qes go up as well (or would that be down?)?
Correct Steven. With QES shifts we also see shifts in QTS and therefore the ability to chose between ported, sealed, and IB application specific drivers (all-in-one of course). The idea of course centering on the fact that QTS is the best determining factor of enclosure type (which I personally agree with totally). My concern is the stray flux created, and the shifting of the fulx with regaurds to cone controll (primarily generating in the gap of course). The idea is pretty sound, but the realism of somebody really using it (like hobbes suggested), or what the actual result is I cannot and would not comment upon.
I believe it does it by controling the pole piece saturation. Without a plug, the pole is saturated, as you add a larger plug, this allows more flux to flow through. I know this would increase BL, but wouldn't Qes go up as well (or would that be down?)? [/b][/quote] The different inserts allow higher BL but because of the larger piece of metal you're sticking in there you increase the air resistance = worse cooling but it seems like you're paying for magnet you're not using when you dont have the inserts in there....... lol
