[richidoo]

Sadly no, this is a considerably more expensive woofer.   Haven't decided on a price for the kit yet, but I want to use this woofer.   I just can't bring myself to "dumb it down" by going with a cheaper woofer.  DiySoundGroup and PiSpeakers offer some excellent kits already, and their 15" two-way kits certainly are not "dumbed down" - they're putting best foot forward, and I should as well.  The only thing I'm holding back on is the rear-firing tweeter, as I do want to reserve that for people who go with finished speakers from me.

The PiSpeaker 4Pi kit (drivers + horn + crossover) ranges from $800 to $1550/pair depending on choice of woofer and compression driver.   I believe the parts I'm using to be competitive with the high-end 4Pi parts, in this application at least; I don't think we normally need the extra-long excursion of the JBL in a home audio application, though there's nothing wrong with having it available.   On the other hand my woofer goes somewhat lower and over an octave higher than the JBL, how 'bout that?  Not that we're running it all the way up, but that top-end extension speaks to how comfortable our woofer is down where we are using it. 

Did I say what woofer I'm using?  I thought I was being secretive about it, but it's bound to come out eventually, especially when I sell the first kit.  Anyway, thanks!

I am glad you are taking the concept more high end, rather than competing for price. As you said there are plenty of cheap econoboxes available now, and will be great for HT. I built an Econowave exactly per Zilch's plan and it was anything but high end sound. I upgraded every part and it was significantly improved. But there were still issues with crossover beyond my ability to fix. Having the whole speaker fully designed with a high end goal by an experienced designer with reputation for great sounding speakers is appealing. 

You didn't mention the woofer, but I found it. Super nice driver, on par with AE-TD15M, with better LF performance and sensitivity. Don't bother to PM me, I won't tell. 

I tried SEOS12 and QSC copy. I loved the limited vertical dispersion of those. It greatly reduced the shouting sound that my room is prone to, even though my ceiling is treated. I can play music louder without the midrange overloads of non-horn speakers.

I prefer sealed mains with big woofers, so that's another appeal of this for me. Big woofers make sealed speakers match the room gain well, allowing clear low, natural sounding bass. But the swarm idea has my curiosity.   Since they are all on one amp I guess there is no individual phase adjustment except for placement? Does it matter? I had believed that coherent phase was pretty important for bass clarity. Thanks
Rich

[Duke]

On a side note, we woke up this morning to 35 inches of fresh snow. It will be fun shoveling the driveway.

Wow!  I woke up to about a foot or so, but won't expect any sympathy from you guys! 

An advantage that a rectangular horn has over a round horn is the closer center to center distance between the tweeter and the woofer thereby a closer approximation of a single source.

Good point, and I should have mentioned that.   

I am glad you are taking the concept more high end, rather than competing for price. As you said there are plenty of cheap econoboxes available now, and will be great for HT. I built an Econowave exactly per Zilch's plan and it was anything but high end sound. I upgraded every part and it was significantly improved. But there were still issues with crossover beyond my ability to fix.

Just for the record, I didn't knowingly virtually copy Zilch's work - I didn't know he was using the Pyle PH612 + a big woofer until after I'd already tried it.   I recall seeing a curve that he ran at some point, and it was impressively flat, but I also could tell that he wasn't taking into account a couple of little things that I pay attention to.  Crossover design is a dark art, and "flat" doesn't always sound "flat". 

But the swarm idea has my curiosity.   Since they are all on one amp I guess there is no individual phase adjustment except for placement? Does it matter? I had believed that coherent phase was pretty important for bass clarity.

Well there are as many different ideas about subwoofer design as there are subwoofer designers (whether they do it for love or for money), and maybe more.   One aspect of my paradigm is, I consider the in-room frequency response to be by far the most important thing.  Far more important than phase, for instance, other than phase response's effect on frequency response (like how subs + mains combine in their crossover region).   The ear is very poor at hearing phase and timing effects at low frequencies, but it is much better at hearing frequency response effects.   

According to information presented in an AES paper I read some time ago (and don't have the reference for unfortunately), the ear cannot even detect the presence of bass energy from leas than one wavelength of sound.   Think about how long bass wavelengths are, and what our listening room dimensions are.   So by the time we can even detect the presence of bass energy, the room is already affecting the sound.  In order to hear the pitch of a bass tone (in the absence of overtones), we need to hear several wavelengths.   So any efforts to carefully preserve phase response in the bass region are trashed as soon as we put the system in a room.   

