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Horn-Loaded Speakers
Topic: Engaging the David Haigner’s ideas

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Posted by Romy the Cat on 08-30-2009
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There is guy in Austria that makes horns speakers. I have mentioned him a few years back at that time it was not a lot of interesting, at least in Web presence. Nowadays David has developed a product that I feel is worth critical acclaim and looking into his direction with some analyses:  The Alphahorn loudspeaker.

http://home.tele2.at/haigner/content_en/alpha_e.htm

I never heard the Alphahorn, here is guy who did:

http://www.theaudioeagle.com/columns/column04.html

What attracted me to write about the Alphahorn ideas is David Haigner’s personal notes about his design concepts. In contrary to insulting and in most cases ignorant BS that most of manufacturers write as their “concepts notes” Mr. Haigner does make a lot of sense in his notes.

http://home.tele2.at/haigner/content_en/notes.htm

I do relate to quite few aspects of the notes and of cause there are some moments that I disagree.  David wrote:

 David Haigner wrote:
  As our big horn systems are quite heavy, managing reviews is not that easy.

I am not planning to write another “audio review” and I would let others to scream “It was the best speaker I ever heard!” and to proclaim the unavoidably-stupid “Now I am listening the music”. However, I am planning to review the David Haigner’s design ideas and talk about the moments where I feel some “skeletons” shall be exposed, or at least named.  If David was craving for a review then he is lucky as it will be more meaningful then Alphahorn will ever see.

If anybody had any experience with Alphahorn then feel free to share it in the thread.  From my side I will compile some of my thoughts during the coming week.

The Cat

Posted by noviygera on 09-01-2009
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Alphahorn seems to incorporate the BMS 4592 coax compression driver. Similar CD horn is already incorporated in the CODA speakers:
http://codaaudio.net/Rx35.3-way_full_range_system2.0.html

The guy from Austria probably gets the German BMS drivers conveniently, good for him! Although his approach is not unique, already refined by Coda and even BD designs and BMS's own triaxial point source speakers are already out:
http://www.bmspro.info/News.802.0.html?&cHash=81226da57d&tx_ttnews[backPid]=693&tx_ttnews[tt_news]=19
David Haigner's goals lead pretty much to this speaker (which doesn't use pesky compression drivers): Funktion One RES 1.5  -- why complicate things?
I have the mid high horn that incorporates a 5" horn laded driver that goes from 520Hz to 15K. From personal experience it beats all compression drivers I've heard.

-Herman


Posted by Romy the Cat on 09-25-2009
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A site visitor pointed me out the I never made an intended write up about the David Haigner horns.  I just forgot about them… OK, let analyze David’s claims and his Alphahorn design. I would say right the way that I do not like the Alphahorn’s ideas.

 David Haigner wrote:
  I started to develop hifi horn systems as someone coming from the prosound camp. Constant directivity (cd) characteristics are not optional but necessary for pa-applications, but obviously hifi fans had learned to live with horn systems that have acceptable dispersion at low to middle frequenciy, but dramatically increasing directivity from 5 kHz up (so called "tractrix" horns). Just like sitting in front of electrostatic loudspeakers, you are limited to sitting in a very narrow "sweet-spot" if you want to hear "hifi" quality. But how about listening together with your family and visitors?

Oh, boy, where to start. If you about listening together with your family and visitors then sit a few feet further but it is not the point. I think what David does in here is misleading himself and others by identifying a false causality and then addressing the “virtual problem” of the false causality. A horn is a relatively narrow dispersion devise but only if not used properly. People love to take any “stupid” horn, load into it any 20-20.000 driver and then scream – look, it has narrow dispersion at HT.  Do not blame narrow radiation of a horn just because you decided to use a horn within an inappropriately-wide bandwidth.

 David Haigner wrote:
Well, many pa-horns with good cd-characteristics at that time suffered in terms of frequency- and time-domain-response. But well done designs from altec, electro voice and others have shown that you can have your cake and eat it, too.

