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Horn Speakers - Is it me or.......

thewas

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thewas

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Maybe a search for David Griesinger patents would be the best way to try to answer this...
That was a great idea, here few results as its outcome:

https://patents.google.com/patent/US7107211B2/en

http://www.davidgriesinger.com/aes99.pdf

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.357.3933&rep=rep1&type=pdf

Also from his personal website http://www.davidgriesinger.com/ :

The next paper, on stereo and surround panning in practice, is pretty good, I think. I wrote it because we were having difficulty preserving the apparent horizontal direction (azimuth) of sound sources in a two channel stereo image when we converted the two channel to 5 or 7 channels with the Logic 7 algorithm. This is interesting because L7 was designed assuming the standard sine/cosine pan law to be correct. We detected the left/right balance of a front sound source, and used the sine/cosine law to find the azimuth. We then adjusted the balance in the three front channels to present it with the same azimuth. Alas, this does not work. We traced the problem to the two channel sine/cosine pan law, which is seriously wrong for most musical sources. (Curiously, the three channel version - that is panning from a center speaker to either left or right - works quite well.) The reason for all this is to be found in binaural theory. Turns out in two channel panning the perceived azimuth is highly frequency dependent, with frequencies above 1000Hz sounding much wider than the sine/cosine law would predict. Suitable averaging over frequency gets the right answer. For some reason this paper has remained undeservedly obscure.

"Stereo and Surround Panning in Practice" A preprint for the AES convention, May 2002.

Matlab code used for the pan-law paper.

....

Surround from stereo is my most complete explaination of Logic 7 and its workings. Worth checking it out

Slides from the AES conference October 2003. Subject is converting stereo signals into surround.
 

andreasmaaan

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That was a great idea, here few results as its outcome:

https://patents.google.com/patent/US7107211B2/en

http://www.davidgriesinger.com/aes99.pdf

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.357.3933&rep=rep1&type=pdf

Also from his personal website http://www.davidgriesinger.com/ :

The next paper, on stereo and surround panning in practice, is pretty good, I think. I wrote it because we were having difficulty preserving the apparent horizontal direction (azimuth) of sound sources in a two channel stereo image when we converted the two channel to 5 or 7 channels with the Logic 7 algorithm. This is interesting because L7 was designed assuming the standard sine/cosine pan law to be correct. We detected the left/right balance of a front sound source, and used the sine/cosine law to find the azimuth. We then adjusted the balance in the three front channels to present it with the same azimuth. Alas, this does not work. We traced the problem to the two channel sine/cosine pan law, which is seriously wrong for most musical sources. (Curiously, the three channel version - that is panning from a center speaker to either left or right - works quite well.) The reason for all this is to be found in binaural theory. Turns out in two channel panning the perceived azimuth is highly frequency dependent, with frequencies above 1000Hz sounding much wider than the sine/cosine law would predict. Suitable averaging over frequency gets the right answer. For some reason this paper has remained undeservedly obscure.

"Stereo and Surround Panning in Practice" A preprint for the AES convention, May 2002.

Matlab code used for the pan-law paper.

....

Surround from stereo is my most complete explaination of Logic 7 and its workings. Worth checking it out

Slides from the AES conference October 2003. Subject is converting stereo signals into surround.

Perfect, thanks!
 

Tim Link

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My experience is in line with tuga as far as long throats not necessarily creating coloration. I've tried the HL-1425 which is a rather long, narrow dispersion horn crossed over at 2K and while sounding very directional I didn't hear any obvious colorations with that horn or measure anything but very smooth, clean response. The stereo image it creates in the sweet spot was really amazing on some recordings. It sounded a little to dry to me on others. Not sure what would happen if it was crossed over at 500Hz. Maybe then it'd start to honk. I suppose I could try it.
 

