Subwoofer: should we even use them at all?

Dear Community,

For years, I looked forward to purchasing a subwoofer. However, I recently became friends with someone in this field who is much more knowledgable than me. His system sounds amazing. He told me that subwoofers should be avoided because of the lack of coherence that inheres in adding a subwoofer. What do you guys think? I currently use Verity Parsifol Ovations.
Of course that isn't always true, but there are certainly many people who consider it a must. As usual, it's a personal taste issue.
This subject has been debated over and over. A review of the subject in the archives will reveal nearly endless varieties of opinion. Personally, I think anyone who issues blanket statements pro or con is oversimplifying the matter. That said, I personally feel if enough care is taken in setup, most quality subwoofers can add more than they subtract to speaker systems that lack ultimate bass extension.
Here's the truth: low frequencies are subject to cancellation and reinforcement by normal room boundaries, resulting in uneven bass. This is unavoidable with any large speaker capable of putting out low bass, in a normal-sized room. If you have large speakers and you want to hear accurate low bass, you need the subwoofer (preferably two) to fill in the frequencies that are being cancelled by the room interaction. However, the addition of the sub(s) could exacerbate the reinforcement problem. Fortunately this can be dealt with in several ways including room treatment, repositioning, or signal processing/equalization.

If on the other hand you are using smaller speakers, the addition of one or two subs will add the low frequencies that you are missing.
Technique and time go on. Subwoofers are a lot faster these days. But also the roomacoustic systems have changed a lot. About 7 years ago I never thought that subwoofers would be fast enough to become one with the loudspeakers for stereo use. In the past my only interest were in big systems like the B&W 800Signature. ( which I owned)

These days it is another world. Audyssey Pro has changed my thoughts about subwoofers in general. Now I have a what I call; stealth integration with the loudspeakers. I never thought this could be achieved with a subwoofer.

I also use a pure silver Audioquest Wild Dog subcable. This one has taken it even to a new and higher level.

These day I cannot imagine not to use a subwoofer. Even for stereo use. I listen these days above 90% in stereo.
I just received my Parsifals last week. I thought they were bass shy initially too. But since the bass is back facing getting the distance right from the back wall makes all the difference. Inches too close and it's boomy, to far and it feels lacking.

Mine is now dialed in and the bass is absolutely standout! Full and well defined. It's been forcing me to play lots of jazz lately just to hear the string bass, vocals drums, etc. Listening to Dianne Krall now - just spooky realism. The staging is so perfect too I just close my eyes and its hard NOT to feel you're in the club with them.

Same thing with Miles Davis before that and Pink Floyd "The Final Cut" prior to that (ok it's not jazz but equally spooky realism).

The bass is suppose to be one of the most famous strengths of these speakers (and I see why). Placement from the back wall is key (along with supporting equipment).

Even side wall placement comes into play according to Verity. They were very helpful and patient over the phone and had some unusual tips. I can't imagine adding a sub would do anything but detract.
Good question, Elegal.

In my opinion, it depends on the system. If your main speakers are cones, add a cone subwoofer. If your main speakers are Magnepan, add a Magnepan sub. If your main speakers are ESL's, the Magnepan sub just might be fast enough.
I avoided subwoofers for 32 years and now have one. It works well for me in my particular situation but I wouldn't cry if some day I don't need one anymore. The less equipment the better. For now though, it integrated well for me.
Just think about what it means for someone to say that others shouldn't use a piece of equipment in their home system that they enjoy, and that improves the overall presentation to THEIR ears.

I personally don't think people should put hot fudge over ice cream is delicious as it is, and hot fudge only adds unnecessary calories and sugar. And if it's too hot, it can cause the ice cream to melt prematurely. The extra 50 cents to 2 dollars it costs to add hot fudge could ultimately be spent on extra ice cream, or a bottle of water to wash the ice cream down. I've been eating ice cream for many years, so I have a lot of experience on the matter. You should listen to me, and never add hot fudge to your ice cream.
I have been using a sub for 20 years...and over that time have joyed getting a more and more seamless integration. the combination of my main speakers being upgraded to the point where the sub is now only playing 40hz and below plus the improved speed, quality of subs and their crossover software has made it a joy for me. The ambience, foundation deep underneath orchestral, live performances as well deep house/electronic is wonderful. Good luck. Good set up is a must...but for me, I will never take mine out. And more owners I know who have my speakers (Wilson X1/Grand Slamm) or the Alexandria's use them with subs than those owners I know who don't.
What's the expression, 'its complicated', and it is. Installed and set up properly, matched to the right pair of main speakers, it can add much to your enjoyment of music. Done poorly, it can spoil your existing sound, and make you much poorer. I've matched two subs to my ProAc 1SC's and have fully enjoyed the effect. Took a while to get the crossover right and positioning of the subs in the right place but it was well worth it.
In the past we did filter them till max 35-60. These days this part has changed a lot. After I got the attention to test it till 120 hz. I test it for the first time. When you use a subwoofer like mine ( low freq. unit is very fast and light ( ceramics) )you can use it a lot further.

