I started a new thread on this because it didn't really seem to fit into any of the Line Array / Line Source or Horn threads already in existence. I certainly didn't want to hijack an existing horn thread or ribbon line source thread to go off on this tangent.
Basically, I am looking for any info about existing line source horn designs. (To clarify: any horn designs that would allow a horn to emit a flat, line source wave, as if it were a stack of closely spaced drivers - very closely spaced for high frequency sounds - or a ribbon or other planar driver)
One such waveguide arrangement is shown here
(about 75% down the page):
http://www.lenardaudio.com/education/07_horns_3.html
This is basically just making a wiggling path in the center of the horn or waveguide, so that the point-source compression driver at the throat emits an apparent line source wave at the mouth. In this way, the waveguide acts as an acoustic "lens" to make the center path longer, effectively slowing down the sound coming out of the middle of the horn, while restricting the sound coming out of the top and bottom of the horn much less.
I had also seen a somewhat similar "squiggle and split" pattern for a horn somewhere on the DIYaudio board - an actual image posted here - but I have not managed to find it again in any searches recently (anyone know where that one is here?)
Another waveguide shape is shown here (look on page 5 in the center):
http://www.sonicdesign.ch/downloads/3_technische_dokumentationen/Line-array-vs-Line-source.pdf
This one is from L'acoustics for use in PA system Line Array cabinets.
Another PA cabinet line source horn arrangement is the "Ribbon-Emulation Manifold" from MeyerSound. While it does not really provide a continuous true linesource, if does effectively split the horn into 4 coherent emissions through the use of a (patented) funny split horn:
http://www.meyersound.com/support/papers/REM/index.htm
Another PA emulation is here:
http://www.renkus-heinz.com/loudspeakers/linearrays/LineArrays-White-Paper.pdf
That document explains quite a bit about acoustic lensing for line source use and has some simplified functional images of their horn/waveguide design. (Though I would love to see exactly what is really on the inside of those horns)
Another PA embodiment is here:
http://www.orbitalsound.co.uk/sales-loudspeakers-dandb-tseries.asp
This one actually has a rotatable waveguide plus acoustic lens arrangement that allows switching between line source and point source emanation patterns.
So, who knows of other designs for this? Pictures, patent applications, etc. I'd like to see anything anyone is doing in this direction for home audio or professional sound reinforcement. Any design where a (compression) driver get bolted on to the back of a horn and results in a line source "cylindrical wave" coming out of the front.
Has anyone here actually ever played with any such thing personally?
Basically, I am looking for any info about existing line source horn designs. (To clarify: any horn designs that would allow a horn to emit a flat, line source wave, as if it were a stack of closely spaced drivers - very closely spaced for high frequency sounds - or a ribbon or other planar driver)
One such waveguide arrangement is shown here
(about 75% down the page):
http://www.lenardaudio.com/education/07_horns_3.html
This is basically just making a wiggling path in the center of the horn or waveguide, so that the point-source compression driver at the throat emits an apparent line source wave at the mouth. In this way, the waveguide acts as an acoustic "lens" to make the center path longer, effectively slowing down the sound coming out of the middle of the horn, while restricting the sound coming out of the top and bottom of the horn much less.
I had also seen a somewhat similar "squiggle and split" pattern for a horn somewhere on the DIYaudio board - an actual image posted here - but I have not managed to find it again in any searches recently (anyone know where that one is here?)
Another waveguide shape is shown here (look on page 5 in the center):
http://www.sonicdesign.ch/downloads/3_technische_dokumentationen/Line-array-vs-Line-source.pdf
This one is from L'acoustics for use in PA system Line Array cabinets.
Another PA cabinet line source horn arrangement is the "Ribbon-Emulation Manifold" from MeyerSound. While it does not really provide a continuous true linesource, if does effectively split the horn into 4 coherent emissions through the use of a (patented) funny split horn:
http://www.meyersound.com/support/papers/REM/index.htm
Another PA emulation is here:
http://www.renkus-heinz.com/loudspeakers/linearrays/LineArrays-White-Paper.pdf
That document explains quite a bit about acoustic lensing for line source use and has some simplified functional images of their horn/waveguide design. (Though I would love to see exactly what is really on the inside of those horns)
Another PA embodiment is here:
http://www.orbitalsound.co.uk/sales-loudspeakers-dandb-tseries.asp
This one actually has a rotatable waveguide plus acoustic lens arrangement that allows switching between line source and point source emanation patterns.
