S15: Econowave DSP - a Constant Directivity vs Dipole study

[Wayne Parham]

I think he was trying to link this:
High-Fidelity Uniform-Directivity Loudspeakers

 

[dantheman]

That's it. I've setting my speakers up like that but away from the corner for about a year. Works as stated.

Thanks Wayne,

Dan

 

[Wayne Parham]

This is the 30th aniversary of the Constant Directivity Cornerhorn. We've been using this configuration for a quite a while now.

I had not heard or read mention of the crossed-axes configuration outside of my realm until the last few years, when it has been adopted by just about everyone with constant-directivity speakers. I think that's great, because it does work very well.

 

[gainphile]

Sweet Spot

Thanks for the link Wayne! I must admit I'm new to this type of speakers and unaware that there is such a goldmine as PiSpeakers! I've been reading slowly the white papers there.

More observation:

SWEET SPOT
I noticed with the CD speakers, when I move around the sofa the sweet spot is very wide. In fact very little changes from corner to corner. Now, the dipoles are known for very wide sweet spot as well. But it's different. The sound image of the dipoles shifts as I moved left and right. The CD on the other hand is more similar, very little change. That reminded me of the Omni, where I could practically walk around the room with little change. The CD can't do that when I tried it but still very wide, and better than the Dipoles.
Score: CD Speaker

Summary so far:

BASS
Score: DRAW

MID-HIGH/Tonality
Score: CD Speakers

IMAGING
Score: Dipoles

SPL/VOLUME
Score: Unsure (CD speakers if mere SPL is the concern)

DYNAMICS
Score: Dipoles

At the moment I put on most weight on Imaging and Tonality. The CD can't image like dipoles, but the dipoles have serious issue with mid-high transition. I was sort of accepting that shortcoming but not after hearing the CD. This is most prominent in vocals.

 

[dantheman]

Gain, my experience very much mirror yours but I never got to do a CD dipole. In the end the tonal issues with dipoles got the best of me. It seemed I was messing with the EQ or toe in all the time and for each recording. It lost its fun real fast. I guess I figured if it doesn't sound good, there's no reason to go on.

The Note may well address the the tonal issues but it comes with a very narrow vertical polar response. That might be an issue with your design as well. Have you looked into that?

Dan

 

[john k...]

The Note may well address the the tonal issues but it comes with a very narrow vertical polar response. That might be an issue with your design as well. Have you looked into that?

Dan

Please don't confuse the optimum vertical listening window of the Note with what it actually sounds like with vertical movement. I realize you can not judge that without hearing them, but there is very little difference in sound with vertical position with regard to over all tonality. The limits I placed on the vertical window are a result of the high crossover point between the mid tweeter coupler and the Neo3 which affects the direct response. But in room response variation with vertical position is not so affected.

 

[john k...]

At the moment I put on most weight on Imaging and Tonality. The CD can't image like dipoles, but the dipoles have serious issue with mid-high transition. I was sort of accepting that shortcoming but not after hearing the CD. This is most prominent in vocals.

I think this may be more of a design problem that something attributable to dipoles. And actually, I think all the categories you are listing except imaging are more design issues and choices that something that can be attributed to dipole or CD.

 

[Robh3606]

I had not heard or read mention of the crossed-axes configuration outside of my realm until the last few years, when it has been adopted by just about everyone with constant-directivity speakers. I think that's great, because it does work very well.

Hello Wayne

You missed the original JBL Everests from back in the mid 80's. The technique clearly has it's roots there. It was one of their statement speakers.

DD55000 Everest


1985 DD55000 EVEREST

Rob

 

[ScottG]

I had not heard or read mention of the crossed-axes configuration outside of my realm until the last few years, when it has been adopted by just about everyone with constant-directivity speakers. I think that's great, because it does work very well.

This really only requires that the speaker "beam" at higher freq.s, NOT that any so-called "constant" directivity pattern be present. Many larger "full-range" drives do just that, and in that regard:

Ted Jordan has been using this configuration for a *very* long time (..with his work at Goodmans I believe in stereo before stereo). Of course it was not with a "constant" directivity pattern, but still using the same idea of greater spl from the far speaker. To my knowledge he is the only one that has expressly and continuously advocated this type of configuration. (..he was also one of the first to use a radial pattern as well, and also a stereo aficionado before stereo recordings were available.)

