Subwoofers for Magnepan 20.1s?

I used Granite Audio's Ultimate Low Bass CD and my 20.1s go to 25Hz at -10dB and my room is 16x26x10 (speakers approx 6ft from back wall and 3.5ft from side walls on ends). I can get -6dB in the 29-33dB range and then it is pretty flat with a slight drop in the 50-60Hz range. I am not a bass fanatic, but on some recordings, I wish I had some further lower bass extension without becoming unnatural sounding/boomy. I know HP likes Nola Thunderbolt subs with the 20.1s. Has anyone tried them or any others? Other system components: Pass X250.5 amp and Xono phonostage, Audio Research Ref 3 preamp and Ref 8 CD player, VPI superscoutmaster reference turntable/10.5 tonearm, Dynavector XV1S cart.
You didn't mention price but with Maggies,Quads,NL's without built in subs you have a need for speed.You'll be happier if you give up octave or epth for transparency.I have been fan of REL's older series (or a spin off company MJ Acoustics) because they used multiple drivers to equal one large plodding sub which is fine for HT but not transparent speakers.Maggie themselves say "Don't go larger than 8" woofer" because they know you might shake the foundations with a Velodyne,JL,or other monster but not get neutrality that blends.I have not heard it but read review of TBI Magellan VII one amp/x-over double box system but 6moons said it was fast and neutral.You might want to check out Martin Logan and though head to head they are supposed to be more like a HT sub than REL they are deep and have multiple drivers for speed.Add a Velodyne SVS external DEQ (not expensive flip it easily if you want) would be last tip.Might improve outcome.But go for transparency,speed resulting in transparency.Now I am going to read about the Nola myself!!!!!!
1. In my experience, I believe the JL subs would work fine. I'd go for the 10 or 13 inch models and use two.

2. JL Audios built in software for room equalization works great and makes it easier to blend the subs with Maggies.

3. Plan on purchasing a seperate external crossover like a Bryston or equivalent. I'd find one so you can rid yourself of the Maggie passive crossovers and use the electronic crossover to work with your Maggies and subwoofers.

4. I've tried blending without using an exteranl crossover before, and while you can indeed improve your sound, you won't really get the ultimate performance without an external crossover.

Have fun!

My guess is that further extention may not be what you're really after -
unless you're a pipe organ guy. If you're down 6db below 33 hz, that's gonna
be inaudible on most recordings. There's a coupla keys on the piano that
MIGHT be slightly diminished, but they're not struck often.

However, that "little dip" in the 50-60hz range is right at the
point where the impact of a kick drum is established. You can certainly place
subs or EQ subs independently of your mains to get more energy in this range
- but you'd need to actively cross from your Maggies at a frequency north of
there, maybe 65-90 hz. A Velodyne SMS-1 sub-controller or SVS
"Audyssey box" (plus an active crossover like the NHT x-2) will
allow for EQing the problem.

The JLs (12" or higher) definitely show more beep bass extention than
the MJs or (almost any of)the RELs on tests. They are also show
"tight/fast" respone (group delay), but not quite as well as MJ or
REL and they are expensive. I chose Rythmik Audio 12" subs which look
like REL/MJ in terms of group delay, but offer better extention.

These observations are based on test results at (seems to be dark
now) and - not on listening experience, so take that FWIW.

Good Luck,

I own a version of these with my hybrid stats. They do as advertised. They were specifically designed with Magneplanars in mind. Give Duke a call or email at He'll give you more facts. Also, a friend of mine has the full tilt Planetarium system (bipolar). Pretty awesome.

