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Old 13th January 2003, 07:22 PM   #1
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Default Open baffle line array

This is a new thread to address some questions I had in a different one. My idea is to use 16 Tang Band w3s-881s (each side) in an open baffle (dipole) line array. This would be mounted above a 10" sub of some sort, in a transmission line. The mid drivers will be mounted as close as possible to each other to help lessen comb filtering effects as much as possible.

So my questions are:
-Is this an idea worth pursuing?
-Am I going to be looking at any nasty artifacts by coupling a line array with an open baffle?

The ideas behind the Phoenix really intrigued me, and I was thoroughly impressed by a friend's DIY line array I heard a few months ago. I'm hoping the marriage of the two will give me a room filling sound that other speakers have lacked (I have a loft with 12' ceilings and an enormous amount of space).

I did some quick 3d mockups of the speaker i'm envisioning. Any feedback would be appreciated.

Click the image to open in full size.

The original layout idea came from http://www.angelfire.com/biz/davidson/
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Old 13th January 2003, 07:24 PM   #2
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Pic #2

Click the image to open in full size.
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Old 13th January 2003, 08:39 PM   #3
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I was at one point thinking of doing something similar with my ESLs.

You will need to make your baffles wider (or add wings on the sides) to get them down to where you can comfortable XO them to the woofer.

I just posted this nomograph for open baffle cut off http://www.diyaudio.com/forums/showt...550#post111550.

Looks like 45" will get you down to 150 Hz. Should sound good if you can get it going. A wider baffle will also give you room for a row of magnetostats (or cheap domes -- ApexJr has some suitable -- 100 for $85 IIRC) if you find that the comb filtering is too great.

dave
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Old 13th January 2003, 08:58 PM   #4
Nielsio is offline Nielsio  Netherlands
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What about impedance? Parallelling drivers lowers resistance, right?

What I'm thinking of:
-Using that amount of Tangbands, so it matches the bass drivers' efficiency. And then:
-Parallelling the bass driver also (Magnificat style).

So:
-No filter / x-over
-TB's and bass driver are run full-range

http://melhuish.org/audio/diy5.htm
http://melhuish.org/audio/diy5.htm
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Old 13th January 2003, 09:02 PM   #5
Nielsio is offline Nielsio  Netherlands
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Also:

I'm thinking about using open-ended tubes (~5" diam, ~40" deep) to minimize excursion and for less baffle cut-off.
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Old 13th January 2003, 09:57 PM   #6
kneadle is offline kneadle  United States
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How is the vent constructed?
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Old 13th January 2003, 10:45 PM   #7
Nielsio is offline Nielsio  Netherlands
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Mistake: second url should have been:

http://www.fortunecity.com/rivendell...d/dddllqd.html

Niels.
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Old 13th January 2003, 11:03 PM   #8
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Quote:
Originally posted by Nielsio
What about impedance? Parallelling drivers lowers resistance, right?

What I'm thinking of:
-Using that amount of Tangbands, so it matches the bass drivers' efficiency. And then:
-Parallelling the bass driver also (Magnificat style).

So:
-No filter / x-over
-TB's and bass driver are run full-range

http://melhuish.org/audio/diy5.htm
http://melhuish.org/audio/diy5.htm
Parallel connection soloution - Line Arrays.
In this configuration, drivers recieve different power according to their position in the array - an attempt to to make a point source I think.
In my experience, to run different drivers in parallel, a zero inductance connection is needed between the drivers, and impedence (series RC network) correction is also required.

Eric.

Line array series/parralel connection.
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Old 13th January 2003, 11:46 PM   #9
Nielsio is offline Nielsio  Netherlands
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Quote:
In this configuration, drivers recieve different power according to their position in the array - an attempt to to make a point source I think.
I've just held my head vertical, and the center stereo-image disappears, and the closest / strongest source is the point where the brain think it's coming from. But: is that a problem? All the same drivers could be in complete parallel, so the energy is optimally divided.
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Old 14th January 2003, 02:07 AM   #10
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A neat trick that helps with the upper mids and highs on a flat panel is to cover the front surface with felt or foam. It won't change the rolloff on the low end, but it will do a splendid job of eating up highs that want to crawl across the front of the panel and re-radiate from the edges.

Grey
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