[Zero]

ACI and Vandersteen are solid choices.  REL and MJ Acoustic are also other worthy contenders. Although I haven't heard all of the aforementioned products, I do feel that without question..the Totem Acoustic 'STORM' sports the speed and tone that would make for a beautiful match with the Maggies.  Self serving though as this may be, I nonetheless encourage you to check out my review : http://www.affordableaudio.org/TotemStorm.pdf : to see if it's along the lines of what you are looking for.

[Duke]

In this post, I am going to advocate an unorthodox approach to subwoofing that I believe blends well with planars.   For the record I manufacture a product that embodies these priniciples, but they can be implemented with other manufacturer's products as well.  My focus here is on a concept, not a specific product.

A sub that works with Maggies... well, that's something I worked on for about a decade, off and on.  I focused on subwoofer transient response, but eventually found out that's not really the problem.  The problem is an acoustic discrepancy between the way a single subwoofer interacts with the room versus the way a pair of dipoles interacts with the room.   

At some point, most owners of Maggies or Quads get the urge for deeper bass extension and try a subwoofer.   After living with mixed results, most revert to using their dipoles without the sub.  Some dipole owners try stereo subwoofers, and these people are more likely to keep the subwoofers in their system - not because they get twice as much bass, but because the blend is much better.  There's a reason for it.

A single subwoofer in a room will produce a distinct peak-and-dip pattern at the listening position.  We can shift that pattern by moving the subwoofer, but we cannot eliminate it (equalization can eliminate it for one listening position, but usually makes the response even worse elsewhere).  However if we have multiple subwoofers in different locations, their respective peak-and-dip patterns will average out much smoother than any single one alone no matter how carefully positioned.  Leading subwoofer researcher Todd Welti advocates using four subwoofers spread around the room as being the best practical approach: 

http://www.harman.com/wp/pdf/multsubs.pdf

Now let's look at a dipole:  A dipole can be modelled as two monopole sources, one with the phase reversed!   So a pair of dipole speakers can be expected to have in-room smoothness comparable to four monopole sources, and indeed such is the case.   Thus we see that our friends who use two subs instead of one have taken a significant step in minimizing the acoustic discrepancy between dipoles and subs. 

Okay, so why not use a pair of dipole subwoofers?  I tried that.  Dipole subwoofers have to be quite large in order to go deep and play loud, and dipoles rarely produce that chest-compression impact that a good monopole does because dipoles cannot actually pressurize the room. 

On the other hand, a quartet of monopole subs spread around the room can give you the best of both worlds - they will acoustically blend well with a pair of dipole main speakers, and you get good extension and impact.   And because there are four of them, they don't have to be very big to keep up with a pair of Maggies.

I can go into more detail about features that contribute to a successful multisub system, as well as placement and phasing options and maybe a little psychoacoustics, if anyone is interested. 

Credit to Earl Geddes for teaching me about the advantages of multi-sub systems in home listening rooms, and for allowing me to use his ideas in my product.

Duke

[Imperial]

Very interesting Duke!
Hsu research and Danley advocate something similar I believe.
They use deep (infra/deep) subs and then mid (50-200hz) subs.
I believe they also use the mid subs as the "chest thumper" devices.

Where would you get these four subs of yours to take over then, frequency wise, Duke?

Imperial

[Mike Dzurko]

Well written Duke, and I pretty much agree although many folks have been able to get a single sub to do a very good job with Maggies. Placement is critical and it does have to be the right sub; transient response, how fast the low pass filters cut off, and lack of out -of-phase cabinet resonances are a must.

That said, I've always felt that stereo subs were the best way to go . . . if the funds and room are available.  A few years ago I mentioned using four subs on a few occasions . . . . I got shot down as "greedy", so I backed off on mentioning it. But you're right, four subs, properly placed in a room can yield phenominal results.

