Please help with my el cheapo LINE ARRAY!!! - diyAudio
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Old 22nd January 2006, 05:17 PM   #1
Klimon is offline Klimon  Belgium
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Default Please help with my el cheapo LINE ARRAY!!!

Hello,

I just bought 16 vintage 5" Philips fullrange speakers, that is dual cone speakers where the whizzers probably take over at around 14 to 16K. The aim is to build a set of line arrays; 8 speakers for each channel. I've done some reading so far and the most tempting example was set on this webpage:

www.geocities.com/dmitrynizh/labaffles.htm

I see there has been some talk about open baffles in this forum so I'm hoping the experts can give me a little push in the right direction. The most appealing solution for the moment looks like a concave open baffle; removing the whizzers and adding a supertweeter with a simple high-pass crossover to adjust to the natural roll-off of the 5" speakers.

I would really like to avoid electronical time-baffle alignments and (expensive) tweeter line arrays, keeping things as simple as possible to achieve enjoyable results.

I gather the downside of the concave array + single tweeter approach would be a very small sweetspot, but considering the other benefits that's a trade I'm willing to make.

Another worry is low-end response. I was thinking about a narrow open baffle with wings + the baskets of the speakers are not very open on the rear so I'm still hoping to get some acceptable low-end behaviour... (60hz?)

I'ld greatly welcome any hints or (constructive or destructive) critique!
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Old 25th January 2006, 12:38 AM   #2
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Be sure and read the link below...most informative.

Jim Griffin's Line Array White Paper is at the following address:

http://www.audiodiycentral.com/resou...wp.pdf#search='Jim%20Griffin%20Line%20Source'

Best of Luck with your project.

Ribbon Project
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Old 28th January 2006, 04:03 PM   #3
Klimon is offline Klimon  Belgium
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Interesting link; thanks
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Old 28th January 2006, 08:39 PM   #4
ScottG is offline ScottG  United States
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Your best link on the subject (as desired):

http://www.geocities.com/dmitrynizh/labaffles.htm
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Old 28th January 2006, 08:53 PM   #5
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I would be disinclined to make the baffles concave. Theoretically that would be ideal, but from a practical matter, not a lot of payoff. Additionally it will be a much more difficult construction.

Check out the full range guys on whizzer cones. I think that it is more typical that they dampen these cones with some foam... stick on foam stuff. Google whizzer cone & foam for good ideas.

The bass will be challenge... and not likely to occur with the 5". I would add sub. I mate by line arrays with Tuba 18's.

Lastly, super tweeters. I don't know the definition exactly but I am guessing 15-22kHz. My opinion for ME is that would be a waste of time/money. If you are more than 30 years old, your hearing senses are rolling off dramatically at 18k unless you have spent your life in a hut hunting monkeys in the Amazon. It's a fact that that native people experience NO hearing loss into their very old age. They have never been exposed to The Who, LIVE!

Anyway, better to add a planar/ribbon or two so you know you have something at 15-20.
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Old 28th January 2006, 09:05 PM   #6
ScottG is offline ScottG  United States
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I actually read the link you posted..

Still, I don't think you'll find a better link on this configuration.

Another option is the 5 driver bessel array (vertical.. NOT horizontal) - utilizing the other 3 drivers for baffle step correction (.. perhaps as a bipole with the 5 driver array in front and the 3 drivers in the rear). Do NOT consider a 7 driver "bessel array".

http://www.prosoundweb.com/install/s...t25_4_p2.shtml

Also consider an angle on the drivers to increase high freq. off-axis performance like Rod has done here:

http://sound.westhost.com/project1052.htm
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Old 28th January 2006, 09:36 PM   #7
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Hmm. Well, rather than using a concave baffle, why not just power-taper the line? It doesn't require complex electronic crossovers, filters or anything else for that matter: just wiring the drivers up slightly differently, as Jim's seminal white paper shows. Then you'll get all the benefits with none of the drawbacks. Note however that his latest arrays don't even bother with that; an they are vertical. The difference is marginal at best in distance terms. Try a straight baffle first, then alter the wiring to power-taper if it proves to be a problem, which I, for one, doubt.

You're going to run into lobing problems running the drivers full-range, or even wide-range though -you really need to be crossing over to smaller domes / ribbons at circa 2KHz. As you want to avoid a tweeter line the central mounting will be best. However, it might be an idea to ensure there's enough room on the baffle to add a line at a later date, so off-set it if you can: I'm not convinced about the single-tweeter, with a line of mid-bass hybrid arrays myself, but there are a few designs like that, so some obviously think they work.

Best
Scott
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Old 28th January 2006, 11:21 PM   #8
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I thin that a single tweet is too much to ask for...

Better yet would be a tweet at ear height while sitting and another while standing. You will notice that you are rarely in between unless the wife is making you cower (about that dang audio stuff). The 2k cross is great except it's premium spread $$$ in the ribbon tweet department.
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Old 29th January 2006, 08:42 AM   #9
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Agreed. Hense the fact that in a single / twin tweeter hybrid, you could simply use domes and have done with it. Dave posted a link to some superby cheap tweeters the other day, but I'm blowed if I can remember where. I must be getting old or something (27 and he's already aiming for pensioner of the month... ).

Best
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