Something wicked this way comes... (2020 speaker teaser content)

Duke LeJeune

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They are calling the min phase as OSWG

Who are "they"?

From a paper Jean-Michel Le Cleac'h wrote about horns, I'll come back and post the link if I can find it:

"Michael Gerstgrasser's min phase horn is a good compromise between the Le Cléac'h horn and the OS Waveguide."

Update: Here's the link: http://www.rintelen.ch/download/JMMLC_horns_lecture_etf10.pdf

It looks more like the power-point slides from a lecture, and the above quote is found on page 125.
 
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Robh3606

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"Michael Gerstgrasser's min phase horn is a good compromise between the Le Cléac'h horn and the OS Waveguide."

Update: Here's the link: http://www.rintelen.ch/download/JMMLC_horns_lecture_etf10.pdf

It looks more like the power-point slides from a lecture, and the above quote is found on page 125.

Hello Duke

Did they ever actually build one?? That is based on simulations using a 3" flat diaphragm. Sims are great but I would like to see how a real horn performs that you can attach a compression driver too. You could use a 2490 but limited high end.

Rob :)
 
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Duke LeJeune

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Did they ever actually build one?? That is based on simulations using a 3" flat diaphragm. Sims are great but I would like to see how a real horn performs that you can attach a compression driver too.

I assume Autotech in Poland has built some "Minphase" horns, but I don't know.


* * * *

In other news, I have received and tested a rather interesting 1.4" throat compression driver. I asked the manufacturer to make a custom version of one of their compression drivers for me and they agreed but stipulated that it would not be "my" exclusive design - that they reserved the right to make it a regular catalog item if they so choose, which of course is fine with me. The improvement over the stock design reduces the moving mass and therefore improves the top-end extension, at the expense of a bit higher resonant frequency and corresponding reduction in low-end extension, and reduced thermal power handling. The latter is not an issue in a home audio application.

The advantage of this development is the feasibility of covering the region from about 700 Hz on up to 18 kHz with a single very high quality driver, with 100 dB ballpark system efficiency, on a really nice constant-directivity waveguide-style horn. There are drivers already on the market which can do this, but they have a significant amount of breakup in their top ends. My compression driver is not entirely free from breakup, but its "settling time" is extremely fast - the diaphragm doesn't "ring". Based on independent measurements I've seen in an industry publication (Voice Coil magazine), the diaphragm in my compression driver has behavior competitive with a Beryllium diaphragm, and arguably a bit better in some respects (such as "settling time"). None of the currently available Beryllium compression drivers can do 100 dB from 700 Hz out to 18 kHz without using a horn that has a very narrow radiation pattern at the top end.

(I've been calling it "my" compression driver, which is only true up until the manufacturer decides to put it into regular production, and then it becomes "their" compression driver.)

Now I'm still waiting on my big custom Oblate Spheroid waveguides to confirm these efficiency projections. The shop that is making my horns is moving halfway across the country, and that may push production of my first horns into early 2021. I hope not, but have no control over it.

However now that I've tested this sweet new compression driver on some off-the-shelf horns, I'm seeing the possibility of doing a considerably more affordable speaker using an off-the-shelf horn.

There will also be a Beryllium diaphragm version of my big Oblate Spheroid speaker, with a system efficiency probably around 96 dB.
 

morricab

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I assume Autotech in Poland has built some "Minphase" horns, but I don't know.


* * * *

In other news, I have received and tested a rather interesting 1.4" throat compression driver. I asked the manufacturer to make a custom version of one of their compression drivers for me and they agreed but stipulated that it would not be "my" exclusive design - that they reserved the right to make it a regular catalog item if they so choose, which of course is fine with me. The improvement over the stock design reduces the moving mass and therefore improves the top-end extension, at the expense of a bit higher resonant frequency and corresponding reduction in low-end extension, and reduced thermal power handling. The latter is not an issue in a home audio application.

The advantage of this development is the feasibility of covering the region from about 700 Hz on up to 18 kHz with a single very high quality driver, with 100 dB ballpark system efficiency, on a really nice constant-directivity waveguide-style horn. There are drivers already on the market which can do this, but they have a significant amount of breakup in their top ends. My compression driver is not entirely free from breakup, but its "settling time" is extremely fast - the diaphragm doesn't "ring". Based on independent measurements I've seen in an industry publication (Voice Coil magazine), the diaphragm in my compression driver has behavior competitive with a Beryllium diaphragm, and arguably a bit better in some respects (such as "settling time"). None of the currently available Beryllium compression drivers can do 100 dB from 700 Hz out to 18 kHz without using a horn that has a very narrow radiation pattern at the top end.

