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

Hello all.  Which subwoofers would give the smoothest response/integration with Magnepan 20.1 speakers?  The rest of the system is Audio research Ref 3 preamp, Pass labs 600.5 amps, VPI ref scoutmaster turntable, Pass Labs XP 25 phonostage, UHA Tape Deck.  Thank you in advance for the help.
I think that the crossover set-up you choose will be at least as important as the sub you choose.  I use Rythmiks with small Maggies and they pair superbly IMO.  However, I use Audyssey bass management and there's no doubt in my mind that it's a big part of this successful pairing.

As to the sub itself, Hsu, SVS, and JL all make some highly regarded subs.  Some of the bigger Velodynes are also excellent.  Many folks swear by REL, too.
Recently heard a friend's 20.7s with Rel subs; outstanding. He runs the Maggies full range and adds the Rels below 80hz. He works for one of the world's top orchestras and the combo makes him & his guests very happy. I am a JL fan, but haven't heard them with planars. Cheers,
20.1's setup 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?

Why do you need a sub woofer for a measly 5 Hz?
...because audiophiles want ALL of it, that's why.
Quality of sub is not that important...just use them to correct dips around the room.
Well the good news is you have the best crossover on the planet made by Nelson to fit right in with your pre and amp the XRV-1. Start with that and also I have heard the newest version of the JL's and their DARO room eq is supposed to be the cats meow according to Nyal Mellor at Acoustic Frontiers. Talk with Nyal he is one of the best acoustic guys out there for doing what you are trying to do. He knows his stuff. 

Also, I totally get the last 5 to 10 hz and the benefits of reducing your load on your main amps, etc. etc. . Read the user manual for the Pass XRV-1. Nelson talks a lot about the benefits of your pursuit. It goes well beyond the improvements of the last 5 hz.
I have had Velodyne in the past JL Audio now, both are excellent, especially if you get the models that have built in EQ (with external microphone).
The GR Research/Rythmik OB/Dipole Subwoofer.
Why not try a pair of the Magnepan DWM woofers.  These are not subwoofers per se, but will add more panel area and will really smooth out that bottom end and it will seem like you added subs.

I heard a pair of the 20.7s with (2) of these and it was superb!
With the 20.1s, it would be great if you put in just one REL Gibralter, which would be much more dynamic and effortless than two cheaper subs. Not sure which size would be best--there are two.  

Save your money......apply it to 20.7s instead......

The benefits will be far outdistanced by all the issues you created.....

But if you must, I'd go with Vandersteeen
If you have a big enough room, there is nothing like a pair of Tympani panels, the T-IV or IVa. Make sure they have been to Magnepan to have their wires re-glued.
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?

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!

I second the Vandersteen.  The 2Wq IMO has a big advantage over the RELs, in that the system high-passes your mains, reducing the deep bass the Maggies have to reproduce.  The rolloff is first order beginning at 80Hz, so your Maggies will need to work down to about 40Hz, but that last octave can really strain a lot of speakers and amps, especially panel speakers.

If you can swing it, the outboard battery-biased crossovers are much more transparent than the in-line filters, but if your amp or preamp has a first order crossover built in, you might be able to use that.  Check with Vandersteen to be sure.

I have owned a pair of the 2Wqs with the M-5HP crossovers for a while now, and I could not be happier.  Quick, deep bass that energizes the room, and they work perfectly in the room corners, as they are intended to, with no need for bass traps or EQ.  Your room might be different, of course, but my 2Wqs are in my system to stay.

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!

Great description, Stickman. I believe REL invented subwoofer integration by hooking up at the speaker output.  

James Kates published a paper in the Journal of the Audio Engineering Society years ago that showed dipoles to have smoother in-room bass than monopoles.   Since getting smooth in-room bass at low frequencies is difficult at best, getting in-room bass from a subwoofer system that can subjectively keep up with dipole mains is even more of a challenge. 

Note that smooth bass = fast bass, because the in-room peaks correspond with longer decay times.  The good news is that when we have smoothed the frequency response we have fixed the time domain response because they are the same problem.

Dipole subwoofers seem like the obvious solution, but dipoles have a subjective lack of impact down low.  They don't give you that chest-compression WHACK! that a good monopole sub does.

One way to have both smooth bass and impact at the same time is to use a distributed multi-sub system.  Four subwoofers intelligently distributed around the room will be inherently far smoother than a single unequalized sub, and that smoothness will hold up pretty much throughout the room, which is not the case with a single or even a pair of equalized subs.  Remember smooth bass = fast bass.  And those four subs can be fairly small because, well, there's four of them. 

The Absolute Sound awarded a 2015 Product of the Year award to a four-piece multisub subwoofer system, so apparently the concept works well.   You can of course cook up your own version with Rhythmics or Vandersteens or RELs or JLs or whatever.  


dealer/manufacturer/multisub advocate

Two points:

- The Rythmik sub plate amp allows for high-level hook-up to binding posts (on the main speaker’s power amp), like Rel’s.

- OB/Dipole subs (such as the GR Research/Rythmik), their figure-of-8 radiation pattern creating a null to each side of the sub, do not excite the sidewall-to-sidewall resonance mode that Monopoles do, therefore creating less of the "room boom" often associated with and attributed to subs.

There is, unfortunately, a price to be paid for those otherwise-advantageous nulls: a corresponding bass cancellation that increases with descending frequency---a 6dB/octave, 1st order acoustic roll-off. Rythmik designer Brian Ding compensates for that roll-off by installing a complimentary 6dB/octave bass boosting "shelf" into the plate amp which comes with the OB/Dipole Sub kit, which counter-acts the roll-off, resulting in bass response claimed to be flat into the teens. Clever fellow.

When using a Magneplanar Tympani as bass augmentation, the panel can be butted right up against a side wall, with a significant resultant benefit: A prevention of the normal dipole cancellation, as the front and back opposite-polarity waves can’t meet and cancel each other, the path obstructed by the wall. That results in the absence of the 1st order, 6dB/octave roll-off inherent in a dipole speaker. Hence, no dipole bass roll-off (at least not from that end of the panel). Free extra output to a lower frequency, with no extra cost, or penalty!

20.1's would get better amps not subs.  I would probably be happy with the pass labs, but you might want to check into something like a boulder.