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Orion vs Abbey - Page 2

post #31 of 141
LTD02 posted a great JBL pdf on the topic of directivity. It was one of the best docs I have found at explaining the differences between non-CD speakers and CD. I have to find it, I thought I had it bookmarked but Its not on the PC Im using today.


Orions are not controlled directivity because they are OB designs and they inherently cause lots of reflections.
post #32 of 141
Found it!!

Quote:
Originally Posted by LTD02 View Post

chapter 5 of the jbl sound system design manual explains it all much better than i have.

the file is too large to post.

starts on page 51 of this pdf:
http://www.jblpro.com/pub/manuals/pssdm_1.pdf

Its some good stuff around page 50 explaining how Directivity works, etc.
post #33 of 141
Quote:
Originally Posted by penngray View Post

No doubt Geddes is doing some marketing but I doubt Geddes is trying to say other Design do not have controlled directivity.

He is saying that because they do not fit his definition. If you accept his definition then they are not CD like he does CD, not to be confused with everyone else's CD or the normal controlled directivity usage.

Quote:
Originally Posted by penngray View Post

I think his biggest point is that his polars are nicer then everyone elses. This is why he has that little program and he is adding speakers to it....I guess its another "marketing tool" for him.

Yes, it is. That doesn't mean it couldn't be useful to other people if it ever became open source. Until then...

Quote:
Originally Posted by penngray View Post

Checking out AES is great when someone wants to buy papers

Unfortunately, if you want good info... You can find most of the better ones for free online, but I will not link to them. It never fails that as soon as I do they get taken down.

Just search for them and read the titles, and statement of intent.

Quote:
Originally Posted by penngray View Post

btw, why do you always "pull your horses" in discussions?

In an attempt to keep me from doing this. Doesn't seem to work though.

Quote:
Originally Posted by penngray View Post

Orions are not controlled directivity because they are OB designs and they inherently cause lots of reflections.

What speakers do not cause lots of reflections at some frequency? Dipoles do have areas on both sides where directivity and reflections are controlled, so they would qualify.

If you stuck constant instead of controlled into your statement above I would agree, as dipoles require the reflected energy from the rear wave to be scattered forward to work, and there is no focusing of the sound into any kind of coverage area, just a null where the front and rear waves meet.

To a degree it is all semantics, as there are no clear cut rules, but there has to be a reason behind your madness, and others must agree with it.
post #34 of 141
soho, Im not sure you know this but your input is always GOOD so I was always curious about you wanting to stop discussions in any thread.

The dispertion patern of an OB is far different then that of a waveguide, no?

Controlled directivity has the dispertion pattern much narrower and focused on the listening area. To consider controlled directivity to be any dispertion pattern makes it kind of a meaningless term.

Constant and Controlled are not interchangable and it seems you have them reverse to what I and others have defined them as.

Constant Directivity just means off axis response slopes equal that of the on axis slopes.

Controlled directivity takes constant directivity one step further and focuses on a certain off axis degree range. The response out side of that range is very, very low dB and not really effecting the sound we hear very much.

Do you have any documented sources that define them differently? Did you read the JBL pdf I linked?
post #35 of 141
Thread Starter 
Soho,

I also enjoy your postings, so please keep your horses running. That being said Like Penn I'm little confused by the manner in which you use Constant Directivity vs Controlled. Are you suggesting that the dipole nature of the OB helps it control directivity through cancellation and thus reduce early reflections reaching the listener in somewhat the same manner as CD reduces early reflections? If I totally distorted your statement I apologize, I'm just trying to get a clear understanding of the gist of your argument.

Thanks
post #36 of 141
Quote:
Originally Posted by penngray View Post

Controlled directivity has the dispertion pattern much narrower and focused on the listening area. To consider controlled directivity to be any dispertion pattern makes it kind of a meaningless term.

It is not meaningless, it is just very broad, and is so on purpose. There is nothing out there to say that it has to be narrow or focused to a certain degree that I have ever seen. (Other than Geddes vision in his "white paper, and from him in that DIYaudio thread.) All that matters is that something is being done to try minimize or direct sound pressure to keep it in or out of a certain area. Waveguide, cardioid, and dipole setups are all examples of Controlled Directivity loudspeakers.

You seem to be using Geddes definitions from the DIYaudio thread.


