The Manipulated Vortex Waveguide speaker - the Event Horizon 210

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Duke

At the recent Rocky Mountain Audio Fest, we showed two new speakers, and since the Dream Maker LCS system already has its own thread, I wanted to start this one on the rather radical new Event Horizon 210.

Here's a shot from the show:

And, here's a shot from my living room:

That may look like a reflex box with big ports, or an under-sized back-loaded horn, but it is neither.  It's a new type of enclosure design, the Manipulated Vortex Waveguide (MVW), patent pending.  This is the invention of Steve Regier and Tom Ewers of Piper City, Illinois, under the brand name Big E Loudspeakers.   I consider myself extremely fortunate to be involved with these two mad scientists, and their associates, in bringing the MVW into the home audio world. 

Now I cannot prove any of the claims I'm about to make about the behavior of these speakers, so feel free to reject my description as pure marketing or whatever other unflattering term comes to mind.  And my understanding of what these speakers do is still evolving. 

Briefly, inside the box are structures whose dimensions have been carefully manipulated to generate a vortex, one on each side of the box.  These vortices are guided to the outside world through the openings, called "bells", on either side of the cone drivers, in such a way that they cover a fairly wide horizontal arc.   Hence the name of the enclosure type, manipulated vortex waveguide, or MVW for short.

Sound propagates more efficiently on the edge of a vortex than through still air, which why jet engines are so freakin' loud.  In fact, the study of the acoustic properties of a vortex dates back to the early 1950's, when efforts were first being made to understand and reduce the loudness of jet engine exhaust. 

One characteristic of the MVW enclosure was highlighted by their less-than-optimum up-against-the-wall placement there at RMAF, and that is their ability to project a decent soundstage (including a fairly wide sweet spot) with much less than optimum placement.   This is in part due to the SPL falling off a bit more slowly with distance than from a normal point source; over in the PA world, measurements taken have indicated behavior in this regard that looks more like what one would expect from a line source, at least up to a certain point, beyond which they seem to revert to typical point-source-approximating behavior.   In other words, the vortex effect seems to have an event horizon, wiithin which their behavior is somewhat unorthodox.

Another interesting characteristic of the MVW is that it exhibits the opposite of dynamic compression, which I guess we'd call dynamic expansion.   The efficiency actually inreases a bit as we crank up the power - sort of like a ramjet engine is much more efficient at high speed than at low speed.  The result is rather startling dynamic contrast.  The real-world efficiency of an MVW speaker seems to be 2 or 3 dB higher than the calculated efficiency, this based on my comparing MVW prototype speakers side-by-side with conventional speakers of known efficiency. 

And yet another characteristic of the MVW speaker is its lack of cabinet-induced overhang on the tail end of the waveform.  Once the cone stops energizing the vortex, it quenches very quickly.  The result is very good clarity, even in the bass region.  Combined with the dynamic expansion characteristic, we get really good impact - it's a very tight-sounding speaker.   Over in the bass guitar cab world, MVW cabs have been on the market for some time now (built by Mike Arnopol, who some of you may know as Patricia Barber's bass player), and they allow bass players to play 1/8 and even 1/16 notes with good definition, instead of it just turning into a wall of mud.

Now the MVW speaker is not without its idiosyncracies.  In some ways, it behaves more like a musical instrument than like a typical speaker system.   For instance the type of wood used makes a significant difference.   Many different types have been tried, and so far Baltic Birch gives the best results. 

These particular speakers were designed by Steve and Tom, and the enclosures themselves built by Sam Crook of Speaker Hardware.   I am licensed to offer MVW speakers to the high-end home audio world, and my primary role is crossover design.  I feel like the crossover was about 90% done when I took these speakers to RMAF; imo, I still have a bit more tweaking to do. 

The Part-Time Audiophile posted some photos of (and commentary) on the Event Horizon 210 speakers, click here and scroll down a bit.


JohnR

Duke, sorry if I missed it but just to get me thinking on the right track, is there a tweeter/compression driver between the two mids?

Duke

Duke, sorry if I missed it but just to get me thinking on the right track, is there a tweeter/compression driver between the two mids?

Yes, there's a compression driver that fires through that slot-like aperture between the mids.   

Crossover between woofer and mids is in the 200-250 Hz ballpark, while the crossover between mids and compression driver is way up around 8 kHz.  Now normally we'd expect side-by-side 6-inch cone mids to beam badly, even if they're slightly cross-firing, if we run them up anywhere near that high.  However such does not seem to be the case.  Rather, it seems that the vortex improves the dispersion in the horizontal plane eyond what we'd normally expect.   The change in tonal balance when walking back and forth in front of the speakers is minor.

