You might google Audio Pro. A Swedish company that makes speakers and subs in reasonable price ranges.

I have an older sub from that company, and I am very satisfied with it. It features two 6" long stroke woofers in a back ported cabinet, and work from 27 to 100 Hz (adjustable). It is driven by a built-in 150 W amplifier, and uses the famous Ace-Bass technology.

This particular model (Ego sub) is out long ago, but they still make many good subs in different price ranges.

Audio Pro web page
NB! Bottom left you'll find a small grey link to the English translation...

try the PSW111 by polk audio. i got it on sale for $300. it hits fairly hard and is really tight. it doesnt go as low as the 10", but its very musical =)

I had an Outlaw LFM-1 which I got for about $700 delivered. It was big and went low, if a bit plummy at times, it was a great addition to my book shelf speakers. It died in the flood, but I have my eye on the updated version the LFM-1ex. Check them out at the outlaw.com website.

No ported subs!

Elemental Designs A3S-250 $350 delivered
Emotiva Ultra 12 $360 delivered
Emotiva Ultra 10 $270 delivered

Have you looked at the 'Final S110' over at Outlaw?

I just ordered one for $199 on sale vs the $499 regular price. There's only a few reviews out on it but they look good and for that price it's worth the chance.

There are a few ported subwoofers that can mate well with planar/quasiribbon loudspeakers but they sure don't cost $200 or even $400. Ports help modest designs achieve higher SPLs but don't well contribute to low frequency program material definition and resolution. A cheap ported subwoofer is very likely to be a waste of money. The best bet for a relatively inexpensive subwoofer to match well with the Magnepan MMGs will necessarily be a sealed design. When considering a subwoofer to use with Magnepan MMGs one is usually not looking for chest pounding bass but something that will reinforce the next lower octave which the MMGs cannot produce and match their detail and resolution.

Dayton Audio Titanic from Parts Express
12" T1203 Subwoofer System Kit $599.79

The kit builds in one hour or so and requires no real technical skills. It's a sealed box that mates well with planar speakers. I've heard this paired with Maggy MMG's and SMG's. Set the crossover lower than you think it should be. Start at 50Hz and go down from there.

For $600 you are just $30 short of a Rythmik Audio F12G.

The introductory offer for the Epik Legend is just $500!

www.jr.com always has some good pricing on 12" JBLs that should provide some excellent bass.

If I were you I'd send back that underperforming subwoofer which is a definite mismatch for the MMGs. For $270 delivered you can get the Emotiva Ultra 10 subwoofer which is a sealed design, has more power, plays louder, extends lower and resolves better, and if you don't like it you can send it back within 30 days for your money back. You can lead a horse to water...

I gotta go with Jackfish on this.

try polk audio psw111. its ported, but the bass is very tight

im using that ATM, i find it to be a really nice match for my old pair of cerwin vegas =p

Here is the information you requested:

JBL ES250P 12" (300mm), 400-Watt Powered Subwoofer

$549 - Suggested Retail Price

$349.99 - YOUR PRICE

www.jr.com

Enjoying is a key word...