Constant Directivity is simply a loudspeaker with the same SPL at all frequencies within the designed set of focusing coverage angles. This means that the SPL is the same over the speakers entire band width, and only exists in it's defined coverage area. This is not really possible. Horn makers use the term to describe their horns which can get close to this idea over a certain portion of their operational range, but eventually the Constant D falls apart and unloads. Then it normally crosses over to a regular box speaker and goes omnidirectional. True Constant D would be a great thing for pro audio as crowd coverage, and keeping PA sound off the stage would be very easy. This is why they started using CD as a buzz word.

Constant and Controlled are not interchangeable and they tend to be used that way all the time. Constant is Controlled, but Controlled doesn't mean Constant.

I didn't read the paper, as I have before, but I did skim through the chapter you indicated, and saw no mention of the topic at hand. I then searched for constant and controlled in the document, and came up with no hits. Chapter 3 is a better read, but it doesn't talk about Constant or Controlled Directivity. It talks about what matters. The usage of Directivity, DI, and the fact that horns unload and throw all that out the window at some point.

Why not throw Uniform Directivity in there as well.
post #37 of 141
Controlled directivity just means it's, errr..., controlled. It doesn't say anything about what that control might be unless you're trying to narrow the definition for marketing purposes.
post #38 of 141
Quote:
Originally Posted by catapult View Post

Controlled directivity just means it's, errr..., controlled. It doesn't say anything about what that control might be unless you're trying to narrow the definition for marketing purposes.

What about when the speaker lists a coverage angle? Assuming that the speaker actually meets the coverage angle specified. If you are wanting to reduce early reflections, would not using a speaker with controlled directivity, angled so that the side wall is outside the coverage area be just the ticket?
post #39 of 141
Quote:
Originally Posted by mjg100 View Post

What about when the speaker lists a coverage angle? Assuming that the speaker actually meets the coverage angle specified. If you are wanting to reduce early reflections, would not using a speaker with controlled directivity, angled so that the side wall is outside the coverage area be just the ticket?

That is the idea, but what does the coverage area mean to that loudspeaker? This is what you have to look at. Is it say 60deg coverage from >300Hz, >1kHz, or >4kHz?
post #40 of 141
Two different designs where one IMO, the Orion has significant limitations on the space it's used in.....and that doesn't mean anything wrong.....just different. The Gedlee designs are a bit more flexible and forgiving in smaller spaces. You can somewhat simulate what controlled directivity means in your space by simply hanging some sort of sound dampening material on the side and rear walls......now you'll hear how those reflections are really smearing the sound. Vocals clean up instantly BUT lose some level as the lower frequencies are still omni and radiating all over the place. How low in FR a system holds CD is dependant on the horn/waveguide. You need a pretty big guide to hold directivity below 1k and IMO that's the turning point. An important thing to note about the Orion in the 'boxless' midrange.......that principle regardless of Dipole radiation is being discussed heavily on other forums where the rear wave is attenuated mechanically while still eliminating box resonance, IMO one of the biggest problem with most designs. That rear wave is baaaad news and maybe why CD devices crossed low have gained so much interest as there's no boxiness in the critical midrange.......Something to ponder.
post #41 of 141
Quote:
Originally Posted by Raul GS View Post

Like Penn I'm little confused by the manner in which you use Constant Directivity vs Controlled.

Hopefully, I have cleared that up a little now.

Quote:
Originally Posted by Raul GS View Post

Are you suggesting that the dipole nature of the OB helps it control directivity through cancellation and thus reduce early reflections reaching the listener in somewhat the same manner as CD reduces early reflections?

I'm not sure if I have suggested that exactly, but yes if you mean the normal Constant Directivity with your CD there.

The thing is that Constant and Controlled Directivity have meaning, and neither on has anything to do with a room. Both can be beneficial in a room to a degree, but they exist and function without a room.

We need a new term for using said speakers in a room to cut down on the confusion. It has to sound techie enough, clearly state what is going on, and be as far away from C, C, & D as possible. Focused Matrix, Focus Cone or something.
post #42 of 141
Quote:
Originally Posted by lbaccoustics View Post

The geddes/gedlee summa aproach is that basically the room should be anechoic or as good as (no reflections) as its the recordings job to give you the listening environment.

Well, no, it's very early (<10ms) reflections that are eliminated or minimized, such that the brain does not include them in localization or the perceived spectral content/balance.

Quote:
Originally Posted by lbaccoustics View Post

Geddes approach is to use a CD (constant directivity) waveguide to his own standards (thats fairly well justified I might add) and basically stop the speaker from producing vertually any sound when you move 45 degrees off axis. This will mean that when the speakers are correctly placed (toe'd in alot) the side walls dont give reflections to the sound as if you were in a semi anechoic chamber- and he is successfull in doing this.

