What are the best subwoofers to use with Magnepan 20.1s?

I heard Maggie 20.1s augmented by a pair of JL Fathom F212s at a high end store’s annual open house. I had started the night listening to Alexandria mk IIs (or whatever it was in 2006) powered by a chain of VTL electronics culminating in a pair of Siegfrieds.

At a little over 10% of the price and powered by Ayre electronics, the Magnepan/JL rig was hardly a letdown. The integration of panels and subs was seamless--smooth with nothing out of phase to distract the presentation.

A pair of F113 v2s would do the trick and cost less than the 212s.

20.1’s set up properly in most rooms go down to 25Hz.
Why do you need a sub woofer for a measly 5 Hz?
What about Image size of 20.1 bass, and sub woofer bass image size?
How do you handle standing waves, peaks, and valleys?
Why bother with bass below 30 Hz, and the associated problems?

NO SUB WOOFER IS NEEDED!

You can’t do this reading a spec sheet and working a calculator. Bass extension of a dipole is very room- and placement-dependent, and sometimes this 25 Hz never materializes at all. Or it may be measurable--measurably 10-15db below the rest of the response curve in which case it’s functionally MIA. Subwoofers that go waaaay down also reproduce infrasonic energy that’s technically inaudible but on the recording and can be sensed, like when a 16Hz pipe organ pedal tone flaps your pants leg. These soundwaves energize the room and create an ambience that sounds more like a live performance--you know, the kind where there’s a sense of energy in the room even before the conductor drops his baton?

What’s cool about the relatively low cost of the 20.7 is that you can add a serious subwoofer or two and get world-class sound reproduction for a fraction of the cost of Wilson XLFs or Focal Grand Utopias.

Integrating subwoofers isn’t nearly as hard these days as it once was. For one thing, the 0-360 deg. continuous phase control makes it much easier to lock it in with the Maggies’ front wave, and the automated room correction and EQ of the better models does most of the heavy lifting anyway. I’ve always been able to dial in dual subs with my Maggie 1.7s in 2-4 hours or less--without auto room correction, but I find the continuous phase control and crossover point selection essential.

+1. Well said johnny, agree 100%. That continuously variable phase control is absolutely mandatory in a sub; the Rythmik plate amps have one as well. That, added to the Open Baffle/Dipole design of the GR Research/Rythmik Sub makes it a particularly good partner for dipole speakers such as Maggies (and ESL's, Ribbons, etc.). Lean, mean, bass machine!

The other advantage of the Vandersteen 2WQs is that it hooks up at speaker level not line level. This is a major advantage with a tube pre amp as it never sees the subs load.
 As Bondmap mentions above the other neat advantage is the Vandersteen High pass units remove the lowest lifting off the main amps  achieving ideal in room bass response that's adjustable to your preference this allows not only lower distortion but dramatically increases the whole systems clarity and transparency.
 Best JohnnyR
 

Subwoofers DO make a positive difference with Maggies!  I know, I use two Rel G2's with my 20.7's.  The primary purpose for using subs with Maggies is not for the reason you might be thinking; more, deeper bass.  My Maggies go down to approx 27 hz in my 17.5 x 26 room which is Plenty Low for most music.  

What I have found is that adding the Rels makes the entire soundfield bigger, more dense, more full, adding to the PRAT, and actually Improving the level of Detail that I hear in all my music.  Yeah I know, you've heard that last one before, but it's True! Once the Rel's settled-in I began to hear intricate details and subtle cues in the music that I had not previously noticed.  

I don't know or understand the physics, but adding the two Rel's took my rig to the next level!  I seldom run the Rels above 28hz or 30hz and always at a very low volume level (typically less than 10).  It WORKS!

I prefer the Rels over Magnepans own supplemental woofers beacuse they do not add an additional Load to your amps; the Rels have a very high impedance so they dont add a burden to your main amps (which are already working overtime to drive the Maggies).  

The Rels make an Excellent speaker, the Maggie, an even better one!