I got even better results using it higher. Low freq. become touchable above 80hz. These days I use it till 140 hz. This gives the best endresults I even heard with subwoofers in general. Playing stereo voices and instruments also become more stable and physical.

This is possible cause of the accuracy of the measurement Audyssey Pro gave. And the use of a very thick Wild Dog pure silver subcable.

At the show were I was in 2013, people said: but your subwoofer is out. Many people were not familiar with this kind of integration.

Going back to the past were we sold most of the time REL subwoofers even with more expensive loudsprekers. It is a new world and a much higher level of integration.
I have a subwoofer, which I use for HT purposes. I have played with several subwoofers quite a few times over the last few decades, but I never could get one to blend seamlessly into a stereo system for music purposes. I have heard a couple of systems that have, but I have heard many more systems that have failed, but the owner does not know it. For me, I will leave the integrating of bass management to the seasoned speaker designer, and buy full range speakers, like your PO's, for music.
What JM said. Subs rarely sound right and you are much better off with a well designed full range speaker......if possible. I have tried perhaps a dozen and did everything known to man to blend them in, but in the end they hurt the music more than helped it.

I am sure it is possible to help the music more than hurt it, but that seems out of reach based on my experience anyway.
"What JM said. Subs rarely sound right and you are much better off with a well designed full range speaker"

These words I said for a long time as well. I never thought that I could be statified and even owning a subwoofer for stereo use.

So what did change my opinion?

When I did test subwoofers in all those years ( 16 years of time) I was often not satisfied with the integration. There were Always music numbers were you could hear that the timing was not perfect. Everywhere I came ( shows and clients) I heard the same limitations. For a perfectionist there is no room for this. Why? Because I get irritated by every single limitation. It is Always my way of working to eliminate every single limitation in a set.

When I bought the Monitor Audio PLW-15 I understand directly that the response is a lot faster than most other subwoofer. The PLW-15 is a very difficult subwoofer to control.

Audyssey did solve the control problems I had with the PLW-15. You can have a very fast subwoofer, but this is no garantee for success.

Audyssey Pro gave me the freedom to control and make it fully integrated with the speakers. This is what I call stealth integration.

Purist Powercable and the new Audioquest Wild Dog pure silver subcable puts it even to a higher level.

But the remarks to use it to a higher freq. level did change it also a lot. These days I use it from 16hz till 140 hz. Blending goes to a new level. You need to hear it before you can believe it.

I had a few surround specialists and also different clients with highend sets who are amazed by the level of integration.

When I put it off you loose it all. When you use it till 140 hz the subwoofers has a much more important part in the overall sound.

I understand the thoughts of most people overhere about integration. But now stealth inegration is possible.

It is not easy to create, it did cost me many tests, time and thinking to create it. But now it is here. A few people in the audio business say; you have to do something with it. You have to let it hear to other people. I am thinking about a way to make it known.
The conventional subwoofer is full of massive compromise in design -overly small cabinet, drivers with massive excursion, requiring huge power and room boundary reinforcement to produce bass. The excursion causes poor transient response extra distortion and reduction of bass detail. The massive power yields thermal compression due to voice coil heating. Having to place so sub can have room boundary reinforcement again causes issue with time arrival, integration etc. Great for high profit but not the best way to generate low frequencies. I myself prefer bass systems- towers, bass horns, IB bass etc over conventional cub sub.
I also tried numerous sub set ups and was never quite satisfied with the synergy to the main speakers. I'm sure there are Agon members much smarter than I that figure out the correct components, set up....
I went a different route. I had a pair of 3-way speakers built with Usher drivers. Uses one 8 inch woofer. Overall very happy with the speakers but found the bass to be a bit lite for some of the rock music I listen to.
I worked closely with the speaker builder tossing some ideas around.
I had him build a second pair of speakers - passive subs using the same 8 inch Usher woofer. The crossover has a very tapered slope and three cross over points. On the back side of the speaker I have three positive taps, one for each cross over point. I drive these speakers from the second set of preamp outs then through an Emotiva control freak (attenuator)- then to a separate Emotiva XPA-200 amplifer.