The Klispchorn, while not designed for this originally, does the same thing for a stereo pair. (..depending on how far away you are from the loudspeakers.)

JBL "borrowed" from the Klipshorn as stereo use via the Hartsfield, and also created the Paragon - and in fact the Paragon is expressly made for stable off-axis imaging (..and was conceived as a center stereo channel).

EV latter started selling what we often think of as "constant" directivity designs (at least horizontally), and again (this time for stadium use) was designed for the same purpose.


The late "resurgence" of this I'd largely credit to Earl Geddes (..though in point of fact there are a large number of reasons why it's being used again).


ALL of this however seems to deny one critical aspect:

-why wasn't it's use more pervasive?


(..I know the reason, but I'm wondering if others do.)

 

[dantheman]

I have no idea Scott, but I'll take the bait. Care to share?

John, I'm not confused. Could you show a bit more of your vertical polar response? I don't want to start an argument here, but if you chose to defend by all means take the floor. I've asked you about this before with no reply. I'm trying not to be annoyed. At the 12 ft distance I can't imagine it would matter much, but near field..... try it for yourself. I have experience here and I actually think it's well backed by Mr. Haas, Dr. Toole, Mr. Parham and common sense(I know Dr. Geddes would refute and refuse to show them)--but you don't really show enough info in this department for the end user to really know. From the 3 lines you show, it's darn narrow. I'm not trying to be insulting. It's just the facts as you have shown. Maybe it's better than it seems with more detail. From the what I can see, it probably is better abetter speaker for a large room--more distant listening especially being a dipole if you buy the theory that dipoles need more room behind them as I do. That's not a design flaw, just a limitation or compromise like every other design. Something to throw in the literature for suggested set up. The other thing your speaker's got going for it is the treble knob. If you have to sit in a response dip, you can just crank it up.

Again, not an insult,

Dan

 

[ScottG]

I have no idea Scott, but I'll take the bait. Care to share?

There are several serious flaws for full *music* reproduction:

1. imaging becomes more focused, or the reproduced source "locus" is more "pin-point" on recordings that shouldn't have that sensation. It's not something you hear in the real world unless you are distant from the sources (..like a good minimalist recorded orchestral or choral work, or a stadium recording). It's also not something you'll hear in a binaural recording of real sound sources reproduced over headphones (excepting recordings which again have significant distance).

2. imaging becomes more fixed between the speakers. Image placement left of left speaker and right of right speaker is considerably foreshortened. The suggested "remedy" is to increase the distance between loudspeakers.. but it isn't really a remedy? Instead, doing so results in source width alterations (i.e. images start getting larger and "fatter" and start to become more diffuse in a non-natural manner). (..note: as you "stretch" an image you also "flatten" it, or rather you trade depth for width.) Also source/images become decreasingly devoid of localization relative to recorded (and virtual) boundaries (walls).

3. Hall sound from the midrange up largely goes AWOL. Advocates with better systems claim that the "sound stage is huge".. but what they really mean is that they have moved the speakers far apart and still have a "sound stage" horizontally that is no larger than the room they are actually in. If they happen to have good low freq. capability then it's particularly odd to hear some of the lower freq. hall sound and not the upper freq. portion - perceptually resulting in a "disconnect" that tends to emphasize the "they are here" phenom (..with some low freq. "baggage".)


Most of this is due to the effects of "enhanced" cross-correlation and additional inter-channel combing, and really - if that's what you are after then why on earth would you listen in stereo? Just go back to mono!

..BTW, I'm a fan of this format for HT.

 

[dantheman]

Very keen observations Scott.

I mixed to mono for years. Surprisingly the errors that should cause in the recording didn't seem to be a problem. I think a lot of that is b/c I have a lot of studio albums that don't have a lot of leakage between the mics and maybe a lot of "direct" recording. I happily did that for years as it eliminated a lot of room issues even though you get no image. My moto essentially is "if it doesn't sound good, why go on?" IOW, the spectral content needs to be balanced first.

