# Line array, need help



## Chester (Feb 19, 2007)

Hello, I am looking to build a line array system for partying/personal reasons  I plan to make a 4 speaker per 'channel' (2 channels so 8 speakers total) system, using a configurable curved line array (each speaker is equidistant from a focus point) where each transducer is independently movable both up and down, as well as forward/backward, with the ability to modify the angling (the axis to which the transducer is perpendicular) also. I have a fairly thought out plan to make the transducers independent and movable, however any ideas as far as 'how you'd do it' would be appreciated.

If anyone has any suggestions/tips about the construction I am all ears; I am planning to use full-range speakers (DC Gold N69C speakers), since they are 6x9's I can get the acoustic centers relatively close together which will help reduce phase cancellation between drivers; also, since I plan to use a curved array that also should (as far as I understand) help reduce phase cancellation also... Thank you for your advice!


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## Anthony (Oct 5, 2006)

Any chance we can get a pic of what you are proposing? I am having a tough time envisioning it.

With the curvature, I think you will have nasty high frequency cancellation effects. There is a reason most line arrays use a ton of midrange drivers and then one high efficiency tweeter. You just can' avoid the comb filtering effect at the high frequencies.

Also, the dispersion pattern of a "true", that is, all in a vertical line, array is a cylinder. If you curve that, I'm not sure how it would affect things. 

Are you curving on the vertical plane or horizontal?

The idea is intriguing and is easy enough to test with a full range driver. Keep us posted!


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## Chester (Feb 19, 2007)

Yea sorry bout that, I have been out of town for a week so I haven't had access to my computer with cad software, I will make up a drawing when I get back  As far as the curve, I was referring to a 'concave' curve, like seen on this page: http://www.hometheatershack.com/for...t-speakers-little-ambitious-curved-array.html, the curving would be in the vertical... I have been trying to find a software package that would allow me to simulate the response as they do in professional line array systems but have been having a tough time with that... the closest thing I have found is something like this ripple tank applet :http://www.falstad.com/ripple/ however while it does show the principles and help me figure generalities out, it does little as far as letting me accurately simulate the interactions based upon the placement of the transducers in space...

The fullrange drivers I am going to be using are fairly costly since I am seeking relatively high SPL and power handling (the system will be used for semi-pro live sound) so I want to do as much research/thinking as possible before I go ahead with the build


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## lsiberian (Mar 24, 2009)

The best commercial solution would be the JTR triple 8's 

Just in case you don't want to deal with the build or decide it's time to just buy it. 

The best full range driver is the Jordan line,. However Fostex offers low cost solutions if interested.


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## Chester (Feb 19, 2007)

thank you for the suggestion however I will definitely DIMS (do it myself)  how much do the Jordan drivers cost? I could not find any prices on the site... I am 99.9% sure I will use the DC gold 6x9's though


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## lsiberian (Mar 24, 2009)

Chester said:


> thank you for the suggestion however I will definitely DIMS (do it myself)  how much do the Jordan drivers cost? I could not find any prices on the site... I am 99.9% sure I will use the DC gold 6x9's though


http://www.jordan-usa.com/drivers.html the driver you want is 720 for a lot of 5. They would absolutely crush that driver you are looking at.


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## lsiberian (Mar 24, 2009)

The box 2.158 ft^3 tuned to 44.38 hz for four Jordan drivers.


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## Chester (Feb 19, 2007)

I fail to see how they would "crush" the driver I am looking at?... I have found very little about the technology behind the Jordan drivers (what they are made of?), I also don't see how I am going to get significantly more SPL (presuming that is what you meant with "crush") using 5x 4" diameter speakers per channel instead of the 6x9's: the 6x9's are 5 db more efficient (93db/w vs. 88 db/w)


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## Chester (Feb 19, 2007)

I appreciate the advice about the Jordan speakers however before changing my mind on which speakers to use I would need some sort of reason more than just a statement that they will crush the ones I was considering...

EDIT: I do realize that a smaller diameter (4") cone will reduce the high frequency beaming effect that a 6" diameter cone may experience, though the transition from 6" to 4" would not be enough for me to think they would be THAT much better, especially since I am looking for loud SPL levels and the efficiency of the Jordan transducers is almost 1/4 that of the DC Gold speakers


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## villain3g (Aug 6, 2009)

Well, Thanks for my first thread linked in another thread. 

I preface this post with stating that I am in no way an expert. With that being said, I'm concerned with such a high ctc spacing. At 6" spacing, the comb filter effect will start around 2k. I'm not sure how strong the effect will be with only 4 drivers. I had a ctc of 2.17". That puts my combing to start at around 6k. It was very noticeable. Maybe its because I had 16 of them. 

My first iteration was curved with fullrange drivers. The second was 2 way and straight. I got the impression that they had more presence sonically when curved. The addition of the tweeter made them crisper. 

My recommendation is go curved. Making them adjustable sounds cool too. But go for a closer ctc and throw in a tweeter. 

DC Gold also has a round 5 1/4" driver. Comb starts round 2.5k. A horn tweeter and an electronic crossover would crispen everything up.


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## Chester (Feb 19, 2007)

Actually I was sort of hoping that the directivity (axial response) of the speakers would help reduce the comb filter effect; the N7R's that I have sound excellent, however the extreme highs do 'drop off' off axis relatively quickly; so I wouldn't think there would be too much interference.... granted I am thinking 10kHz+ so I don't know. I wish I could get a hold of some software that could predict the responses (based upon the spacing) such as that which Meyer Sound uses, however I believe their software is only going to work with models of their speakers, nothing abstract.


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