Originally Posted by armystud0911
DS-21, I don't think you have the parameters entered correctly, Kevin adjusted them so the voice coil resistance is already wired up, I am getting a higher Qtc of 0.68 with 140L and a (gasp!) qtc of 0.666 for 150L, with some stuffing it will lower a bit, but not as much as you are showing.
Thanks for double-checking!
Looking at the numbers I had in Unibox, there was a typo in Qes; I had it as 0.36 for some reason. That changes the model to a Qtc of .593 (140L) with heavy fill (0.686 no fill), and a near textbook-perfect Bessel of 0.579 (150L) with heavy stuffing (0.667 sans stuffing). In the past, I have found Unibox's heavy stuffing numbers to correlate well with reality. I guess I'll find out my enclosure's volume when I measure the new woofer on its own and then see what my final Qtc is when I measure it in situ. True, I could also find the invoice for the enclosure, but that would be extra work for something that doesn't much matter. Assuming they come out close to original spec, I think I could live with either answer.
Actually, even a box as small as 100L sealed seems reasonable for this driver, with a Qtc (heavy fill) coming out to .647 in Unibox. Of course, to reach full excursion in a tiny box like that, one will need a bit less than 3kW. But for someone who wants a compact sealed supersub, a 100L Maelstrom-X powered by an XTi4000 sounds like quite the ticket. And someone more concerned with movie boom than audio fidelity could probably get away with going as small as 75-80L, which would give a 0.7ish Qtc with heavy fill. Kind of makes one wonder why nobody before has offered an 18" driver with such an obviously superior compromise of suspension and motor parameters. (Or maybe the ur-Maelstrom was similar, albeit with a little bit more than a third the throw and no Faraday rings in the motor if memory serves. I don't have the specs for the Avatar/Adire Maelstrom on hand right now.)
Originally Posted by Kevin Haskins
I'm building one for myself. I'll probably build a 200L cabinet, with a pair of PR
-18s. Tune them to about 17-18Hz, use 100% fill in the cabinet and with the Woofer Widget a 17hz subsonic filter with a Q=.707. That looks good with up to 3000W on the woofer which is FAR more than I'd ever push it except to show-off.
Sounds like a whole lot of fun. Practically 120dB (on paper) from a single relatively small sub at 20Hz, with full use of the driver's excursion for the 20-30Hz half-octave. Even a 140L box tuned to 17Hz looks bloody impressive, with a bit of help from the Crown XTi2000s DSP. Hmm...now how much were those PR
's again, and does anyone know how difficult it is to cut into eD's standard black finish?