Help with line array please

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Hello All:

I have also posted this on the planar forum...I hope this doesn't break the rules. Please let me know. Anyway here goes....

I have aquired some ribbon drivers and a quantity of 6.5" mid/bass units and need help designing a set of 3 arrays for my Trinaural set-up. For those of you unfamiliar with the Trinaural, please see:

http://www.ampzilla2000.com/trinaural.html

What I have are a total of 6 30" Gold Ribbon Concepts drivers, which are similar to the BGs in that they are push-pull planar magnetics, supposed to be good from about 300 to 30kHz according to their designer. Along with these came 16 6.5" poly units that appear to be Audax and spec at avg. res of 38 Hz with avg Qt of .45.

I want to use the ribbons monopole to keep them near the walls of my smallish room--I don't like to feel crowded by loudspeakers, especially large ones. Also, I would like to use sealed woofer boxes for several reasons, not the least of which is that I intend to eq the bass response a'la Roger Russell's McIntosh designs. BTW, I usually listen at moderate volume levels to Jazz and Classical.

So here are my thoughts...please give me some feedback before the sawdust flies....

Center speaker is to be 24" wide and 7' tall and about 8" deep with 2 of the ribbons centered vertically one above the other, the ends of which would be aprox 1.5' away from ceiling and floor. This array is to be flanked by 4 of the midwoofers on each side spaced on 24" centers and tucked as close to the 5.5" wide ribbon frames as possible. This would provide the horizontal symmetry I want for the center channel.

The L and R side speakers would be the same 24" wide and 7' tall, but would only use a total of 4 each of the mid/woofs to the outside of the ribbons, again spaced on 24" centers.

Listening distance would be 11 to 12 feet from the arrays and I forsee using some typr of digital crossover/EQ. Assuming a crossover in the 300-400Hx range at 24-48dB/octave slopes, would the woofer spacing be close enough to avoid audible combing effects at these frequencies? Would I have the "Blooming" problem so oftened mentioned by line array users? Any other problems you see with this design? All opinions and comments are welcome.

Many thanks and hope that all have a Happy New Year,
David
 
Dave, you are in luck, you can download the Dr. Griffin's white paper on design of near field line array loudspeakers. You can do a search on google. I have his web site on file on my other computer and if you can't find it let me know.

You can also go to www.audiocircle.com and look up GR research and Selah audio which both make new line array designs and there will be many helpful hints on that web site.

I am now making some line arrays with the help of www.miniscusaudio.com who are building the cabinets. Do a search of line arrays on this website and you will find a web page by Ted Hamilton who also recently designed and built a set for his recording studio. This design seems to be catching on but there are some design issues that you must be aware of to get the best sound. dave
 
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