[Duke]

AudioKinesis and James Romeyn are proud to introduce a new class of product, the system-enhancing Space Generators. The Space Generators can make most home listening rooms sound bigger and most home stereos sound better.

The ear judges the size of an acoustic space largely by the time delay between the first-arrrival sound and the onset of reflections.  We can fool the ear into thinking the room is bigger than it really is by introducing a fairly strong surge of reflected energy that arrives after a fairly long time interval.  The Space Generators, developed using James Romeyn's Late Ceiling Splash technology, do exactly that.

But the Space Generators do more than just make your room sound bigger.  They address a fundamental shortcoming of most home stereo systems.

Today we have speaker systems that are quite good at getting the first-arrival sound right, but they usually fall short of recreating a reverberant field that reasonably approximates the live event.  We need a good first-arrival sound and a good reverberant field to create a convincing illusion. Simply adding more early-onset reverberant energy is not the solution because too much of it will start to mask the first-arrival sound.  We need to selectively add fairly late-onset reverberant energy. 

The Space Generators accomplish this by aiming their output so that it takes a fairly long time to reach the listening position (ten milliseconds is a “fairly long time” in this context).  The ear interprets this generous helping of late-onset reverberant energy as an indication of room size, and perceives the room to be larger than it actually is.  In particular, soundstage depth and a sense of envelopment are enhanced.  Timbre is also enriched because this additional reverberant energy is spectrally correct.  The first-arrival sound is not masked, the reverberant field is finally in the same league, and the net effect is greater than the sum of its parts.

The Space Generators are easy to add to most existing systems.  Their high impedance load in parallel with your current speakers will typically be well within your amplifier's comfort zone.  They have passive level and top-end “tilt”controls, and are suitable for use with speakers having a 2.83 volt sensitivity ranging from the lower 80's to the lower 90's. 

The introductory price is $1800/pair plus shipping.  That's a lot less than increasing the physical size of your room would cost. 

[TomS]

It's great to see designers who have both big and original ideas as well as the proven ability to implement them. This looks fascinating and as usual, I'll look forward to visiting this weekend.

Tom

[poseidonsvoice]

+1. You can tell us a lot more when we stop by! Have fun setting up on Thursday!

Best,
Anand.

[jtwrace]

This one I look forward to!

[Tomy2Tone]

Interesting to say the least....

Would this allow for a quick A/B testing of how the room sounds with/without the space generator?

[Duke]

Thank you, Tom and Anand and Jason!

Interesting to say the least....

Would this allow for a quick A/B testing of how the room sounds with/without the space generator?

Yes, that's definitely part of the game plan. 

[matt.w]

Sweet!

How do walls impact placement? Any limitations?

[Duke]

Sweet!

How do walls impact placement? Any limitations?

The Space Generators fire upwards at a slight angle such that their output can be directed bit, and some wall bounce is fine because it's at such a shallow angle that it will take at least one more bounce before the directional sound makes it to the listening area. 

One limitation is, the Space Generators should be at least a foot further away from the listening area than the main speakers. This is because there will be some low-level sidelobe energy and we don't want it to arrive before the "precedence effect" kicks in because it could confuse the imaging.   

[poseidonsvoice]

In front of or behind the speaker if we are talking side wall? What do we do with the ceiling?

Heights recommended? Bare? Diffuse? Doubt absorption unless you have a very low ceiling height. Most ceilings are 8 ft as it will be at RMAF. Mine are 10.5-11 ft.

Without disclosing the specific drivers, can you tell us size and arrangement? Is it a quad array?

I'm reading that the efficiency into 2.83V is variable with a passive level control in the signal path between high 80's and low 90's. Bandwidth and impedance variation over what bandwidth? I figure impedance will have to be consistently high for this to work electrically.

Best,
Anand.

[smk]

You certainly have your work cut out for you overturning the conventional wisdom of the less in the signal path is better mentality. Sounds to me like one of those headphone switches to add reverb to the sound stage for loudspeakers. Like what Headroom used to manufacture. Good luck!

[RDavidson]

Kind of reminds me of Winslow Burhoe's Silent Speakers, and a couple of his EPI designs.
http://directacoustics.com
...Same base principal but in a unique application.

Is it "purist?" Maybe not. But no one lives in an anechoic chamber. I like seeing creative solutions to the room problem. I can see where something like this could be better or more enjoyable on many levels than dealing with (intrusively large and often ugly) room treatments.

[Duke]

In front of or behind the speaker if we are talking side wall? What do we do with the ceiling?

Heights recommended? Bare? Diffuse? Doubt absorption unless you have a very low ceiling height. Most ceilings are 8 ft as it will be at RMAF. Mine are 10.5-11 ft.