No again, the off-axis SPL is more attenuated, not shut off, -6dB defining the beamwidth, which is more like 70° than 90°, actually, with Geddes waveguides. 90° is the physical flare; the dispersion pattern is somewhat narrower.

Quote:
Originally Posted by lbaccoustics View Post

There are still reflections when using the geddes approach, but they are way after the fundemental (actual sound from the speaker)( - it will depend on the sise of the room, but were talking 40+ms) and fairly far down in volume compaired to the fundemental too. This means that the ear wont be very sensitive to it.

Also no, with the Geddes recommended toe-in, the first reflection is low IACC contralateral from the opposite wall, at 10ms or longer delay, to generate spaciousness cues. As may be seen in Toole, since it is originating more on-axis from the opposite speaker, its SPL may not be significantly attenuated with respect to the off-axis direct sound at the listener, i.e., it is a strong first reflection. What most matters is that it is delayed, and thus does not alter the localization of the image or spectral quality of the program.

"An anechoic presentation" is clearly a mischaracterization of Geddes (and similar ) loudspeaker performance. Yes, the intent is for the direct field to dominate, but not at the expense of spaciousness....
post #43 of 141
Quote:
Originally Posted by soho54 View Post

It is not meaningless, it is just very broad, and is so on purpose. There is nothing out there to say that it has to be narrow or focused to a certain degree that I have ever seen. (Other than Geddes vision in his "white paper, and from him in that DIYaudio thread.) All that matters is that something is being done to try minimize or direct sound pressure to keep it in or out of a certain area. Waveguide, cardioid, and dipole setups are all examples of Controlled Directivity loudspeakers.

You seem to be using Geddes definitions from the DIYaudio thread.


Constant Directivity is simply a loudspeaker with the same SPL at all frequencies within the designed set of focusing coverage angles. This means that the SPL is the same over the speakers entire band width, and only exists in it's defined coverage area. This is not really possible. Horn makers use the term to describe their horns which can get close to this idea over a certain portion of their operational range, but eventually the Constant D falls apart and unloads. Then it normally crosses over to a regular box speaker and goes omnidirectional. True Constant D would be a great thing for pro audio as crowd coverage, and keeping PA sound off the stage would be very easy. This is why they started using CD as a buzz word.

Constant and Controlled are not interchangeable and they tend to be used that way all the time. Constant is Controlled, but Controlled doesn't mean Constant.

I didn't read the paper, as I have before, but I did skim through the chapter you indicated, and saw no mention of the topic at hand. I then searched for constant and controlled in the document, and came up with no hits. Chapter 3 is a better read, but it doesn't talk about Constant or Controlled Directivity. It talks about what matters. The usage of Directivity, DI, and the fact that horns unload and throw all that out the window at some point.

Why not throw Uniform Directivity in there as well.


You are wrong about controlled directivitiy not needing constant directivity because controlled is a sub set of Constant (atleast from all discussions so far but hey, proof would be great and Im not worried about being wrong if proven wrong). To have controlled directivity you have to first have constant directivity. You do not have to have controlled directivity to have constant directivity. Think of controlled directivity as a finer resolution of constant directivity. If you have a link to your definition and why you think controlled directivity does not have to have constant directivity it would be great. Better yet give me an example of a speaker that is controlled but does not have a constant directivity.

When you do not apply some angle/value to controlled directivity it simply becomes constant directivity so in a broad scope of the discussion sure controlled directivity can be just constant directivity.
post #44 of 141
Quote:
Originally Posted by Raul GS View Post

Soho,

I also enjoy your postings, so please keep your horses running. That being said Like Penn I'm little confused by the manner in which you use Constant Directivity vs Controlled. Are you suggesting that the dipole nature of the OB helps it control directivity through cancellation and thus reduce early reflections reaching the listener in somewhat the same manner as CD reduces early reflections? If I totally distorted your statement I apologize, I'm just trying to get a clear understanding of the gist of your argument.

Thanks


Im not confused about the definition at all (too many hours in waveguide threads to be confused any more), the end result is that I know exactly what each speaker does in any room, its all out there for anyone to read. Soho, is not reading it right. OB has MORE reflections then ANY OTHER DESIGN since the rear wave is completely uncontrolled.
post #45 of 141
post #46 of 141
Constant Directivity definition.

