Ported Horn

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Has anyone ever tried a reflex enclosure with a straight horn loaded at the front of the baffle board. That is, the driver and the port mounted on the same plane, at the throat of the horn (15").
I was thinking of a conical horn flare of about 1100mm long with a horn mouth of about 1400mm x 600mm. i have seen some horn designs utilizing a bass reflex port (W-Bins), but never in the throat area.
The idea here is to utilize the concept of putting the backward radiating sound waves to some r good use, other than just reflex boosting, such as the higher efficiency of horn loaded designs.
 
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arrie,I would refer you to the ALTEC,Voice of the Theatre speakers, typically the A7 model,where a front mounted horn boosts the O/P in the mid-range spectrum.This application has a limited freq. coverage of around two octaves,but in conjunction with a multi cellular H.F. horn gives a controlled directivity that was the design intention.In fact horns in general can only offer improved efficiency over a limited bandwidth and do so by narrowing dispersion.
 
Ported Horn 2

Thanks for the referance VaNern!
the A7 is indeed a horn combined with the reflex design, but the reflex port is seperate from the horn. does this mean that a port in the throat of the horn is a bad idea. what if one were to load only the port of a reflex enclosure with a front horn and have the driver seperate from the horn?
 
"does this mean that a port in the throat of the horn is a bad idea"

Yes.

"what if one were to load only the port of a reflex enclosure with a front horn and have the driver seperate from the horn? "

Mixed results.

Most of these have small horns on the port and have a peak in the 100hz~200hz region. If you have a really big horn for the port this is called a scoop. Also see Tapped Horn, the latest and greatest idea.
 
"does this mean that a port in the throat of the horn is a bad idea"

Yes.

Also see Tapped Horn, the latest and greatest idea.
A port in the throat of a horn may or may not be a good idea.
Tom Danley, inventor of the tapped horn (as we know it) has many horns that use bass reflex ports as well as speaker band pass ports at various points between the throat and the mouth.

Martin Audio's ASX, using a 30 mm Xmax 21" driver, is using bass reflex and a front horn for very high bass output, with ports virtually part of the horn exit.

Art
 
It's an interesting idea. Simulating it could be a challenge but it would not be difficult to test with a prototype and try with and without the port.

I do wonder if it's worth it. The port output is not required if the horn is adequately sized. If it isn't adequately sized, then I'm not sure a port is going to help much.

Perhaps more interesting would be a bandpass horn. In other words, a 4th or 6th order bandpass coupled to the horn throat. This is essentially what happens with a Synergy horn. The advantage is acoustic filtering of the driver at the throat and then horn loading is applied to the acoustically filtered output of the driver.
 
I tried this years ago on a 50 hz horn , long throw 18" car sub with (2) 4" low tuned ports all firing into the throat. Tuned it like a regular BR with the addition of the horn flare. Frequency response was fairly flat from 50-130hz ,it put out a hell of a lot of punch and even when driven with a equal voltage down to 30 hz the cone didn't unload enough to bang the backplate. Big box though!
 
"Simulating it could be a challenge but it would not be difficult to test with a prototype and try with and without the port."

The back volume required for the driver for a regular horn and a ported horn are quite different, just porting the optimum horn won't work. The other issue is at some higher frequency the port will absorb throat pressure causing a dip in output.

BFM investigated this many years ago in Speaker Builder Magazine.

A PR driving the throat may solve the absorption problem, there is a patent on a speaker like that.

Patent US5898138 - Loudspeaker having horn loaded driver and vent - Google Patents

"In other words, a 4th or 6th order bandpass coupled to the horn throat. "

Like this drawing?

http://www.google.com/patents?id=Txa_AAAAEBAJ&printsec=abstract#v=onepage&q&f=false
 
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I've built a portable barn door setup to attach to the front of my stacked pair of 15" ported subs. About 40" x 80" at the mouth, 2ft+ deep. Adds about 2db in the low end, about 6db in kick frequencies, plus whatever you get from optimized driver coupling. The bass really seems to carry outdoors. I've only used it once, but it was beastly. It can be modeled in Hornresp with a enclosure, port and horn behind the driver, and a horn in front of the driver.
 
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