Change to Horns or stay Dynamic

So Change to horns or stay with cones?

I guess this is the right answer not in my words:

Your argument about home audio listening is valid if you listen at fairly low average spl levels of lets say, around 75db. Because for a good sense of dynamics a loudspeaker must be able to easily handle 20db peaks above the average level with no compression. That is the minimum requirement and unfortunately the Scan-dinavian favorites (the drivers used in most high end dynamic speakers) fall short of this target at anything above mid 90's db. So if you want to listen at realistic average levels of say 95 -100 db you will need the speaker to handle a not-so-unrealistic 120db peak levels and that's at the listening position no less.

For audiophile drivers core size and voice coil size are of secondary importance. Contrast this with the pro drivers' big voice coils and oversized and vented magnetic cores that can sustain prolonged periods of abusive power (read 400-600 watts) with just maybe 2db of thermal compression while playing at around 120db average level. There really is no comparison! Thermal compression is real and one of the most important as well as overlooked parameters in loudspeaker performance. It's perhaps not surprising that this is the case for the audiophile speakers as the driver core is the most expensive part of the assembly and the designers using the same logic consciously chose this set of compromises.

But make no mistake, as excessive as these db levels might seem at first, for the person that wants realistic reproduction at the home this is what will be required of the system. (Manga)

Is there a need for an audio system to produce 120 db peak?

Symphony orchestra is playing one flute, but in the next second the orchestra barks with the whole power.
Most of the brass instruments can alone produce 120 db. There are 120 or so different instruments in the orchestra.

You are sitting at row 20, a flute is about 40-45 db. The orchestra BARKS. It is about 120 db at the row 20.
The difference is 80 db.
CD can record 90 db of a difference (called dynamic range). Recording engineer has to compress the sound. Some engineers can hide compression better though, but all sounds are too BIG to fit on CD.
No matter what it is, Jazz you name it. I bet to record a girl with the guitar some 6 db of compression is still needed. (Yurmac)

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 constant 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 result over a half-hour or so is listening fatigue - literally, a head-ache because the ear/brain system 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.

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. (Audiokinesis)

Wonderfully put by this fellow audiogoners....

Horns sure have their fans, but to my ears, they sound nasty. To each his own, YMV, etc.,etc..

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

Horns sure have their fans, but to my ears, they sound nasty. To each his own, YMV, etc.,etc..

Unsound,

I agree that horns can sound harsh and have colorations and just plain sound bad, but what loudspeaker technology doesn't have it's bad examples? Factors affecting horn performance include abrupt mouth termination, discontinuities in the profile (diffraction horns are notorious for this), forcing a horn to play outside of it's design bandwidth etc.

I am sensitive to horn artifacts and the main reason I originally brought up these two speakers is because by all accounts they do not have the traditional horn sound. Lynn Olson, a well known speaker designer and a person that by his own admission is very sensitive to horn honk, was impressed by the Jazz Module when he auditioned it at one of the shows. Keep in mind that both the Summa and the Jazz module use waveguides, that are shallower than wide with straight sided walls and have smooth round-overs at the mouth termination. As i mentioned earlier waveguides and the theory behind them, have been developed by Dr. Geddes who is also the one that coined their name. Suffice to say that there are key differences between waveguides and horns. This last statement does not of course preclude the fact that horns can sound good and some actually do so, namely some examples of the pro monitors mentioned by Shadorne.

George

Fair enough. I have heard most of the highly touted, and might I add fairly expensive horns, but not the Geddes "waveguides". I will try to remember to make an effort to do so. If the Geddes "waveguide" systems are indeed so different, perhaps they shouldn't be grouped with horns at all?