So your rooms DON'T have four walls, a floor and a ceiling? I simply don't see how you can simply exclude these factors just to make your point. Yes, this is where we differ. My rooms are all fully enclosed because thats th only kind of "room" that I know of.

But if you do what you are saying outdoors where there are only three intersecting planes then I agree with what you are saying. The corner will add 9 dB to the free field response and it will direct the sound along the walls - so long as the source is within 1/4 wavelength of the corner.

But with the other walls present the situation is completely different.

The larger the room, the more its corners act like a pure eighth-space. That's why I would look at room modes and launch boundary separately.

At any rate, this has been a lively discussion and I appreciate your input.

I had hoped to have a discussion about various speakers and horn flare types, not so much a debate about room corners. We could look at monopoles, dipoles and horns. We could look at simple horns like round megaphones with conical, exponential or tractrix flares. We could look at radial shapes and early CD's like the Manta-Ray. We could also look at more modern CD's like Peavey's Quadratic throat horn and some of the things you're doing too. Maybe we'll have to start a new thread and talk about those things.

This discussion tended to get stuck on the energy patterns caused by room modes. So maybe it would be nice to start a thread about room layout. That would be a good topic for the Studio Room forum, since it's really a matter of room acoustics. We could discuss radiator placement and the use of acoustic devices like bass traps. Or maybe better yet, talk about the use of multiple radiators to combat nulls. So one of these times soon, lets start a thread in the Studio Room forum to discuss these kinds of things and offer some concrete solutions instead of minutia.

Again, it's been a good talk and I appreciate your comments.

"By changing the crossover filters to a 2nd order Butterworth lowpass at 900 Hz for the woofer and a 3rd order Bessel highpass at 1,300 Hz for the horn, the combined response is decisively better."

Is this along the lines of what you're doing?

• Using Crossovers in the Real World

I have a computer model of the crossover that I manipulate that uses the actual polar measurements to predict the total field response. I adjust the component values to get the best overall response - the flatest response in the sound field from +30 to -30° across the entire audio band. The resulting filter is highly unlikely to be a "Bessel" or "Butterworth" or any other name brand filter. They are both 3rd order and are definately not tuned to the same frequency.

• http://steinman.mesls.org/stereo/J%20Kalinoski%20Loudspeakers%20101.jpg

Very interesting debate, even if a little bit "harsh" for the average audiophile like me.
Being currently involved in the pursuit of perfection with my future horn system, I would kindly say that WAYNE's interesting question is closer to a pro sound consideration that to an audiophile problem.

Here are my reasons (I only consider here listening music)
1) WAYNE, how many times a year do you really listen to music for your pleasure with somebody beside you ? Personnally very seldom because listening music is something very selfish. Your wife (or anybody else) is not obliged to appreciate the same record in the same time as you for many reasons. So I consider that most of audiophiles use to seat and listen their system ALONE and consequently naturally seat in the best position possible very close to the famous sweet spot.

2) I hope you will agree with me if I say that your question concerns mainly the medium range due to ear sensitivity (LF and HF are accessories here)...

3)...so I think that audiophile horns are necessary directing to get the most natural song, because any discontinuity in the flare may cause distortion, standing waves, reactance, etc. That's a conclusion you can find after reading the test reports from different audiophile forums. And that's why, IMHO, EDGAR's system is so appreciated.

4) CD horns were designed to solve this problem at lowest cost possible, but require an EQ which is OK for pro sound but not good for audiophile reason

5) To my knowledge from the numberless and endless opinions expressed among the forums about horns, the only horn to match your wish would be something like the ALTEC 1505B multicellular horn, specially designed to solve the directivity problem with eventually real audiophile qualities but apparently overtaken by a well designed tractrix horn

6) Now maybe the compromise here will afford a solution :
http://aa.peavey.com/downloads/pdf/qwp1.pdf
But once again it is a pro sound consideration. Never seen any "audiophile" test report with such horn.

I hope you understand my opinion. I always try to stay in the simpliest way to get the most natural sound. Any complication is not good for sound reproduction.
Your comments are welcome.

With best regards,
ERIC

• http://aa.peavey.com/downloads/pdf/qwp1.pdf

But I will be very honest. I think the attraction of some of the round horn designs of the last ten years or so is mainly hype. I think some of them are attractive in an eclectic way, sort of retro looking and cool. But I don't really like the way they sound. They're just not for me.