Now one of my goals with the Swarm is to de-correlate the bass energy.  Highly correlated in-room bass energy gives us strong, widely-spaced peaks and dips from the room modes, and that sounds unnatural.   Decorrelated bass energy results in far more peaks and dips, spaced much closer together, such that they tend to average one another out, both in the actual in-room measurement and perceptually.  So we end up with many smaller peaks and dips, more closely bunched up.  If our peaks and dips are close enough together, the ear tends to average them out perceptually, rather than hearing them separately, but they need to be within 1/3 or maybe 1/4 octave of one another for this psychoacoustic phenomenon to come into play.   So the audible benefits of a multisub system get an added litttle boost there from the ear's averaging-out characteristic, beyond what we might expect from the improvement in the measured in-room response. 

Another way of looking at it is, the larger the room, the more strongly de-correlated the bass energy will be (in general).   Small rooms tend to have sore-thumb peaks that result in some bass notes "blooming".   A distributed multisub system helps to bring big-room low frequency characteristics into a small room by introducing strong decorrelation.

The amp that comes with the Swarm has a 0-180 degree phase control, which is probably plenty to get a good blend in the crossover region.  As for the phase of the individual woofers, some users find they get smoother in-room response by reversing the polarity of one of the subs.

[richidoo]

Thanks for explaining!

[jimlevitt]

Hi Duke,

How close to the wall (behind the speakers) can the mains be placed? And how close to the side walls? My room is 14' x 20', but due to traffic flow the actual sitting area isn't as deep. I'd love to find some speakers that sound good while positioned close to the wall rather than three or four feet out into the room.

Will you be offering stands for these? If so, any idea on pricing?

Glad to see you're still kicking out designs for home users.

[jtwrace]

Thanks for explaining!

Now it's time for you to step up! 

[opnly bafld]

How close to the wall (behind the speakers) can the mains be placed? And how close to the side walls? My room is 14' x 20', but due to traffic flow the actual sitting area isn't as deep. I'd love to find some speakers that sound good while positioned close to the wall rather than three or four feet out into the room.

http://audiokinesis.com/product_ak_rhythm-prism.html

"Placement close to a wall, and even in a corner, is feasible thanks to the highly adjustable bass tuning system."

[poseidonsvoice]

Now it's time for you to step up! 

LOL! +100!

Best,
Anand

[Berndt]

Looks good Duke.
The round wave guide could always be machined on the back side to make fitment a walk through.
I would be happy to do this if you need any squared away.
Look forward to hearing about these dream maker 2's turn out...

[Quiet Earth]

I'd love to find some speakers that sound good while positioned close to the wall rather than three or four feet out into the room.

Let's see now,,,, who else makes a speaker that thrives on rear wall proximity, gets excited with single digit tube watts, has a broad and even power response with good dispersion, and never requires a subwoofer? It's uh,,,  it's um... it's..... Well, it will come to me eventually. 

Your speakers look great Duke. Keep up the good work! 

[Duke]

How close to the wall (behind the speakers) can the mains be placed? And how close to the side walls? My room is 14' x 20', but due to traffic flow the actual sitting area isn't as deep. I'd love to find some speakers that sound good while positioned close to the wall rather than three or four feet out into the room.

Opnly baffld has got it right; we can reduce the bass energy from the mains significantly by plugging one or even both ports.   The large-diameter midwoofer + constant-directivity waveguide + severe toe-in significantly reduce interaction with the nearby walls over the rest of the spectrum.  Yes there will still be some boostage in the lower midrange, but it won't be unpleasant - just a bit of warming up.

With a floorstander enclosure and generous boundary reinforcement, we could start thinking about going subwooferless.

Will you be offering stands for these? If so, any idea on pricing?

I think four-post stands from Skylan would be better and less expensive than what I could do. 

[Duke]

Let's see now,,,, who else makes a speaker that thrives on rear wall proximity, gets excited with single digit tube watts, has a broad and even power response with good dispersion, and never requires a subwoofer? It's uh,,,  it's um... it's..... Well, it will come to me eventually. 

Yah, but mine use rear-firing ports!!  Oh wait... nevermind...

I think all of audio should take note of what those guys are doing. 

[jimlevitt]

Yah, but mine use rear-firing ports!!  Oh wait... nevermind...

I think all of audio should take note of what those guys are doing.

I've been away from AC for a while, so I'll admit to being clueless: who are "those guys?"

Duke, is this new speaker an improvement over the Rhythm Prism? Is the floorstander version likely to be more or less room-friendly (in terms of bass response) than the stand-mount plus Swarm?