I love this set up since it provides close to the flexibility of a subwoofer set up but without synergy concerns. Main speakers run full range through a separate amp.
The passive sub cross over's slope is so gentle it ends up filling out the entire bass region, not just the lowest octave. When dialed in correctly the blend is seamless. So much better than any subwoofer set up I've used. The whole set up was cheaper versus the pricey Velodyne I purchased previous to this set up. Gives me flexibility for different source material too.
Every single tool has his limitations. Horn loudspeakers are not able to give a physical inimate image. Even when people would gave me 100 dollar each day I would not listen to this in my house.

You can go on and on about everything!
The limitation of Velodyne subwoofers is their response. They need to use lighter and faster material. Even that it can play loud and has a lot of dynamics. It is still not fast enough. With a few simple stereo test this comes to the surface quite easy.
"Horn loudspeakers are not able to give a physical inimate image. Even when people would gave me 100 dollar each day I would not listen to this in my house."

I respect your experience and believe that you have achieved good system results through experimentation, but the above statement is certainly not true. I have owned many speakers, and horn speakers have provided me with a more intimate experience than any other type of speaker I have owned. I believe there are others reading this who will have a similar opinion.
At shows The horn loudspeakers Always gave a less intimate stage than how I create an intimate stage. Even when I was sitting in the middle. My image is a lot more stable and blacks are superior to any horn loudspeaker I ever heard on a show. The level of physical 3D stage ( blacks are here a part from) is not that precise.

With the hornspeakers it is more difficult to have a good image when you sit at different places.
Bo1972, my experience is different. My Audiokinesis Dream Maker horn speakers give me lots of intimate image. Although they aren't nearfield speakers but excel even more at the huge concert level. And they give a wide listening sweet spot.
Also, I own a Velodyne DD18 and know that, yes, it can be pushed forwards (1-2 feet in front of the main speakers) to get some added transient coherence and depth, but this is not practical in my room, and I get good results also closer to the wall, running the sub in 90 degrees phase.
Thanks to everybody for these responses. There is a lot to think about. I guess the only reasonable option would be to sample some sub's and see how they work. However, I don't know if a dealer would let me try something out on such a basis.
Regarding the way a speaker of any type presents music, I don't feel that imaging, which mine do well (depth much less so) is not the source of perceived "intimacy". Spectral balance and tonal density are more impotant in that regard to me.
The first time I heard the Velodyne DD18 I was amazed by the roomcorrection system of the sub. He had 2 of them. There was no acoustic problem in the low freq. But the thing I found out was that the timing with the loudspeakers (Revel) was not ideal. This is caused by the lack of speed in response.

Depth is a very important part for the absolute sound. I understand that people like horn speaker for there speed and ability to play loud.

I also can play at extreme levels. With Pro roomacoustic measurement I can play as loud as I want to. My speakers have a spl of 118 db. For a not horn speaker this is quite extreme for a small speaker. But I have an extreme deep and wide stage with a physical intimate stage to die for.
I've had subs for years and just can't get it right. They sit there unused most of the time. A floorstander that can do deep enough bass is so much more satisfying.
Bo, please go away.
You have no credibility, nothing to add, and nothing but bluster and me me me me me.
I is your favorite word.
Because most of all subwoofers do not have a response what is fast enough. This is why many people are only interested in bigger floorstanders. I had the same thoughts till 2007.

What do tou use as active crossover, and how is your system set up? I'm looking into this right now. Actually posted a new thread on the Tech Talk section.
I use the crossover of the Monitor Audio PLW-15 itself. Without Audyssey Pro this subwoofer is very difficult to control

I even can choose between 6, 12, 18 and 24 db/octave

24 give the best sound.
Bo1972: did you try positioning the subs further out from the wall, closer to the listener position, to get better timing? I have my Velodyne DD18 on a low trolley. When I want the best performance I wheel it out, one foot or so in front of the speakers.
Yes I did try different places from the wall. I am a person who likes to test. Testing means; trying many different things.

The nice thing about testing is collecting information. This you use for the best endresult.

