Why not horns?

The very best horn designs run at about 3% THD when played loud and this will distortion is audible and in treble.

Conventional non-horn designs can play loud at 0.3% THD and often much lower in the treble - pretty much inaudible.

You are talking at least a factor of 10 more distortion in a compression horn design...

The principle advantage of horns is that they are more efficient and play louder with less power. This efficieny comes at a price which is compression in the horn throat and a higher level of distortion at louder levels.

At modest levels horns can be very competitive in terms of sound quality/distortion.

I have yet seen or heard any speaker which can play loud with such low 0.3% THD.

ATC claim this on their highest end designs such as the SCM300 while playing at 121 dB SPL (definitely loud). I am skeptical that they can actually achieve this down to 20 Hz but I imagine it is not far off the truth especially with a 6 db bass boost from a typical soffit mount - certainly from 40 to 20 Khz it can probably be done. Of course, at normal volume levels the distortion is probably even slightly lower but 0.3% THD is definitely approaching the limits of speaker technology even at moderate volume levels.

See this review

I find this interesting as the baffle in the "soffit mount" is what gives you the 6db of gain.

I should add "in the bass region" which is where it is nearly impossible to keep distortion low at high SPL's.

You get even more bass SPL gain by placing a speaker tightly in a corner but this exacerbates room modal issues severely and is detrimental to mid range and treble as you get early side wall reflections.

This is the same property as a horn with all of its issues.

Well sort of...a horn takes this to extreme by coupling the transducer to a very narrow/small chamber(s) and this can cause non-linear distortion due to heavy compression of the air within this small space (when played at higher levels). Technically short wide open horn shapes (like you see on many tweeters) are called "waveguides" and they do not cause distortion although they can alter dispersion in a desirable manner.

FWIW: horns have one huge advantage over conventional designs in addition to their efficiency => lack of compression. Generally a horn will preserve the dynamics of the music at high levels much better than a conventional transducer. In conventional designs the voice coil gets very hot (thermal compression) and large excursions mean non-linearities (distortion). Horns are an excellent approach to many high end applications as they do have distinct advantages.

Horns have unexploited potential. Lets get busy harvesting their potential. Most other options seem to have reached their limits long ago

Horns are great. They are the BEST solution for many applications.

However, you cannot dismiss other options so summarily. You are generalizing too much.

A good horn in the right setup can be the optimal solution, just as a conventional dynamic driver can be optimal in another situation.

For example: What about the midrange. Most horn designs crossover around 800 to 1000 Hz. Many people believe this is not a good region to have a crossover, as it is right bang square center in the sweetspot of all music.

All designs involve trade offs. Horns have some extremely useful characteristics for live audio and stadium audio. In fact they are probably the best #1 choice in most large venue live applications - as the narrow dispersion allows better control of the sound field so each listener gets an optimal experience. Line arrays are another powerful tool for live venues. However, these advantages do not always translate to making these designs the #1 choice in the home or in a studio.

Horses for courses.

Ralph,

I would agree - they are at their very best in farfield applications (12 feet+). This allows the narrower dispersion to better integrate with the room. Horns are outstanding in larger rooms and large venues - in these applications they can outperform conventional dynamic designs both in low distortion and in sound quality. As you get to really big spaces, conventional designs just can't cut the mustard in terms of dynamics, overall SPL whilst maintaining low distortion).

Movie theaters sound absolutely awesome and they almost ALL uses horns.

Bass is pretty much omnidirectional until about 500 Hz. Running even a 15 inch woofer to 400 Hz should be fine.

Please refer to the Chart 3-6 in this manual (kind of a bible for horns)