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Old 31st March 2012, 09:41 PM   #11
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Hi Patrick (john), all
Speaker Dave has posted a couple pictures of the microwave horn / reflector that inspired the Paraline.

That microwave horn / reflector worked vary well and was the backbone of our cross country telephone system for a long time and lead to the discovery of our cosmic background radiation.

The problem when applied to acoustics is that unlike microwave, one is dealing with a variable wavelength signal and “how a reflector works” is partly dependant on how large it is. In the reflection based system, one has to have a reflector many many wavelengths across before it starts to be something like what we think of as a mirror (the same at different frequencies).

Being sort of a horn guy I guess, I wanted to find a solution that was compatible with horn loading as well so that kind of steered my direction.
The Paraline only uses the path length and natural point source radiation of the driver pressure and is free from the variable reflector issue.

If you picture that from the blue line forward forming the vertical plane is one thin slot and the upward horn ends at the blue line, the blue line is a slot that connects the two layers.
Sound acts like a simple pressure, like a fluid, flowing around a corner if the dimensions are small relative to the wavelength while it can act like light if the dimensions are very large. This depends on the dimensions being small for the sound to bend, it’s own pressure makes it go the right place.
The shape of the Paraline slot defines where the radius of curvature or equivalent origin is for the exit wave front relative to the incoming wave front.
In the Paraline most in use, the configuration is a radial sweep of the first idea.
The VTC graphic is nice and shows the guts of the one they use.
The driver connects through the opening and the sound bends to radiate away radially 360 degrees but within a thin airspace.
The thickness dimension is too small to allow a reflected signal, in order to bend around the two 90 degree corners, the dimensions have to be no more than around 1/3 wl at the highest frequency. Radiating away from the driver, it has a 360 degree expansion.

After wrapping around the slot, the timing / pressure produces the desired exit waterfront which converges at the center, bends 90 degrees again and enters the rear of the horn. This imparts the same curvature one would have if the horn were made conventionally but was very very deep physically.
The ones we use are very similar to the VTC units and your right one advantage is they can be placed end to end easily. The GH-60’s at Lambau field use them .
One other less obvious thing is that as the sound radiates away from the driver, the spl is falling according to area. This means with a constant thickness, the top and bottom are automatically -3dB relative to the center. The wider the vertical pattern angle, the greater the amplitude shading the center relative to the ends. Anyway since when the dimension is small one can think in power per area, the spl in that plane can be tailored to a degree.
The “J” cabinets use something kinda like a paraline that I called a layered combiner.
You can’t add high frequency drivers together without making an interference pattern up high, Y throats don’t work and a well known 4 driver combiner is only about 4 dB more powerful than a single of the drivers on a normal horn.
That single driver limit had always been the loudness limit on the Synergy horns but the J horns with the combiner I could get around that by producing the radiation of a single source.
As soon as the patent orifice has it available to the public it can explain it.

This was I think the hardest nut I ever had to crack, it took 4 months to get a workable design in the JH-90 (J1) but the latest one has 64 hf drivers that add into one wave front (obviously had to have a working name of the mosquito beater haha). At one point I was getting bummed out and afraid I had been wrong when I said ‘I think I see a way to do it” but ultimately, the solution was very much like the fleeting idea months before.
A couple J cabinet video demo’s using the combiner;

Adjust the volume to scale to live at about 1:30 when the operator walks up to the guy next to the camera guy and talks. It was pretty loud then but later a bunch of people (stadium sound people) took off in cars to hear from farther away (with these the sound changes very little with distance compared to normal speakers), the cops came and they were not happy. Anyway, except for his mic being squashed by the subwoofer, I thought his video captured being there pretty well.

Danley Sound Labs - YouTube

This was a larger space using three J cabinets facing right, left and center, they are the little dark blob under the scoreboard. Keep in mind a stadium is a pretty live place with no people.

Penn State Demo.MOV - YouTube
Best,
Tom Danley
Danley Sound Labs
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Old 2nd April 2012, 12:00 AM   #12
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Tom - thanks for posting this info! I've learned a lot from your posts. I've been following them for about a decade.
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Old 2nd April 2012, 12:07 AM   #13
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Click the image to open in full size.
Click the image to open in full size.