(I've been calling it "my" compression driver, which is only true up until the manufacturer decides to put it into regular production, and then it becomes "their" compression driver.)

Now I'm still waiting on my big custom Oblate Spheroid waveguides to confirm these efficiency projections. The shop that is making my horns is moving halfway across the country, and that may push production of my first horns into early 2021. I hope not, but have no control over it.

However now that I've tested this sweet new compression driver on some off-the-shelf horns, I'm seeing the possibility of doing a considerably more affordable speaker using an off-the-shelf horn.

There will also be a Beryllium diaphragm version of my big Oblate Spheroid speaker, with a system efficiency probably around 96 dB.

Very cool. What will be the cutoff on the horn? I can get comfortably down to 800Hz with the 18 Sound XT1464 + Beyma CP750Ti. With a bit of EQ it gets pretty flat out beyond 18KHz and sounds very clean doing so. The Radian with Be doesn't sound any cleaner up there. But you are using something now with carbon fiber or graphite, right?
 
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Duke LeJeune

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Very cool. What will be the cutoff on the horn? I can get comfortably down to 800Hz with the 18 Sound XT1464 + Beyma CP750Ti.

On paper my horn looks good down to about 700 Hz, but actual measurements will tell me whether I should push it that low.

The 18Sound XT1464 has some very nice characteristics. It may well end up in a future product of mine.

The Radian with Be doesn't sound any cleaner up there.

Was the comparison between the 1" throat Radian 475 on the Iwata, and the 1.4" throat Beyma on the XT1464?

If so, which Iwata horn was it, if you don't mind?
 
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Robh3606

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My compression driver is not entirely free from breakup, but its "settling time" is extremely fast - the diaphragm doesn't "ring". Based on independent measurements I've seen in an industry publication (Voice Coil magazine), the diaphragm in my compression driver has behavior competitive with a Beryllium diaphragm, and arguably a bit better in some respects (such as "settling time").
Hello Duke

Boy you have my attention! So it's damped. JBL uses aguaplas for this. Make a big difference on an ETC measurement. Are you using a synthetic like Teonix? JBL is using this or something similar in the new ring radiators. I have a pair of 590's that use it and it's sounds smooth.

If you can't say no problem :)

Rob :)
 

Duke LeJeune

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But you are using something now with carbon fiber or graphite, right?

Boy you have my attention! So it's damped. JBL uses aguaplas for this. Make a big difference on an ETC measurement. Are you using a synthetic like Teonix? JBL is using this or something similar in the new ring radiators. I have a pair of 590's that use it and it's sounds smooth.

If you can't say no problem :)
I'd rather wait until our product is launched before saying what the mystery compression driver is, but once it's launched the beans will be spilled.
 

Fred Crane

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AudioKinesis has never really done a “statement” speaker system before, but with a little luck 2020 will be the year, and What's Best Forum will be the front-row seat.

We won't be shooting for "absolute best speaker for a big room", nothing against big rooms, but where we have the most to offer is in small to medium rooms.

Nor will we be shooting for "absolute best" anything, as that sort of claim would call for a much higher-paid marketing department than ours. Instead, we will be shooting for something like "a unique and enjoyable combination of attributes, without any disqualifying colorations." Some of what we'll be doing will be refinements of things we've done before, and some of it will be new territory for us.

By way of overview, we aspire to combine the liveliness, palpable sense of presence, and tube-amp-friendliness of a first-rate horn system; the immersion and utter lack of listening fatigue of a first-rate dipole system; and the disappearing act and low-end solidity of a first-rate conventional system. We expect to do so in a way that is unusually adaptable to less-than-ideal rooms. We will be making some trade-offs along the way, so we'll mention those too.

First up in the "new territory" category is a proprietary horn which combines the directivity control and freedom from coloration of Earl Geddes' Oblate Spheroid geometry with a large-format compression driver. Heretofore, to the best of our knowledge, Oblate Spheroids (and their derivatives) have been confined to small-format compression drivers. For what we are trying to accomplish, we think this particular horn will outperform anything else we are aware of.

But there will be a tradeoff relative to some high-end horns: Because the Oblate Spheroid profile is constant-directivity, the highs are spread over a wider area than would be the case with a tractrix, exponential, spherical, or hyperbolic horn. Our on-axis efficiency in the high treble is a little under 100 dB, which becomes the limiting factor. This isn't bad efficiency, but it does fall short of many high-end horn systems. (Just to be clear, our horn puts out as much high frequency energy as these other types, but it is not concentrated into a narrow on-axis angle).