YES, but the CD horns are not a solution but the addressing of the contrived “virtual problem”.

 David Haigner wrote:
 

Point source and constant directivity characteristics over the widest possible frequency band (wide sweet-spot)
LF and HF sections are time-aligned, working with the same polarity
High sensitivity and high electrical impedance, as constant as possible (easy amplifier load)
Smooth amplitude response, without detectable coloration
Shallow acoustical crossover slopes (even better imaging and naturalness)
Moving mass as low as possible

Ok, let leave the damn “point source” phrase also – people love to use it but they have no idea what they are taking about. David claims that widest possible frequency band and the “constant directivity” assures wider sweet-spot. I personally see absolutely not connection. The LF and HF sections are time-aligned? Good, the mouth of your LF section and your HF end up at virtually same location and they are time-aligned? This is ONLY an indication that your LF section does not act as horn- loaded at LF. Where is 6dB of this upperbass horn’s equal stops? I bet it is above the 100Hz. The  high impedance, good amplitude, shallow acoustical crossovers and low moving mass are good however…

 David Haigner wrote:
  Even outside of the nominal +- 45 degrees radiation window the response is very well controlled over a wide frequency range (the horn is designed to work from about 1.5 kHz up).

This is a typical CD horn argument but I disagree with it I think I need to address the whole CD misleading.

 David Haigner wrote:
  The nearly perfect constant directivity characteristic is one reason why our loudspeakers are easy to integrate into your room acoustics, presenting the music over a comfortably wide listening zone.

 

Actually it is very much not true. The CD horns do have wider HF directivity and this make them more toss HF to the side walls. So, the wider directivity horns “see” the rooms more.  I do not say that it makes them harder to integrate but it is NOT make them “easier” to integrate. So I find what David said is misleading.

OK, I think I need to address the major subject of Mr. Haigner’s design – the CD or the constant directivity.

I have to admit that what I first saw he David’s horn I was taken by the elegance of the elliptical horn idea. Then looking deeper I understood that it was not a cool elliptical horn but David’s way to deal with the facts that CD horn can demonstrate constant directivity ONLY within one surface.  The CD horn does the constant directivity trick in horizontal plane by killing directivity in vertical plane, so it is not “getting richer” but rather the redistribution of the wealth. There is however in this “redistribution of the wealth” some ugly moments that the “constant directivity” devotees fail to realize. Pay attention that I took the “constant directivity” in quote and it was not an accident. The constant directivity is just a marketing BS phrase, the very misleading one as there is not such a thing as constant directivity. There is a “slightly better directivity” and it is what it is. Let look in past.

The notion of constant directivity was injected into use by Electro-Voice in mid seventies. Whoever are interested find the Broadus Keele’s AES paper where he will-defined the rules of the game of CD concept.

http://www.xlrtechs.com/dbkeele.com/

The CD horn has is by nature a triple-bent horn where flare move from hyperbolic to exponential and then to conical profile. The whole idea is based upon the navigation of the edge diffraction around the bends.  Sounds elegant, doesn’t it? Well, only on a paper and if the directivity was the ONLY concern that a loudspeaker has. The CD horn have very-very bad  on axis equalization characteristic – try to get + 6db from CD horn and you will see. So, to get some equalization of juts the “horn gain” the CD horns shrink vertical dissipation and make itself narrow-rectangular.  Sure, the narrowing the radiation angle helps to find a few dBs of horn gain but it makes the wavefront  non-spherical – here is where the imaging goes… The pro audio folks hardly care about imaging as they never have it. Imaging is not a commodity of pro audio and they juts case to pass FCC (or whoever regulated them) limits by less expense. The CD horn was perfect for them and it allows spreading sound across wide area - with minimum efforts.

