Hi William
As you suspect, the advantage of the Tapped horn goes away as the size of the horn is increased, by the time you have a full mouth and a half wavelength path at the low cutoff, there is no advantage. I forgot to link to the White paper with more of an explanation but I see Ivan did link it.
Pretty much my whole life people have said my horns were too big and / or heavy.
I suppose that actually started with one of my first big ones that didn’t fit through my parent’s back door and spent its short life outside serving as both a wasp nest and target backstop, until a picnic bonfire in the fall..
Anyway, I am pleased having found a way to make a bass horn a bit smaller.
To me, when I compared to what I could get in a conventional small bass horn or vented box of the same size, it did seem like the Tapped horn was something of an acoustic breakthrough and is why I applied for a patent.
Ivan posted a TEF screen capture for 4 115’s at 400w, here is a curve for 4 boxes –6dB from that (like the others.).
At 50Hz, the sensitivity is about 109dB which is about 50% efficiency, above that, there is a rise in response which is not increased efficiency but rather from forward directivity.
One does not get a flat response curve or this efficiency with anything like this physical size using a conventional horn.
Since it is easy to fudge or misinterpret numbers and hard to fudge a response curve and since they are easy to take, it would seem like response curves should be a common form of loudspeaker data presentation.
I suppose it is partly because loudspeakers are by far the weakest link in the reproduction chain and in some cases the ability to fudge numbers, that makes measured curves “not too common” among some of the big guys.
I have not seen any measured curves on the speakers you mentioned, although it seems to me that they hired somebody who posted on the forum to do that quite a while ago.
In the interest in identifying actual reality, I would encourage people to measure / compare loudspeakers.
I have seen some marvelous examples of highly fictional specifications in pro sound, perhaps fictional assumes too much maybe they just have different dB and frequency scales than I am used to.
To me, there is just no excuse for stating a subwoofer’s sensitivity based on what it did at 800 or 1800Hz, for over stating the acoustic output by a factor of 10 or 100 or the low cutoff stretched a half octave from where it measures. No excuse for using vague, unstated or non-standard signals or practices (seemingly to avoid replication / verification of the numbers.)
In any case, the point is that what ever a speaker does, can be measured and compared to the spec’s or other products and that is reality.
Every so often the Lab sub guys get together and have a shoot out or the live-sound guys, a listening test, that is probably the best thing available for the attendees and readers to separate the wheat from chaff.
Best Regards,
Tom Danley