Quote:


A horn provides more sound pressure level (SPL) at a given listening area by increasing the directivity of the sound towards the listener. There is more sound at the listening area, and less sound outside of that area. By analogy, think of focusing a beam of light (from a flashlight or torch). A widely focused beam spreads the light around, reducing the intensity at any one point. However, a narrowly focused beam provides much more light intensity at the center, and much less in the surrounding area. Properly designed horns can also act as a waveguide that actually serves to spread higher frequency sounds out in a much more consistent manner than would otherwise happen. Round horns and radial horns tend to change their angles of spread (their directivity, measured by the directivity index, or DI) as the frequency changes. This means that high frequencies, for instance, might be more highly directed, and therefore sound louder to someone in a central location than to someone else outside of the center (but still within the horn's low-frequency area of enhancement). To cope with this problem, the constant directivity (CD) horn was invented. The design goal of the CD horn is to provide the same SPL at all frequencies within the designed coverage angles. The term "Constant Directivity" is a trademark of ElectroVoice but has become somewhat of a catchall phrase to describe constant-beamwidth horns. In 1975, Electro-Voice introduced a single-cell horn that consisted of three-stages. The design incorporates a hybridized hyperbolic/exponential throat section coupled to a conical, vertically flared, radial bell section. Flanges that correct for midrange beaming caused by edge diffraction are comprised of a second, wider conical, vertically flared, radial bell-section. As with classic radial horn designs, the sidewalls are straight, but in two flange sections. Having constant beamwidth in both the vertical and horizontal directions, and an unprecedented high directivity index, these horns became the model for virtually all-new horn designs for the next decade. Additionally, they horn loaded the driver well, and as a result sounded very good.


Amazingly I can not find a true definition of Controlled directivity (Outside of marketing spin).

I did find this from Mark Seaton on another forum

Quote:


Controlled directivity has become the latest buzzword used equal or more often by those who don't understand the realities as those who do.

Some friends just did some comparisons with some quality speakers with very high directivity and were quickly sobered by the reality that it doesn't give you a free pass on the setup. Improved directivity *reduces* the early reflections and can greatly help with clarity, intelligibility and the audibility of natural decay in instruments and sounds.

It can make a bad room sound less bad, and changes how the speakers interact with the room possibly changing where you might want to direct your first efforts in acoustic treatment. It won't "take the room out of the equation," but rather reduce the significance of the effect.

Does anyone have a REAL definition for controlled directivity at all?
post #47 of 141
Quote:
Originally Posted by mjg100 View Post

What about when the speaker lists a coverage angle? Assuming that the speaker actually meets the coverage angle specified. If you are wanting to reduce early reflections, would not using a speaker with controlled directivity, angled so that the side wall is outside the coverage area be just the ticket?

That is called the directivity index and that is part of the constant directivity world and so is controlled directivity
post #48 of 141
Quote:
Originally Posted by penngray View Post

You are wrong about controlled directivitiy not needing constant directivity because controlled is a sub set of Constant (atleast from all discussions so far but hey, proof would be great and Im not worried about being wrong if proven wrong).

This is wrong, wrong, wrong. What discussions are you talking about?

Quote:
Originally Posted by penngray View Post

To have controlled directivity you have to first have constant directivity. You do not have to have controlled directivity to have constant directivity. Think of controlled directivity as a finer resolution of constant directivity. If you have a link to your definition and why you think controlled directivity does not have to have constant directivity it would be great. Better yet give me an example of a speaker that is controlled but does not have a constant directivity.

As I keep saying only Geddes says this, because he doesn't want his horns mixed in with other ConstantD horns, so he says his CD is different, it's ControlledD, and came up with a new definition for an old term. Half the time he talks like he came up with ConstantD and ControlledD himself years ago. Find one other person in the know who will agree with this. No one else did in the DIYaudio thread you linked too earlier. He and JohnK spent the whole time saying how the other person was wrong.

Quote:
Originally Posted by penngray View Post

Soho, is not reading it right. OB has MORE reflections then ANY OTHER DESIGN since the rear wave is completely uncontrolled.

No you seem to be missing the point, all speakers have omnidirectional sound at some point. OB/dipole speakers just have the front and rear halves out of phase so part of the circle cancel each other out where they meet at the edges. They have no more reflections than any other normal speaker. You can shape the reflections better though with OB/dipole, and control the ones you want. That would be Controlled Directivity. It's the same with Cardioid speakers, as you control the rearward waves levels.

Quote:
Originally Posted by penngray View Post

Here is Geddes directivity PDF.