Don't get me wrong - I don't dislike them either, any more than I dislike a nice pair of planars with good amplification or any other system that is done with care. Each technology has something to offer. If you are right in one spot on-axis and the room cooperates, they can sound very good.

But when you move around the room, they fall apart. They just don't sound good except in a very tight area. And even when sitting perfectly on-axis, since the reverberent field is non-uniform, room reflections send energies back to the listener that are unnatural. So I just don't like the way they sound.

About equalization, it is important to realize that it's the compression drivers that need EQ, not the horns. Horn shapes that provide collapsing directivity provide equalization acoustically rather than electrically, that's all. Basshorns are a different matter. Even though they're physically large, they're usually undersized compared to wavelength. Because of that, they need EQ to smooth response peaks and augment the deepest bass. In this case, equalization is needed for the horn and not because of the driver.

A horn with collapsing directivity provides equalization just as surely as an electrical circuit does. But a speaker that uses horns with acoustic EQ doesn't account for the power response and only compensates for response on-axis. It's not too bad if DI is matched at the crossover point, but if it isn't, it really messes up the tonal balance of the reverberent field. So whatever energy is reflected from the room back to the listener is wrong, tonally unbalanced and very unnatural sounding to me.

This isn't a prosound issue. Certainly pattern and coverage are important in prosound, but I would argue that it is just as important in the home. Maybe even more so.

Large sound reinforcement installations with lots of speakers have special needs that make pattern and coverage very important. But most prosound setups have less than a dozen speakers in a fairly large environment. That makes coverage pretty easy, really. In that kind of an environment, you can pretty much just point your speakers where you want. Sure, there are a few things to avoid, but the typical installation is pretty easy.

Home systems are usually in rooms that are smaller and where the room really becomes part of the sound system. You can treat the room all you want, but the fact is that the directionality of the speaker becomes just as much a part of its sound character as does any of its other attributes. Room reflections sort of voice the speaker, so the speaker's directional characteristics are a big deal. Some like a lot of ambience, some prefer more of a headphone sound. So preference is a factor too. But no matter how you look at it, the directionality and the quality of the reverberent field are a big part of the sound character, especially in a relatively small room.

There is also the matter of appearance. You didn't mention it, and it has nothing to do with sound. But I think appearance is important. While some designs using round horns make an art form of the shapes, some are not so attractive. I've seen some really cool looking speakers based on round horns, but some of the others look awkward, even ugly. I just can't get excited about those.

That's my take on it. I like the sound and appearance of other loudspeaker systems much better than those containing round horns. I've seen and heard some that were very good, but I can show you some that I think blow them away both in terms of sound quality and appearance.

I'm sometimes blessed with a lot of free time to enjoy listening to music and sometimes not. This month, I haven't had much free time. It's a sad fact that the few times I've had free, I've mostly watched movies, and I seem to nod off even during those. But the audio system where I'm watching is pretty good, and sometimes the soundtrack really knocks me over. That's pretty cool too.

Sometimes I am able to listen a lot, usually during the day while working. I am blessed to be able to play nice music while working, and sometmes find myself distracted enough by it to take a break and pay attention. If I have to concentrate, I better turn it down because it will grab me and take me away.

I have a couple of critical listening modes in addition to just background listening. One critical listening mode is when I'm listening to the equipment. The other is when I am listening to the music. When listening to the equipment, what I mean is that I am evaluating the performance of a system. It's usually after a prototype is built. After all the design and measurements are done, I will just listen to key passages that I use to compare with. Sometimes I will put a known system side-by-side with a new prototype. Sometimes I wil have two exact same systems side-by-side but with different drivers. So when I am listening to the equipment, I am not hearing the music so much as I am listening for sound quality, artifacts and other anomalies.

The other critical listening mode is when I am just listening to a performance for the music's sake. That's the normal mode for me. When a system is done and in use on a regular basis, it disappears for me. I give it no more thought. Some of my loudspeaker designs have been around for years, decades even. With them, I haven't "listened to the box" for years. I just listen to the music. So when I purchase a new record or CD and listen, I am hearing only the performance. This is the most enjoyable thing for me. I like to put the design away in my mind forever, and just listen to the music.