SEOS 30 synergy

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SEOS15 has shown to be a good choice and one would think bigger would be better. This very large SEOS extends pattern control lower and requires a 2" exit CD, which supports a lower crossover frequency. Aside from the cost, I don't see any negatives but there are some unknowns. Auto-tech does not publish the polars and only the one photograph from which its hard to judge potential issues in attaching woofers. I wouldn't use a version with an extended neck tapered down to a 1.4" or 1.5" CD; that seems a potential cause of diffraction and might push the woofer entry holes too far forward.

Why would rectangular be a compromise? Rectangular gives you lower horizontal pattern control than vertical but also a listening window that is wider than it is tall, which seems appropriate. On the other hand, a rectangular horn with a 30" x 30" mouth would do a better job of limiting floor and ceiling reflections but where can you get a ready made horn of those dimensions?
 
There are a couple diy theads on building a Synergy horn using the SEOS-24 with positive meaurements and listener feedback. You should expect some SPL loss at high frequencies because the SEOS-24-30 uses a 1.4" compression driver instead of 0.75" or 1" used in perfectionist multi-horn speakers. No reason the larger SEOS-30 would have poorer performance, but the devil is in the details of port shapes and complex crossovers.

The Klipsch K-402 plastic horn has been used in a few diy Synergy builds / threads. The sides on the K-402 have enough flat area to mount Synergy drivers. A K-402-Based Full-Range Multiple-Entry Horn - Technical/Modifications - The Klipsch Audio Community

If you have a large budget, a BMS coaxial compression driver like the 1.4" diameter BMS 4954nd can cover down to 450Hz and simplify a home synergy construction.

The cut-off frequency for a horn is set by the mouth area. The mouth area should exceed (Cutoff_wavelength^2) / 4Pi

SEOS-30 = 780mm x 527mm = 41106sqmm = 90Hz lowest cut-off frequency. Baffle step and adequate horn loading from the small/narrow woofer ports cut into the SEOS-30 will push this up closer to 180Hz.
 
Interesting idea this. Judging by the drawings it should be possible to put some drivers on there. I'm myself contemplating a synergy build for the winter (it's coming..), and was planing to use one of the BMS coaxes. I'm currently thinking of BMS 4590. It's one of the cheapest options, and it looks like it has the smoothest response (according to the data sheet).

Any idea of the cost of the horn?
 
The catch with that is you will most likely find you need to adjust the port locations, port wall thickness, and sizes from what you calculate. With $500/ea fiberglass horns, I'd be nervous about planning on getting it "right" on the first shot. Of the synergy/unity type horns I've made, I've needed to tweak midrange porting for each type at least once. That's the advantage of cheaper plastic horns or of 3D printing the horns, there isn't the need to avoid iterations.

Probably you could use fiberglass patch to refill and move ports if/when needed, but cosmetically that won't be so nice. Or you could get them close enough to work some (avoid deep nulls in-band) and then use external EQ to force it all to work.
 
I found this:
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Source

See also the PSE-144 horn discussions thread here
 
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Those curves (normalized to the on-axis measured curve, it appears) don't look none too good to me. 16dB per division graph and HF bumps nearly an entire division? Pretty nice below 4kHz perhaps. Perhaps he should have normalized to 20 degrees or so off-axis, then all but the on-axis would probably look a lot better. On-axis brings all the equidistance-reinforced physical effects into play (and it's a relatively narrow part making up the entire power spectrum. And with toe-in, not an angle of particular significance).
 
The Klipsch K-402 horn for a synergy like application would be wizard! Good luck trying to get hold of one of these...

If anyone knows where to buy the damn thing (even a knock off) please let me know.

Kris

Take a loon craigslist. Where I live, there are a lot of people who will 3D print things for a reasonable cost.

If I were looking for a k-402, I'd design it in 123D and have it printed for me.

Shapeways is basically useless these days because their prices are completely insane now.
 
3D print a K-402? How many pieces would that have to be printed in to do it on usual large-format printers?

It's not much bigger than what you printed right? I can't find dimensions on the Klipsch site, but I believe it's about 30" in diameter.

It's basically the same profile as the QSC waveguide I'm using, but twice the diameter.

Another option might be to use the waveguide from the MeyerSound Acheron. Just call them up and tell them you need a replacement waveguide. Parts list is here: https://www.meyersound.com/mail/2016/160401_ddr/pdf/2016_sppl_final.pdf

QSC has happily sold me a bunch of parts. No issue whatsoever. Much faster shipping than ordering from Parts Express. (PE is in Ohio, QSC is in CA)

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Danley SH50 waveguide, 30" x 30", wood

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MeyerSound Acheron waveguide, 31" x 15.5", plastic

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Klipsch Jubilee waveguide, 30"? x 18"?

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QSC Waveguide, 15" x 10", plastic
 
It's not much bigger than what you printed right?

No, my big printed waveguide is only about 20" wide. I have to print it in two parts.

Though I just printed a waveguide "stub" last night that can attach to wood panels to make any size I want. 13 hours of printing, and not quite a full kg of PLA filament..

But as you've seen, my house and so-called "Listening Room" aren't big enough to practically use anything much wider than the 20" waveguides I printed. That's one reason why I resorted to array effects to get directivity lower in frequency without a bigger horn.
 
I'm eager to see how the measurements turn out on mine, but I don't personally see any good reason to use anything bigger than what you're using.

All the data seems to indicate that you can control directivity with an array that's wrapped around the waveguide, a la "Small Syns"

And if that's true, the only advantage of a larger waveguide is higher efficiency. Which isn't terribly important to me.

If I were selling loudspeakers for a concert or a theater, I could see the appeal, but I'm not.
 
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