That brings me to another set up I've tried with great results--placing the speakers more straight forward but still with some toe in and placing a broad band absorber between them. Seems to give less width, but even greater imaging and depth. I only had that set up briefly so that's a bit premature, but it will be back soon for more experimentation. I was definitely ecstatic when I first set it up. Next time it will be with some better speakers.

There's no one way to skin a cat. Informed compromises all around.

Thanks for the insights,

Dan

 

[dewardh]

if that's what you are after then why on earth would you listen in stereo? Just go back to mono!

Interesting that you would say that, because for most of the music styles best suited to this kind of loudspeaker the "house sound" *is* mono, or very close to it. Were it not so the house sound guy would be deluged with complaints of "can't hear the xxx" on the "yyy side". And movie voice tracks (the "center channel") are almost universally mixed mono too.

But wait, there's more . . .

It is also the case that the overwhelming majority of currently popular music is heard *live* through horn-and-big-cone PA systems, with all the inherent colorations that entails, but when produced (in the studio) for recording it is recorded "clean". So if you play those recordings on what we used to call a "high fidelity" sound system you will *not* get the sound of a live performance, just as when you play a movie sound track at home you will not get what you hear in the theater. Unless, of course, the speakers you have at home add some of the same colorations that theater speakers or the "house" PA system do. Note, though, that I said "*some of* the same colorations. The home listener still wants cleaner, clearer sound than a bad PA system. They just do not want it so clean that it loses the sound of "live" (as they are accustomed to hearing it). Thus we see the resurgance of "better than pro-brand x" small horn systems for home use, with the simultaneous complaints from (what's left of) the old "hi fi" community that they "don't sound right" when reproducing live acoustic music (orchestras etc.). Indeed they don't . . . but they're not intended to.

Different strokes and all that . . .

 

[bwaslo]

This really only requires that the speaker "beam" at higher freq.s, NOT that any so-called "constant" directivity pattern be present. Many larger "full-range" drives do just that, and in that regard:

I can't agree with that at all. I've been toeing in speakers for years and can say that without CD it works only a little. With cone and dome or wide panel speakers, one good seat might be widened to two almost-as-good seats, but after that the character of the two speakers change. Moving closer to one speaker off-axis doesn't resemble the sound of moving further from the other on-axis and any image falls apart. I spent my time endlessly fooling with the balance knob. Not so with CD waveguides.

Also can't agree with all of your list of weaknesses of CD/toe-in. No image outside the speakers? Maybe I haven't heard the speakers you have, but the CDs currently in use here do better on that than anything else I've used. And image size? In most live venues, as said, there really is NO image other than from the people sitting around you and room ambience. With close seating with quartets and small groups there is of course an image, but in recordings of those, the image size from the CDs seems pretty close to my ears. Not perfect, but compared to stats or minimonitors? No contest, except maybe from the line source planars (needing a bigger room). All this is subjective, of course, so no one much is likely to agree...

 

[Wayne Parham]

You missed the original JBL Everests from back in the mid 80's. The technique clearly has it's roots there. It was one of their statement speakers.

Very cool speakers, no doubt. But I was doing this in 1980. I built several pair, and some of the first ones are even still being used.

As a matter of fact, over the holidays, I was chatting with my brother about one of his friends that bought a pair of the early cornerhorns. He said he was still using them, now over 30 years later.

 

[Godzilla]

>>> He said he was still using them, now over 30 years later.

Yup, good stuff lasts!

I suppose the basic formula of a two way using good quality parts is an idea that's stood the test of time. The more modern parts we have today allows us to revisit, tweak and enjoy. Doesn't mean they sound any better but maybe they do. The idea of revisiting these ideas with currently available parts is really a great idea!

 

[john k...]

I have no idea Scott, but I'll take the bait. Care to share?