JohnR

Thank you Duke. I will read and digest.

playntheblues

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Hi Duke, congrats on a great show (RMAF)!  What are the specs on these bad boys?  DB of Eff, 3db down points etc.

Berndt

Not one, but two new designs unveiled?
Youvguys are killing me. How low do they go?

playntheblues

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I found the eff. in the article....96db

konut

Fascinating. A few questions. Is the mid-high cab separate from the bass cab? Do the mid drivers also  benefit from the MVW technology? How do you address the cancellation caused by the cross-firing mids? Any plans for single bass, single mid, tweeter, cab?

nullspace

Brief video of the speakers @ RMAF: http://youtu.be/pGgaIeCz7lY.

From what I can hear, sounds great Duke -- wish I had made the trip to hear them. Best of luck with the new speakers. What's the impedance look like? Amenable to high-Zo amps? Ballpark price?

Regards,
John

Berndt

High efficiency, prosound drivers, danley style Crunk .

Duke

Hi Duke, congrats on a great show (RMAF)!  What are the specs on these bad boys?  DB of Eff, 3db down points etc.

I don't have exact specs on the low end, and this isn't a technology that we can model with accuracy yet.  Still too young.   I think the bass response sort of approximates a low-Q sealed box, as far as having a gradual rolloff, but we're able to use higher efficiency woofers than would be suitable for a sealed box.   I'd probably claim ballpark lower 40's/upper 30's, but we played a pipe organ recording that someone brought and, once we turned the volume up a bit, it made the room shudder.  We played part of a kodo drum track and the exhibitor two doors down came into the room to track down the rumble that had permeated his room, at first he thought his subwoofer amp was dying a nasty death and trying to take its woofer with it.  So there is more happening way down low than my claim implies, but the low end isn't apparent until something like that comes along.

The calculated efficiency, based on the woofers' Thiele/Small parameters, is in the 96 dB ballpark.  But the characteristic of the vortex enclosure that causes its efficiency to increase a bit as more power is applied results in a somewhat higher "real world" efficiency.  We probably get an extra 3 dB or so once the vortex generators get hit with some power. 

Not one, but two new designs unveiled?
Youvguys are killing me.

'Bout killed me too!  I hope to never do that again - two new designs at one show, that is.

I didn't give out much in advance on the MVW speaker because frankly I wasn't confident enough in my ability to get it up to audio show level performance.  We had a few hurdles to overcome along the way - it has enormous potential, and in some ways corresponding challenges, given the attention to detail that is called for in the home audio market.

In my opinion, a good home audio speaker has to do two things:  First, it has to do something so well that you can close your eyes and suspend disbelief and get lost in the music.  That something can be timbre, imaging, impact, coherence, clarity, sense of immersion, whatever.   Doesn't have to do them all, but has to nail at least one of them.   And then (this is the hard part), the speaker has to NOT turn around and do something so wrong that it spoils that illusion.  So my primary job is detecting, identifying, engaging, and functionally destroying audibly significant colorations and distortions.
 
I've done some work in the prosound world in bass guitar cabs, and in a live sound setting the bar is not nearly as high as far as minimizing coloration.  A little coloration isn't going to spoil the illusion because there is no "illusion" - it's reality that you're experiencing, and a little coloration is just part of it.   Not that this is anything new of course, but beating a prosound-type speaker into home audio smoothness can be a challenge.  I believe that I have done so with waveguide-style horns, and now my job is to do so with this new type of enclosures.  Fortunately I'm able to work closely with the inventors, who come up with amazing outside-the-box approaches to help me do my job.  It's like I'm struggling to think in freshman algebra, and they're thinking in differential equations without even being aware of it. 

Fascinating. A few questions. Is the mid-high cab separate from the bass cab? Do the mid drivers also  benefit from the MVW technology? How do you address the cancellation caused by the cross-firing mids? Any plans for single bass, single mid, tweeter, cab?

Yes, the mid-high box is just sitting atop the woofer box, connected only by wires.  The crossover is in the base, at the bottom of the wooferbox - the inside of the enclosure itself is too busy for me to shoehorn the crossover into it. 

The mid drivers are indeed also loaded by manipulated vortex waveguide enclosures.  They cover roughly 220 Hz to 8 kHz, so a lot is asked of them.

As to how the design addresses the cancellation caused by the horizontally-spaced cross-firing mids, I don't fully understand.  I have worked with splayed arrays in the past (mostly with fullrange drivers), toed both inward and outward, and always felt they had poor clarity and only so-so radiation pattern. 

That being said, the toe-in does prevent a strong on-axis hot-spot.  Then we have the output of the mids encapsulated by the vortex, to the left and to the right.  The vortex energy, particularly the lower-frequency vortex energy if I understand correctly, acts as a carrier wave and so you have propagation of the shorter-wavelength mids and highs that is guided more by the vortex than by the physical dimensions of the drivers themselves. 