Jukebox

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Currently I am using Auro3D as an upmixer as it is the most pleasant of the offerings in my SDP75 processor. Some of the parameters and its overall level of contribution can be adjusted which is useful. However, my expectations are not high, looking only for a slight enhancement of spaciousness and envelopment. It will never replace true multichannel recordings.
Looking back, the best upmixer I ever had was in a Lexicon processor - Logic 7, developed by David Griesinger. It also could be adjusted, as I recall, and at its best it pretty much left the soundstage alone, adding only a gratifying envelopment. I liked it, but it is long gone, sadly.
Turning it off, reverting to stereo, could be truly depressing.
Had the same experience with the Auro 3d. Like it better compared with Dolby Atmos and dtsX. And being customizable in some degree makes it even better. Unfortunately not many producers of AVR embrace it or movie producers for that matter
 

restorer-john

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Looking back, the best upmixer I ever had was in a Lexicon processor - Logic 7, developed by David Griesinger. It also could be adjusted, as I recall, and at its best it pretty much left the soundstage alone, adding only a gratifying envelopment. I liked it, but it is long gone, sadly.
Turning it off, reverting to stereo, could be truly depressing.

Did you ever play with the Yamaha DSP-1 back in the day (~1986)? In terms of revolutionary, there is really nothing to compare.
 

Floyd Toole

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Yes, I remember the DSP-1 as what I would describe as a "concert hall synthesizer" adding a hall/room effects to existing recordings, which already had hall sounds in them. Compared to the oversimplified, amateurish "Hall effect" algorithms of the time, it was very well done, but not what I personally wanted, which was an upmixer that extracted hall ambience from the recordings and delivered them in a more persuasive manner than two-channel stereo.

Since then the most impressive add-on effect was another Griesinger/Lexicon device. It was a reverberation enhancement device derived from the technology in their very successful recording studio spatial synthesis technology. Called LARES (Lexicon Reverberation Enhancement System) it was very effective in manipulating performance space acoustics for different genres of music or art.

David Griesinger. developed a much simplified version for homes (LARES Light). I experienced it and found it very impressive. When the combination of four microphones and loudspeakers and processor were set up, one could walk into a domestic room and instantly all sounds that were generated sounded as if they were made in a large auditorium (which could be adjusted). Hand claps, voices, etc were are heard as if they took place in a large room. Playing stereo simply added an orchestra or band to the sound sources within the created "space". It was enticingly transparent and enveloping. I remember demonstrating it in the Harman home theater. I would play an upmixed stereo recording, which would have a comfortable surrounding envelopment, while gradually mixing in the LARES Light effect - nobody ever noticed. Then I would suddenly pause the music, and the artificial room reverberation would continue. As the inevitable comments came, they were heard in the ambiance of the concert hall. It was a mind bending experience. I thought it would find a ready market with well-heeled audiophiles, but it never was marketed or demonstrated well. There was at least one imitator but I have no knowledge of what happened to it.

I liked the idea of not only embellishing recordings while they were playing, but of feeling as though one was in a concert hall during silent intervals. Very cool! A home concert hall in addition to a home theater.

In retrospect I regret not being more aggressive in trying to promote it while at Harman, but I was in engineering , not marketing. There were other missed opportunities. Nowadays it could be a nice feature to include in elaborate multichannel digital processors. With all the extra immersive channels to play with very persuasive effects could be generated.
 
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Newman

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Currently I am using Auro3D as an upmixer as it is the most pleasant of the offerings in my SDP75 processor. ....Looking back, the best upmixer I ever had was in a Lexicon processor - Logic 7, developed by David Griesinger. ... I liked it, but it is long gone, sadly...
Not that long gone: the new SDP55 processor has it. Or at least it has Logic 16, which I assume is the same system applied to more channels.....
 
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Newman

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The difference between waveguided speakers and "real" horns is that the directivity of the former becomes narrower as you move up the frequency range from 300-500Hz upwards whilst a "real" horn speaker will have constant narrow directivity across most of the spectrum....

