I sent this to chalugadp in a PM I guess it is time to share this since both of these designs are done.
I'll need to explain the situation in the rallying thread so everyone knows what is going on with the 15's.
What was going to be the Fusion-15 V2 and the speaker in the video I had posted is probably going to be the Karma-15. That one uses the Eminence CA154, it's an inexpensive woofer that performs exceptionally well for its price and the reason why we were originally thinking it should be the Fusion-15. The problem lies in that we could not find a decent 15" driver for less to use in a Karma-15 and so we decided to bump it down to the Karma-15 even though it performs well enough to use as the Fusion-15 and use another better (more expensive
) driver for the Fusion-15.
The Fusion-15 will use the Deltalite 2515 which has lower inductance and measurably lower distortion compared to the CA154 in the Karma-15.
Both of these drivers share the same cone and dust cap so their raw frequency response is quite close, as such the crossover circuits are very similar though not quite the same because the CA154 is a 4 ohm driver and the higher inductance plays a roll in what parts I need in the crossover to get the transfer function and steep roll off I was looking for. The final frequency response of these two designs are very closely matched about +-1dB of each other and are voiced the same. Above the crossover they are pretty much identical and the crossover frequency on these two are right around 1000 Hz.
The CA154 in the Karma-15 will dig deeper in a set volume then the Fusion-15's 2515. Its efficiency (not sensitivity) is lower, about 96dB, being a 4 ohm design its 2.83v sensitivity (+3dB) is the same as the Fusion-15 which is 99dB. In the ~2.9cuft test box I have here the Karma-15 will dig down to the mid 40's, about the same as the Tempest. The Fusion-15 trades some extension for the higher efficiency and gets to the mid 50's in that volume. Depending upon room gain you could end up with useable extension 10-15hz lower.
If you're really interested in going full range with the 15" designs then I would suggest using a larger enclosure, the 2.9cuft enclosure is really at the bottom edge of what is reasonable for these drivers but if crossing to subs around 60-80hz you really don't need anything much larger. If you do want something full range these would be prime candidates for a tower enclosure, doing well all the way up to 8-10cuft tuned to the mid-upper 30's with 5-6 cuft tuned to 36-44hz being a happy medium.
I would not next expect large tower flat packs or baffles for these designs but it would not be hard to add a blank panel the same width as the baffle below it to make a taller baffle for use in a tower. I'd love to see someone try and build something like the JBL M2 or S9800/9900, that is something I have wanted to try and emulate with the SEOS-15 and 15" woofer for a while.