Horn Loaded Line Array ? - diyAudio
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Old 9th November 2004, 05:33 PM   #1
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Default Horn Loaded Line Array ?

Is a rear loaded horn line array using the PE 49cent specials a reasonable idea? With their Fs of 105 and Qts of .76 , it seems like a logical way to get bass. Design it for corner placement to keep the cab width down, with maybe even just a deep narrow cab requiring exact placement so the walls form the horn mouth.
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Old 10th November 2004, 08:50 AM   #2
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If it's a stupid idea, I can handle it, fire away. How about some input either way.

While I understand that the drivers might not be the right choice, I think the idea is promising for a room that has corners available.

I was thinking about a vertical array of drivers in a relatively narrow but deep cab that contains the compression chamber and first 2 horn segments. The 3rd segment would be formed by the cab and the walls and the mouth would be the formed by the walls. Use a top and bottom cap cut to fit the corner making perfect placement a snap. Then just attach and seal it to the wall.

Just imagine....Reasonable WAF, "Honey all I need is the corners"....Line array sensitivity and dispersion advantages...Plus architectural bass horn type extension and output due to the huge horn mouth area...Even a SET amp could drive it to THX reference levels.
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Old 10th November 2004, 01:30 PM   #3
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Won't work. A rear loaded horn works with low Qts low fs, not high Qts high fs. Check the specs on Fostex/Lowther drivers for rear horns:Qts around .2, Fs around 30-40 Hz.

You can get the PE cheapies to work to 80 Hz corner loaded, then crossover to a sub.
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Old 10th November 2004, 03:42 PM   #4
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Thanks for responding Bill. I read somewhere that Fs/Qts should be 120 or more for good results in a rear horn and hoped that would apply to even a driver with a Qts as high as the cheapies. How high a Qts do you think I can realistically use and obtain good results considering that this is an array, not a single driver?

Is it reasonable to think that subwoofer type extension can be achieved with drivers having a relatively high Fs? Does the horn length and mouth area make up for the natural rolloff of the driver below Fs?
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Old 10th November 2004, 05:47 PM   #5
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Qts doesn't matter, it's fs that's the problem. With a rear loaded horn about the best you can get for a horn cutoff is perhaps 90% of fs, so lower than 90 Hz isn't going to happen with these.
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Old 14th November 2004, 07:37 PM   #6
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Bill,

In HornRESP I modeled a 16 driver array rear loaded horn using the NSB drivers and end up with a nice flat response of 100db from 35hz-160hz. The big Sd of multiple drivers and large resulting horn make the low extension possible.

This cab shows some real promise for all the cheapie line array guys with available corners and a sizeable room. It's 8" wide at the front and 13" at the back with a 31" depth and is 8ft tall. Using the side wall and corner to form the final horn segment really smoothes response and reduces the high end cutoff to right where it needs to be. It has 2 folds plus the corner with an overall horn length of about 10 ft. Since it really only relies on 1 wall for loading, you could easily change the design to use only rear wall placement, but each one would use up about 3ftX2ft of real estate.

I did have one version with a 40hz low cut and no corner placement, but I didn't save that version and haven't been able to recreate it.

This shows so much promise that I'm going to have to break down and figure out the T/S parameters of the 4" array drivers I use. $70 worth of drivers including a pair of super tweeters, plus 7 sheets of plywood and some work for a pair of crossoverless (other than a cap on the supertweeter) line arrays that have 100db of sensitivity from 35hz up is almost too good to be true.
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Old 14th November 2004, 10:40 PM   #7
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I have 8 PE cheapies and 12 Onkyo tweeters in corner placed TL arrays, they run from 80 Hz with about 100 dB sensitivity and only extend into the room six inches, are less than 4 feet tall. Bass duties are covered by my Tuba 18 that's 3.4 cu ft and hides in a corner behind my recliner, also giving around 100dB sensitivity. Aside from pleasing WAF issues I prefer to feel that my speakers are guests in my livingroom, not the other way around.
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Old 14th November 2004, 10:59 PM   #8
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JohninCR... How's about a dwg or sketch?
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Old 14th November 2004, 11:36 PM   #9
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Bill,
I completely understand the WAF issue of big arrays. Once I got the idea in my head, I wanted to see how far I could take it.


Chipco,
Here's a top view drawing, not to scale. Just enough to get an idea of the fold layout. Other than the driver holes, the hardest part of construction would be making and attaching the numerous horn dividers that would also function as braces between the panels making up the horn walls.
Attached Images
File Type: jpg corner array drawing top view.jpg (14.9 KB, 308 views)
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Old 15th November 2004, 01:22 AM   #10
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Quote:
WAF issue of big arrays
So last week the wife says to me, "Would you make me a small set of arrays for my office?"

I said "Of course, dear."

Anyway John, are we talking 36" deep cabinets? That's a pretty hard sell on the whole WAF deal. You got your cost of speakers, crossover components, sheet lumber, and then that BIG trip to the jewelers.

I think my last beig project before the divorce will be the McIntosh XRT29 clones. I will, however, need a large sub cabinet to move into.
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