I thought it might be fun to try out some fullrange drivers and car coax that are sitting around here in a Synergy style horn. To be more precise, the Cosyn horn by Bill Walso calculated by his fabulous spreadsheet. (Thanks Bill)
This horn is the same size as Bill's Cosyn horn at 24" (60cm) wide, but with the throat adjusted to 2.8" for the FaitalPro 3FE25 driver. I plan to try these with various other drivers, including the FaitalPro 4FE35, the good old Vifa TC9FD, some TV speakers, car speakers and JBL ceiling speaker.
The horn is simply made of Dollar Store $1 thin foam core and hot glue (thanks XRK971)
It does work, it does do something - and seems to play down to about 125Hz, which is what I would expect from this driver. More to come.
This horn is the same size as Bill's Cosyn horn at 24" (60cm) wide, but with the throat adjusted to 2.8" for the FaitalPro 3FE25 driver. I plan to try these with various other drivers, including the FaitalPro 4FE35, the good old Vifa TC9FD, some TV speakers, car speakers and JBL ceiling speaker.
The horn is simply made of Dollar Store $1 thin foam core and hot glue (thanks XRK971)
It does work, it does do something - and seems to play down to about 125Hz, which is what I would expect from this driver. More to come.
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Thanks. It is kinda test pattern. My video engineer training is showing. 🙂 Yes and no on the rear enclosure, I'm trying with and without.
Ooh, yes, measurements please! I have a load of foam board left over from when I last tried the cosyn psreadsheet with a tweeter.
When taking horizontal polar measurements you'll find there is some diffraction that bunches up the 3-5k area and up but if you turn the horn vertical and do the same you will get linear seperation.
When taking horizontal polar measurements you'll find there is some diffraction that bunches up the 3-5k area and up but if you turn the horn vertical and do the same you will get linear seperation.
i may have to start another thread with some questions i have on an old Vidicraft switcher i have.
as i've played with foamcore and a few horn ideals and i can attest to attaching reinforcing ribs to the backsides of panels (but i've also contemplated adding some DML's to the mix)
Yeah, I've thought about ribs and will add some. 
This thin foamcore vibrates like mad. Thanks for mentioning it.
This thin foamcore vibrates like mad. Thanks for mentioning it.
I fooled around with 3 different drivers today. All three sound different and measure different on axis and off. They don't play nearly as low as Hornresp predicts, but maybe the my back chamber isn't great. I do like the FaitalPro 4", especially with a little midrange EQ.
Yeah, I've thought about ribs and will add some.
Hi Pano...a one driver synergy?? oxymoron isn't it ? 😉
Albeit very cool !
I bet the thin foamcore really does vibrate.
Heck, 2" foamboard vibrates in one my horn builds.
It's one of the few things I don't like about the stuff.
Sometimes i think because it's so lite, maybe it has air trapped in in the cells that can vibrate with lower freq energy...i dunno...
Yes it is, but you know how headline writers are, they never read the article. 😛
These came about because I was thinking "If a Synergy horn is meant to be a coherent point source, couldn't you use a coax driver in a similar horn?" I'm not the first to think this and there are a number of thread and posts about it. In practical terms there is a theater where I run sound in which this might work well for the center cluster, because I put nothing but actors' voices there. Maybe a nice 12 or 15 inch coaxial in a flared conical horn could work well.
I have some 5.25" car coaxials and some JBL 6.5" coaxails from ceiling speakers and thought they could work as proof of concept. I haven't gotten there yet, still at the 4" fullrange stage.
Today I built a second horn, trying to do it "right" this time. I even cut the foamcore on the table saw.
. But true to form, the second build was a complete cockup. Bill Waslo is right, you'll need to practice this build.Anywho.... In stereo with the FaitalPro 4FE35 as the horn driver, it's not bad. I did a 3L sealed rear chamber, well stuffed, behind. Sounds OK, but bright. Some of that is because there isn't anything below ~100 Hz, and partly because on axis they are close to flat. And that sounds bright. If I walk up to right in between the horns then the tonal balance is good, and the image comes from about 6 feet back. At the normal listening position the phantom image is strong and stable, the image is fairly large. Depth is decent, but not remarkable.
Considering this is a horn/waveguide that could be used 150-16000 Hz, it's not too shabby. I'll try to get a woofer under them.
Getting it to go that low is a challenge. Will it succumb to axial resonance, or the floor/ceiling reflection. Should it use the secondary flare or be full sized.. non-asymmetrical?
Yes, 100-120Hz is really asking a lot for a 24" wide horn/waveguide. This thing is so shallow it seems like much more of a waveguide than anything else.
A few years back at LSAF in Dallas - Dave Slagle and crew had a field coil Lowther in a big conical horn. Wow did it sound good. That one has stuck with me.
A few years back at LSAF in Dallas - Dave Slagle and crew had a field coil Lowther in a big conical horn. Wow did it sound good. That one has stuck with me.
Yes it is. It gives me more appreciation for the tar filled and sand filled horns.
Hello mate, will you be uploading measurements at all? I have 4 3FE25 upstairs I might try if it looks good 🙂
ah the age old sounds better then the measurement suggests, when that happens to me i squint and let my eyes water...makes most graph's look better...or have a scotch and comtemplate....
Good stuff Pano,
i think the idea of putting a horn around a coax (or a full-ranger)has great merit, and like you say, a bunch of folks have explored it.
DSL puts small horns around coaxials is their Studio series, and in their live sound boxes such as the SM series.
It will be neat if you get the directionality i think you're looking for out of a traditional synergy conical horn, on those full-rangers.
It will be even neater if you get some horn loading gain as well. And i do think you just might.
Danley's SM-80 has become a live-sound favorite for small to medium events. I believe it uses the B&C 12cxn76 coaxial. It's in a box 26"Wx24"Dx13"D.
Guys on the prosound forums say the coax couldn't reach the SPL it does without the benefit of the surrounding horn/waveguide.
I tried to dupe the SM80 kinda. Although i wanted to get strong response down to 100Hz opposed to the SM-80 which is petering out without boost by about 150Hz.
Here's my stab...uses a larger b&c 15cxn88.
And some foamboard for the "horn" !!!! 🙂
Anyway, good luck...will be watching...
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That looks very nice indeed Mark. Is that pink insulation foam? Did you sand it to get it so smooth? I suppose I've heard the SM-80, but don't remember it.
Alas I think this waveguide is too shallow to allow much, if any, gain. I was surely hoping for it, but it doesn't seem to be there. I suspect that it would have to be twice as deep to have any gain.
That said, even with the crap-o foamcore and hot glue construction they do a great disappearing act. And they are very clear and articulate, maybe because there is no muddy bass. Are they better in a horn than without? I'm not sure yet.
Graham. I'll upload the measurements in a couple of hours. Need to go clean up the garage of glue droppings and scraps of foamcore.
Alas I think this waveguide is too shallow to allow much, if any, gain. I was surely hoping for it, but it doesn't seem to be there. I suspect that it would have to be twice as deep to have any gain.
LOL, yes. With 1/3 octave smoothing and a large scale, it looks OK. But really, they do sound like they measure, I.E. too bright and sort of rough. But of course my big Altec horns sound amazing rolled off below ~600Hz when there is a woofer with them. Without the woofer it's horrid. I'm hoping that's some of the problem with these.
That said, even with the crap-o foamcore and hot glue construction they do a great disappearing act. And they are very clear and articulate, maybe because there is no muddy bass. Are they better in a horn than without? I'm not sure yet.
Graham. I'll upload the measurements in a couple of hours. Need to go clean up the garage of glue droppings and scraps of foamcore.