How come Horn + woofer designs are not more popular?

Pbrain wrote: "A couple years back, I had the fortunate opportunity to take part in a double-blind mono test between a Revel Salon2 (very high-end, 6-way, traditional dome-tweeter design) and JBL M2 ("master reference" horn-based 2-way design) speaker."

I recall reading about that test on another forum.  Very interesting!

This was a "mono" test, I hadn't caught that detail before... single speaker vs single speaker?  If so, I assume the speaker being evaluated was at one end of the room, a little ways in front of the wall, and in front of what would be the midpoint of that wall.  Is this correct?

"Post analysis showed that I preferred the Revel on every sample, and to my ears during the test, it was obvious which speaker was which. I just couldn't warm to that up-front, in-your-face shoutiness of what is admittedly maybe one of the best and accurate horns designs of all time."

I assume there was no audible "horn coloration" from the M2, just a more "in your face shoutiness" to the presentation, at least in comparison to the Revel.  Is that correct?  

You see, I suspect two significant differences between the M2 and Revel were in play, in addition to (and in part arising from) their obvious physical difference (horn vs cones & domes).

First, according to the measurements I've seen, the Revels have a more "continuously and gently downward-sloping" in-room response, while the M-2's sort of "plateau" off-axis from 1 kHz to 10 kHz, which would give it a more "forward" or "in your face" presentation. 

Second, again according to the measurements I've seen (and implied by their respective configurations), the Revels have a wider radiation pattern, which, while not quite as uniform as the M2s, is still very good.   This results in more spectrally-correct late-onset reverberant energy, which is beneficial to timbre and a sense of depth (less "in your face-ness") and immersion.  In general, a well-energized, spectrally-correct reverberant field tends to sound rich and relaxing. 

Now I wasn't there of course, so this is just supposition on my part - but does any of this seem consistent with what you heard?

Duke

>>>>>>>Yeah. Dead center and about 6' from the front wall. The speakers were on a greased skid, so they could be positioned quickly an accurately at the same point for each test run. According to Dr Toole, speakers show their deficiencies much more in mono than in stereo, and a good mono speaker generally makes a good stereo one. All that's fortunate, because the logistics of testing in stereo are daunting.<<<<<<<<<<<

"Post analysis showed that I preferred the Revel on every sample, and to my ears during the test, it was obvious which speaker was which. I just couldn't warm to that up-front, in-your-face shoutiness of what is admittedly maybe one of the best and accurate horns designs of all time."
I assume there was no audible "horn coloration" from the M2, just a more "in your face shoutiness" to the presentation, at least in comparison to the Revel. Is that correct?  

>>>>>>>I don't remember gross colorations from either speaker. For obvious reasons with a dozen testees (yeah, I said it...) we couldn't spend much time with each of the 10 audio samples. Colorations not immediately obvious could have come up over time, but it's to Harmon's great credit that there weren't obvious ones.
If you consider stridency/edginess a coloration, then I did hear that on the M2 on a couple of the audio samples with a lot of high-frequency energy. I found the sample from Jackson's Thriller almost unlistenable on the M2. Again, that's probably just due to my particular set of head holes<<<<<<<

You see, I suspect two significant differences between the M2 and Revel were in play, in addition to (and in part arising from) their obvious physical difference (horn vs cones & domes).
First, according to the measurements I've seen, the Revels have a more "continuously and gently downward-sloping" in-room response, while the M-2's sort of "plateau" off-axis from 1 kHz to 10 kHz, which would give it a more "forward" or "in your face" presentation.
Second, again according to the measurements I've seen (and implied by their respective configurations), the Revels have a wider radiation pattern, which, while not quite as uniform as the M2s, is still very good.   This results in more spectrally-correct late-onset reverberant energy, which is beneficial to timbre and a sense of depth (less "in your face-ness") and immersion. In general, a well-energized, spectrally-correct reverberant field tends to sound rich and relaxing.
Now I wasn't there of course, so this is just supposition on my part - but does any of this seem consistent with what you heard?
Duke

