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I have been using 7 or 8 of these 18" bad boys [JBL 2224H] for many years in many rooms for home theater use.

Currently, two of these are residing in my living room along with 11 other full
range JBL speakers - mostly L100 three way monitors. Both 18" drivers are rated 8 ohms, but one driver is in a vented [ported] box and one is in a much smaller sealed box.

Over the years, I have found that the smaller cabinets that are sealed have more umphffff and are louder. This is contrary to everything I have read about speaker box design.

So, back to the issue at hand. My larger ported box with the 18" woofer is putting out some nice bass and is being driven by an inexpensive power amplifier [Dayton 250 watts]. This works great. However, why waste an 18" inch subwoofer? So I hook up the sealed box woofer in a parallel way with the ported box woofer that should present a 4 ohm load to the power amplifier.

The volume [DB] of the sealed box is very low but the ported box woofer still puts out the same volume [DB}. WHY IS THAT HAPPENING?

I have several Crown XLS power amplifiers and also a Crown XTI - 4002 that I am considering pressing into duty. Is this a better route? My only gripe with the XLS Crown amps is that they are some times gives out a HUM.



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The volume [DB] of the sealed box is very low but the ported box woofer still puts out the same volume [DB}. WHY IS THAT HAPPENING?
Typically ported subs are more efficient than sealed subs, and as a result play louder for the same wattage input. If you want to level match them, each will require its own amplifier with gain controls, line one of your Crowns.

Regards,
Wayne
 

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Sorry, but for HT I would classify those drivers as useless. The FS is 35hz!!! This is not a subwoofer driver. It’s for kick drums and bass guitars in a live situation.
I recommend you learn more about speaker design.
 
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