 But the edge diffraction around bends of the CD horn are very tricky as they behave different at different db levels. Try to make 90 degree turn in your car driving 30 miles and 130 miles per hour. Feels different? Take a camera-obscura and observe the diffraction. Diffraction is a deviation of light in the region of geometrical shadows. The deviation of light in the region of geometrical shadows will have chromatic aberrations. It is because color of light raven with different speed and different speed had different diffraction power. The example with you, taking 90 degree turn in your car become very intuitive…  Ironically the very same happened with CD horn – the diffractions around the profile’s bends are subject of pressure change and it makes the directivity horns to sound different at low and high sound levels.  At low levels they lose the “more constant directivity” effect and at high levels they sound like overdriven direct radiator.  A properly designed and used Tractrix driven with a proper SET in class A1 has very clean ability to raise dymick – it happens gracefully and very effortless. The horn juts does not care how much pressures it handles – if the horns driver and the amp can do it then the horns has no attitude about it. With CD horn, that has the broken up profile, the raise dymick is always accompanied with unproportionally-high elevation of distortions.

There is another thing that the CD horn enthusiasts do not mention.  In horns there are no fantasizes - you have pressure and your have dissipation angle - you have one converted into other.   Wider angle – less pressure and here is nothing you can do with it. In CD horn HF are tossed wider out of the horn and therefore the CD hoe loose HF much fasters then it shall.  To combine the CD horn with a supplementary tweeter is not a good idea and the whole idea of CD horn is to put one ass on all chair and to have so called wide-bandwidth horns. If we have multiple channels then they would not suffer from any directivity “problems” and the CD horn would not be needed to begin with. So, how the CD horn enthusiasts deal with the problem of high frequency lost in CD horns? Well, they use one of two methods.  The first method is to use VERY horribly hard-sounding drivers for the horns that have LOT of HF energy in them. The second method is to electronically equalize the CD horns driver with first order, almost writing the RIAA curve into the driver. ALL , with no exception,  so-called constant directivity horns are driven by super-bright drivers  (mostly in very cheap models)  of equalized electronically….

Well, didn’t not you think that it all abs it too much price to pay for the opportunity to “listening together with your family and visitors” at the distance of one-two feet closer than you would do otherwise? Do not forget that the “constant directivity” idea was invented ONLY to get rigid of the multi-channel configuration and to make the horn installation cheaper.  Cost - it was the ONLY a key as a properly made multi-channel has no narrow directivity disadvantage. So, I think in high-end audio, where we do surface cost and comfort for some result the we believe are worthy I think the CD Horns is not too much useful concept. I would be interested if David Haigner convert his CD Horns in elliptical horn of CONTINUES profile, get rid of his  QE, use better drivers and add a few more channels.  Well, he might end up with Macondo configurations then but does not know about it yet….

Rgs, Romy the Cat

Posted by Reno on 10-11-2009
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Hi Romy,

as distributor of David Haigners products to Austria and Germany I think I should make some comments on your...hm...review of a speaker you have never heard.
I will not comment on the theory of CD horns here. It should only be noted that the Alpha is not a copy of a vintage Electro-Voice horn. David did quite some research and practical experimenting that went into the design of the Alpha. But yes, the intention was to reduce directivity in the horizontal plane. We would not like a speaker which forces you to sit stiff in a narrow "sweet spot" and loose sound quality and imaging by just moving your head a few inches. We also think that listening with you friends and family is a wonderful thing for anybody not severly autistic. And BTW a wider sweet spot comes a lot closer to the experience of listening in a concert hall. The Alpha offers you great imaging even if your not sitting in perfect position. Also HF response is not a concern and we neither use electronic equalization nor a "super bright driver". The BMS is pretty smooth, and there are also Alphas in use with Goto-drivers (which need an extra tweeter of course...). I will not loose a word on the Macondo here because I refuse to make comments on systems I have never auditioned...