When I put it closer to the wall the dynamics are stronger. I will loose too much drive when I put it more away from the wall. The pro measurement gives you the freedom to put it were you want to.

My low freq. unit is made from ceramics. This one is a lot lighter compared to the material of the DD18.

That's why you have a much faster response. This is easily to hear in the level of integration.

Velodyne should use lighter material for a much faster response. Because they have every part for a good subwoofer. The only limitation is their timing.

The new level I have with my subwoofer is that you feel more energy. And I am not only talking about low freq. Also in freq above 80 hz you feel more energy.

The Audioquest Wild Dog and the Stillpoinst togheter give you a much higher level in speed. You need to hear it before you understand what it makes special and new.
IMO, a well executed subwoofer/mains system is very hard to beat. However, the "well-executed" part is the trick. All of the best sub implementations that I've heard use digital bass management and/or room correction and a lot of folks here won't go that way on principle.

If that approach bothers you, I'd agree that you might want to pass on adding a subwoofer. BTW, I'd never add a sub to Verity speakers (I own P/Es), unless you plan to ditch the bass pedestal units. The Parsifal design is terrific, and I love mine, but IME they are not designed for flat, extended bass response. Adding a sub without some EQ in the mid-bass would almost surely be a mess and, even with EQ, the octave to octave balance of the speaker would be substantially altered.
I agree with Martykl...a good combination is tough to beat in my opinion.

I cannot say if my own X1/Grand Slamms plus Velodyne DD18 would work for others...but it works for me. And I know more owners of the big Wilsons who DO use Subs with them (in parallel...not cutting off the Wilsons) than those who do NOT use them.

At below 40hz, I honestly find the solidity of foundation is wonderful, and I find the 'blending' to be quite good after months and months of fine tuning every few weeks.
Hi all.
Bo1972 - dynamics is no problem wherever the dd18 is placed. It is a very forceful sub. The trouble is integration, as I am sure everyone here is aware of. If you think the sub is too slow, do the obvious thing, move it up front, closer to the listening position. Works quite well with the DD18. For space reasons this is not so easy for me. James Romeyn (associated with Audiokinesis) suggested, if you have to line it up more towards the wall, turn it to 90 degrees phase. This has worked well in my context, using big bipole speakers.
In October 2011 Jeff Hedback (Hd Acoustics) and Nyal Mellor (Acoustic Frontiers LLC) published "Acoustical Measurement Standards For Stereo Listening Rooms." Hd Acoustics clients include Ozzy Osbourne, Lifehouse, and Trevor Horn. Page 19: “To obtain the best possible LF response boundary interference issues can be tougher to address. Varying the fixed distances from ‘speaker to boundary’ and ‘listener to boundary’ will reduce strong cancellations. It is a balancing act as one location that may offer a smoother LF response may not provide the optimal midrange and treble response ” (emphasis added) Page 20, paragraph 2: “ everyone desires a ‘flat’ LF response and no modal ringing. Simply, this is a tough achievement. The absurdly large collection of interrelated variables between two fullrange speakers and the room (speaker design, speaker/listener location, room size/construction and acoustical control within) makes this so. It is up to the individual to determine what their limits are as regards placement and acoustical treatments ” (some emphasis original, some added note the qualifying phrase “absurdly large“)

Let us narrow the discussion to bass reproduction systems (subs or full range speakers) properly tuned with appropriate system Q. Audiophiles wrongly describe such systems as having "fast" or "slow" bass, and such descriptions are misleading or worse. Would you want a low E string on a 6-string guitar to be "faster" than the high E? No, of course not. Low E is 82 Hz, high E is 328 Hz. Obviously, the Low E must be "slower"...two octaves "slower" to be exact.

Guess what? Bass is a slower wavelength vs. mid/treble. Of course it must be slower. Double basses are larger than violins by design.

"Slow" bass more accurately describes a bass mode effect unrelated to the speaker itself. Even though modal effects often result in Frequency Response windows of 15 dB or worse, that is not their worst and most audible effect. The worst and most audible effect is that the mode wavelength is completely outside the diatonic scale and unrelated to the original bass note pitch. After the bass note ends on the program, the modal effect continues bouncing between boundaries. Imagine two bass players, one of them plays perfectly, while the other bass is tuned a quarter tone off (sometimes plus, sometimes minus, depending on the mode), and he holds bass notes about a 32nd note too long. This is the inherent effect modes cause, which results in audiophiles wrongly using terms like "slow." Yes, the note didn't end, but the speaker is not reproducing the note, the boundaries make the note. We're talking about the equivalent of over 100% THD. We're talking about bass notes not on the music program.