I have experimented with several other, smaller configurations, and will continue to do so.   Most have not had side-by-side drivers, but I find no degradation of the horizontal dispersion from using a side-by-side driver format with this technology.   I know, this is all goes against everything you and I both know about loudspeaker design, so I don't expect you to take it at face value, but just be open to the possibility that there is something going on that is outside the norm.

This is all like weird science fiction, so let me offer an analogy:  Suppose we lived in a world where Helmholtz resonance had not yet been discovered.  We have two types of speaker enclosures:  Sealed boxes, and open baffle dipoles.   Along comes this idiot who cuts a small hole in his sealed box and claims that the result is more powerful bass, when we all know good and well that a hole in a sealed box turns in into a poorly designed dipole, so we know the result is going to be less bass.  And we would be wrong.

So I don't ask you to go so far as to believe any of what I'm saying - just be open to the possibility.  I'm in a fortunate position at the moment - my and Jim Romeyn's "conventional" (relatively speaking) Dream Maker LCS system was deemed a success by many who heard it, so that gives me a little credibility.  I'd like to cash in on some of that credibiliy by saying that I wouldn't be actively engaged with the Manipulated Vortex Waveguide if I didn't believe that it was doing something special. 

« Last Edit: 17 Oct 2013, 02:51 am by Duke »

Duke

Brief video of the speakers @ RMAF: http://youtu.be/pGgaIeCz7lY.

From what I can hear, sounds great Duke -- wish I had made the trip to hear them. Best of luck with the new speakers. What's the impedance look like? Amenable to high-Zo amps? Ballpark price?

Regards,
John

Thank you, John!  I hadn't seen that video before. 

The impedance is 16 ohms, not perfectly smooth, but then when it's that high, we can live with less than perfect smoothness.  The amp we used was the Atma-Sphere S-30, which does 45 watts into a 16 ohm load, and has an output impedance of about 7 ohms.  Never pushed it all the way during show hours, but we did after the show Saturday evening, when everyone had gone to dinner.  Played that Kodo drum track all the way through, with the meters peaking out, but I didn't hear obvious clipping.  It was thunder.  Made my wife scream three times, and she was white-knuckling it all through the track - she said it lit up her "fight or flight" response.  That's something these speakers do well for some reason - they hook into the limbic system and sound very exciting, conveying that aspect of live music very well.   

Haven't figured out pricing yet, it's a very labor-intensive box filled with expensive parts, and we haven't solved the finish puzzle yet.  The finish you see is a black stain that my wife applied about two days before the show, as we'd run out of time to have the cabinets professionally painted.  I kinda like the look, as much for what it's not as for what it is.  It's a change of pace at least.   For now, let's say eight grand ballpark, but that may only apply to a "utilitarian" finish version.

High efficiency, prosound drivers, danley style Crunk.

Okay, now we're getting into the fun stuff!!  This is a 128 dB ballpark capable speaker.  The designers have pumped 900 watts into it on a Techmaster cut that has strong 22 Hz fundamentals without the woofers farting out.  That was with the drivers wired in parallel for 4 ohms; obviously I went for the OTL-friendly 16 ohm configuration, but either is quite feasible. 

We're used to nice smooth laminar flow of our backwave energy, in a ported box, backloaded horn, or transmission line.   Nothing wrong with that, but it's not the way of the vortex.  Vortex = turbulence, and turbulence = de-correlation.   If the energy coming from the bells was nice and laminar, the speaker wouldn't go down very deep because the path length isn't long enough to support low bass - we'd get cancellation instead of reinforcement down low.  But instead the energy that emerges from the bells is de-correlated, emerging in quasi-random phase, so its net effect is to reinforce the energy off the front of the cone, but not perfectly so.  In practice we get roughly +3 dB from the de-correlated vortex energy, instead of the theoretical +6 dB we'd get from a back-loaded horn at the frequency where its output is in-phase with the front of the cone - but then our back-loaded horn would also have a very deep null where the backwave energy emerges 180 degrees out-of-phase. 

Why doesn't this de-correlated sound from the bells screw up the clarity?   Well, we get our timing cues from the first-arrival sound, and then the de-correlated later-arriving energy is conceptually consistent with what we're doing in the Dream Maker LCS system!  Just as, counter-intuitively, the extra scrambled-up (de-correlated) reverberant energy from the effects speakers in that system actually improves the clarity and three-dimensionality of the presentation, likewise the delayed & de-correlated energy emerging from the bells actually improves the clarity and three-dimensionality of the MVW system.   It's like we're using the inside of the box for our turbulent path-length-induced time delay, rather than taking the long bounce from floor to ceiling.