So, who knows of other designs for this? Pictures, patent applications, etc. I'd like to see anything anyone is doing in this direction for home audio or professional sound reinforcement. Any design where a (compression) driver get bolted on to the back of a horn and results in a line source "cylindrical wave" coming out of the front.
Has anyone here actually ever played with any such thing personally?
MaVo said:
Well... I don't know, actually. I have no idea what's on the inside of Tom Danley's latest breakthrough. I have been wondering about the GH-60 since I saw the picture at the bottom of the page here:
http://www.danleysoundlabs.com/pdf/GH60%20vs%20Line%20Array%20Summary.pdf
(below all of the very impressive graphs)
Anyone have any autopsy photos? What is IN there? [note to Tom Danley or Mike Hedden: sneak me some pictures and I promise I won't divulge or imitate...]
I have been a huge Danley fan since "Elephant Subwoofers" thru ServoDrive thru Tapped Horns (including the Matterhorn) and Synergy Horns. I guess the Genesis is the next super-efficient miracle.
I also really admire the fact that he shares enough information on his discoveries for the rest of us to start playing with our own designs using his principles (but without a complete "recipe" that gives away the farm and injures his commercial ability to keep innovating).
Since Danley's stuff tends to be all point source gear (and compete very well against line arrays even in their preferred battlefields, I am going to assume that the GH line will not have any line source components.
I DO really want to know what is really going on behind the scenes there. Paraline Lens Technology? Shaded Amplitude Lens Technology? If I had seen those "patent pending" terms anywhere else I would have likely dismissed it as marketing fluff, but based on the track record, I know there is some sound science behind it.
"Paraline" sounds like some sort of line source trick, so maybe it does fall into this thread. "Shaded Amplitude" sounds like some sort of cool coverage control technology (maybe a bit similar to the acoustic lenses of many years ago?)
Thanks for the link to the white paper, MaVo!
That looks like a horn-loaded line array for the LF sound for sure. Very cool-looking room, and makes me wonder about actually living inside the mouth of a giant horn. (or even living in the compression chamber)
BTW, if that guy is married and getting any high SAF on the system, his wife just replaced my "dream girl" definition (um... Guinness heiress, long fingernails...)
What I am looking for (and may not be explaining well) are designs where a single driver is mated to a horn/waveguide which results in a line source.
BTW, if that guy is married and getting any high SAF on the system, his wife just replaced my "dream girl" definition (um... Guinness heiress, long fingernails...)
What I am looking for (and may not be explaining well) are designs where a single driver is mated to a horn/waveguide which results in a line source.
MaVo said:
OK MaVo, you have nailed it after all.
I found this on the Paraline system:
http://www.vtcproaudio.com/paraline.html
And a 3-D exploded sort of animation here:
http://www.vtcproaudio.com/paraline02.html
And some more details halfway down this document:
http://www.vtcproaudio.com/downloads/press/vtc_cat.pdf
It makes for a very "shallow" horn ("less than one inch deep"), but appears that the sound path has rather extreme angles to get around. I would love to hear one of these (or a floor to ceiling array). I would also like to know if this waveguide design could be made to work lower in frequency.
This one definitely falls into the category I was asking about. ("weird waveguide resulting in line source emanation")
Any more of these out there?
I'd love any pics or links to patents or patent applications.
I don't want to infringe on anyone's designs really, but I do want to start working on some line source horns - especially some with a bit of extended range. The ones for PA use seem to only be used from about 1kHz up (and sometimes only from 3500Hz up).
With all of the "full range" drivers out there, it might be fun to try making a live source horn that gets from, say, 400Hz up (or even lower).
It's sort of a cool alternative to just packing a million drivers in a line to get the spacing less than 1/2 wavelength from center to center.
I'd love any pics or links to patents or patent applications.