Without disclosing the specific drivers, can you tell us size and arrangement? Is it a quad array?

I'm reading that the efficiency into 2.83V is variable with a passive level control in the signal path between high 80's and low 90's. Bandwidth and impedance variation over what bandwidth? I figure impedance will have to be consistently high for this to work electrically.

Good questions! 

We definitely want the Space Generators behind the main speakers.   

As long as the ceiling isn't deliberately absorptive, we should be in good shape with the range of tonal adjustability the speaker has. 

I don't yet know whether diffusion or reflection works best, as I haven't tried them in a room with good diffusion on the nearby room surfaces.   Ceilings up to 16 feet tall work fine, and I haven't tried it low-ceiling rooms, but should still work as the 10 milliseconds Earl likes between the direct and reflected sound isn't a hard boundary but rather a fuzzy transition zone.  [That's not meant to imply that Earl would agree with what I'm doing - I'm pretty sure he wouldn't - but he is one of my sources of information.]

The driver is a 10" coaxial.   That seemed the way to shoehorn the most radiation pattern control into the target 12" square footprint.

Bandwidth is 60 Hz to about 18 kHz.   The attenuation is purely in the form of series resistance, so I had to keep the impedance curve smooth so the frequency response isn't modulated by the level control.  It tracks quite well as we go from 88 down to 78 dB voltage sensitivity (you want the Space Generators to be several decibels down in volume relative to the mains).   I'm using an acoustic filter inside the box to deal with the impedance peak at system resonance.   It's not unlike something one might use for targeting a pervasive bass peak in a room, but on a smaller scale.

You certainly have your work cut out for you overturning the conventional wisdom of the less in the signal path is better mentality. Sounds to me like one of those headphone switches to add reverb to the sound stage for loudspeakers. Like what Headroom used to manufacture. Good luck!

Originally I delved into polydirectional speakers (bipolars) as a means of getting the basics right - specifically, tonal balance.  The relatively poor spectral balance of most speakers' off-axis energy is arguably detrimental to their typically rather good direct sound.   So if we can significantly improve the spectral balance of the off-axis energy by pulling it in the right direction, we're probably going to improve the speaker.  That's where the rather wide range of tonal adjustability of the Space Generators can come in handy - a slightly tipped-up balance can be dialed in to compensate for the rolled-off top end of most speakers' off-axis response.

Anyway in the course of working with the Late Ceiling Splash concept, the increase in apparent room size stood out as perhaps more beneficial than the improvement in timbre.  So that's what I'm putting the spotlight on. 

I don't think what I'm doing with the Space Generators would appeal to the engineer in a recording studio, but it might appeal to a fair number of music lovers.  I may send a pair out on "tour" for people to try in their systems. 

When I remembered to ask people whether they felt like they were hearing "more of the recording" or "more of the hotel room" with the Space Generators engaged, everyone who responded said "more of the recording".  That's not a scientific survey, but agrees with Toole's findings that the ear/brain system can better decipher complex sounds when it gets multiple "looks" via spectrally-correct reflections.

But you are right that it will be an uphill battle.  All of the worthwhile ones are!

Kind of reminds me of Winslow Burhoe's Silent Speakers, and a couple of his EPI designs.
http://directacoustics.com
...Same base principal but in a unique application.

Is it "purist?" Maybe not. But no one lives in an anechoic chamber. I like seeing creative solutions to the room problem. I can see where something like this could be better or more enjoyable on many levels than dealing with (intrusively large and often ugly) room treatments.

The difference is, the Space Generators are meant solely for use as secondary speakers.  They sound decent as main speakers, but more like for background listening, as their first-arrival sound is weak and not well differentiated from the subsequent reflections in that role.

When acousticians studied what the difference is between a good seat and a poor seat in a concert hall, here is what they found:  A good seal has a clear first-arrival sound, and then after some delay, a good reverberant sound.  In a poor seat, the two run together too much.  My theory is that most speakers can be positioned to give a good first arrival sound, with a reasonably long delay before the reflections come in strong, but that the reverberant field is inadequate in most rooms, in quality if not in quantity.  We lose liveliness when the two are not well differentiated, and by making the onset of reflections a more pronounced event in many systems, I think the Space Generators will improve liveliness. 

Now we don't want too much reverberant energy either, there's a "goldilocks zone" that will vary with the specifics of speakers, room, speaker locations, and listener locations.  But such variables are already in play, and I think the Space Generators are a tool that can move the reverberant field in the right direction for most systems.

[ACHiPo]

Duke,
Kudos for continuing to bring innovation out.  I need to figure out a way to hear your speakers one of these days.

Congrats on a successful show and more interesting products.

