Change to Horns or stay Dynamic

Thanks for the mention Manga, and the clarification, Kana813. The ones that got the award are indeed bipolar, kinda like their designer....

The subject of fullrange horns came up. Well, the Edgarhorn (with Seismic sub) and Classic Audio Reproductions Hartsfield are in my opinion excellent examples of fullrange horn systems. And I bet JohnK has some highly competitive offerings of his own in this arena.

As one who builds hybrid horn systems, my vote on "dynamics vs horns" is totally predictable - but probably not for the reason you'd think.

In my opinion the single most important benefit of a good horn is not increased dynamic contrast, but improved radiation pattern control (though it's nice to have both). The radiation pattern of most loudspeakers narrows and blooms and narrows again very significantly across the spectrum. The result is that the reverberant energy - mostly composed of off-axis radiation - has a different tonal balance from the on-axis sound. Since the ear/brain system is constantly analyzing incoming sounds as either first-arrivals or reflections, and using spectral contant to do so, a large discrepancy in the spectral balance of the first-arrival and reverberant sound makes correct classification more difficult for the ear/brain system; in effect, CPU usage goes up. Often the the result over a half-hour or so is listening fatigue - literally, a head-ache because the ear/brain system is having to work harder to correctly classify the reverberant energy whose spectral balance is unnatural.

But, don't get the idea that reflections are bad - early ones often are, but late-arriving ones are usually beneficial. A dense, late-arriving, highly diffuse, slowly decaying, spectrally correct reverberant field is what makes a good concert or recital hall sound so delicious. Indeed, much of the appeal of a good omni or quasi-omni or dipolar system is because of the relatively large amount of beneficial reverberant energy such a system puts out into the room when set up properly.

Some people talk about a good horn system as having a natural-sounding tone, and when you consider that most of the sound that reaches your ears is actually reverberant energy, a good horn's superior off-axis (reverberant field) performance starts to seem like a good idea.

Duke
dealer/manufacturer

Dgad,

Thanks for asking for clarification - it sounds like I was giving an incorrect impression.

Horns don't ordinarily give a more diffuse reverberant field than direct-radiator dynamic speakers. If anything, their typically narrower pattern results in a less-diffuse reverberant field; but that narrower pattern often makes it easier to "aim" the horns to minimize early-arrival reflections.

You see, reflections arriving before 10 milliseconds (corresponding to a path length of about 11 feet) are usually detrimental, whereas reflections arriving later than that are usually beneficial, assuming good spectral balance. This is why Maggies and such sound great 5 or 6 feet out from the wall, but have coloration and poor clarity when pushed back against the wall. Likewise, when you see MBL demo'ing their omnidirectional Radialstrahlers they are positioned well away from all walls, again to avoid detrimental early reflections.

A highly diffuse reverberant field arises from a combination of wide loudspeaker radiation pattern and diffusive room surfaces - like book cases and plants and furniture, or even diffusion panels, instead of bare walls or Sonex-lined walls.

In my opinion most loudspeakers don't put enough reverberant energy out into the room, hence my top-of-the-line speaker is a bipole - but if it can't be positioned properly then its monopolar little brother sounds better. My reason for using horns is to control the spectral balance of that reverberant field; the bipolar pattern is where I get my additional diffusion from, and then I like a fairly "live" room as opposed to a "dead" room.

Let me know if this doesn't answer your question.

Duke

Unsound, many horns do sound quite nasty. I have yet to hear a prosound hornspeaker that doesn't, especially at high volume levels.

Two potential sources of nastiness are frequency response problems and diffraction. Horns all need some sort of equalization, and usually fairly complex equalization, before their frequency response is reasonably smooth. Not all designers go to the trouble to smooth the frequency response - perhaps because many horns still sound edgy even after they measure smooth. Which brings us to the second problem: Diffraction.

Diffraction occurs where there is a fairly sharp discontinuity in the horn flare or profile. For example, many horns have a fairly sharp-edged mouth, which results in diffraction at the mouth. Others deliberately induce diffraction within the horn to widen the radiation pattern. Diffraction has little measurable effect on the steady-state frequency response curve, but it's audible because of where it occurs in the time domain: Just a little bit later than the original sound. The ear is good at masking (ignoring) a lower-level coloration that occurs at the same time as the main signal, but very poor at masking a coloration that occurs later in time. Also, the ear's sensitivity to the type of coloration diffraction imposes is level-dependent; that is, diffraction becomes more audible (and more objectionable) as the level goes up. Those prosound horns that drill your ears at high volume levels - that searing edginess is probably diffraction (and higher order modes - a diffraction-like phenomenon that occurs within any horn, but is worse in some than in others).

So to get back to Unsound's comment, not all horns are created equal, and not all horns are employed equal. In fact, historically low coloration has not been the top priority in horn design, perhaps because knowledge of how to build a truly low-coloration horn was lacking. Dr. Earl Geddes is the leading expert on low-coloration horn design; he calls his devices "waveguides" to emphasize that their function is guiding the sound waves (controlling the radiation pattern), rather than acoustic amplification. The "horn" that I use is a Geddes-inspired waveguide.

Duke