Horn-loaded PA speakers and other subjects

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Hi. I have several questions. First of all, what is the speaker box design that produces the most gain?

I was hanging around a small venue the other day and noticed a pair of speakers with a horn-loaded woofer. These speakers were made by EV. Are there any special considerations to be made when coming up with designs for horn-loaded woofers? What about the sound waves that don;t go through the relatively narrow horn opening? Do they simply die? Could this chamber be ported or opened to the outside in some way to take advantage of the rest of these sound waves (like a combination horn-loaded and 6th-order bandpass)?

Also, I saw a pair of TOA loudspeakers (PA speakers) with a woofer opening that was a vertical rectangle about 15" high and 4" wide. Are they crazy for obstructing the woofer like this?

Here is an illustration of my idea. Copy the address into your browser's address blank.


The top image is of the EV loudspeaker I was talking about. The bottom shows my concept horn-loaded/hybrid subwoofer. Notice that the chambers to the right and left of the horn opening are ported, creating a sort of bandpass enclosure.

I appreciate your input on my design ideas.
Speaker enclosures don't have gain, per se. There's no way to increase the acoustical energy that the driver produces. The trick is to waste as little of it as possible, so it becomes a question of efficiency.
Unquestionably, the most efficient enclosure is the horn enclosure. That efficiency comes with a price tag, however--distortion. For PA use, though, you're on the right track. If you're wanting to build horns, I'd suggest finding a good book on horn design at reading it cover to cover before starting, as there's a great deal more to it than you would guess at first glance.
The sound waves from the back of the driver must be taken into account, whether you use a sealed enclosure, ported, or another horn.
The rectangular opening over the front of the driver you described for the TOA speakers is probably a mechanical low pass filter. The dimensions are critical. The same technique is often used at the throat of a horn in order to reduce distortion by limiting the upper bandwidth. (Before someone asks: Slot loading a driver is something with limited application in home use. Very few commercial designs have used this technique. Off the top of my head, I can only remember two examples and one of those was fifty years ago or more.)

Nearly everything I learned about horns I got from books that are long since out of print (trust me...there ain't nuthin' new as far as horns go--for that matter the last Big Thing to happen in speakers was Thiele-Small, and that was the better part of 30 years ago, now). The best, most compact source for horn info I've ever read was a three part series by Dinsdale from the early '70s in Wireless World. Beranek had a chapter or two in his book Acoustics. Perhaps a good technical library would one or both.
There is a horn ring on the web somewhere, but I can't seem to lay hands on a URL to get you started. Start poking around. You'll fall into it sooner or later, and someone will have design info out there somewhere. How accurate? How complete? I can't say. The thing you'll be up against is that, by definition, a horn ring will be run by horn enthusiasts, and may not provide an unbiased overview.
I'm completely at a loss as to what to tell you about slot-loading drivers, should you wish to explore that option. It's not a well-handled topic in most places I've seen; ignored by most. The best you can hope for there is to find a horn site that just happens to give good info for slot-loading as a means of introducing the sound into the throat of a horn.
Perhaps on some far-off sunny day when I get an extra thousand hours and nothing else to do, I'll crank up a website and put all this esoteric stuff down in one corner for those who wish to prod into the obscure ways and means to get sound from point A to point B.

Horn guys

I am laughing as you say that horn lovers are biased. I don't have any horns, but have friends with some Klipsch models (KHorns and LaScalas) Technically they may not be correct, but they do sound nice. The LaScala fires its woofer through a slot, which defines the beginning size of the throat. It then has a funky flare, which keeps the cross sectional area the same for about seven inches, then flares again. It was originally a p.a. speaker design. Still, some folks just love it. Listened to a CD by David 'Fathead' Newman, a tribute to Duke Ellington. Wow, was it mellow, while still sounding like they were right in the room with you.

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