Kind regards
Reno Barth
Vienna, Austria

Posted by Romy the Cat on 10-11-2009
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Reno, I do not think I commented anywhere that Alpha is a copy Electro-Voice horn. David well described in his writing how he ended with Alpha and how the CD ideas were guided him. BTW, you are repeating the David’s faulty (in my view) notion that a wider "sweet spot" has any relations to extended directivity in the horizontal plane.  They are just apples and oranges… even both are fruits…

About you “neither use electronic equalization nor a super bright driver".  Reno, come on, I just call to your common sense. Look, let pretend that we have a horn that is operating wide bandwidth with a driver that was designed to output a flat resonance let say from 500Hz to 15kHz after it was EQ by a conventional exponential horn. Then we takes the same driver and sticks it into the Alpha horn that uses some CD techniques and has wider directivity at HF. The output of any acoustic system comes from dB of driver over the angle of sound dissipation. The narrower angle - the more dB are focused just think about the garden hose knozzle. So, if the Alpha horn use conventional diver and has CD-like reduces directivity then it might be done ONLY by burning the output at HF. You do not need even to read the CD theory – it is just a common sense. If you wish to dig deeper then you might look here:

http://www.goodsoundclub.com/pdf/Keele%20(1975-05%20AES%20Preprint)%20-%20Whats%20So%20Sacred%20Exp%20Horns.pdf

If the Alfa horns use the CD ideas , has “constant response over the whole frequency range from 30 – 21000 Hz” and use the driver that is flat in exponential horn then it would violate the Newton's Laws of Motion. Where do you get the juice to make HF to shoot wider if your driver was linear?  You shoot wider - you lose efficiency…

The Cat

Posted by Reno on 10-11-2009
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ok. maybe we have a different understanding of "electronic equalization". We do not use active (i.e. electronic) equalization in the amplification chain. There is of course some equalization in the passive crossover but I really don't see what's wrong with that. Sensitivity is still at 104dB/W/m and the construction gets me a convenient wide sweet spot, which is a fact everybody who listened to the Alpha has noticed.

kind regards
reno


Posted by Romy the Cat on 10-11-2009
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 Reno wrote:
ok. maybe we have a different understanding of "electronic equalization". We do not use active (i.e. electronic) equalization in the amplification chain. There is of course some equalization in the passive crossover but I really don't see what's wrong with that. Sensitivity is still at 104dB/W/m and the construction gets me a convenient wide sweet spot, which is a fact everybody who listened to the Alpha has noticed.

Reno, there is acoustic equalization and there is electronic equalization. The acoustic equalization is shrinking the horns profile, use phase plug, front chambers and many other things. The electronic equalization is a use of inductive and capacitive elements in crossover in order to write curve in band-pass of the horn. Of cause, if you use CD concept, then you use “some equalization in the passive crossover” and you burn the sensitivity. I did not say that it is “wrong” if it done properly, I just insisted that you do it. Would it be better avoid doing it? Pay attention that this equalization is necessary ONLY because you guys decided to take all that sound from one horn. Theoretically if you EQ more then you can get even bass from the same horn – way don’t you do it?

Furthermore, let me to stress it again: the “convenient wide sweet spot, which is a fact everybody who listened to the Alpha has noticed” HAS ABSOLUTELY NOTHING TO DO with extended directivity. This is a purely BS notion that you guys spread as a fraudulent marketing. If it is your true conviction then I would encourage you to reexamine your concussion.

The Cat

Posted by Romy the Cat on 10-12-2009
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 Romy the Cat wrote:
Furthermore, let me to stress it again: the “convenient wide sweet spot, which is a fact everybody who listened to the Alpha has noticed” HAS ABSOLUTELY NOTHING TO DO with extended directivity. This is a purely BS notion that you guys spread as a fraudulent marketing. If it is your true conviction then I would encourage you to reexamine your concussion.
  
Well, thinking again I feel that I bit overstated my claim. Instead of saying “has absolutely nothing to do” I had to say “has little to do practically”.  The synchronization of the dispersion patterns between all channels would affect the width of the sweet spot but in CD horn we not even taking about the synchronization but about a very little improvement of HF off-axis radiation and we pay for it a by a lot of other compromises. So, I sell not absolutely deny that wide sweet spot has something to do with extended directivity but I do question that it is the ONLY reasons there are plenty illustrations with wide directivity installations and still narrow sweet spots…. 

The Cat

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