I think you got this back-to-front, at least in relation to convention. I believe convention has it that the original use of a horn, and hence the term horn speaker, was designed to be an acoustical transformer that efficiently converts the impedance mismatch between driver material and air. The resultant shape tends to produce a ‘beamy’ wavefront where the beam width narrows as the frequency increases. And that the use of the term waveguide applied to devices designed primarily for a constant beamwidth, in other words, to guide the wave front, hence waveguide.

cheers
 

tuga

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The resultant shape tends to produce a ‘beamy’ wavefront where the beam width narrows as the frequency increases.

This is from an Avangarde Uno XD. If it were using an extra way/horn or two it would produce a constant narrow beam-width from above 200Hz or even lower. Many horn speakers use only one or two horns for simplicity or cost reasons but a competent design would need at least 4 ways.

10-UNO-hor.jpg
 

Newman

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Much as AG want to call them horns for marketing purposes, their spherical contour is actually a waveguide class of device.

PS the AG website is one of my least favoured, carrying so much marketing BS, misinformation and disinformation. It would have to be one of the worst sites to visit if one wants to learn objectively about horn/waveguide behaviour. Phrases like “zero distortions” “8x higher dynamic bandwidth” and “10x more details” put me off very quickly.

cheers
 

tuga

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Much as AG want to call them horns for marketing purposes, their spherical contour is actually a waveguide class of device.

PS the AG website is one of my least favoured, carrying so much marketing BS, misinformation and disinformation. It would have to be one of the worst sites to visit if one wants to learn objectively about horn/waveguide behaviour. Phrases like “zero distortions” “8x higher dynamic bandwidth” and “10x more details” put me off very quickly.

cheers

I don't read manufacturers' websites. Or reviews.
 

johnp98

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Has anyone experimented with 30PPI waveguide foam? I have done some reading about it as it is suggested by Geddes and wondering if people had experience / thoughts on it and if it is worthwhile.
Thanks!
 

Andysu

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I rather like the JBL horns was for years using JBL 2371, and recently a light-year cheaper than the fish and chips universe, on he ebay, got get the JBL 2380A thou not heard them personally at a cinema mostly JBL 2360A and smaller JBL 2370A at smaller independent cinema years ago. I looked at the specs for 2445 and saw they are not far off from a JBL 2360A looked at the spec for 2380A and thought these should be a step up and was and still tuning them to see how far they can go down without breaking them. A lot of turning and alignment of the diaphragm on the phase-plug that is rather tidies but once done and EQ tuned they sound like cinema in the home without the harshness. Sure been to some Dolby JBL cinemas and the HF horns was unpleasant to listen too. Warner West End, London, sounded toppy with 'Maverick' (1994) in Dolby SR THX. And years later saw one of those X-men wolfman or reen whatever the hell it was it was dreadful sounding "Dolby cinema digital video projection" I think the screen channels may have been changed to Martin Audio as I notched the surrounds was no longer JBL. I had to cover my ears and even stick the earplugs in as it was a dreadful sounding auditorium with no THX staus anymore as I saw no THX trailer.

I wouldn't hear of harshness on my JBL horns takes a bit of tuning once done they sound grand.

The 2007 THX JBL three-way at Empire Leicester Square sounded dreadful. The original 1989 THX JBL two-way sounded light-years better not once had to cover my ears was loud and exciting. Three-way JBL THX was painfully hash and had to cover my ears on movies like, Transformers 35mm SR-D, X-files want to believe, but mostly "heard dogs barking" rubbish movie, few times covered my ears on the dogs baking up close in some scenes.
star trek into darkness, thou I call it, star trek into DEAFNESS worst atmos jj abrams trash I ever heard! Saw it twice cos I was checking out this Atmos thing? Once at front and centre row them second show middle circle and still IO had to cover my ears and when I do that is a sign its a poorly tuned sound system.



140642702_10158856122190149_3186193677952171779_o.jpg
 
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Ro808

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In terms of sound quality, it seems that the constancy or smoothness of change in DI is more important than the DI itself. The dominant effect is spatial, not timbral. There is much discussion of this in forums, and personal preference is a factor.

Two aspects that are often ignored or even rejected. It's good to know your opinion.
 
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Tom Danley

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This would parallel that the sharper a change in frequency response, the more noticeable it is at least in large systems. A change in DI would be modulating the spectrum of the off axis energy in the room.


