Horn Loaded Line Array ?

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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.
 
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.
 
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?
 
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.
 
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.
 
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.
 

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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.
 
Chipco,

That was just round 1 before trying to make it smaller. I've gotten it down to under 18" from the front of the baffle on the right side in the drawing to the wall, so under 18" deep and the left front corner of the baffle is only 10". Still 33-150hz response. This small one may work out really well because the horn length is right at 90" which just happens to be the wavelength of 150hz, so it looks like the phase of the horn output and the front driver output will be right on at the acoustical crossover point.

It's looking like 3 sheets of plywood will be enough for a pair and I can probably get away with 1/2" due to the much shorter distances and extensive dividers/braces. I need to draw it out and just go ahead and build one.

I'll keep you posted.
 
Let's not jump the gun we're still talking about high Fs and Qts drivers in about a 30hz horn. It might not sound good. Construction is pretty simple, so I'll have to give it a try. I also tried some fairly wide variations of T/S parameters since I don't have NSB's just something similar, and the response changed very little. I think I won't even bother measuring mine.

I tried modeling 8 drivers for a test run, but it would need a whole redesign.

Previous post edit...the 10" from left corner is to the wall, so this thing really hugs the corner and the baffle is going to need to be on an angle. Also in drawing the folds to scale it looks like a 20-22" depth of the right side will be required, but we're still talking about less than 2'x2' needed in the corner.

Paul thanks for the info on those drivers, but they won't work as well. I couldn't get them to go lower than 30hz without a tremendously longer horn. The short horn gave way too narrow a bandwidth and less extension. Plus they'd need a real xover that I want to stay away from.
 
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