There are really only two ideal solutions, neither of which require any EQ nor acoustic treatment for small 3 to 6 dB FR windows, and virtually no timing errors as described above. One is a Distributed Sub Array, the other is a Dual Bass Array. The latter might perform even better than the former, but the latter also costs about twice as much and ideally requires subs built into both front and rear walls.

A properly installed Distributed Array has no integration issues up to about 80 Hz because it solves the bass mode before it occurs. All other solutions are band aids attempting to fix the mode after the fact, including EQ, which can't solve the timing error.

Initially, three or four subs seems like 2 or 3 too many. When you hear the performance level, you'll wish you found out about it earlier and never look back. Even 1cf subs can reach -3 dB @ 20 Hz with enough power for HT or music. That's another benefit: ideal bass works just as well for music as it does for HT.
Dynamics is something totally different than response. This is what is the weakest part of Velodyne.

I like the drive and eq system of the DD18 when I heard it the first time. But still I didn't like the integration.

I have showed this to some Velodyne owners at my home. Then it is easy to understand what a faster resonse does.

This makes a subwoofer go to a different level.

Then you get stealth low freq. I am Always looking for the best. This search never stops. People often ask to me if life is not more difficult to be so demanding. In my view it is not. It is who I am. Doesn't cost a lot of energy, it works just natural.

In audio it needs to be the best, the rest I don't!
That is why people can feel offended. I want the best for my clients as well. I want for them they same level as I want for myself. There is not difference, that is why I think and work for my clients as I do for my self.
Hi Bo1972, as an owner of Velodyne DD18 (original), I think I know where you are coming from. How is the DD18+ by comparison?

Have you ever heard JL Audio, Krell Master Ref Sub or the new Magico QSub? Just curious since it would be fun to hear from someone who has. I certainly have read many good things about JL, but curious if you've heard them how you would compare them with my trust old DD18. Thank you!!
I have heard the DD18 several times. Not the DD18+

I never heard the DD18 reach the stealth speed I have at home. This is my Reference level of timing. So I compare everything with this quality. When it is less, it is fully useless in my world.

A know a few person which I sold cables who own JL subwoofers. You don't see them here a lot in the Netherlands.

I never liked any Krell speaker. It is better just focus on one thing....for them it is amps.

Magico subwoofer is of an extreme price. When there is a demo here in Holland, I will go for a listen.
Shameless tangent!

Marty: I'm interested in your experience with room correction. I also use Rythmiks (two 12" very heavy DIY boxes) in a stereo setup. I'm looking into Dirac for room correction (as my only source is a highly optimized computer), plus an active crossover to high-pass the tube amp and send the bass to the subs. Was wondering what your experience was with active crossovers?

Now, more relevant to the original post: I have small floorstanders (B&W 804S), and adding a sub was a good improvement. I started with a REL Storm III as reinforcement to the low end. Using measurement software/mic and a lot of time, I achieved good integration and I was much happier than without the sub. That REL has one 10" driver.
Then I replaced the REL with two 12" Rythmik subs. Much better! Initially they were also used as reinforcement in the lowest bass. I used Earl Geddes approach: both subs running a summed-up-bass signal, both set up with different crossover pounts, different phase, volume, etc (and different adjustments in the PEQ section) to get a smoother room response. And indeed it was a lot better!

Lately I tried an experiment: high-pass the tube amp (and hence the speakers) thru the crossover built into the plate amp of the Rythmiks, that crosses over at 80 Hz. Subs were kept in the same location (for now), but are now used as stereo and with different settings from before. This gave me a better sound. Better soundstage, imaging. I think the explanation is my speakers, while they can reproduce below 80 Hz, do so with higher distortion. Plus the tube amp must not be too happy to go down there either.
So in my experience subs are a very good thing for music. They do take significant effort and time to get right. And the reasons why they are a good thing aren't only about reaching down deep in the bass, but in some cases relieving the amp and speaker from playing where they are not most comfortable doing.

Above 80hz low freq. become touchable. That is why when you use your subwoofer a lot further ( 120-140hz) you become what I call stealth low freq.

That is the main reason why you need an extreme fast subwoofer in response to use easilly to higher freq.

Using till max 80Hz, is like using subwoofer during the 80's!! That was the past, it is about now.