Why not add a high efficiency supertweeter? Because we have found that time-domain coherence of the upper harmonics is worth preserving, and that cannot be done in the analog domain with a supertweeter. So we will be using large-format compression drivers which have sufficient top-end extension.

New territory for us will include (estimated) 100 dB efficient, 16-ohm main speakers. This translates to a 97 dB/2.83 volt sensitivity, and compatibility with a wide range of specialty tube amps, including the Atma-Sphere M-60 OTL amp. We are designing with the M-60 specifically in mind, and it may well prove to be the ideal amplifier for these speakers despite its relative affordability. Solid state amps can of course also be used, and most will deliver half their 8-ohm rated power into these speakers (hence the 97 dB/2.83 volt sensitivity), but typically with lower distortion. In practice a solid state amp's reduced wattage output into the 16-ohm nominal load is unlikely to be a limiting factor because of their high efficiency.

Familiar territory will include an upwards-and-backwards firing "Space Generator" section, whose purpose is to add some spectrally-correct, relatively late-onset reverberant energy. This results in a more effective presentation of the spatial cues on the recording. So on a good recording we can achieve that "you are there" sense of envelopment which relies on the recording's spatial cues dominating over the playback room's acoustic signature, and which is normally out of reach without a very good large room (and a suitably capable system). The Space Generator section we will be using is more advanced than what we have heretofore displayed at audio shows. The Space Generator is our secret weapon; it is what will distinguish what we do from other high-efficiency systems.

We will also be returning to familiar territory by using the Swarm subwoofer system for the bottom couple of octaves, as we think it combines the pitch definition of good dipoles with the bottom end extension and impact of a monopoles. Can it "keep up with" horns? We have customers using the Swarm with 107 dB efficient fully-horn-loaded systems (well, "fully horn loaded" except for the Swarm), including one who replaced his horn subwoofer with a Swarm. For those intimidated by the thought of having to find places for four subwoofers in a small to medium room, their footprint is only one square foot, and their placement is very flexible. In situations where extension well below 20 Hz is required, options will include a 10-Hz Swarm (which will have a larger footprint).

The combination of very good radiation pattern control, independently adjustable reverberant sound (via the Space Generator sections), adjustable top-end "tilt" and midbass tuning, plus the highly adaptable bottom end of the Swarm, combine to make our approach exceptionally real-world room-friendly. Not that there wouldn't be further improvement in a well-treated dedicated listening room, but in general we offer less sonic compromise in ordinary or problematic rooms than most other approaches. And if the services of an acoustician are engaged he or she will not need to "fix" the speaker's off-axis response, but rather can concentrate on improving the room's acoustics.

To the best of our knowledge, nobody else is doing a 100 dB ballpark system that can convey the sense of envelopment of a good dipole system in a modest room. Unless someone beats us to it, we'll be the first.

So at this point (about 11PM on January 1st, 2020) the custom tooling we need is being fabricated by a machine shop. We have some custom parts on order, and will be ordering other custom parts in the near future. We are working with a master woodworker who is a longtime industry veteran on the cabinet design. And as you can probably tell, we are highly optimistic. Which shouldn't be surprising - I think the only ones left in this industry are the optimists!
Looking forward to it Duke!! I've always loved your rooms.
 

Solypsa

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- I think the only ones left in this industry are the optimists!
Perhaps, but your style is so optimistic and exuberant that I read your posts and replys eagerly. Thanks!
 
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Robh3606

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Hello Duke

So how is it going on your speaker system?? Things may be opening back up!

Rob :)
 
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Duke LeJeune

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So how is it going on your speaker system??

Cooking slowly while we reach for some low-hanging fruit.

At the suggestion of my partner Jim Romeyn, we are developing a couple of products which are arguably fairly unique, with greater market potential, and (perhaps MOST important) will be MUCH much easier to ship for in-home auditions. No, not phono cartridges. In my NEXT LIFE, I'm doing phono cartridges instead of big speakers and multiple subwoofers.
 

cal3713

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I'm also looking forward to the updates Duke. I'm considering moving down to Panama and starting an import/dealer service to help bring good audio to expats down there (and obviously anyone else). Sounds like your lines might be ideal given the ability to play well in challenging rooms. As you may know, the houses (small) and surfaces (hard and reflective) down there are far from ideal.
 
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Folsom

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Cooking slowly while we reach for some low-hanging fruit.

At the suggestion of my partner Jim Romeyn, we are developing a couple of products which are arguably fairly unique, with greater market potential, and (perhaps MOST important) will be MUCH much easier to ship for in-home auditions. No, not phono cartridges. In my NEXT LIFE, I'm doing phono cartridges instead of big speakers and multiple subwoofers.

