Suitable midrange cone, for bandpass mid in Unity horn.

Interestingly enough, I found out a couple things from the video:

1) There isn't anything special at the throat; it's just a plain ol' array of neodymium compression drivers
2) The driver in the video appears to be the Celestion CDX1-1425, but with a truncated motor. Basically it's been narrowed so that they can fit together more closely
3) According to the video, 14 of the Celestions had an output level that's equivalent to six 'conventional' compression drivers. Considering that the diaphragm and the voice coil are much smaller, this sounds about right.

Kinda cool that the Celestion is getting some love though; I *do* find that it sounds 'sweeter' than my B&Cs and the Dayton D250P clone.

Midrange appears to be six of the RCF M8N301s:

rcf-mr8n301-350.gif


$1800 for six :O

The mids are 5" custom units and not the M8N301. Still don't see how they can compete on price with Danley unless they sell at a loss until they get their scales of economies up. You can see what EAW is doing is throwing a lot of money around with custom drivers to do what Danley does with off the shelf parts. Its just my opinion, but from an engineering perspective this makes EAW look pretty bad and exposes their lack of innovation.
 
I do not see any bandpass 'ports' or holes, only drivers mounted in a V :confused:

Let's see, there's a bunch.

1) The woofers use slot shaped ports in front of the drivers. These slots have three purposes. They act as an acoustic low pass. They move the apparent source of the woofers towards the edge of the enclosure, so that the center to center spacing is a better match for the crossover point. And they slots reduce how big the woofers appear to be. (Same trick that Nexo does with their phase plugs.)

2) The midrange ports do the same thing, but it's a bit more 'gimmicky' imho.
An externally hosted image should be here but it was not working when we last tested it.

They're shaped like fibonacci spirals, but overlaid on top of each other. (It's in the patent.) I have no idea if this has any acoustic benefit, or if it's just audio voodoo. But it's patentable. According to EAW, "Reason Three: The Fibonacci Spiral. This is a spiral pattern found throughout nature, from seashells to sunflowers to pine cones. It's derived from the numerical sequence known as Fibonacci Numbers. by crisscrossing Fibonacci Spirals along the high frequency waveguide's surface, we laid out holes that make its wall 20% open and 80% solid through any cross-section. The waveguide acts simultaneously as two mechanical filters: a low-pass filter for the mids and a high-pass for the highs. The holes are evenly distributed for symmetrical midrange response off axis, yet their randomized shapes and sizes avoid audible high frequency nulls."
It's actually how I found the speaker, because I was trying to make a spiral phase plug (see my thread '28 days later') and I figured that *someone* must have made a spiral phase plug by now.

3) The compression drivers are actually straightforward. Just an array of 14 very small compression drivers, appears to be a variation on the CDX1-1425 that I use for most of my projects.
 
Mid cylinder packed with wedges, instead of a frustrum.
Does that trip up highs as they cross the bigger hole?

I was kinda thinking a phase plug that would begin with
a frustrum. Filled with fusible beads of metal or plastic
or glass. That we might grade the density of packing to
expand the breathing spaces between as the frustrum
actually narrows toward the exit...

Just think that might be easier than making wedges or
rings in complex shapes... And then the front face of the
frustrum is a bunch of loosely fused beads instead of an
empty hole.

Near the mid cone, beads would be fused more densely.
As the space between beads becomes unreasonable to
fuse, we can maybe switch to an open cell foam...

Probably work in a cylinder too for compression loading,
though simple cylinder maybe not the ideal phase plug.
 
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I would be interested in seeing your data. Thank you.

Rgs, JLH

Values are taken just out-off-the-box, with no preliminary burn-in!

Fs = 609Hz
Re = 7,1 Ohms
Qms = 7,83
Qes = 5,69
Qts = 3,30
Bl = 3,20
Cms = 3,23E-05
Rms = 1,07
Sd = 59,86 cm^2
VAS = 0,165 L /* By the wattage conversion efficiency method */
Le ~ 0,33 mH /* This a neighbourhood-value, since I don't have an LCR-meter and the multimeter method is not yealding expected values */

I do apologize for the extensive use of commas - I'm european:cheers:

/Thomas
 
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Question about port location relative to wavelenght:

I know that this has been disgussed on numerous ocassions, but I need get it cleared one more time!

Can one just place the holes to best fit as long as they are located such that, the distance from anywhere on the driver surface to the nearest hole will be less then 1/4 wavelenght relative to the x-over?
Won't turbulence cause some of the the waves to travel to the farthest hole, or is this negligible?


/Thomas
 

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Question about port location relative to wavelenght:

I know that this has been disgussed on numerous ocassions, but I need get it cleared one more time!

Can one just place the holes to best fit as long as they are located such that, the distance from anywhere on the driver surface to the nearest hole will be less then 1/4 wavelenght relative to the x-over?
Won't turbulence cause some of the the waves to travel to the farthest hole, or is this negligible?


/Thomas

You can use Akabak to look at the air velocity at the ports, and also the horn cross section. As long as it is kept below about 17 m/s it should be fine.
 
You can use Akabak to look at the air velocity at the ports, and also the horn cross section. As long as it is kept below about 17 m/s it should be fine.

Now you've just completely lost me:confused:

Maybe I didn't asked the right question - I'll try to rephrase.

With a 6.5" driver you have diameter of appx. 130mm. Let's say you have to place the holes near the egde of the cone and not far apart. This means that soundwaves emitted farthes away from the ports will travel appx. 98mm. before it hits a port With a 1500Hz x-over a 1/4 wavelength is 57.3mm. Will this not cause delay/phase problems?

/Thomas
 
A couple of random updates on Unity-type speaker builds:

1) I've been messing with BG NEO8s, and it appears that they'll work as a midrange on a Synergy horn, Unity horn, or Paraline. I thought I'd posted some measurements in this thread earlier today, but either it was deleted, I posted to the wrong thread, or it just didn't go through.

Bottom line - ribbons don't just work at the apex of Synergy horns. They also seem to work as midranges.

I'm going to build one today and post some measurements.

2) The other day I built something that comes as close as I've heard to that Unity Horn Magic. I built a two way with the Dayton ND91 as a direct radiator, with a clone of the Beolab lens on the top. So a basic two way, but with the Sausalito Audio Works lens on top.

images

^^ basically my project looks like this

This thing gets REALLY close to that synergy that makes the Unity horns so remarkable. The one thing that I notice with Unity horns is an ability to make five drivers sound like one full range drive, and the Sausalito Audio Works lens does this very very well.

I think the reason that the sound is so similar is because the driver spacing is very very tight, and the direcitivity of the woofer and the tweeter is basically the same at the crossover point. You don't get this with a regular two way speaker; in a conventional two way the directivity of the tweeter narrows as you go higher in frequency, which gives it that unnatural sound that tips us off immediately that we're listening to a loudspeaker, not the real thing.

Also, the configuration of the SAW lens tightens up the vertical spacing of the drivers, and it physically time aligns the voice coils. In fact, the magnets of the woofer and tweeter are within an inch of each other!

But check out the measurements of the SAW lens and you'll notice that it's directivity is wide, matching the woofer, and that wide directivity stretches all the way to about 15khz.

It does all that 'goosebump inducing' stuff that the Unity does. Like listening to vocals, getting up out of your chair, and finding that the sound doesn't vary as you walk around the room. And hearing loads of details in recordings, because of the very tight spacing of the drivers. Hearing things in your music that you didn't know were there.
 
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