Okay, so we have the extra energy from the vortex adding to the energy from the front of the cones, and this effect roughly doubles the air-moving capability of the speaker.  Over in the bass guitar world, Mike Arnopol's MVW cabs behave as if they have twice as much displacement (woofer cone area x linear excursion) as they really do.  The woofer I'm using is the Eminence Kappalite 3010LF.  Go calculate what sort of SPL you could expect from four of those babies per side, and that's the ballpark we're in.

Where this technology is really going to dominate is in sound reinforcement.  Leland Crooks of Speaker Hardware is bringing the MVW cab into the PA world.

Since the enclosure isn't relying on resonant characteristics for its low end (as do sealed and especially vented boxes), there is no overhang added to the tail ends of the waveforms.  The result is great clarity, even down through the bass region.  The de-correlation characteristic that I mentioned earlier accomplishes pretty much the same thing that I aim for with my distributed multi-sub Swarm system, which is to get the in-room bass energy combing in quasi-random phase, resulting in a net smoothing effect. 

One listener on Saturday summed up the Event Horizon 210 pretty well I think.  He just said, "That's the live sound".   Yup, that's what it does well. 

MJK

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Quote
Sound propagates more efficiently on the edge of a vortex than through still air, which why jet engines are so freakin' loud.  In fact, the study of the acoustic properties of a vortex dates back to the early 1950's, when efforts were first being made to understand and reduce the loudness of jet engine exhaust.

Vortex and fluid flow go together, I get that and remember some of my fluid dynamics from a long time ago. But sound propagation is not net fluid flow, it is just tiny vibrations of air molecules back and forth without any net displacement.

At first glance this reads like some major snake oil. I am not saying the speaker does not sound good or that there is nothing special going on, I am stuggling with the "vortex" as an engineering/physics/acoustics description of what produces this enhanced performance.

Sorry.

Berndt

I am seeing the MVW with a LCS behind it and calling it good.

*Scotty*

I would be interested in seeing a quasi-anechoic full frequency measurement sweep and an impedance sweep. Bass extension would be documented and the impedance curve in the bass region would tend to indicate at what frequency the system's bass resonance occurs, if there is one.
 It might be something new and measurements would document it.
Scotty

Duke

Vortex and fluid flow go together, I get that and remember some of my fluid dynamics from a long time ago. But sound propagation is not net fluid flow, it is just tiny vibrations of air molecules back and forth without any net displacement.

At first glance this reads like some major snake oil. I am not saying the speaker does not sound good or that there is nothing special going on, I am stuggling with the "vortex" as an engineering/physics/acoustics description of what produces this enhanced performance.

Sorry.

I don't blame your BS detectors for going off, and thank you for being civil about it.  They should go off!!

My description may well have been imprecise and/or incorrect in some ways.  Getting back to the jet engine example, the vortex generated by a jet engine has a profound effect on the sound of that engine well beyond the distance that the swirling vortex itself extends. 

MJK

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Getting back to the jet engine example, the vortex generated by a jet engine has a profound effect on the sound of that engine well beyond the distance that the swirling vortex itself extends.

OK, but a jet engine has a whole lot of air flowing through and exiting out the exhaust. The air flowing past or over an exhaust structure will produce many vortices. But for a speaker there is no net air flow, just very small air oscillations. Maybe the internals of your speaker enclosure use standing wave resonances very creatively to generate an increase in efficiency and great sound, but I have my doubts about any vortex being created.

Duke

OK, but a jet engine has a whole lot of air flowing through and exiting out the exhaust. The air flowing past or over an exhaust structure will produce many vortices. But for a speaker there is no net air flow, just very small air oscillations. Maybe the internals of your speaker enclosure use standing wave resonances very creatively to generate an increase in efficiency and great sound, but I have my doubts about any vortex being created.

I don't feel at liberty to comment on details of the internal structure, but that's obviously where any intentional vortex shedding would be happening, and it would be somewhat level-dependent. 

Duke

I am seeing the MVW with a LCS behind it and calling it good.

That is a definite possibility.  Unless we do a major redesign, we'd have to drive the LCS effects speaker with a separate amplifier to get the levels to match up, as there's a considerable efficiency mismatch otherwise.

I would be interested in seeing a quasi-anechoic full frequency measurement sweep and an impedance sweep. Bass extension would be documented and the impedance curve in the bass region would tend to indicate at what frequency the system's bass resonance occurs, if there is one.
 It might be something new and measurements would document it.
Scotty

Last I heard, the frequency response measurement protocol that seemed to work the best was to take a reading outdoors at some distance using full-spectrum pink noise instead of a sine-wave sweep.  That's not something I could easily do, but at some point it will probably happen. 

Berndt

Duke, I can see why you wanted me to wait now.
Super interesting.