>>>>>>>>>I can't really comment much on any measured in-room response on the Revel. All I can say is, that the anechoic response on both speakers is about as flat as I've ever seen in 60 years of fiddling with audio. John's room isn't particularly large or live, and we were seated only about 8' away from the speaker under test, so we were just outside of a near-field situation. Room effects weren't egregious or even noticeable above Schroeder.
I think the in-your-face character of the M2 is mostly due to its higher directivity index across the audio band. That's not atypical of horns in general.  In my experience in dealing with feedback in PA systems, you're gonna get a concentration of energy directly in front of a horn, even if specs say it disperses at 90 degrees.
We also can't forget that, in 2-way horn systems, the crossover's typically down so low that the horn's delivering almost all of the directional energy from the whole box. The M2's crossover is 800 Hz, so its horn is, from a directionality standpoint, just about the only thing you're hearing. That means that most of the M2's directional energy is essentially coming from one point in space--that compression driver down in the horn's mouth. It's no wonder it sometimes sounds like it's shouting! Directional energy delivery from the Salon2 above about 600 Hz is spread out vertically across 3 drivers, so there's just less energy density there. Also, the whole speaker system has a lower directivity index than the M2, so it disperses more widely horizontally. Like I said, we were seated right in front of these speakers and about 8' away. That's probably close enough for these spacial artifacts to make an audible difference.
Once again, I'm not saying that a horn's a bad idea, just that I like the way other treble drivers present music much better. It's just a preference. Because this test was done with some rigor, and because it compared a state-of-the-art representative of each technology, it really helped me to define the differences between dome-based and horn-based systems in what's left of my mind! If you can arrange even a casual comparo between two speakers like these, I highly encourage it. You'll learn a lot.<<<<<<<<<<<

Thank you very much pbrain for that in-depth reply.

"I think the in-your-face character of the M2 is mostly due to its higher directivity index across the audio band. That’s not atypical of horns in general."

I agree.

My study of acoustics and psychoacoustics and the implications of the size rooms we listen in at home leads me to think that all reflections should be spectrally correct; that early reflections (those arriving within the first ballpark 10 milliseconds) are likely to be detrimental; and that late reflections (those arriving after about 10 milliseconds) are likely to be beneficial. To clarify a bit about the early reflections, they have some benefits and some detriments: They can widen the soundstage and make the speaker less obvious as the sound source, but they can also degrade clarity and cause coloration. Just about everything that late reflections do is beneficial, assuming they are spectrally correct, and assuming you don’t have a significant room acoustics issue like slap echo. A sense of immersion and envelopment comes primarily from the late reflections, which come from all directions; the ear/brain system is able to pick out the ambience information already on the recording from these late-onset reflections, identifying it by its harmonic structure.

So in the shoot-out, with the single speaker far from both side walls, you had no early-onset sidewall reflections to possibly degrade the sound. Aside from the floor and ceiling bounces (which are subjectively relatively benign), all of the reflections were late-onset, and spectrally correct. So what I THINK is that the significantly greater amount of late-onset reflections for the Salon 2’s helped them to sound more natural.

With a more conventional stereo setup, left and right speakers being much closer to their respective side walls, I think the M2’s would have benefitted from their narrower radiation pattern reducing the amount of energy in those early sidewall reflections. But in all fairness, my understanding is that Toole finds these early reflections to be generally beneficial, while Geddes and Griesinger find early reflections to be generally detrimental, so there are well-informed differences of opinion on the subject.

My own somewhat unorthodox approach to horns involves fairly narrow patterns, and then additional drivers aimed such that their reflected outputs arrive "late" (more than 10 milliseconds behind the first-arrival sound). In other words, my best horns speakers might be called "polydirectionals", to use the term coined by the late great Richard Shaninian. I’m trying to minimize the amount of energy in early reflections, but then increase the amount of (spectrally-correct) energy in late-onset reflections.

It’s has not been obvious to me which is the most beneficial: Minimizing early reflections, or increasing late reflections. But the test you participated in seems to suggest that increasing the amount of energy in late reflections probably matters the most, which is something I’ve been working on. And THAT’S why I personally find this test so interesting.

By any chance will you be attending T.H.E. Show in Long Beach in two weeks? If so, I would REALLY welcome your brutally honest critique of what I’m doing. Imo your background makes you uniquely well qualified.

Duke