I've used several active x-overs and I divide them into 2 groups. The analog models included a tubed Marchand, an NHT x-2, and the internal active x-over in my Theta Casablanca. The Marchand was too noisy for me, but that might be unique to that piece, rather than the model, since I've been told that others had more success. The NHT is an excellent piece (and IMHO a great value), but I ended up pairing it with a Velodyne SMS-1. The resulting performance was excellent, but the set-up was a giant PITA (thanks to the Velodyne) and the multi box/cable arrangement was inelegant. The Theta is a really flexible and good sounding unit, too - and a one box solution.

I moved to an Onkyo 5509 pre-pro after I heard Audyssey xt-32. A lot of A/B testing at a couple of local places led to a loan of an Integra pre-pro which I felt was (much, to my taste) superior to the Theta. The crossover in the Onkyo (like most modern pre-pros) is effected in the digital domain. I ended up buying the Onkyo version because I couldn't hear a difference in sound between it and the Integra version, it was significantly cheaper, and I preferred its appearance.

To the x-over question: It's hard to separate the performance of the digital x-over (vs the analog x-overs) because they were integral (pardon the Onkyo Integra pun) parts of two very different pre-amps/pre-pros. In the end, I like the Audyssey powered one-box solution of a pre-pro for my main 2 channel system and that means a digital x-over comes as part of the deal. Whether it's the digital cross, the room correction, the balance of the preamp circuitry, or any combination of the above, the bottom line is that I found it to be a better mousetrap. Since I had already effectively stopped listening to LPs in favor of a server (and consequently didn't really have to deal with the cognitive dissonance presented by ADC and DAC for my analog LPs) I retired my ARC LS-25 and Joule LA-150 without much indecision. As always, YMMV.

Hope that helps. BTW, I've never heard the Dirac correction package, but I've done a bunch of research on it: There's definitely some interesting software there. If you do pull the trigger on Dirac, I'd be grateful if you posted your take on its performance.
I also use the Onkyo PR-SC5509 with Audyssey Pro.

Above 99% of all people use Audyssey as Audyssey say you should use it. There is a big but......Audyssey does not think from the head of how highend is being used. And how big instruments and voices need to be in proportion.

The other limitation is the lost in dynamics. The first 2 times I did it as they tell people to use it. This was in 2010. I was not satisfied enough.

I had thoughts how it could be better. I developed my own way of measuring. These days we measure at totally different places and Heights.

We also measure the subwoofer differently than they do.

They endresuls are way superior to their quality in endresult. I never will share this information with another person. Even not for money. With this I have an extreme advantage over all my competitors. I never had such a big and convincing advantage in audio before.

The differences are: superior dynamics, speed, blacks integration, sharper focus, resolution and atriculation of voices.

The subwoofer is also a lot more dynamic and controlled than you can achieve with the Audyssey way of Pro.

We modified the microphone stand. The Audyssey stand is fully useless. We measure at mm precision.

The new outcomming Onkyo PR-SC5533 in September will not have Audyssey anymore. I will test it for Onkyo when it comes out. For me it will be far inferior in endresult. I still can sell the old one, The new one is good enough for me to sell. The level is not good enough to be used for myself.
I, too, dislike the idea of calling bass response "slow" and prefer the term underdamped. I also like the idea of multi-sub arrays and have experimented with variations on the theme pursuant to some great posts by Duke of Audiokinesis, so I agree with a lot of this post, but....

Spkrplus wrote:

A properly installed Distributed Array has no integration issues up to about 80 Hz because it solves the bass mode before it occurs. All other solutions are band aids attempting to fix the mode after the fact, including EQ, which can't solve the timing error.

If "no integration issues" means "no room integration issues", this is an overstatement. You won't remove room effects with four (or more) subs, but you can greatly reduce their impact on direct FR and power response with careful placement. As a side note: EQ fixes the problem before it occurs, too. Once EQ filters are set by room analysis, the subsequent electrical (music) signal is adjusted prior to reaching the driver. Tho the filters are calculated "after the fact", that does not a band-aid make. If you doubt that this approach works, simply do an RTA of the direct and power response in the room (I use white and pink noise) post EQ. The benefits in both graphs are obvious, tho usually more dramatic IME on FR than power response.