FWIW, I feel that a relatively small # of sub owners, whether they own a single sub, or ten, get them really optimized in their system. Here's the rant   folks will spend all kinds of time experimenting with all sorts of stuff, but they want to have the sub (s) sound perfect with very little effort.  And here's another part of my rant. Much of what we experiment w/ in audio is difficult if not impossible to measure. Yet subs AND room treatment optimization can be greatly assisted with some time spent measuring and analyzing results.  And IMO, the music lover can realize far greater gains with time and money spent on these two factors than they will on all kinds of other issues . . .

[denjo]

I second the ACI recommendation!  I use a single Force XL with great results tho' I agree a pair would sound  better balanced. The Force XL has given me the support I need for low bass, especially with movies. Easy to use, built like a tank, reliable. I am one ACI Force XL haapy camper! Previously using RELs but feel the ACIs are much better (and cheaper too!).

[Jazz and Baroque]

 For the record I manufacture a product that embodies these principles, but they can be implemented with other manufacturer's products as well. 

Duke

Duke,

I went to your website and could not find any mention of subwoofers. 

Could  you point me in the right direction??

Thanks,
Mike

[Bob Reynolds]

.
.
.
 Here's the rant   folks will spend all kinds of time experimenting with all sorts of stuff, but they want to have the sub (s) sound perfect with very little effort.  And here's another part of my rant. Much of what we experiment w/ in audio is difficult if not impossible to measure. Yet subs AND room treatment optimization can be greatly assisted with some time spent measuring and analyzing results.  And IMO, the music lover can realize far greater gains with time and money spent on these two factors than they will on all kinds of other issues . . .

I could not agree more.

[Duke]

Thanks, Imperial and Mike Dzurko.

Mike D, yup it's all an insidious plot to boost our subwoofer sales!  I think I've got 'em softened up a bit now...

;o)

I think you are right on about subwoofer setup, and the dividends paid from taking the time.  To a certain extent, the person has to be very open-minded about setting the level and frequency, because what he thinks will work best often isn't what works best.  It's all too easy in audio to have a philosophy that sounds great on paper but doesn't fit the real world.  Also the controls on plate amps may not be as precisely calibrated as we'd hope, so for instance the actual lowpass frequency may not be what we'd assume from the control setting.

Imperial, normally I recommend running the main speakers fullrange and using the multiple subs just to augment the bottom octave or two.  Crossover frequency and crossover slope play a role in positioning as well.  If the slope is fairly shallow and/or the crossover frequency fairly high, the subs need to be kept in the general vicinity of the main speakers so they aren't detectable as separate sound sources.  If you are going to place subs well outside of the area of the main speakers, I suggest a 4th order cutoff at a frequency of 80 Hz or less (but this isn't necessarily carved in stone). 

Personally I advocate asymmetrical placement of multiple subs, and I'm not very precise about it.  Here's a link to a study by Earl Geddes on symmetrical vs asymmetrical placement:

http://www.gedlee.com/downloads/sub%20study%20.pdf

Note also that having the subs all equidistant from the listener may not be critical.  The ear doesn't even register a very low frequency tone until more than one cycle has reached it.

To Jazz and Baroque (the other Mike), unfortunately I don't have my subwoofer system up on my website yet.  If I don't get it up there in the next couple of days, I'll post something over on one of the Industry pages.  Or you can shoot me an e-mail for details.

Duke

[John Casler]

OOps     looks like DUKE was posting whilst I was composing sorry for any overlapping info.

That said, I've always felt that stereo subs were the best way to go . . . if the funds and room are available.  A few years ago I mentioned using four subs on a few occasions . . . . I got shot down as "greedy", so I backed off on mentioning it. But you're right, four subs, properly placed in a room can yield phenominal results.

I have been watching this post and find it interesting.  Like Mike and Duke, I have a commercial interest in subs that I offer from several manufacturers, but am not promoting any.

I have in my personal system 4 subs, and pretty much agree with both Mike and Duke's advice and assessments.

That said, in looking "specifically" at the Maggies, and I have had some, and several of my clients have them, I think it is valuable to consider several factors.