Here's a drawing of an underdash horn, using the same reflector assembly that's in the paraline and in the SAW lens.

Here's an explanation of what's going on in the picture:
  • The red triangle defines the forward angle, and is 20 degrees, just like the paraline patent
  • The yellow triangle is the 'initial' wavefront, off of the compression driver
  • The blue rectangle is the footprint of the horn. Basically it's there to define how much space we have for the horn. In this case, it's 5" by 15"
  • The dark blue line is probably the most important curve in the whole horn. This is the reflector, which is designed to bend the wavefront. One thing which isn't obvious, but is very important, is that the wavefront is flat. This is a big deal in car audio, because it 'drags' the image towards the center. This might not be obvious, but flattening the wavefront drags the image towards the center because it creates a time delay. (it basically delays the center of the wavefront, and since the horns are cross-fired in a car, it 'drags' the speaker backwards. Basically drags the image towards the left.
  • The black circles are simply there to reduce diffraction. Each circle reduces diffraction at the mouth of the horn.

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Old 2nd April 2012, 01:57 PM   #14
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Quote:
Originally Posted by Tom Danley View Post
The “J” cabinets use something kinda like a paraline that I called a layered combiner.

This was I think the hardest nut I ever had to crack, it took 4 months to get a workable design in the JH-90 (J1) but the latest one has 64 hf drivers that add into one wave front (obviously had to have a working name of the mosquito beater haha).
Tom,

64 HF drivers should help keep up with the 18 dB air loss of 10kHz at 400 feet, a “mosquito beater” indeed!

Would you share a peek under the hood showing the arrangement of the drivers?

Art
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Old 2nd April 2012, 02:16 PM   #15
KSTR is offline KSTR  Germany
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Did I read 64 HF drivers? OMG!.... Tom, your're sure one hell of a crazy guy
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Old 4th April 2012, 12:01 PM   #16
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Did I read 64 HF drivers? OMG!.... Tom, your're sure one hell of a crazy guy
Click the image to open in full size.

I wonder how low you could cross that over. 64 compression drivers have more surface area than a pair of 12 woofers!

Obviously you couldn't get away with a 80hz crossover on a compression driver, even if you use an array of them, but that much surface area could definitely allow a lot of flexibility on the crossover point of a synergy horn.
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Old 5th April 2012, 12:01 AM   #17
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Hi Guys
I got into audio by being a DIY’r so there aren’t a lot of things I enjoy more than explaining a new invention or lurking as others go through the process figuring them out like you guys.
I wish I were able to be of more help at times too, Art, I wish I could explain how the combiner works but at the moment I can’t.
If you are going to infocom, I can show you there.
We are running a race where the largest companies strongest legs are image marketing creates and it’s budget and our only strong leg is what people hear in a side by side demo.
What seems to be happening is when you make something that nothing else does, people find uses for it. The Jericho cabinet came to be when a sound guy we know said he bet if you could do a live show up to a couple thousand with one box per side that sounded like an SH-50, that would sell.

Well the concert sound industry largely “knows” all about line arrays, rigging, nice color mapping programs, the things needed to get concert sound. In the stadiums, it is the same concert sound stuff that is being bumped out because it sounds dreadful in a side by comparison.
The market where the acoustic problem is the hardest and a solution most appreciated (by people who couldn’t care less about a name or approach they never heard of) is commercial sound especially now in stadiums and that is where the focus is.

The 64 hf driver device is for very long distances where the hf air absorption can be severe. The first time I heard a stadium install playing CD’s with the Jericho’s and 812’s (BYU) I walked the stadium and then sat facing the system from the far side (about 750 feet).
The two things I thought were wow, they could play movies like U-571 through this and if I had a bit more twinkle, it would sound like the speakers were 20 feet away. In hot humid weather, the hf absorption is greater. The cool thing about a CD point sources is except for the hf absorption, the spectral balance doesn’t change with distance while interference pattern arrays have a pronounced maximum usable throw and constantly variable frequency response that requires fancy colorful displays to hide that feature set..
This box should satisfy the very large scale sound requirements for "giant fi".

