Hello everybody,
My ears were ringing so somebody has been talking about me . . . well, no, the ringing is tinnitus from too much loud sound over too many years, and I heard about this discussion from Gene DellaSala
Horns. They established themselves as the only practical way to deliver sound to large audiences. Back then 10 watts was a typical power amp. They were very directional - to hit the audience and nothing else, and they sounded dreadful. There really was no waveguide science to guide them and drivers were crummy.
They are still the way to deliver quantities of sound to thousands of people, but now the science has improved. Coverage can be calculated and designed into the horns, and arrays of horns, and with multi-kilowatts of amp power instant deafness can be delivered half way down the auditorium. They now can sound surprisingly good if they are given a chance.
What we hear in auditoriums and cinemas may start with a system with horns in it, but what we hear has been equalized, sometimes to the detriment of good sound. I wrote a paper about that for the Journal of the Audio Engineering Society last year. It is open source so anyone can download it. Go to
www.aes.org, click on publications, click on open source and type in Toole. It is free except for the cost of the 30 pages you will print.
Please note the spinorama curves in Figure 20. That is the JBL Pro M2 - with a new style of horn and a new style of compression driver. The curves are superb, the sound is superb, the directivity is wide (120 x 100 deg) because it was designed for control rooms, home theaters, stereo listening rooms, etc. The directivity is very well behaved with the result that the (high resolution, no smoothing) home theater room curve shown at the bottom is without any EQ. The room curves of the same speaker in that room and in cinemas and screening rooms ranging from 24 to 516 seats shown in Figure 19 are also without "room EQ". Above the transition frequency they are very similar.
I lust after having three across the front of my HT, and the L & R in stereo are absolutely killer. In blind tests they are not distinguishable from cone and dome systems - until you turn up the volume. The "ring" would sound just fine. In stereo some music benefits from even wider dispersion - more early reflections in the listening room. That has to do with limitations of stereo itself and with certain styles of recordings. There is no single perfect solution with the industry in its present non-standardized state. For multichannel programs there is much more flexibility because ideally the ambiance is in the recording.
The point: a good speaker is a good speaker, horn or not. Most horns in the past had characteristic sounds - we believe we know why - we needed more science. And please, if you have a truly good loudspeaker, horn or not, don't equalize above the transition frequency. This too is spelled out in that paper.
You may think twice about sound in movies and cinemas after reading it . . . it is a mess.
Now, back to writing the next edition of my book.
Cheers,
Floyd