| Help with Potential Line Array Project [message #60828] |
Thu, 10 September 2009 22:20  |
mayhem13
Messages: 7
Registered: September 2009
Location: New Jersey
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Esquire |
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First Post and First potential attempt at a Line array project so please be kind......and gentle......
This dilemma arises from neccessity as we just purchased a new home and a 'different' media space that will be used for HT and Critical 2 channel audio but i'm forced to make concessions....listening/stage wall will have built in cabinetry comprised of lower cubbards and upper bookshelves on either side of a centrally located flat screen above a bumped out low fireplace....free standing/space speakers won't fly.
Listening distance is 14.5 ft
If it matters, i've got a few conventionl designs under my belt and lots of DIY subs.
So the thought is a 'built in' array of 55" or so in height but no more than 6" available width
1/3 lower portion will be 'wide baffle' in nature as cabinet doors will be on either side
Upper 2/3 line will be sided with open display shelving roughly 12" deep.
Available enclosure depth will be roughly 12"
Line will be actively crossed to stereo sealed subs of 12" at 120hz 2nd order...flexible placement. Unibox sim in the proposed volume shows F3 118hz sealed
I submit this driver for your considerations as it's priced attractively and response looks good.
http://www.madisound.com/catalog/product_info.php?products_id=8659
Drivers mounted frames touching,12 per side.....C to C spacing 3.9 inches
I don't expect a response from Wayne considering my 'Newbie' status here but.......1st order XO at 8khz to a centrally mounted dome?...tapered line of course.
Lengthy post i know but it's more to shoot down....so enjoy!
Remember....be gentle.
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| Re: Help with Potential Line Array Project [message #60834 is a reply to message #60828] |
Fri, 11 September 2009 11:46  |
Marlboro
Messages: 403
Registered: May 2009
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Illuminati (1st Degree) |
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First follow-up question:
Have you read Dr. Griffin's Line array white paper. Its the research bible that we all use now to make line arrays sound right?
Sounds like it could work. What tweeter are you using?
Marlboro
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| Re: Help with Potential Line Array Project [message #60838 is a reply to message #60837] |
Fri, 11 September 2009 18:56 |
Marlboro
Messages: 403
Registered: May 2009
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Illuminati (1st Degree) |
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So.... you are planning to use a single b29 tweeter in each array, combined with the mid ranges.
OK.... all this is MY opinion.
I would caution using a 6 db/octave crossover at 8Khz. Your mid ranges will run out of room before they start screeching or simply drop out at 16Khz which is one octave above, and 6 db down won't cut them back enough for that. You need at least a Rane AC23 24 db/oct or behringer where you can dial up the crossover to 72 or 84 db/oct, in my opinion.
Comb filter distortion won't start until 3400hz on the mid ranges at that c-to-c, so there is no reason why you can't drop your tweeter down to 3400. You will still be covering the critical 120-3000 range with just one speaker, and giving your midranges better headroom, but i still don't like the 1st order cross on them.
The single tweeter use won't give you a problem with comb filter distortion, and if you use an electronic crossover and your tweeter amp has a volume control, you can just dial up its output. But without running the numbers on the 12 mids I suspect that their combination SPL will be in the neighborhood of 104-108, way way way above the 94 db sensitivity of the tweeter, so you will be forced to either put the mids down(not a good idea) or ramp the tweeter up(an even worse idea).
But I'm not sure that I would go so cheap on the tweeter if I'm not going for a line array for the tweeter line. To get the sensitivity you need you would need to go with a horn tweeter, but to get a horn decent enough for this application you would expect to pay around $400 each, and due to the air in the throat its hard to get their FR as linear as your mid ranges even if you can get the sensitivity up to 104-108.
Were you planning on separate enclosures for each of the midranged or ganging them all on one big box?
Is any of this right?
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| Re: Help with Potential Line Array Project [message #60839 is a reply to message #60828] |
Fri, 11 September 2009 19:09 |
Marlboro
Messages: 403
Registered: May 2009
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Illuminati (1st Degree) |
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AND AGAIN this is more of my opinion....
Using the mid ranges and a 3.9 c to c, and 12 of them, your vertical height is only 55 inches. You need 70% of the distance from the floor to ceiling to get a line array coupling. Additionally listening at 14 feet won't put you in the nearfield for such a line array, and your one tweeter will not be enough to put listening in the nearfield.
The lack of coupling with the ceiling and floor, and the lack of nearfield listing, will make the whole system not a line array but a big point source system.
Your single tweeter will not give you the incredible low distortion that the multiple array tweeter does, nor will it give you the nearfield or coupling.
I would have to say that unless you make major modifications in your plan, I would go with a much less labor intensive standard HT system with a center channel.
Marlboro
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| Re: Help with Potential Line Array Project [message #60850 is a reply to message #60846] |
Sat, 12 September 2009 11:29 |
Marlboro
Messages: 403
Registered: May 2009
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Illuminati (1st Degree) |
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Mayhem,
The line array is workable but would entail more than you want to do, I should like. You need to either spread out the mids or get more of them. You would need a could of Foster super tweeter horns which have a 108 spl at 322 bucks a piece. You would need a Beringer crossover so you could cross from the mids at about 5000 with a 48 or 72 db/octave crossover. You would need to angle the system to avoid issues with angle dispersion.
It could work but I think its more than you want to do. And your other choice would probably be as effective, especially since you want it mostly for HT, not listening to Schubert or Beethoven symphonies.
Marlboro
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| Re: Help with Potential Line Array Project [message #60857 is a reply to message #60856] |
Sat, 12 September 2009 19:35 |
mayhem13
Messages: 7
Registered: September 2009
Location: New Jersey
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Esquire |
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While scouring the net looking for array info before landing here, i came across lot of talk about the 'ideal' HF transducer with no gaps in the line and an ability for close proximity to the mids and the magneplaners seemed encouraging. Granted, they're not very efficient and don't handle a lot of power BUT in Griffins theory, they'd provide the best performance by concept.......and they're not too expensive If you can get Magnepan to sell em to ya.
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