Here is a video of the J2 being used on it’s maiden public test last fall.
This is more powerful than the J1 and J3 I have posted previously and this Synergy horn has 42 drivers, 12 are hf compression drivers.
In this case, with a live band, to me it sounded like too much high end in this use, given how far away it was.
Also, normally, these would be flown and aimed “at the back row” so the underside of the pattern tapers the spl.
If you get the pattern bottom’s shape and flying height dialed in, the spl only varies a small amount from the closest to farthest seats.
Best,
Tom

Danley Jericho PA speaker, J2 at 300 Yards - YouTube
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Old 5th April 2012, 03:04 PM   #18
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Originally Posted by Tom Danley View Post
Hi Guys
I got into audio by being a DIY’r so there aren’t a lot of things I enjoy more than explaining a new invention or lurking as others go through the process figuring them out like you guys.
I wish I were able to be of more help at times too, Art, I wish I could explain how the combiner works but at the moment I can’t.
If you are going to infocom, I can show you there.

The 64 hf driver device is for very long distances where the hf air absorption can be severe. The first time I heard a stadium install playing CD’s with the Jericho’s and 812’s (BYU) I walked the stadium and then sat facing the system from the far side (about 750 feet).
The two things I thought were wow, they could play movies like U-571 through this and if I had a bit more twinkle, it would sound like the speakers were 20 feet away. In hot humid weather, the hf absorption is greater.

Here is a video of the J2 being used on it’s maiden public test last fall.
This is more powerful than the J1 and J3 I have posted previously and this Synergy horn has 42 drivers, 12 are hf compression drivers.

Best,
Tom
Tom,
I couldn’t hear a whisper (or twinkle ;^) of cymbals (8K +) in the J2 video, but plenty of high mids, the steel drum sound was certainly ringy!
12 HF drivers per cabinet seems a bit light on the VHF for 900 feet.

Upping that to 64 HF drivers you finally got around to fixing the problem I brought up (and Ivan Beaver acknowledged) 10/7/10, and now you won’t show me how ;^) ?

Wish I could make it to infocom, but have another trip north east around the same time.

This guy has the best collection of audio calculators:
Calculation method of absorption of sound by the atmosphere air damping dissipation absorbtion - Attenuation of sound during propagation outdoors outdoor - sengpielaudio Sengpiel Berlin

Hot and humid environments have less HF atmospheric absorption than dry, the opposite is true when the environment is cold. Somewhere in the middle temperature range both are pretty bad.

In the high desert of New Mexico outdoor concert season we see temperatures in the 90’s and relative humidity in the 20s, we need two to four times the HF horsepower from my native Minnesota, which could be 90 degrees with 80+ relative humidity.

With summer temperature often ranging as much as 50 degrees during day to night here, some drastic EQ changes sometimes need to be made, the crisp clear sound in the early morning quickly turns to mud once the sun shines.
Then the thermal gradients start to happen, even with a single point source they can point the sound in a different direction than the cabinets..

Perhaps you should make temperature/humidity/thermal gradient angle adjustment actuators optional on your stadium installs :^).

I don’t miss the Minnesota humidity, but I miss the HF, have the double whammy of age and absorption going on here :^(.

Art
Attached Images
File Type: png HF Air Loss.png (147.1 KB, 566 views)
File Type: jpg Air Loss.jpg (111.1 KB, 557 views)

Last edited by weltersys; 5th April 2012 at 03:12 PM.
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Old 5th April 2012, 09:13 PM   #19
gedlee is offline gedlee  United States
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The world would be a much simpler place is we could do acoustics by simply drawing straight lines. Problem is that sound is waves not light rays and they don't work like light rays. They go arround corners and diffract at edges, all kinds of things that "rays" do not account for. So I simply discount any argument that uses "rays" to explain what happens. Like the "acoustic lens" thing that was shown earlier. Measurements of a real device show that it doesn't act much like it is supposed to except over a very narrow range of frequencies. But thats OK, it looks cool and marketing likes that - so it doesn't actually have to work. The real disappointing thing is that the techniques that actually do work aren't all that "cool" looking and tend to be much larger than we would like. So its just easier to do it wrong and looking good.
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Old 7th April 2012, 07:58 PM   #20
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Mr. Gedlee - what range of frequencies do you think lenses would work at?
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