"The main obstacles to natural-sounding bass reproduction are the inevitable room interactions - which impose large peaks and dips on the bass response. By using multiple subs spread asymmetrically around the room, each sub will produce a unique peak-and-dip pattern at the listening position. The combined average of these unique peak-and-dip patterns is much smoother than any one of them would be, resulting in more natural-sounding bass with excellent pitch definition. The Planetarium bass system also avoids the subjective slowness of most subwoofer systems by taking room gain into account. Typical in-room extension is to 20 Hz, but the main advantage of this approach is bass quality, not quantity."
Powderdocter, take a look at my review here on the GON regarding why I now have a pair of Martin Logan Depth i's sitting behind my biamped MG-20's. You will be amazed at what the right Subwoofers will do to the soundstage depth/width, layering in the soundstage, and "ease" of your 20.1's, not forgetting the extension on the bottom end. I just want to share if you don't have your MG-20.1's on Myesound stands you have not heard their true potential sonicly.
I recently voiced a pair of Martin Logan CLXs with the M-L Descent i subs.

They were smooth, went deep, were lively and dynamic, and blended almost seamlessly with the CLXs.

From that experience, I'd suggest that the Descents would go nicely with the Maggies.

Of course, you need two of any sub for the best sound, so I'm referring to a system with two, most definitely NOT one.

See relevant comments beginning at post 190 in this thread:
Very few subs will mate with the 20.1. My advice is to try one of the JL Audio subs. The ported bass of the Rel makes it sound a little sluggish in tandem with the 20.1. In my experience, only a sealed sub has any hope of keeping up with the bass panel.
Dukes Swarm is a good design. Martin Logan Descents work well,but you will need at least 2. Also KSC has a 31.5in driver in custom bass system which was designed with large loudspeakers like maggies in mind. Low excursion bass systems have far better transient responce over large excurtion floor corner reinforced subwoofer systems with all there many comprimises in design. The large driver only moves slightly so less detail is lost than hi-excurtion designs. Lots of detail in low bass most never experance this since they use conventional sub designs.
John--several of us noticed that you used the (slightly) less expensive version of the 31.5" driver in your bass cabinet and were wondering what your thinking was in making that decision? The more expensive one appears to have a free standing resonance frequency, doesn't it?
I meant lower free resonance frequency.
Yes, I agree go sealed with low group delay and large woofer. It will be expensive as a good tight sub means less SPL output - so you need really big rather than a high output resonant sub
One word of caution re: subs w/extra large large drivers.

Just be sure they can be crossed HIGH enough in frequency to suit your needs. I know that people generally like to cross as low as possible, but if you eventually decide that you want to EQ problems in 50hz to 60hz region, you'll be crossing at 75, 80, or 90hz. I don't know the 31.5" driver in question, but I'd imagine that it's not designed for optimal performance that high up, since some manufacturers of 15" drivers caution potential buyers about this issue.

Just food for thought.

I heard a pair of 20.1s supplemented by a pair of JL Fathom f212 powered subs, each sitting right next to a 20.1 panel. This was at a high end shop's open house. I could not detect any discontinuity, discrepancy in speed, lumpy response, or any of the other pitfalls for blending subs. They extended the slam, extension, and room-filling abilities of the 20.1s about as much as you could hope for.

Since this was a balls-out demo with near unlimited funds, I'm sure you could get much of the same effect in a normal-sized domestic room from one or two of their Fathom f110.
Gladstone its the new Fostex fw800hs. My web masters cheap and I got what I paid for;) I asked for corection about a month ago should be changed soon. The older version is not designed for the cabinet I use more for inwall mounting.
Marty, The Fostex fw800hs 31.5in woofer can be used up to 250hz with no issues. Which drivers are you referring to that you have experience with that can not be used around 100hz? Large drivers have many benefits if designed proper, great transient response,very hi-efficiency, massive cone area. But costly -large.

Rythmik Audio does not recommend crossing their 15" model above 80hz. Meniscus Audio, a custom builder (that often -but not always - uses the Rythmik drivers) told me the same thing and added that they prefer to cross most 12" drivers at or below 100hz (even for a stereo pair). I gather that they feel these drivers behave optimally below these frequencies - not that they're incapable of providing linear response above that point. Maybe it's just an abundance of caution.

John--ah, I see. I bet it's phenomenal!
Well, this is a tough one. I would also recommend 2 smaller subs for speed and balance in the room.