I don't want to infringe on anyone's designs really, but I do want to start working on some line source horns - especially some with a bit of extended range. The ones for PA use seem to only be used from about 1kHz up (and sometimes only from 3500Hz up).
With all of the "full range" drivers out there, it might be fun to try making a live source horn that gets from, say, 400Hz up (or even lower).
It's sort of a cool alternative to just packing a million drivers in a line to get the spacing less than 1/2 wavelength from center to center.
I have no idea what your real goal is... but take a look at how a Beveridge ESL is constructed. Maybe you can find some ideas there...
If all you want is a large smooth line source, why not build or buy a ribbon like the BG??
_-_-bear
If all you want is a large smooth line source, why not build or buy a ribbon like the BG??
_-_-bear
bear said:
I have built, bought and borrowed ribbons, and love them.
For some reason, efficiency is becoming an issue for me lately. It is sort of a weirdness that we accept that a loudspeaker can be awesome when it emits 99% heat and 1% changes in barometric pressure. Some horns make it to 20% efficiency (admittedly at some cost).
Your statement about my "real goal" is valid, however -- I don't have one. As a small intermediate goal, I would like to see if a decent near-full-range line source horn can be made, maybe only because no one else seems to be trying it. I could spend 200 hours making another floor-to-ceiling ribbon, and get close to someone else's performance. It is a pretty straightforward exercise (not easy, and not cheap) and maybe if the cost of permanent magnetism comes down by about 99% we'll have them available at every Wall-Mart.
It's just a different direction I am looking in for a bit here. I originally had some ideas on a line source horn many years ago, and now see that several manufacturers in the sound reinforcement field are busy patenting their waveguide designs (that all seem to look like several of my old notebook sketches) and so I wanted to know what is currently the state of the art in this area.
Line Arrays are now the bandwagon that all PA manufacturers have now jumped on in "me too" fashion. They pretend it is some sexy new technology, and use it primarily for coverage control of huge arenas that are really bad listening rooms.
Horns in general are so cool, and some of them sound great. All of the good ones are point source devices, and I'd like to just take a look at making a line source one.
True ribbons and other planar types (magneto planar, and ESL) CAN be true line sources at high frequency. The stack of tweeters version can nearly get there, but unless you can stack them very tightly (1/4 wavelength is ideal, but 1/2 wavelength is a minimum) it won't work correctly. So, to make a non-planar line source array seems that we would need our tweeters at about 1/3 of an inch apart center to center AND the dispersion pattern of each tweeter needs to be completely hemispherical. When we need a million tweeters to do this, we settle for a ton of $1 tweeters that we would likely not ever want to listen to separately.
A line source horn may possibly give us another opportunity to use a single good driver to accomplish a true line source.
So, that my reasoning.
A line source horn may possibly give us another opportunity to use a single good driver to accomplish a true line source.
So, that my reasoning.
bear said:
Bear, I did look at the design of the Beveridge ESL - that's a pretty incredible, innovative design. And yes, his lens is doing horizontally what I am trying to do vertically to some extent. Like the reverse direction - taking a planar wave and using a horizontal lens to compress it to a linesource.
I'd love more pictures of the inside of those toys. There were really only two on the site and I am still trying to get a better visualization of exactly what is in there.
I'd also love to hear a pair some time. It seems like they combine linesource + monopole + ESL + cabinet (aka "doing something useful with the back wave to extend response") in a very creative way. Also, actively driving both the stators AND membrane with a signal is genius.
I saw a post from you (back in 2005?) where it looked like you might have had a chance to pick up a pair of Bevs. Any chance you managed to get your hands on them?
For anyone that hasn't seen them, I highly recommend taking a look here:
http://www.beveridge-audio.com/technical_details.html
and then wandering around the rest of the site.
Also take a look at the DIYaudio thread here:
http://www.diyaudio.com/forums/showthread.php?threadid=51103
...where the son of the founder explains some of the innovations.
No, I never got any Beveridge speakers myself.
The "line array" speakers that are popular for PA/SR probably are no good for the near-field home use that we have. Maybe if you were in a very large factory loft space, they might play for you.