More stuff? Interesting.
 
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cal3713

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Duke, I've seen you state a few times that you design around the Atmasphere M60s, but most of your specs make it look like the power from an S30 would be more than enough. Is that true, or do you feel that the speakers generally do benefit from the extra power (over and above the other advantages of monoblocks)?
 
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Duke LeJeune

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I'm also looking forward to the updates Duke. I'm considering moving down to Panama and starting an import/dealer service to help bring good audio to expats down there (and obviously anyone else). Sounds like your lines might be ideal given the ability to play well in challenging rooms. As you may know, the houses (small) and surfaces (hard and reflective) down there are far from ideal.

I found out the hard way several years ago that it's just not practical to try to go through dealers. We're way too small to have good economies of scale. Thank you very much for being interested, but for now at least I don't think it's practical.

More stuff? Interesting.

Yes. I don't know if you remember the prototype Space Generators that Jim Romeyn brought to your friend's house a little less than two years ago, but there has been some evolution and a commercial version is not far away. It won't be a universal match with everything out there, but we think it will make a worthwhile contribution in many cases. We're now learning more about what those cases may be.

There is a loudspeaker concept which is now feasible, thanks to a particular woofer which was recently introduced by a European manufacturer: 15" woofer + horn, no subs "needed". Most modern 15" woofers which can go up high enough to be used in a two-way system don't also go all that low; in other words it's hard to fill the shoes of the old Altec 416 series. This woofer is not as efficient as the Altecs, but in return we can get away with a smaller box than the Model 19 and go deeper.

And we continue to evolve our "statement speaker" concept. We're now investigating the feasibility of doing two versions, one optimized for tubes and one for solid state, so that the solid state guys have fewer excuses!

Duke, I've seen you state a few times that you design around the Atmasphere M60s, but most of your specs make it look like the power from an S30 would be more than enough. Is that true, or do you feel that the speakers generally do benefit from the extra power (over and above the other advantages of monoblocks)?

Some of my stuff is S-30 friendly, and some I hesitate to make that claim so I go with M-60 friendly. Most can be driven by the S-30, but in some cases the higher output impedance of the S-30 can result in too much bottom end in many of not most rooms.
 
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morricab

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I found out the hard way several years ago that it's just not practical to try to go through dealers. We're way too small to have good economies of scale. Thank you very much for being interested, but for now at least I don't think it's practical.



Yes. I don't know if you remember the prototype Space Generators that Jim Romeyn brought to your friend's house a little less than two years ago, but there has been some evolution and a commercial version is not far away. It won't be a universal match with everything out there, but we think it will make a worthwhile contribution in many cases. We're now learning more about what those cases may be.

There is a loudspeaker concept which is now feasible, thanks to a particular woofer which was recently introduced by a European manufacturer: 15" woofer + horn, no subs "needed". Most modern 15" woofers which can go up high enough to be used in a two-way system don't also go all that low; in other words it's hard to fill the shoes of the old Altec 416 series. This woofer is not as efficient as the Altecs, but in return we can get away with a smaller box than the Model 19 and go deeper.

And we continue to evolve our "statement speaker" concept. We're now investigating the feasibility of doing two versions, one optimized for tubes and one for solid state, so that the solid state guys have fewer excuses!



Some of my stuff is S-30 friendly, and some I hesitate to make that claim so I go with M-60 friendly. Most can be driven by the S-30, but in some cases the higher output impedance of the S-30 can result in too much bottom end in many of not most rooms.
Vented box for the woofer or something else?
 

Duke LeJeune

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Vented box for the woofer or something else?
Vented box with multiple pluggable ports for adaptation to different boundary reinforcement conditions and/or amplifier output impedances, my paradigm being "amp + speakers + room = a system within a system".
 

ddk

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There is a loudspeaker concept which is now feasible, thanks to a particular woofer which was recently introduced by a European manufacturer: 15" woofer + horn, no subs "needed". Most modern 15" woofers which can go up high enough to be used in a two-way system don't also go all that low; in other words it's hard to fill the shoes of the old Altec 416 series. This woofer is not as efficient as the Altecs, but in return we can get away with a smaller box than the Model 19 and go deeper.
I remember the Model 19 well and I think I still have a pair in storage. That 15” woofer needed quite a bit of current and some decent power to sound right, otherwise it was just muddy and slow, part of it was because of the impedance dip around 130 Hz. The dilemma was how to drive it, the horn part liked lower powered tubes and the bass needed current. Hope you don’t run into this issue.

david
 

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