[Duke]

Looks good Duke.
The round wave guide could always be machined on the back side to make fitment a walk through.
I would be happy to do this if you need any squared away.
Look forward to hearing about these dream maker 2's turn out...

Thank you for the offer Bill.  Very kind of you, but I'll probably pass.

The last round-waveguide Dream Makers are, I suppose, version 1.1.  The forthcoming version 2.0 will use a rectangular waveguide-style horn, and will forgo the solid-wood-over-plywood construction (very expensive and heavy) in favor of veneered MDF, which will bring the price down considerably. 

I've been away from AC for a while, so I'll admit to being clueless: who are "those guys?"

"Those guys" are Audio Note, who do a superb job of taking advantage of boundary reinforcement.  I sometimes get razzed for saying that rear-ported speakers can go close to the wall if the box is tuned appropriately, and Audio Note has been proving for years that the technique works very well.

Duke, is this new speaker an improvement over the Rhythm Prism?

Yes, but then it's a considerably more expensive speaker, even if we take away the Swarm and make it a floorstander. 

Is the floorstander version likely to be more or less room-friendly (in terms of bass response) than the stand-mount plus Swarm?

The Swarm is more adjustable and therefore more adaptable to a wide variety of room situations than the floorstander version would be, but the floorstander version would still be much better than average in that respect. 

[James Romeyn]

Congratulations Duke on what looks like a great and promising new loudspeaker!

I was scheduled to hear this beauty but last minute issues prevented my audition the day Duke shipped them.  For persons who have not had the pleasure of hearing Duke's latest work, he inches closer and closer to the see-through transparency of the world's best electrostatics.  I heard the late Bob Crump's CES demo shortly before he passed, with Blowtorch preamp, hot as witches brew Halo JC-1 mono blocks, and huge Sound Lab stats sited 1/3rd the room's length from the front wall.  Also auditioned Sanders' big 'stat panels at recent CES.  It's amazing to approach that transparency but with a huge sweet spot (stats often have the smallest sweet spot).  Also, if you've never heard a speaker that does not thermally limit, you're in for a treat.  But be forewarned, the experience will permanently ruin your perception for this level of unrestricted output.  It's quite amazing how a speaker's thermal limitations restrict its sound stage size as level increases.   

Battery powered fanatics: if battery powered power amps exist, bring them to audition this speaker at the first opportunity. 

My setup advice for Duke's Distributed Sub Array changed over the years.  My current advice is reasonably easy to replicate in any room within a couple hours, give or take depending if you have help and how fast you work.  The FR results speak for themselves.  One sub setup in the smoothest location yields a 13 dB FR window at the sweet spot, much worse variation at other locations, and about -6 dB @ 20 Hz.  Conversely, four subs, one inverted, yield a 6 dB window, barely worse even in the corners, and -1.5 dB @ 20 Hz.  Without EQ and without room treatment.   

The 7 dB tighter window is obviously good.  But better yet is timing accuracy and the fact there are no hot spots such as result from EQ; bass is generally similar everywhere in the room.  Bass systems other than Distributed Array result in severe timing distortion in the bass.  The worst and most obvious error is bass notes continue bouncing between walls after the new note appears, resulting in two disharmonious notes.  Imagine a double bass section with double the number of instruments called for in the score, and on certain notes half the bass play the wrong notes while the other half play the right notes.  This is a good analogy for bass mode effects.  Frankly, after becoming accustomed to a complete lack of this phenomena, it is easily noticed and strongly disliked when you hear it later in lesser playback systems.

I remember Bob Carver once told me that humans have extremely high tolerance for HD in the bass, approaching levels in the range of 30% THD.  If true, then it is wasteful to spend money only for lower HD in a sub woofer.  But this tolerance does not extend to timing, where bass modes cause two disharmonious fundamental tones, potentially spaced by as little as a half-step on the music scale.  I don't know the math formula to calculate such distortion, but I feel sure it's exponentially higher than 30%, maybe approaching 300%. 

When I worked at VMPS I was convinced low distortion caused the extreme clarity in Brian's huge, floor to ceiling separate bass towers, each with four or six active 12s.  I walked up next to the towers and marveled at their pitch clarity and overall presentation, while they effortlessly played St. Saens organ symphony or whatever huge score Brian chose.  The active drivers moved little except on large transients.  Now I'm convinced their best quality is that such towers damp the worst mode, the floor/ceiling bounce.  Plus they are so large that their physical presence in the room minimizes modal effects.  They do barely distort, but not for the reasons most people suspect.  The fact of their size, weight, and cost are separate issues, all usually negative.       