I'd suggest that you stick with straight horns if you want high-efficiency speakers and just optimize them. Honestly, I don't see an effective way to combine the ouput from multiple compression drivers into a "line source" that is truly homogeneous.
Since you don't need the SPLs in a home from multiple compression drivers, you can really just skip that part.
No free lunch, and it's all a compromise, just pick the areas where you are comfortable with the biggest compromises.
Then sit back and enjoy listening.
_-_-bear
The "line array" speakers that are popular for PA/SR probably are no good for the near-field home use that we have. Maybe if you were in a very large factory loft space, they might play for you.
I'd suggest that you stick with straight horns if you want high-efficiency speakers and just optimize them. Honestly, I don't see an effective way to combine the ouput from multiple compression drivers into a "line source" that is truly homogeneous.
Since you don't need the SPLs in a home from multiple compression drivers, you can really just skip that part.
No free lunch, and it's all a compromise, just pick the areas where you are comfortable with the biggest compromises.
Then sit back and enjoy listening.
_-_-bear
bear said:
Pretty much no good for home use by design since very few of them approximate a true line source, with gaps in coverage and drivers spaced too widely. At around $4000-5000 per unit (times 7 to get from floor to ceiling and times 2 for stereo) a "pair" ends up costing about $70,000. Also, the total power handling would be about 30,000 watts, and I would be tempted to try and use it. That would be downright unhealthy.
All they are shooting for is loud and controlled dispersion. So until my home theater has seating for more than about 20,000 people, I am definitely not going to go there.
I HAVE heard a few single units that make a decent point source, as a WMTMW arrangement. I have also auditioned a few ribbon-based PA cabinets that I might be willing to listen to in small spaces.
What I am looking to experiment with is a single compression driver mated to a weird horn with a floor to ceiling mouth and some appropriate winding waveguide paths that make it phase coherent as a line source from top to bottom. Some good compression drivers work well from 500Hz up to 18-20kHz, so i could crossover at 500 and a line of woofers to supplement could be spaced near 2 foot apart ctc. (or - yikes! - another horn to go from 500 down to where a sub could take over)
It's unconventional, but I like the sound of SOME horns, and MOST line source systems, so I was thinking of a hybrid of the two. Not as a "hey this is gonna sound great" system, but as more of a mad scientist proof-of-concept.
And it is weird idea like a tapped horn or a synergy horn or horn loaded ribbons. Not quite as weird as a plasma tweeter, and just about as weird as an ESL. (still less weird than a fan subwoofer, or a Servo-Drive, weirder than a T-Line or excited NXT panel, and just about the same level of weirditude as big dipole woofer)
So, I will eventually get to answer the question "why hasn't this been done before?" With a predictable "because they are big and ugly and sound like crap"
Or not.
I found another type. This one effectively does with acoustic mirrors what others do with acoustic lenses:
http://www.gtaust.com/filter/11/09.shtml
This is the Nexo Geo approach. (Another example from the PA/Sound Reenforcement side of things)
With a parabolic or hyperbolic reflector, a virtual point source of the sound can be placed actually outside of the enclosure, with the real source inside.
This design doesn't immediately appear to lend itself to a home audio system.
I also wonder what sort of magic surface material can be used to reflect all frequencies equally like this.
http://www.gtaust.com/filter/11/09.shtml
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
This is the Nexo Geo approach. (Another example from the PA/Sound Reenforcement side of things)
With a parabolic or hyperbolic reflector, a virtual point source of the sound can be placed actually outside of the enclosure, with the real source inside.
This design doesn't immediately appear to lend itself to a home audio system.
I also wonder what sort of magic surface material can be used to reflect all frequencies equally like this.
Interesting variety of different approaches to the same goal.
What were the conditions of the measurements, distance and environment?
Did you do vertical and horizontal off axis measurements on any of the units, or with multiple (as they are designed to be used) units ?
I'm working with a line of two of these right now:JBL VRX932LA-1 Horn Assembly 364432-001 | Speaker ExchangeSpeaker Exchange
Don't care much for it though, 1}they don't go low enough 2) they don't integrate well at 4 meters
Don't care much for it though, 1}they don't go low enough 2) they don't integrate well at 4 meters
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