I would add there is what i think of as the "source spatial identity issue" which is not easily measurable (as it is within the difference between two signals reaching ones ear / brain system that creates the 3D sound world we live in).
Imagine two different design speakers which have essentially the same Frequency response.

You walk into a room with either set playing and they both sound good.
In the stereo sweet spot, they sound entirely different so far as the image.



Ok first off, this could be the difference in sidewall reflections so you move outside on a quiet day and they still seem very different so far as stereo image even with no room reflections.


Now you listen to just one speaker at a time. With eyes closed, it is easy to point at the direction of both speakers BUT with one speaker, with your eyes closed you can easily guess how far away it is but the other is much harder, in fact with a soft muffled voice with reverb you guess it is much farther than a dry voice that sound up close. The difference is the ones that are still easy to hear usually radiate a complex radiation pattern that carries the clues your ears need to localize the source (my conclusion).


The pair that are easy to hear how far away they are, are the ones that stand out as part of the stereo image no matter what it was, they anchor the sound to that location in space, the ones that were hard to tell with your ears are the ones the disappear behind the stereo phantom image and can produce the most solid phantom image and your least aware of them as a source.


The problem with horns in most multi-way system is that if you have sources separated in space, your ears can also detect that as the source in time and space because there are small difference between the sources.

The more horns you have and or the larger they are (and true of direct radiators) the more spatial information those separate sources can carry in addition to the signal.



In other words once you are far enough away to not detect multiple sources, you still may well be able to localize the location in depth by the separate info reaching the right and left ears.


I would bet some reading this are skeptical about what i am saying about "hearing aspects of a loudspeakers radiation" and the effect on the stereo image part.
For those curious, I can point you to a simple DIY construction project which will I think cement what i am getting at.
First get 2 of these small full range drivers, i use these at work, they are pretty amazing.
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=401000100


Make yourself a flat baffle about 2 feet square or maybe larger using 1/2 inch plywood, put a hole for the front mounting the driver in the center and cover it with 1/2 inch foam (use spray glue like super 77).


Then open the hole a bit and mount the driver through it and screw it down so it compresses the foam. You can add a small back box and go the T&S alignment if you wish.


This driver here radiates as a simple half space omni point source over much of it's range and can be eq'd until it complains and on axis goes up quite high but it is the very simple radiation over much of it's range and the wonderful stereo image these produce that is the point.
I have a friend that made these and he liked them so much they are his office speakers.
At work, the objective is this kind of simple fractional space single point source radiation but over smaller angles using CD horns

Best,

Tom Danley
 

Tim Link

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Has anyone experimented with 30PPI waveguide foam? I have done some reading about it as it is suggested by Geddes and wondering if people had experience / thoughts on it and if it is worthwhile.
Thanks!
I've experimented with foam, not sure if it was ideal 30ppi waveguide foam. It attenuates the highs, which means equalization is required to get the frequency response back. I can't say I really heard an obvious improvement, although it sounded different because I couldn't get it equalized perfectly the same as without the foam. I also tried to see if the impulse response looked any cleaner, and couldn't see anything. The HOMs are an interesting idea but without some measurements of their reality it's hard to say just how important it is to calm them. From my simple analysis it seems mouth to throat reflections are by far the major issue. If you have a nice big round over and an adequately sized mouth it doesn't seem like there's a lot of sound to be bouncing around for long at all inside the horn, especially if it's a fairly wide flare rate. The narrowest flare rate is actually in the phase plug of the compression driver itself, so that's where at least high frequencies could theoretically hang out for a while, bouncing back and forth between the relatively parallel surfaces.
I'd like to see a measurement of HOMs with and without foam to prove the foam is working and we're not just hearing a subtle difference in frequency response.
 

Newman

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Two aspects that are often ignored or even rejected. It's good to know your opinion.

Except that Toole’s opinion was formed in controlled listening test conditions. Toole is not talking about personal preference in casual listening: that is not what you want to take from his statement.
 
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