The JL Audio f110 is -3db at 25HZ, so if you go the JL Audio route I think you would at least need the f112 which is -3db at 19HZ, since your Maggies are already -6db at 31HZ, according to your measurements.

I would think two JL Audio f112's would be the right size for you in this particular setup, however I'm not saying that they will keep up with Maggies, actually nothing probably will, but at least they'll have a chance.

However, I'm thinking of going another route. How about the Wilson Benesch Torus Infrasonic Generator?

I've never heard these myself, but you must admit they do sound interesting.

Although, not as fast as your Maggies, I have a pair of Kharma Mini Exquisites, and sometimes I would like a little more bass, however I live in a Condo, so I don't think my neighbors would agree, but if I did add a sub; the Wilson Benesch, Kharma (for my purposes only), JL Audio, and REL would be on my short list too.

I've owned a REL Storm in the past with a pair of Sonus Faber Speakers, and although the REL's are musical, I also didn't think that the bass was fast and tight enough for me. Possibly, the larger, more expensive ones are better.

Martin Logan also has a pretty decent less expensive Sub, that has three fast 8" subwoofers in one box, that have to keep up with their panels.

06-02-09: Richlane
I would think two JL Audio f112's would be the right size for you in this particular setup, however I'm not saying that they will keep up with Maggies, actually nothing probably will, but at least they'll have a chance.
Yes they will keep up. Totally. And they'll blend and integrate well with the Maggies. The Maggies aren't the fastest panels out there. JLs have no problem keeping up.
Marty You confuse crossover cutoff with frequency range, [so sub is not locatable bass is non directional under 75hz] When running 1 sub best to run under 75hz or so. Otherwise you will hear where subs located. Also the driver you mentioned is a hi-excursion doughnut surround type, these need massive power and are only designed for sub bass use mostly for HT. Heck I have designs that use 12in woofers up to 1500hz and I'm not alone. Most 15in-18in up to around 1000hz, 12in 1500hz or so. 31.5in woofer 250hz is no big deal. I will not offer any doughnut hi-excursion design for they do not do proper justice to music. These designs need floor,corner boundary reinforcement,and massive power to generate bass. A 31.5in woofer does not. The doughnut drivers are jumping about when they produce bass frequencies the 31.5in has only 2.3mm xmass. It hardly moves allowing much detail and wonderful transient response a key to great sound with music. So no problems running large drivers in bass frequencies. This is what they where designed to do.

The crossover point deteremining "locatability" was NOT the issue. The reason I added the note in my original post about "even in stereo" was because I asked that very question. Rather, I'm sure that you hit it with your descrition of driver type and suitability for use only in the low bass region.

That's why I advised any buyer to determine the suitability of any sub with an extra large driver for use at higher frequency. I didn't recommend avoiding large drivers in subs, just double checking for enough flexibility to deploy as desired. I sure wasn't aware, however, that a 31+" driver had such flexibility. Thanks for the info.

As to suitabilty of such a "doughnut" driver for music, I'm working on that right now. It sounds different from my previous (Velodyne 8" x 2) subs - that much is clear. So far, I'd probably have to disagree with you, but my experience to date is too limited to take a really informed position. When I've had some more time with it, I'll post further.


One further thought:

A lot of folks are going to be limited by cabinet size at SOME point - probably well before they could consider a box housing a 31.5" low excursion driver. The ability to accomodate a huge driver with minimal excursion is a luxury unavailable to many (probably most) music lovers.

Your preference for trading off driver size for excursion may be 100% correct, but I suspect that most people are weighing 8" vs 10" vs 12" (maybe vs 15" drivers). Depending on any buyer's particular need for deep bass performance, their choices may therefore be limited to driver designs you'd prefer to avoid. This being the case, I'd still advise anyone to double check the recommended high frequency limitations of the driver (particularly if they're thinking 15") in their prospective subwoofer purchase, since most of the commercial subs out there seem to use such drivers.