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Old 22nd October 2006, 06:52 PM   #1
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Default bass-mid-Unitys???

I just had an idea.
I realy like the Unity speaker. You know. Tom Danley...Danleysoundlabs...
But i would like to build a bass and mid unity.

something like a small 4 - 6˝ inch lightweight papercone/strong magnet type of driver, driving the horn from its mouth. 300 to 1500 Hz. And a couple of high power pro 12 inch drivers coupling in a bit down in the horn. 40 - 300 Hz
That way you should have a wideband highpower horn with quite small size??!
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Old 22nd October 2006, 08:02 PM   #2
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Quote:
something like a small 4 - 6˝ inch lightweight papercone/strong magnet type of driver, driving the horn from its mouth
Throat...
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Old 25th October 2006, 03:58 AM   #3
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Have you seen the Unity that I'm building? I think I've documented how to do it quite thoroughly. Of course it's still a work in progress.

My Unity

I've considered doing the same thing, here are my thoughts on it.

Unities are tricky, because every single element in the horn is interdependent.

This is just off the top of my head, but here's how I would do it.

The low frequency driver is the tricky part, so let's start there. The low frequency drivers are in a bandpass enclosure, so you'll be lucky to squeeze two octaves out of them, if you're lucky. Maybe an MCM 8" woofer would work? Get four of them, and put each one in a bandpass box tuned to 160hz. You should be able to cover two octaves, from 80hz to 320hz.

Now that you have the low end taken care of, you need to find a driver with high efficiency to cover 320hz and up. If you're rich, go get a 2" compression driver, which will run about $300. If you want to do a "proof of concept", try the Dayton RS52. DWK had good results, and it looks like a good candidate.
http://www.partsexpress.com/pe/pshow...number=285-020

Honestly, I think this would work.

Here are the drawbacks. First, it's going to be huuuuuuge. To get coverage down to 80hz requires a mouth with a diameter of SEVEN FEET. Yes, that's right, SEVEN FEET! But you could always put it in your garage or something

Getting the transition to work is tricky. John Sheerin's written a lot about this. If you run the RS52 to 325hz, it's going to distort. But if you cross it over above 325hz, there's going to be a hole in your response.

Is there a driver that you can put at the apex of the horn that can go down to 325hz without audible distortion? That's the trick.

Good Luck.
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Old 25th October 2006, 06:28 AM   #4
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Thanx for the reply Patrick Bateman!
I have read your story and i loved it! I think its a very good solution to use the dashbord and windshield as a part of the horn. Your dscription of the unitys is very intresting. I learned a lot from it. Thank you!

Its not a fullrange Unity i want to build.
Its a pure bass and midbass Unity. Only covering 25 hz to 1200 hz. On top of that i would like to place a normal 2 inch compression driver on a normal horn.

Soo i was thinking something like two 15 inch drivers for the deep end and a pro 6˝-8 inch driver for the midbas.
Yes its going to be really big, but thats basshorns.

The crossover should probably be somewere around 100 - 200 hz.
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Old 25th October 2006, 02:43 PM   #5
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I'm not quite sure I see the benefit to this approach. Aside from 'coolness', what would a bass/midbass Unity really do that isn't easier to do in two separate units?

The main advantage of the Unity arrangement is that it provides horn-loaded efficiency AND uniform power/phase response over a band of frequencies where it's really tough to do this conventionally. A horn-loaded mid and horn-loaded tweeter are each large enough that when stacked the vertical polar response is horrible. For a bass-midbass xover in the 100-200 range, this just isn't the case, since it's easy to get 1/2 to 1/4 wavelength coupling.

I don't see anything that would make what you're trying to do unusually difficult, though. Start with say a B&C 6PEV13 in a BIG 60-degree conical and see what kind of bandwidth you get out of it; ~250-1500 should be possible, maybe lower. From there, it "should be" possible to find some pro 10's or 12's that can be loaded down the horn at the appropriate spot for an xover.

Remember, though, that since this is a straight conical flare AND that the 12's are close to the mouth, your horn-loaded gain will be far lower than if you put them in a 'proper' horn. Note that even Tom's SH-50's and the TD-1's only go down into the ~60 Hz range @100dB efficiency, which really isn't all that different from what the drivers would do in a reflex. If you want 'sub' frequencies (even the 40Hz that passes for 'sub' in live/pro applications), you may be in for a challenge.
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Old 27th October 2006, 07:49 PM   #6
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Quote:
Originally posted by Circlomanen
Thanx for the reply Patrick Bateman!
Its not a fullrange Unity i want to build.
Its a pure bass and midbass Unity. Only covering 25 hz to 1200 hz. On top of that i would like to place a normal 2 inch compression driver on a normal horn.

Soo i was thinking something like two 15 inch drivers for the deep end and a pro 6˝-8 inch driver for the midbas.
Yes its going to be really big, but thats basshorns.

The crossover should probably be somewere around 100 - 200 hz.

Thanks for the feedback! My unity has been a great project. I've posted another update as well.

I took some time to put your ideas into Visio. Let me know what you think. The pictures are small, so I've hyperlinked PDF files that have much more detail.

Click the image to open in full size.download the pdf

Here's what you described. A unity horn with two 15" woofers, crossed over to a 6.5" midbass at 96hz.

Click the image to open in full size.download the pdf
Here's my response to your idea. What if you could reduce the size? That's a good thing, right? Here's your Unity, but with more gain and a smaller footprint.
Click the image to open in full size.download the pdf
Here's the last pic. Why bother with three woofers when you can get away with one? There's a guy named Tom Danley that I stole this idea from.
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Old 6th November 2006, 05:38 PM   #7
curtisc is offline curtisc  United States
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Hello all,
I've been researching horn loading techniques for an audio class and came upon this site (full of info, thx all),

My question;
why can the bass horn be reduced to a 5 degree coverage while the normal unity is a 60 degree coverage? is this a tradeoff of bandwidth or just some voodoo?

Thanks
Curt
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Old 7th November 2006, 01:47 AM   #8
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Why can the coverage angle be reduced from sixty degrees to five degrees? That's a good question.

The simple answer is that the coverage angle is irrelevant at low frequencies; we all know bass is omnidirectional.

There's a complex answer that's worth thinking about though. ANY device will become omnidirectional at ONE SPECIFIC frequency. And you can determine that frequency by simply dividing the speed of sound by the size. For example, a horn with a 15" mouth will go omni at 920hz.
(speed of sound / size) = (13800 inches per second / 15") = 920hz.
And this formula applies to nearly everything. It applies to horns, to woofers, even to ribbons.

One more thing happens as you narrow the coverage angle of a conical horn. Efficiency goes UP, but the response gets peakier and peakier as the angle collapses.

Imagine a graph. On the left side of the spectrum is a conical horn with a coverage angle of five degrees. It will have high efficiency, but it will be VERY peaky. On the right is a conical horn with a coverage angle of sixty degrees. It will have a higher F3, but it will also have MUCH smoother response than the narrower one.

Tom's tapped horn is a clever way of getting the low F3 of a narrow angle horn, but smoothing out the response problems that come with one.

:: PB ::
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