DIY Speaker - Build your own driver?

[Olijo]

I made some DIY drivers too. Here's a video of them:
DIY Speaker Driver Tutorial (Aperiodic 3-way Loudspeaker from Scratch) - YouTube

I also made smaller and a little more simple versions to make a gift to my brother.

 

[Disco-Pete]

So here is my little project. This is a JBL 2245. the serrated base will fasten to the rim of the basket, angled upright struts to the top rim. Remove existing surround and add to existing cone with either accordian integral surround or new 30" rubber/foam surround. I think an integral accordian surround pressed into the additional cone extension would be best. Can anyone predict with a seriously ballpark estimate how t/s will change? TIA

 

[Disco-Pete]

I guess not. Well, Fs would obviously go down considerably. That's a good thing, no? Probably need a 75 cu.ft. BR box to make it work, though. I was thinking more on the lines of OB. to work with my Acoustats. ?? Aperiodic?

 

[bolserst]

There are too many variables to say for sure, but if we assume that the suspension stiffness and mechanical damping is dominated by the spider with minimal contribution from the surround, you can get an idea of what to expect. Estimating that you will add roughly 100g to the moving mas, and increase radiating area from 1300cm^2 to 3500cm^2, resonance will drop from 20hz to about 14Hz. Qts will increase a bit from about .3 to .4. Mid-band sensitivity will increase by roughly +3dB. The big downside, is that the Vas will increase as the square of the radiating area, from about 820ltrs to nearly 6000! So yeah, if you plan to put it in a box, it will need to be a really big box. OB sounds like a better plan.

 

[Disco-Pete]

I have a pair. I got some kevlar for the extension. The plan is to turn a wooden mold on a lathe and dope it ala B&W/Kef. I'm thinking SD/mms will overcome the low Q and thus won't be over damped?