The 18SW115 is history...lets see what a 21" can do!

I really had no qualms with the performance of the tank-like B&C but after carefully studying the Data-Bass archives, an undeniable truth has descended upon me. The distortion measurements in particular have caused me to look toward a driver size that 8 years ago would have been unfathomable, unworkable, and too expensive to even contemplate. However, along comes neodymium, and along with increased xmax, superfluous BL, increased building skill and a bigger budget, the cabinet can be kept smallish and the performance improved...even in a dual opposed setup, which is becoming more and more enticing. I can imagine the overkill of a 2x21" setup in 1200 cu. ft. but for now I embrace merely one.

The moment I read about Ricci's dual 21SW152 setup I have been trying to figure out how to trade out of the 18SW, and that was only about 3 or 4 months after completing the build. Actually it was the discontinued 21SW150 that excited me because the BL was very high, with qes/qts both being low enough to make it very suitable for my type of application. However, Ebay STILL has that thing going for well over $700.00 and it has been there for about a year now.:huh: I looked at the 18 Sounds 21LW1400 but it is no match for the B&C below 20 Hz even though it can be had for much less. Failing to find anything in the league of the B & C 21's, I knew that group buys and vaporware really bug me, so anything outside of the pro sound arena didn't really excite me, especially in lieu of the T/S parameters and of course the Data-Bass archives.

I don't know how I missed the RCF LF21N451 but after reading the specs, I was thoroughly impressed and it seemed like the closest thing to a 21SW...the problem? The price, especially on Parts Express. It would be quite an investment to sell the 18SW for less than I paid and fund the difference for minimal gains, but out of the blue I found one that wouldn't break the bank. It really is a lateral move considering my venue of 1200 cu.ft. SPL is out of the window but extension is another matter. The 18SW at 3.3 cu.ft. gave out at about 14 Hz, with anything below that not really relevant to the conversation or sound signature. Perhaps the RCF 21 will get me to 10 Hz, with my bottom room mode being 40Hz. About 1/2 an octave of extension...that's about all that can be expected from the sweat of a reworked cabinet. 3.5 Hz for a dollar-cost average of $29 per, but...I'll take it!

I suspect that the T/S parameters will be off, as they were for the 18SW. Factory Fs said 32 Hz but after a 40 hour break-in, the cold Fs was actually 26Hz...measured with a home-built impedance analyzer. That means qes,qts,qms and vas were all different than the factory specs. Unibox showed me a qtc. of .48 with full fill and an Fb of 52Hz. It came in at about 52.5, so I achieved the critically damped response that I always crave in a system. I will need an Fb of about 60Hz to achieve a similar result from the RCF...hopefully I won't have to expand the cabinet beyond an additional 3/4" baffle. Much thanks to the humble seller for helping make all this possible. I await the driver!:T