Unity Horn - budget drivers, active x-over

[TerryO]

Originally Posted by AlexQS

I really enjoyed reading about the horn you made. Wow, looks very complex with getting the througjt right, and everything smooth.

I hope that you'll also document the building of this folded horn beast of a subwoofer. I am one crazy enough to try something like this. Though I've never built a speaker, I am right at home in the shop, have tools, added a room onto my house, etc. Is this too much for a first build? I think I could do it.

"Whether you think you can, or you think you can't...
Either way, you're probably right!"

Henry Ford

[jmorken]

Originally Posted by AlexQS

I really enjoyed reading about the horn you made. Wow, looks very complex with getting the througjt right, and everything smooth.

I hope that you'll also document the building of this folded horn beast of a subwoofer. I am one crazy enough to try something like this. Though I've never built a speaker, I am right at home in the shop, have tools, added a room onto my house, etc. Is this too much for a first build? I think I could do it.

The documentation that CSS sends along are very exhaustive, and without them this project would be out of reach of most amateurs. They are detailed enough that I think anyone with a table saw and (most importantly) lots of patience could take it on.

[mwmkravchenko]

Skill saw will work in a pinch. Heck even a jig saw if you are patient enough. It is a fairly simple box when you look at it correctly. No extreme angles or anything hard like that. I tried to make it as simple as possible with the best performance possible.

[AlexQS]

Originally Posted by mwmkravchenko

Skill saw will work in a pinch. Heck even a jig saw if you are patient enough. It is a fairly simple box when you look at it correctly. No extreme angles or anything hard like that. I tried to make it as simple as possible with the best performance possible.

That was my thought,.. that all the lines looked pretty straight. I have a table saw, and a router.

The way I envision myself taking on a project like this, mostly what I need is tape measure, pencil, good instructions, and lots of patience.

To me the difficult part about speaker building (or shall I say the part I need to learn the most), is what kind of equipment to get to measure the sonic responces, and then how to interpret the data, use the data to make appropriate adjustments using crossovers and whatnot. I think I have much to learn -With this kit, the design part is done, just follow the directions to the proven design. The woodworking is a much lesser challenge to me.

[mwmkravchenko]

Go for it buddy. You have never heard the likes of what this box will produce. Few people have. It is a real eye opener. And most importantly ear opener.

[johnbomb]

Jmorken, your unity looks fantastic! First rate work. I would like to build a horn that's basically a slightly longer version of your design that uses two Eminence alpha 6 mids.

Can anyone draw up what I have attached in google sketchup, so that I can know the dimensions and miter angles? I have a shop full of tools and lots of woodworking experience, but I haven't yet figured out sketchup. Maybe there's a simple way to modify jmorken's design that he posted here? I have attached it here as well.

Suitable midrange cone, for bandpass mid in Unity horn.

Thanks very much,
John

[Patrick Bateman]

Originally Posted by johnbomb

Jmorken, your unity looks fantastic! First rate work. I would like to build a horn that's basically a slightly longer version of your design that uses two Eminence alpha 6 mids.

Can anyone draw up what I have attached in google sketchup, so that I can know the dimensions and miter angles? I have a shop full of tools and lots of woodworking experience, but I haven't yet figured out sketchup. Maybe there's a simple way to modify jmorken's design that he posted here? I have attached it here as well.

Suitable midrange cone, for bandpass mid in Unity horn.

Thanks very much,
John

I don't use Sketchup - i do my stuff in 2D because it's faster, and then I draw the 3D model by hand. (Having made a bunch of these, I can draw it out in less than an hour now )

But these parameters are unfortunately impossible to build. For instance, the throat chamber volume and area is set to zero. Which means there is no throat chamber. And that's perfectly valid, as long as the area where the woofers enter the horn is large enough. But it's not - it's set to fifty square centimeters, which is a small fraction of the woofer's size.

That's the reason that the very very small woofers start to look attractive for a unity horn. You can squeeze a pile of them very close to the throat, and get the surface area of a much larger woofer, basically subdivided over an array of small drivers.

Taken to the extreme, you see the layered combiner that Danley has been talking about lately, with sixty four drivers at the apex of a horn(!)

[johnbomb]

Originally Posted by Patrick Bateman

But these parameters are unfortunately impossible to build. For instance, the throat chamber volume and area is set to zero. Which means there is no throat chamber. And that's perfectly valid, as long as the area where the woofers enter the horn is large enough. But it's not - it's set to fifty square centimeters, which is a small fraction of the woofer's size.

You're right about the parameters. However, this model doesn't accurately depict what we do w/ these unities. I've simulated the alpha 6 mid in winisd as a 4th order bandpass box, and I want to see what happens when I build that box and mate it to the horn. I'll also have to seal the back of the alpha 6.

As far as the woofer offset, you're also right about the model. However, as I'm only using two drivers, I can extend a shelf off the sides of the horn to allow for overhang, much as Paul Spencer has drawn out on his blog, as well as offset the entry tap (great idea, Paul!).

Finally, I don't necessarily plan to have the entry tap at 7 cm from the apex- I'll likely move it closer but will experiment w/ placement via removable wooden plates, onto which the woofers are mounted. As long as the woofer is close enough, the high end roll off won't happen too soon (I've played around w/ hornresp a lot, changing up the L1L2 and S2 to see what happens). I'll likely use a BMW 4550 and a miniDSP for this project. I'm shooting for a fair amount of flat FR overlap between the mids and the CD. If I get it, I'll bisect the overlap for my XO frequency, and use the minidsp to adjust delay and individual driver EQ.... an analog purist I'm most certainly not!

Yeah, this may make an unnecessary pile of sawdust, but I've always been more of a trial and error guy than a modeler. Anyway, I'm starting to learn sketchup on my own, and I'll start a thread when (if!) I get everything together.

John

[Patrick Bateman]

Originally Posted by johnbomb

You're right about the parameters. However, this model doesn't accurately depict what we do w/ these unities. I've simulated the alpha 6 mid in winisd as a 4th order bandpass box, and I want to see what happens when I build that box and mate it to the horn. I'll also have to seal the back of the alpha 6.

Unity horns are hideously complex; I've been studying them for close to a decade and I don't think I understand even half of what's going on.

WinISD is completely unsuitable for simulating them. Hornresp and Akabak are pretty darn good, but they still miss a few variables because they don't simulate the device in three dimensions.

I really don't mean to sound like a wet blanket, but I've built a dozen of these, and I had to waste a lot of time before I got results that were even halfway acceptable.

If anyone's curious to follow my latest one, I am documenting it here:

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