John, I'm not confused. Could you show a bit more of your vertical polar response? I don't want to start an argument here, but if you chose to defend by all means take the floor. I've asked you about this before with no reply. I'm trying not to be annoyed. At the 12 ft distance I can't imagine it would matter much, but near field..... try it for yourself. I have experience here and I actually think it's well backed by Mr. Haas, Dr. Toole, Mr. Parham and common sense(I know Dr. Geddes would refute and refuse to show them)--but you don't really show enough info in this department for the end user to really know. From the 3 lines you show, it's darn narrow. I'm not trying to be insulting. It's just the facts as you have shown. Maybe it's better than it seems with more detail. From the what I can see, it probably is better abetter speaker for a large room--more distant listening especially being a dipole if you buy the theory that dipoles need more room behind them as I do. That's not a design flaw, just a limitation or compromise like every other design. Something to throw in the literature for suggested set up. The other thing your speaker's got going for it is the treble knob. If you have to sit in a response dip, you can just crank it up.

Again, not an insult,

Dan

No offense taken, the Note is what it is and I tried to document it as thoroughly as possible so that thoose who build it will not suffer any surprises. I'd be happy to provide the in room response at different positions but unfortunately I don't have the Notes set up at the moment. Perhaps the next time I have them set up I will make the measurements and add them to my site.

 

[gainphile]

I think this may be more of a design problem that something attributable to dipoles. And actually, I think all the categories you are listing except imaging are more design issues and choices that something that can be attributed to dipole or CD.

Of course. I keep in mind that for both of these types of speakers they are 1) built by an amateur, 2) uses budget component, and 3) limited to my room/environment.

An "ultimate" comparison perhaps would be Orion/Nao Note vs. Gedlee/PiSpeakers/JBL. But obviously I don't have them.

 

[gainphile]

It is also the case that the overwhelming majority of currently popular music is heard *live* through horn-and-big-cone PA systems, with all the inherent colorations that entails, but when produced (in the studio) for recording it is recorded "clean".

I think we need to be careful in selecting recording, as "Live" music amplified and sent through loudspeakers really can't be a reference (?). But live, unamplified acoustical recording are better.

What about Karaoke, is that even better? Let say from mouth => mic => amp => speakers. No studios involved.

 

[dewardh]

I think we need to be careful in selecting recording, as "Live" music amplified and sent through loudspeakers really can't be a reference (?). But live, unamplified acoustical recording are better.

For me, yes, because live unamplified asoustical music *is* my "reference". But for people who listen to "rock" at a concert or in a club the sound they hear there is *their* reference, whether conscious or not. They will hear "cleaner" sound when they listen to a recording on their headphones, or sometimes their system at home, and they may like, or even prefer, that sound. But it won't sound "real". Just as many orchestral recordings don't sound "real" to me, even when I can hear the instruments more clearly than I can "live". We are picking at nits when we attempt to address recording problems with our loudspeakers . . .

And I don't mean to pick on "rock" (got a few of those recordings myself <g>) . . . consider what happens when recording an opera, and then get back to me about "soundstage" and "imaging" . . .

In live performance the orchestra is in the pit, and it’s mono. You cannot localize sound from the pit in the house . . . period, paragraph, chapter, book. Meanwhile on stage the singers, typically overweight and in silly costumes, looking miss-cast and acting, well, stupid, wander around and occasionally break into song . . . at which point they universally gravitate down stage center (as far as their blocking will permit) and “do their thing”.

Nobody records it live. How could you.

The almost universal practice for opera *recording* is to record the orchestra like a orchestra (with full “stereo” spread), and close mike the singers and mix them center . . . sort of what you’d see in a “concertante” performance, but acoustically pretty much the opposite of a fully staged show. Sometimes the voices are spread (or even panned hard left and right, for “dramatic effect”), but it almost always sounds contrived and silly, if not downright bad. You generally do not want the young lovers singing the duet standing behind the speakers on opposite sides of the room (even if they are staged that way at the beginning of the song). In fact some of the best sounding opera recordings that I own are recorded . . . mono. And it works out OK, more or less . . . unless you play them on horns, which sound terrible. Unless the “opera” is “Tommy”, in which case it sounds like it’s supposed to. One presumes . . .

I find it . . . odd . . . sometimes, how we go on and on about spatial illusion which in reality has almost nothing to do with the music . . .