Will This Work? Adding Mass to Buyout 299-106

[supermike]

Everyone seems to have complained about the big box sizes that the 10" [and 12"] buyouts require. In the past, I used to press Mortite into the cones of woofers to get a sufficiently low Fs.

It would always produced deeper bass, but at the cost of reduced efficiency, and, for some reason, reduced mid-bass output [often significantly].

Anyway, anyone have any opinions about the efficacy or effects of adding mass to the 299-106? Perhaps coaxing F3 of, say 35Hz in 1.5 ft3?

[charlielaub]

Adding mass will also raise Qts. Look at the equations in the Wikipedia article on Thiele-Small parameters. Compute the values that result in the current parameters (Mms, Cms, Rms, etc.) for the driver (or take them from your favorite modeling program) and then increase Mms to simulate adding of mass. You will see that:

Qt ~ √(Mms)
Fs ~ 1 / √(Mms)

Unless Q is already pretty low for a driver, you cannot add much mass before it gets so high that it is no longer very useful.

-Charlie

[critofur]

It's not that uncommon for speaker companies to do this. Equalization in the plate amp, if that is available, might be a better option?

Reducing midrange output is usually a benefit in a subwoofer / low woofer when used passively - it might mean you can avoid, or reduce, expensive low frequency low pass crossover components.