1) is what Duke suggested about dipole and monopole integration.  The more "specific" part of this is the crossover frequency used.  Bass frequencies, by their very nature become less direction as the frequency drops, so the "critical" issue is just where such a crossover takes place.  If you cross down around 40 or 50, you are getting into the area where bass becomes more of an encompassing radiator into omnidirectional space.

If you cross in the 60/70/80 or above, then you are moving into more direct radiation paths, and must take greater care at integrating.

2) If you are using 1 or 2 subs and crossing rather high, then you will need to take great care in addressing Phase/placement issues.  That is, if the sub(s) are to integrate well, then they must be placed in a position (generally ITU) that will cause no phasing issues to the frontal wave launch.  This also might mean a very steep crossover sloop to reduce problems.  And by this, I mean "both" speakers need to be "passed" properly and not depend on natural rolloff.

If natural roll-off is employed, then the slope might be better to be not so steep, and it requires even more attention placed on positioning to make sure that the drivers producing "overlapping" frequencies are in the exact same plane and distance from the ears.

3) It might also be best, if you are going to use a "higher" crossover (pass on both speakers and sub) that you make sure and look for a sub with the capability to play with low distortion, and one that has the ability to play frequencies "well above" those needed, to insure clean clear bass detail, which is what most maggie owners are looking for.  While many subs can fill that bill, it might also be wise to look for those that have limited cone travel or smaller drivers, assuming they might have quicker response, but that is not always the case, since response speed is determined by other elements to, such as magnet size and strength, and cone rigidity, and weight.

In the end, it is a series of integrated considerations and trade offs, that will yield the ability to cleanly address the frequencies you want, with a sonic integration that will not intrude on the listening experience.

[walkern]

One other thought for a fast, powerful and clean (low distortion) option would be the 12" kits from Rythmikaudio.  Their servo controls and low Q drivers should match up beautifully with Maggies.  They are reasonably priced (particularly if you source your own boxes or buy from the likes of Parts Express) so you could probably afford 2 of them and still stay within your budget. Check out the user feedback on their site and you'll notice enthusiastic buyers using them with dipoles and electrostats as well.

Just a thought.

Neil

[Duke]

I probably painted with an overly broad brush in my previous post...

Underlying my crossover remarks is a reluctance to use the speaker-level high-pass filter built into a plate amp - based on misgivings about the capacitor likely used in it, and an awareness that a generic "80 Hz" high pass filter is probably something very different once it's interacting with a given speaker's impedance curve.

For some applications (especially those that approach either the thermal or mechanical limits of the main speakers), it would be best to use a high pass filter.  Preferably active, unless you build your own custom high-quality passive one (which can get both expensive and complicated if the main speakers have a system resonance near the crossover frequency).  

As a general rule, it's a good idea to match up the net acoustic rolloff slopes of the high pass and low pass sections, and if one is to err in my opinion it's best to err on the side of the subwoofer not mucking up the upper bass produced by the main speakers.  So I lean towards fairly steep-slope lowpass filters, as most speakers use vented boxes and have a 4th order rolloff below the tuning frequency.  I would guess that Maggies have a 3rd order rolloff below the panel resonance.  Obviously there are opposing views on this subject (like those of Richard Vandersteen), and I'll readily admit that some excellent subwoofers out there embrace a very different approach from mine.  

[Jazz and Baroque]

Some dipole owners try stereo subwoofers, and these people are more likely to keep the subwoofers in their system - not because they get twice as much bass, but because the blend is much better.  There's a reason for it.

Multiple subs will suppress room modes.  The easiest example is one sub located against a wall.  This sub will excite half-wavelength resonances that bounce back and forth against the opposite wall. 

Setting up a second sub on the opposite wall will tend to cancel out this half-wavelength mode. 

However, this model assumes that the same bass signal is coming out of both subs. 

If the recording engineer has close-miked the bass instrument, and the mixing engineer puts all the bass on one channel, then the advantage of the multiple subs disappears.  This was done on some great jazz LPs from the '60s.

