How does a Tapped horn work??
Maybe I can fill in some blanks for you.
The Tapped horn came about while I considering the cancellation notch that appears when one mounts a driver forward of the small end of the horn.
In the Synergy horn and earlier Unity horn, it is that notch that limits the upper frequency response of the side mounted drivers, otherwise it acts like it's mounted in the normal location (at the throat).
The principal of operation for both the Synergy and unity horns are that the drivers used MUST be acoustically close enough together so that they combine into a single new source (such as closely spaced subwoofers do).
The spacing distance for this coherent combing is required to be under about ¼ wavelength. With a spacing a half wavelength or larger the two sources radiate independently and produce an interference pattern which is a pattern of lobes and nulls in the polar patterns.
Anyway, when say the mid or low drivers on a Synergy horn are operated higher in frequency, as the wavelength gets shorter, there is a point when the sound from the speaker enters the horn a quarter wavelength from the throat.
Now, some of the sound goes towards the throat and then bounces back, the problem being the total path length is now ½ wavelength and so the reflected sound cancels the sound from the driver, viola, a notch in the frequency response.
I had these modeled in akabak already and though ok what if I substituted a source of the opposite polarity for that reflection from the closed end of the horn. I could do that with the same driver by using the back side of the same one. Now, just like a transmission line there is a frequency where both sides of the radiator add together and like other mutually coupled radiators, the feel each other's radiation. After a couple weeks of fiddling, I had a few glimmers of what looked promising and then a model for something to try.
The first few i built had various issues and like all computer models, it takes a while to figure out the rules and to add the fudge factors needed to make a computer model look like the measured results.
I think we introduced the first real product Tapped Horn at a trade show in 2005 or 2006 and now they are widely used from Stadiums like Lambau field and BYU, Las Vegas stage shows (Like Beatles love, Chris Angel and such) and the largest Imax theaters like the Chicago Museum of Science and industry theater.
A low frequency horn, like is normally built has a low frequency corner related to it's length and the rate of expansion, that being something like a high pass corner masking the resonances while the length of the horn and it's quarter wavelength resonance are what dictates the lowest peak and the arrangement of peaks and dips.
A horn that is the right size doesn't have those (peaks and dips) but no one makes portable bass horns the right size so real ones have peaks and dips.
The smaller one makes the mouth area relative to the length and the ideal, the larger the difference between the peaks and dips are and so at some point, the call is made, the horn is too small to be usefull.
Where there is a peak in the response, one has an acoustic load placed on the driver, the gain of the horn is working while the dips between are a diminished acoustic horn loading and efficiency.
At the low corner of a Tapped horn it is the driver at the throat that feels the entire acoustic load while the sound from the mouth end driver face travels down the horn and back but delayed 180 degrees and so the front radiation is largely self canceling.
Here, the ideal driver has parameters suited for driving the quarter wave resonance and not those desired for horn operation higher up.
AS the frequency climbs, the reflected front radiation begins to be less canceling and where the first and largest dip in a normal horns response is, one has both faces of the driver adding together to (ideally) offset the insufficient horn loading on one side.
These are much harder to design than a vented box or even a normal horn and have some unexpected rules but I have NEVER had a tool like this available for making bass and I have been in sound in one way or another most of my life. Anyway, I hope this helps.
Some background if interested;http://www.prosoundweb.com/article/p...dio_technology
Here is a demo of a new full range speaker with a large Tapped horn. This was an impromptu demo our Reps arranged in December, part of it was outdoors with this new full range speaker. I saw a fellow with what looked like an Iphone or something tiny on a handle but didn't think anything if it.
Anyway, I fell in love with his video and audio except when he is close to the tapped horn, you're out of the pattern of the full range speaker and the mics are overloading.
To get an idea how loud this was, at about 1:20 the operator walks up to the guy next to the camera man, adjust the headphone volume to put that voice in scale. As the attendees were interested in large scale sound, what I like to think of as hifi for a crowd, they were standing a ridge at 150 yards, at about 2 min plus he pans out to the field where the people are. Also note where the speaker is relative to the big beige building.http://www.youtube.com/watch?v=5MOG_sPejGA
These are different than large speaker systems used everywhere now, wind doesn't bother them and the sound is very constant everywhere while concert arrays sound different everywhere and have a maximum usable distance.
Another large scale demo early on;http://www.youtube.com/watch?NR=1&fe...&v=pk54IFD4znw
A more recent one of three loudspeakers in a stadium, an install (with subs) I think in 2013.http://www.facebook.com/photo.php?v=...type=2&theater
Our web site is out of date, the most recent stuff is here;http://www.facebook.com/DanleySoundLabs?ref=ts
Danley Sound Labs