If I only knew about Duke's bass philosophy, and how to implement it prior to spending a lot of money on professional room treatment including three-sided acoustic ceiling soffit, in my last room.  You or I or both of us would choke if I disclosed the cost.   

From my reading, only Double Bass Array seems competitive performance wise with properly implemented Distributed Bass Array, but the former costs considerably more and is more complex to properly implement. 

[jhm731]

I guess you have to hear this set up to appreciate it, but IMO it's plug ugly compared to the lower cost Jazz Module.

[James Romeyn]

I guess you have to hear this set up to appreciate it, but IMO it's plug ugly compared to the lower cost Jazz Module.

Again, I've not yet had the pleasure of auditioning this latest AK Planetarium model.

I humbly apologize for any errors in this post and trust Duke will immediately correct them.  IIRC the JM arrived about a decade ago, in the early-mid 00s.  By the late 00s TAD discontinued the JMs super-powered 10" (nominal) mid bass.  Because the JM achieved considerable cult and collector status for its unique combination of attributes, including its cosmetic appeal mentioned above, Duke speculated many times about a JM II, but none has appeared. 

In my personal and business experience, MSM grossly under-report (i.e. blatantly and knowingly lie about) inflation stats.  Every central bank in the world floods their markets with currency.  Since 2008 US debt jumped 50%, though of course little of it landed in the pockets of anyone reading this.  Sorry for the mini lecture.  This is a long way of saying the cost for a new released-today JM would bear absolutely no resemblance to the $4500/pr price posted at Duke's website.  I would estimate something much closer to about $6k.  The most pertinent fact is that no new JM currently exist, and that's not much open to debate.  The only source for JM is the resale market.   

I talked with Duke at length about his latest 15" mid bass, the compression tweeter, and the wave guide employed in this new model.  Every report is glowing, especially the mid range and treble, which appears to equal or possibly exceed that of every prior AK model.  I have lots of listening time with both the JM and its big brother "Offset Vertical Bi-pole" Dream Maker.  At least one AK model after the JM and DM (sorry I can't remember the model) has lower audible distortion and more electrostatic-like transparency.  I'm not saying every JM and DM owner would prefer the new model, but I am saying I would.  There is something intangible about the JM and DM that is very endearing.  They remind me of my best memories blasting around Mt. Tam on my early-mid 70s Yamaha RD350. 

Beyond that, at this date, it's quite difficult to argue against the "theory" that the ideal domestic loud speaker must be split into two systems, one below and one above the Schroeder frequency.  No quantity and no type of EQ or room treatment or wishful thinking can change this.  Any and every one-piece loudspeaker, the so-called full range single-column speaker, compromises audio performance in a real and tangible way. 

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…” 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…” (One maker/seller of such treatments instructs audiophiles to purchase as much treatment as their wallet can afford.)

Each reader can determine the degree to which they accept the compromise, but the existence of the audible compromise is easily shown in the math and in the audible performance: it is a virtual mathematical certainty that the ideal site for the mid/treble differs from the bass.  Also, a Distributed Array (and apparently the more costly and ideally-installed-in-wall Double Bass Array) offer proven performance solutions available in no other bass system.       

   

[jhm731]

Guess I should have got a pair of JMs when they were available.

[richidoo]

James Romeyn, with your comments about overlapping bass notes are you suggesting that distributed bass system effectively reduces low frequency reverb time of a room? I am under the impression that only absorption or an active cancellation scheme can do that. That would surely be a great benefit if it were true that passive, randomly placed subs can actually cancel modes, not just flatten FR. I thought that a swarm simply averages out the pressure distribution through the room to make flatter FR despite the room modes, but not able to reduce reverb and dry up the room. 
Thanks
Rich

[totoro]

What would the floorstanding version without the subwoofers cost? In my case I already have subs, and want floorstanders so my pets can't knock them over, so I guess I could go sealed and not worry so much about extension.

[Duke]

What would the floorstanding version without the subwoofers cost? In my case I already have subs, and want floorstanders so my pets can't knock them over, so I guess I could go sealed and not worry so much about extension.

A pair of Planetarium Delta 15 main modules in floorstander version would run ballpark four grand. 

I'd propose low-tuned porting, so that the mains are making some contribution way down deep, and thereby increasing the number of in-room bass sources you have distributed about.  Of course if you prefer, you can easily plug the ports supertight with a plumber's expandable test plug.  The ports would be on the back, out of sight. 

Also, I'd want to discuss with you the exact dimensions of the enclosure.  Theoretically we could keep the same footprint and just make the box taller, but we might want to look at a more deliberate ratio of internal dimensions.