This is a good reason to mix the left and right channels of the low bass, even with a set-up that uses multiple subs. 

It is a why I am interested in finding small subs with 8-inch drivers. 

And why I think that a 300-pound array of six large drivers in one cabinet is going the wrong way, unless, of course, you can afford two of them and have no trouble moving them around the room to find the best set-up.   

Just my thoughts on the matter,
Mike

[TONEPUB]

When I still had a pair of 2nd Rethms, I had great luck with a pair of Tannoy TS-8's.
They were very easy to place in different spots, had plenty of power and were pretty
fast too.

Not too expensive either, bought a pair of demos from my dealer for about 700 bucks.

Good luck on the sub project.  It's hard to get right, but once you do it's pretty enjoyable....

[Jazz and Baroque]

Duke,

I looked at the Geddes discussion.  He recommends:

"one sub in a corner, and three subs located randomly but one of them placed closer to the ceiling." 

I'm not sure how I would hang a 50-plus-pound sub from the ceiling. 

Mike

[rajacat]

Is it acceptable to use subs of different configurations, say one 10" and one 12" sub of the same or different design and power?

[John Casler]

Duke,

I looked at the Gedlee discussion.  He recommends:

"one sub in a corner, and three subs located randomly but one of them placed closer to the ceiling." 

I'm not sure how I would hang a 50-plus-pound sub from the ceiling. 

Mike

You actually don't need to "hang" it.

I have two 135# subs on 4' stands which makes their top over 6' tall.  The idea is to energize the room from postitions other than the floor.

Maybe a (very solid) high bookshelf would work well, but you certainly would want to also secure the sub like we do here in "earthquake country", with connection to the wall, so that it didn't vibrate off the shelf.

[Jazz and Baroque]

Is it acceptable to use subs of different configurations, say one 10" and one 12" sub of the same or different design and power?

It may be more difficult to balance the power output for the two subs. 

If one sub goes much lower than the other, then you will not get the "multi-sub" benefits for that unmatched portion of the frequency band.

If you have a big sub and a small sub, put the small sub up on the ceiling. 

Mike

[satfrat]

You can also build a 84' subwoofer stand(depending on how high your ceiling is). Mine is 32" high and sits next to and just below my 7" Scan-Speak driver. In a word, seamless. 

FWIW, I used a 48" Real Traps Soffit with 2" oak platforms top & bottom, with 2" soffit corners w/1" square cuttout that fit over the Soffit sides for added support. I finished the stand with 2" Audiopoints. Works great as does the 4' RealTraps Soffit plant stand (finished with1" oak platforms on each end) that sits in the corner behind the sub. I don't think Real Traps are selling these Soffits anymore and that's a shame. These cardboard boxes filled with fiberglass were soo flexible and worked great for tighening up the bass. 

Robin

Robin

[JoshK]

Duke,

I looked at the Gedlee discussion.  He recommends:

"one sub in a corner, and three subs located randomly but one of them placed closer to the ceiling." 

I'm not sure how I would hang a 50-plus-pound sub from the ceiling. 

Mike

Dr. Geddes' recommendations are always for a dedicated [home theater] room and not the typical room.  He is firmly in the camp that if you don't have a dedicated and treated room, then you don't have hi-end and there really is no point.  This isn't my beliefs, those are his, just thought I'd put his ideas in context.  He is also heavily multi-channel biased. 

Personally if I wanted to add subs to Maggies I'd look no further than a W frame dipole sub (actually two) so that you keep dipole dispersion throughout the spectrum.  This helps in blending immensely as the power response is even through the crossover.  People overlook that point too often.

[Jazz and Baroque]

Dr. Geddes' recommendations

Personally if I wanted to add subs to Maggies I'd look no further than a W frame dipole sub

Thanks.  I have corrected my initial misspelling of Dr. Geddes' name. 

Could someone post a link to a picture of a "W frame dipole sub" for those of us who have no idea what this is??

Mike