Help with sub upgrade

I'll vote for the JL Audio F112's. I have one in a stereo setup and it's accurate, fast, deep and built like a brick house.

You don't mention a budget. Mdowns' JL recommendation is a good one, but they are expensive. Test results (not head to head listening comparisons) suggest that the SVS subs look like a good alternative for significantly less $. I use Rythmik subs in a music only system. They are terrific in that application and I'm sure they'd be very good for HT use, as well - although probably less good than the comparable JL or SVS subs. Look at the subwoofer test results on the forums at HTshack.com for a lot of good info on this subject.

Marty

+1 for the Rythmik sub suggestion. The intergration between the servo driver and plate amp make it a very strong contender at a reasonable price. I own one and it replaced a Vandy sub.

I have read a bit about the Rythmik subs but am unclear how low they will go for HT? Two of the rythmiks and and a sub eq together would be a lot less than a single JL. I have looked at the svs as well but their box subs are too deep. I need a sub around 20 in deep to fit in my cabinetry. The cylinder subs don't do it for me.

Docrobbi,

A pair of 12" Rythmiks will produce (near) state of the art performance data down to app 35hz @ 100db - anechoic. In my room, I get flat response to 30hz w/no EQ and 25hz with app 4db boost below 30hz. I filter to eliminate response below 25hz, because it's a music only system and I have (virtually) no music w/info below 25hz.

I can't measure THD, but I certainly don't hear any and there is very little travel from the drivers at my max listening levels so I imagine it's pretty low. In short, I believe that there's plenty of room for more clean output and/or deep bass extension in my set-up, I just don't have the program material/spl needs to ever access it. Your room, listening levels, program material etc may well differ, so YMMV.

Marty

PS HT.shack has the Rythmik test results under DIY subs. The model that they tested was evidently a kit that, according to Brian @ Rythmik, was a WIP predecesor whose performance was similar to, though not quite as good as, the current model.