# Speaker design questions



## Nathan S (Oct 1, 2008)

Hi, I’m new here and have been lurking for quite some time. I’ve been thinking of doing a large set of towers for my basement. I have read some about line arrays and the benefits of them and would like to incorporate that design into my idea. I do know I have to overlap the tweets, mids and woofer Hz ranges but I have no experience with crossovers and ohms. I have read some about ohm's law and I believe I am looking to do passive parallel crossovers, but that's about it. My brother is a carpenter and will be helping me with the woodworking, so no worries there. We would be able to do a dedicated enclosure for each mid and woofer if necessary. I would be looking to drive the two towers with a Crown xTi 1000 or 2000 or something very similar. Here is a very quick, rough picture of what I am looking to do. Can anyone point me in the right direction for crossover and ohm help or anything else you can think of. Do you see any initial flaws in what I am looking to do? Thanks.


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## Yad (Oct 19, 2009)

wow ... line array system! Bravo! 

Use active Behringer DCX2496 or DBX driverack 260 controllers and 3-amped system. :T this will be much better and more effective , than passive filter network.


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## fbov (Aug 28, 2008)

Nathan,
These won't be cheap or easy to design. Look up sites where others have built line arrays first to understand what you're doing. I've seen designs that use MTM arrays, but I'd still do the research. Some things work very well, but not everything!
Frank


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## JCD (Apr 20, 2006)

There are a few things I can mention:

You'll want to line up ALL of the mids in a vertical alignment. It has to with the dispersion characteristics of a vertical array.
Depending on the tweeter you go with, you may not need a lot. The plan I'm going with has only one super efficient tweet to handle only one or 1.5 octaves at the high end. Traditionally, line arrays use ribbons for the tweet. It's because a ribbon has the same dispersion characteristics as a line array. I'm going with only one horn loaded tweet partly because I'm no concerned about the non-sweet spot listening.
I'd consider getting rid of the two woofers and get more mids. You can eq the speaker system to get the two the lower octaves and not have to worry about combining the mids and woofers. Part of the benefit of the line array is the minimal crossover needed.


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## JCD (Apr 20, 2006)

Oh, and there is a lot of info out there regarding line arrays. There is one "paper" I've seen (can't remember who/where/what) that has some good info, but also some info that has become less "accepted". For example, the paper mentions tapering the drivers (i.e., less wattage to some). I've heard from some others that this approach has lost favor and that all of the drivers should get the same power directed towards them. My only point would be that when you go out looking, there is a lot of different theories regarding the design -- look at as many points of view and see what looks best.


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## soho54 (Jul 22, 2006)

A few pointers...

You do not want more than one line of drivers playing the *same* frequencies. You will end up with extra horizontal comb filtering you do not want in a line array.

Keep the center to center spacing in mind. You want the drivers spaced ideally within a 1/4 wavelength distance of the crossover point. A 1/2 wavelength will work in a pinch.

Vertical comb filtering is a given in most tweeter based line arrays. Power tapping "tapering" will help the comb filtering, but will reduce the directivity of the array. It is better suited to large arena sized lines where there is a huge distance between the array ends.


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## Doug Plumb (Mar 16, 2007)

You may want to consider wiring your vertical drivers in a Bessel configuration. This will reduce vertical plane lobing. Its also a good idea to have only one column rather than two so that your horizontal radiation pattern remains less affected. Side wall reflections may be poorly balanced otherwise.


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