Originally Posted by brianinpdx
cooper - the way I'd explain the "pain" factor is...
HLCD designs have a horn loaded behind a midbass transducer. It fires up and out shooting the high frequencies back to the rider at 50-70-100ft and beyond. It has a narrow focus and in general terms shoots out like laser beams to those distances. It's effective but has a "live" sound attribute to it. For those boats that have lower towers (think Mal Illusion ) those laser beams can be in your face up close. Bottom line: sitting close to an HLCD speaker thats 100+db efficient can be quite an intense experience.
-Brian / Exile
To clarify a few things, just elaborate really....
HLCD designs have a compression driver attached to the back of a midrange driver. They connect to the horn flare out in front of the midrange driver through a straight length of tube
that travels through the middle of the midrange driver. Just like any straight tube, (think trumpet, trombone etc) the straight section of the horn combined with its length emphasize particular notes and frequencies. When you see a trombone player push his slide out, the pitch goes down. This is a good example showing how length of straight tube affects the resonant frequencies of these types of horns. With a coaxially mounted horn typical of most, you really have a very short trumpet or bugle-type horn. Remove the compression driver off the back of the mid and you can literally play it like a bugle. Try it; you will find the horn wants to play specific notes.....
The "live" sound of these horns as Brian describes it can actually be attributed in large part to the resonance peaks that are caused by the straight pipe section of the horn. You get resonant peaks at basically the same frequencies that you can create if you blow on it like a bugle or trumpet. These horn peaks usually sound nasty when you try to play music through them. It is the effect of coax-mounted horn geometry, specifically the staright section of pipe, that makes horns painful up close...
There are many examples of high-end horn-loaded audio systems that use horns. What the high-end stuff has in common is that none have that straight section of pipe. If you go to Crutchfield and search home speakers from highest price down, you will find some very nice Klipsch speakers for home listening that are 100% horn-loaded. Go search for high-end horn-loaded speakers on the interwebs and you will find some very exotic stuff. Some looks like it was pulled from the sea. Very round, very smooth, constantly changing area at any length along the horn.
You can find HLCD tower systems that do not have the "live" sound. All you gotta do is look for the one that has the horn geometry that does not have that straight section of tube that is required for the coaxial designs.
I figured a little elaboration might prove helpful. HLCD speakers can sound good up close, even when you have them cranked up loud, when you design them from the beginning to be free of harmonic resonances that create the "live" sound.