Why not horns?

"why would "Horns have a greater potential than any other approach."?"

I'm in agreement with you on this question, Unsound. I gather from Microjack's most recent reply that he may be referring to the general masses, rather than what is already known by those who have studied horns for years.

Macrojack, horns have have historically had some of the biggest companies spending the most money trying to develop them. I don't see why you think they are capable of lower distortion. Yes, I think horns are more archaic. There's a reason there are so many more cones and domes, they make more sense. Even panels and omnis make more sense, at least to me. Speaker designers no longer need to compromise their products due to the limited availability of high powered amplifiers. Other speaker designs are capable of filling residential sound rooms with enough volume without the need for additional mechanical volume enhancers. Horns have been well understood for decades. Perhaps there might be advancements due to CAD, improved drivers and digital cross-overs, but those types of advancements will be probably bear more and sweeter fruit for other designs. Truth be told, many if not most of the advancements that might be available in horn development for home use, will probably never see the light of day, because they probably aren't worth the investment due to market considerations. What ever future horn development there might be, will probably be geared to commercial venue applications in which high fidelity might not be the highest priority.

Unsound wrote:

"Macrojack, why would 'Horns have a greater potential than any other approach.'"?

Well I'm not Macrojack, but I did stay at a Holiday Inn last night...

Okay, my design experience is limited to systems that use a direct radiator woofer and a constant-directivity-horn (or waveguide)-loaded compression driver. Focusing on the horn section, here are a couple of inherent advantages as I see them:

1) Well-controlled radiation pattern, which results in a reverberant soundfield that has very nearly the same spectral balance as the first-arrival sound. Not all horns do this, but constant-directivity ones have this potential assuming you get a few other things right. Live sound sources usually result in very little spectral discrepancy between the first-arrival and reverberant energy, but most speakers fail to preserve this relationship. I think it matters because, in most listening situations, most of the energy that reaches our ears is reverberant energy.

2) Presevation of dynamic contrast due to negligible thermal compression at normal in-home listening levels. This can actually be detrimental if the horn is not paired up with a woofer that has similar characteristics; if the woofer compresses and the horn doesn't, then the system sounds brighter and brighter as the volume level goes up. But when the dynamic contrast in the recording is properly preserved (including correct tonal balance regardless of loudness level), the emotion that the musicians intended is more effectively conveyed because musicians often use dynamic rise and fall to convey emotion.

Disadvantages include:

1) Coloration. This is a complex subject, and briefly all horns produce coloration of some type, but not all horns are equally objectionable in this regard, and some types of coloration can be dealt with in the crossover. The best horns minimize those colorations that cannot be readily addressed by the crossover, and then the crossover does the rest. Unfortunately reduction of coloration to negligible levels by a properly designed and implemented horn cannot be proven in an internet forum post, so this subject is hotly debated. My comment here would be, just as not all cones or domes or ribbons are created equal, so too not all horns are created equal.

2. Challenging crossover design. With rare exception, horns call for fairly complex crossovers in order to minimize their colorations and provide a smooth transition to the woofer section. Those few horns that are exceptions are not constant-directivity types, and thus do not have the reverberant-field characteristics that matter in my opinion. Some people hold that complex crossovers in and of themselves are bad, and this I disagree with; as long as the crossover does its job unobtrusively, the component count has no audible consequence.

If horn colorations can be reduced below the audibility threshold, and if dynamic contrast and the reverberant field really do matter, then a good horn system offers worthwhile advantages over a conventional system. I think the colorations can be rendered insignificant with proper system and crossover design, to the point where a good horn system is quite competitive with conventional systems in the same price range. But I think one has to start with a very good horn to begin with, as most horns have audible problems that cannot be solved by the crossover.

In general smaller horn systems need less distance to "focus" than larger ones do; one of my customers was listening to one of my systems (10" woofer + 10" round waveguide) at slightly more than arm's length, with (to my surprise) no audible problems.

Now it might be possible for a conventional speaker to match the thermal compression charactics of a good horn system, but at a higher price. And I do not know of any low-cost techniques of radiation pattern control that are as precise as what a well-designed horn or waveguide can offer in this regard. That being said, I think a good planar system that inherently has good radiation pattern uniformity can also be pretty spectacular, but that's a different topic for a different thread.

Duke

Duke, thank you for your thoughtful response. It has been argued here that that though they might appear similar that wave guides and horns are different enough as to require them to be categorized differently. Wouldn't such a controlled radiation pattern reduce the size of the sweet spot and reduce the sound-stage, especially for multiple listeners? I've not heard this to be the case with horns. Wouldn't the amount of reverberant sound be greater in most indoor live venues too? So long as the reverberant sound is not too close in time, shouldn't we be able to hear this as a reverberant sound and not as distortion? Furthermore, couldn't this reverberant energy be controlled via room treatment and/or room correction? If my budget permitted, I'd guess that I'd move from cones & domes 'n boxes to top quality omnis. Perhaps the antithesis of what you've described as an advantage. Aren't there already existing remedies for such thermal compression in many cones & domes and not really much of an issue for alternative drivers? Am I correct in assuming that the cross-overs you describe aren't digital and therefore are probably incapable of preserving correct time and phase? It would appear to me that this ideal matching of non-horn loaded woofers to the rest of the horn loaded drivers must be rare in deed, all the horn loaded systems I've heard are blaringly bright. I have still yet to hear a horn system that's colouration's are below audibility.

One thing that Duke did not cover is the drivers in use in the horns. Many speakers have breakups which contribute to distortion; if a horn driver exhibits this the result can be really bad. I know of at least one driver that has no breakups in the passband (its a true beryllium dome) and is helped by a kapton suspension that prevents artifact at the edges of the passband (250Hz-12KHz). This driver is very fast, very detailed and very smooth.

The other area that can be a problem is the interface of the driver to the horn- the throat area. The 2" TAD driver and 500Hz machined maple horn were an excellent example of this problem- right at the crossover/passband limit there was a peak followed by a dip before it smoothed out and it was not pleasant.

BTW this was in the Classic Audio Loudspeakers up until about 2 years ago when a new horn and driver (field coil) was introduced that fixed that problem (Valin gave the new driver on the old TAD horn Best Sound at Show and a few months later when the new horn was added declared that the new horn/driver combo was 'the biggest improvement he had heard in any speaker'). Its a fact that CAD has helped out horns immensely!! TAD **has** to have known about that problem but over the years/decades they did nothing about it.