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In Reply to: Re: multi driver reflex posted by Duke on February 8, 2007 at 12:02:11:
The only problem I can think of is if the line gets so long that it exhibits quarter wave resonance near the tuning frequency. You get around that by making it a TL to take advantage of the length.
Follow Ups:
Thanks Bill,
My goal would be between 6 in an enclosure.
Wont go very tall (per enclosure).Not to bore you but this will be the experiment: (Do this all the time and 1 in 20 does something useful)
3 speakers wide and 2 to layers high making 6 in an enclosure.
Each of the 3 wide will have its own horn (all identical of course).
The horns of all three will meet up at the mouth. The horns narrow in width and expand in height. The mouth will be 3 and 1/2" wide when all three meet together side by side. The sq inch of the mouth will of course be more than the throat but not by much.
Going 2 layers high this would be 6 drivers and a box about 22" high.The goal is to see:
1) If comb filtering can be eliminated by the closeness (and narrowness of the horns) in the side by side placement. Allowing if successfully a line array of 3 wide instead of the mandatory 1 wide (because of comb filtering).
2) To see at what point if at any point the sheer number of drivers can catch up in sensitivity to the horns thus create a wide range reasonably flat response.Would rather not have to enclose just 3 speakers at a time for bass reflex potential problems.
I've got 16 car speakers to play with that I bought at a flee market. So still very far from ordering a bunch of Alpha 8 speakers.
Usually use 1/4" mdf and hot glue for most small horn experiments. Goes pretty fast really.In any case nothing really seems to be a wast of time. Always something to learn even when they fail.
Any thoughts are always well come.
BarryPS
BTW Bill thanks very much for the previous advice you gave me here at this forum. Went with 2 delta 12LF (instead of 1 3015LF), 2 beta 8 and APT 80. They (at the church I built them for) were very pleased with the sound.
I'd abandon the side by side driver notion. Yes, you can eliminate combing if the centers are tight enough, but what you can't eliminate is the narrowing of horizontal dispersion with the widening of the radiating plane. I can't visualize exactly what your topology looks like, do a picture and I could offer a critique. Enough direct radiators can catch up with horn sensitivity depending on how many horns are used. However, if you go to the maximum region of flat power response with both the horns will remain at least 3dB more sensitive than the direct radiators.
Thanks for the imput Bill.
"what you can't eliminate is the narrowing of horizontal dispersion with the widening of the radiating plane"Will extending the horn beyond the meeting point a few inches and flaring it out those last few inches? This was an alternative in the experiment.
"I can't visualize exactly what your topology looks like, do a picture and I could offer a critique."
I'll have something up in a few weeks when some better whether come in to build on my porch."Enough direct radiators can catch up with horn sensitivity depending on how many horns are used. However, if you go to the maximum region of flat power response with both the horns will remain at least 3dB more sensitive than the direct radiators."
So the best I could hope for (unless it can be tweaked somehow) is -3 db under fc?
Barry
"So the best I could hope for (unless it can be tweaked somehow) is -3 db under fc?"
No, but since the best you can hope for with direct radiators is about 25% efficiency, while horns can get better than 50% efficiency, if you want to level match a mix of horns and direct radiators you must be sure not to use too many horns.
That is something that I did not know Bill. I have much to learn for sure.Thank you once again for your advice and expertise. It really is, and has been very helpful.
Barry
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