SPL question with scoops I have, changing out drivers

[DJ SHO]

I aquired a pair of jbl 4530 15" scoops not too long ago. They came equipped with JBL 2226H drivers, which really aren't the best drivers for these cabinets, due to their low BL product of 19.2 (I read somewhere drivers with a BL lower than 20 shouldn't be used in a rear loaded box). I have also seen a few 2241H's blow from being used in scoops, immediately replaced with B&C 18TBX100's and it was like night and day performance. Anyways, one of my 15's has a weak dustcap and cone and is pretty much shot (it rattles and sounds like death). My amplifier is a Crown XTI2000, currently running at 8 ohm stereo for the JBLs, doing 475 rms each. Gonna replace the subs and was thinking about the Dayton PA-380. It has a higher BL of 23.44, and a 1.5 higher sensitivity of 98.5 db vs the jbl's 97. So it theory, the Dayton should be louder at 500 watts, correct? Xmax shouldn't be a huge factor with these boxes (the JBL is a bit higher than the dayton).

Now the other thought was to go all out and throw a pair of B&C 15TBX100's in these boxes. I have heard plenty of the 18TBX100's in scoops and they hit you hard, I'm a fan! Cost aside and looking at specs here, I was going to bridge the XTI2000 to run the B&C's because they can handle 1000 watts rms, which they would each get if bridged (2000 rms at 4 ohm mono, 1000 to each 8ohm sub in parallel). But, they have a lower sensivity to start with, vs the Dayton's, which is 96 db. I did the calculations on an SPL calculator, and at 1000 watts on the B&C vs just 475 watts on the Dayton, the B&C is only .8 db louder (but it costs almost 4 times as much as the Dayton!).

My bottom line question is, with the above listed power ratings for the related drivers, do you think the B&C will really just be a tad louder (at its .8 db advantage), or will it surpise me and blow the Dayton out of the water because its a beast of a subwoofer? Obviously, the Dayton hands down is the winner when it comes to value, only $75 vs $295. Curious to see which way you would go given these two drivers.

Thanks.

[billfitzmaurice]

Re: SPL question with scoops I have, changing out drivers

Driver swapping should be done by modeling the proposed driver in the cab with a response modeling program, like HornResp. That's the only way to be sure of the result.

[wg_ski]

Re: SPL question with scoops I have, changing out drivers

Heat dissipation is SO much better with the B&C drivers compared to lesser ones. Even if the Dayton modeled exactly the same as the B&C, you'd probably pick up 3dB driven with the same amplifier, not even considering xmax. The JBL is somewhere in between, and obviously you've found their limits. I run two B&C per side on a QSC 5050, and they won't heat up no matter how hard I clip it. I've had Eminences (which model better) run hot and just drop output all night. The models don't take this into account. But the cooler it runs, the closer to the model the result will be.

Model it and make sure you've got the right B&C. As Bill pointed out, swapping can backfire. If you're spending that much money, there are other options besides the TBX with different tradeoffs beweeen BL, Xmax, and weight. I'm using the TBW18. You'll get lower compression compared to the Dayton with ANY of them.

Use the Daytons if you are very limited on amplifier power, say 200 watts over a long extension cord or off a generator/inverter. They will be impossible to beat in BL per dollar, but rememeber the BL falls when they run hot.