The difference in power response improvement is - to me - the primary conceptual benefit of an array vs EQ, but per my own measurements, I wouldn't personally describe that delta as dramatic. My own array experiment - admittedly not ideal, two Velodyne SPL 8s and two 12" Rythmiks optimized for power response - showed power response improvement over the dual Rythmiks, but not wildly different. In fact, the power response and FR performance of that array was clearly improved by the application of Audyssey, too.

Proviso - a different subwoofer array implementation might yield different results, but my attempt was reasonably diligent. Had I gotten more dramatic results, I'd likely own an Audiokinesis array right now. To be clear, I wouldn't bet against me buying one in the future, but I'll still use Audyssey with it.

As for long wavelengths reflecting off boundaries (2 bass players), this happens with distributed subwoofer arrays as well as single subs. As a technical matter, it happens more - reflections for each sub are inevitable (4 or more bass players). Careful placement of the subs relative to the walls can smooth the response anomalies caused by each of these reflections, but they're simply smoothed in aggregation, not removed.

It's also unclear what "timing error" EQ can't solve. If you're talking about decay characteristics of the room, I don't see how a sub array would be helpful there either.

As for in-wall woofer solutions, they do effectively address the issue of reflection off the wall behind them (this is generally the worst IME) but there are still side wall, floor and ceiling issues which are certainly not trivial.

To be clear, I'm not dissing the idea of subwoofer arrays. I actually think it's a great idea. I'm just pointing out that the particular benefits of an array are overstated in this post and the objections to EQ are also overstated. Of course, the bottom line is a listening session. IME, thirty seconds with Audyssey should be adequate to demonstrate the benefits to most people (simply disable it during play). That doesn't mean it's preferable to a well implemented array, it just means that it's a very effective solution for the bulk of the problem. The best practical solution that I know of is an array with Audyssey, but, if you really want to "fix" the issue, an anechoic chamber (or room that effectively behaves as one) is the only solution that I'm aware of.
Audyssey Pro Is far superior in endresult compared to XT32.
The authority is a lot better. You get a different kind of sound in comparison to XT32.

It goes deeper and you have a much better timing and integration.

Thanks for the answer. Was wondering how is your signal chain configured? From server, do you go out through USB? Straight into the Onkyo? Then the Onkyo does the crossing over, the room correction, and where is the DAC performed?

I asked the miniDSP folks about suggestions involving Dirac Live and crossovers. One option they suggested was Dirac at the server and their nanoDIGI 2x8 for a crossover in the digital domain, but also a second DAC dedicated to the subwoofers. The additional DAC I'm trying to digest...I guess any timing differences between the different DACs used would be compensated by the room correction...still not easy to digest. And I also wonder about additional jitter in the chain.

What are your thoughts on this configuration?
So what is the conclusion?

The thread starter was warned against a sub due to "the lack of coherence that inheres in adding a subwoofer". I think this is system and room dependent. Bass has to be integrated anyway. There is no general rule that it is better inside a (costly) speaker than with (less costly) speakers and a sub, even if it often works out that way. So there is nothing bad that "inheres" in choosing a sub.
New techniques and faster subwoofers has given us a much higher level of integration than what was possible in the past.

I never thought that this would be possible. Now I know it is possible!
faster subwoofers? are they midranges
When you use lighter material, you get a better response. The poweramp also has influence on the control and speed.

Ceramic woofers are very light and are a lot faster than some 'slow' material used by other brands.

In a simple stereo test you can compare the differences in integration. It is so simple!

I've used several different configurations, but I'm currently taking the digital signal out of my QSonix server straight into the Onkyo via coax. The Onkyo does all DSP including x-over. The twin sub out of the Onkyo goes straight to my Rythmik subs and the main out goes to (at the moment) a pair of Cary 805s and on into a pair of OHM 100s. Sometimes, there's a different amp/main speaker combo, particularly if I'm using my Maggie MMGs, which require more grunt than the Carys can deliver.

BTW, I've previously used both of my current stand-alone DACs (Cambridge DAC Magic and Benchmark) for conversion, but - as I've noted - simplicity is important to me and I prefer the simplicity of one box. As to SQ, it's audibly different with each DAC (especially Benchmark vs Cambridge) and a matter of personal taste, but I like the sound of all three options and settled on the internal Onkyo DAC for the reasons stated above.

Further, BTW - there's an upgraded version of the Onkyo from one of the specialists (Upgrade Company?) that offers an in-home trial. At the moment, I'm kicking the idea of a trial around just to check out any potential improvements. If I pull the trigger, I'll post my impressions