I am running JBL 2226 in the horn 2 way speaker to the left of the subwoofer. I built a pair of speakers using the 2226 and my set are a tweak of Wayne Parhams 4pi.
The 2242 is a true subwoofer. I think it sounds excellent running along side the 2226 speakers.
The 2226 is not a subwoofer and it is thought of as more a Mid woofer... I think running the 2226 as a sub would be pushing it to do something it isn't necessarily made to do.
Some don't like this old school JBL 2242 / 4645C due to the low freq... These go down to 25Hz but drop off. I think a sub built with a 2226 would have the drop off above that.
I like watching live concerts. Having this DIY 4645C is nice for concerts. This thing sings well in the wheel house range it runs in. I got the 1000 W Dayton subwoofer amp. This has a 3dB bass boost at 25Hz. The boost is nice. The amp is pretty solid. A good $$ to performance ratio I guess. This does 500W to 8ohm. Just 500W into this sub is louder than hell !!! At a moderate volume this has a nice fast and warm sound to it.1000 W Dayton subwoofer amp
I've thought about build up another sub for the low end. I'd be curious to hear peoples thought on just a low frequency sub to run along with this JBL 4645c. Something that would run in just the 35Hz or so down. A Subwoofer subwoofer.