AC

[Occam]

Duke,

Kudos to you and James for that brilliant concept of moving the Haas effect generation from incorporation into the stereo mains, to separate, controllable auxiliary speakers.
Prior implementations, Olsher's CBAE, Linkwitz's Pluto &LxMini, Ritchie's Omnis, etc...  are straightforward, no extra boxes solutions, but constrain what we get via direct sound as they provide both the direct and delayed sound field.

A couple of questions -

Lets assume I'm using my subjectively ideal amps to drive my subjectively ideal direct radiating speakers, but the amps are operating near their limits given the speakers awkward impedance characteristics. Assume paralleling your Space Generators are simply too difficult a load (Yes, one could simply get a more appropriate amp).
1. Would it be practical to drive those Space Generators from a separate control amp, one with a volume control to dial in appropriate levels, and take the input from the preamp or directly from speaker terminals?
2. Given the precedence effect, what (subjective) impact does the quality of the amp driving the Space Generators have in comparison to the amp driving the main speakers.
3. If the answer to 2 above, is that the Space Generators driving amp is not (as) critical, would it be feasible to apply spectral adjustments via the SG's separate amp, with something like a mini-dsp, that could optimize overall spectral response, in addition to increasing percieved room size?

TIA,
Paul

EDIT: Just read about the 20 Ohm nominal impedance on the SG's so the concern about driving them in parallel with the mains is of minimal concern, but the Qs regarding additional processing for optimal spectral presentation, above and beyond the extant controls you offer, still stand.

[Duke]

Duke,
Kudos for continuing to bring innovation out.  I need to figure out a way to hear your speakers one of these days.

Congrats on a successful show and more interesting products.

Thank you!

Kudos to you and James for that brilliant concept of moving the Haas effect generation from incorporation into the stereo mains, to separate, controllable auxiliary speakers.
Prior implementations, Olsher's CBAE, Linkwitz's Pluto &LxMini, Ritchie's Omnis, etc...  are straightforward, no extra boxes solutions, but constrain what we get via direct sound as they provide both the direct and delayed sound field.

Thank you!

Yes the basic principles are known to many, but we're thinking that our implementation generally has more upside with less downside.

A couple of questions -

Lets assume I'm using my subjectively ideal amps to drive my subjectively ideal direct radiating speakers, but the amps are operating near their limits given the speakers awkward impedance characteristics. Assume paralleling your Space Generators are simply too difficult a load (Yes, one could simply get a more appropriate amp).
1. Would it be practical to drive those Space Generators from a separate control amp, one with a volume control to dial in appropriate levels, and take the input from the preamp or directly from speaker terminals?
2. Given the precedence effect, what (subjective) impact does the quality of the amp driving the Space Generators have in comparison to the amp driving the main speakers.
3. If the answer to 2 above, is that the Space Generators driving amp is not (as) critical, would it be feasible to apply spectral adjustments via the SG's separate amp, with something like a mini-dsp, that could optimize overall spectral response, in addition to increasing percieved room size?

Well Occam your questions kinda cut right to the heart of the matter, almost as if you were using a blade of some kind...

The Space Generators can absolutely be driven by a separate external amp, particularly if their effect on the impedance that the main amp sees is too great, or if their range of level adjustability is insufficient.

If you use a separate amp, its quality is far less critical than that of the main amp. 

And using mini-DSP on the Space Generators would indeed give you the power to really dial it in for your system.  Fortunately the configuration of the Space Generators already does the job right in the one area that is outside the scope of what DSP can fix, which is the radiation pattern itself.

[JLM]

At Duke's suggestion I added a Late Ceiling Splash tweeter behind each speaker.  Refer to my recent speaker review here on AC ("LCS tweeter add-on").

[poseidonsvoice]

At Duke's suggestion I added a Late Ceiling Splash tweeter behind each speaker.  Refer to my recent speaker review here on AC ("LCS tweeter add-on").

http://www.audiocircle.com/index.php?topic=137934.msg1468316#msg1468316

Best,
Anand.

[Duke]

Thank you very much JLM, and thanks for the link Anand!

[fakamada]

Duke, how would you describe differences between LCS placement options:
1. LCS touching front wall
2. LCS right behind wide baffle speakers (Zephrin style)

What I'm thinking is that 2nd option might be better fot mid/high frequencies but worse for low/mid.
(wide baffle casts bigger "shadow" for higher freq but lower freq wrap aroud it and interfere with direct sound)
While 1st option is more even for both hi/low freq but also requires a lot of distance behind main speakers because LCS is not so well hidden behind an obstacle.

What's your take on this subject. Which is better Zephrin style or regular LCS at front wall?

[fakamada]

I'm also thinking that open baffle LCS might be a smart solution. Hidden behind main baffle it would cancel out lower frequencies in a proper plane, so would not have sound wrapping around main baffles!