Yes, this is the PR "white paper" I am talking about. This is just marketing. If you re-read it you will see that his CD is not Constant Directivity like everyone else uses, but Controlled Directivity.
Quote:


The idea of an “ideal” directivity will be examined and it will be shown that CD (Controlled D)alone is not enough, in a small room one needs a narrow
directivity that is also CD.(Controlled D)

You see in the paper he is just saying you need more than just Controlled Directivity in room. This is common sense. A 90deg Controlled Directivity speaker is useless in a room for keeping sound away from walls. For Focused Matrixing you need Controlled Directivity speakers with a throw that complements your placement/boundary/coverage situation.

It is in the DIYaudio thread where he goes over the EGO edge, and admits to changing the definition of Controlled Directivity for his own purposes,
Quote:


To me, the point is that Constant Directivity is not restrictive enough, and so in this sense I believe that Controlled Directivity is the more stringent (quite the opposite of John).

Quote:


I did not consider it "Controlled Directivity" if the goal was High-Q. There are no standard deffinitions to any of this stuff, which is why people use them in whatever fasion they want and John and I have completely opposite definitions. It's no wonder its confusing.

Quote:


So I started using CD to mean Controlled Directivity, meaning that the directivity was specified to be something required by the application and not simply the default directivity defined by the implimentation.

See he just made it up to fit his needs, and to heck with everyone else, and the confusion it will cause.

Quote:
Originally Posted by penngray View Post

Constant Directivity definition.

Google says that is the Sweetwater def. Looks pretty close to what I have been saying.

Quote:
Originally Posted by penngray View Post

Amazingly I can not find a true definition of Controlled directivity (Outside of marketing spin).

That is because it is marketing spin. It means only what it says. This device tries to control it's directivity in some manor.

Quote:
Originally Posted by penngray View Post

Does anyone have a REAL definition for controlled directivity at all?

Catapult already gave you the best definition there is, "Controlled directivity just means it's, errr..., controlled."

That is it. It just means there was an attempt to alter the polar directivity in some manor. There is nothing else to it.
post #49 of 141
I see constant directivity as a subset of controlled directivity, not the other way around. Earls speakers aren't constant D because they go from 90 degrees coverage to 360 as the frequency changes. But they are controlled because they have the polar response he wants.

About dipoles having more reflections, not true compared to an omnidirectional woofer. A dipole or a cardioid will have a summed power response (average of measurements around a sphere) 4.8dB lower than an omni. A horn drops that even more of course but the big question is whether the mismatch in power response between the low end and the high end is a problem are not. Dipole fans say it's a big problem, horn fans say it isn't.

All this design theory aside, a good power response test is how does it sound from down the hall or in the next room? If it sounds like there are live musicians in the other room, the power response is pretty good. If it sounds like there are speakers playing in the other room, it isn't.
post #50 of 141
Quote:
Originally Posted by catapult View Post

All this design theory aside, a good power response test is how does it sound from down the hall or in the next room? If it sounds like there are live musicians in the other room, the power response is pretty good. If it sounds like there are speakers playing in the other room, it isn't.

This is interesting. Never though about it this way, and I always crank the volume up to hear it in other parts of the house while working.

I may have to play with this the next time the wife is out of the house.
post #51 of 141
I don't think that an ideal Linkwitz and a Geddes room are very different at all both talk about rather live acoustics.
Getting back to the speakers sound.
The Linkwitz is ideal for well recorded two channel stereo like classical music. But it may bring out the flaws of poorer pan-pot recordings.
The Geddes is ideal at much higher volume levels. Also better for multi-channel home theater.
post #52 of 141
Thread Starter 
Quote:
Originally Posted by Speedskater View Post

The Linkwitz is ideal for well recorded two channel stereo like classical music.
The Geddes is ... better for multi-channel home theater.

Hi Kevin,

I suspect I know why you state this, but could you elaborate? What if one is pursuing two channel, would you say Geddes is at a disadvantage if high SPLs are not required?

Thanks
post #53 of 141
I own a pair of Abbeys, and have auditioned the Orion (I was originally trying to decide between these two).

Both of these designs achieve controlled lateral directivity of mid and high frequencies, but through different means - dipole or waveguide. A fundamental difference, however, is that the dipole also radiates to the rear whereas the waveguide does not.

The Orion is designed to provide a flat frequency response down to 20 Hz, whereas the Abbey, with it's sealed design, starts tailing off at around 100 Hz. The Abbey, therefore, requires at least one subwoofer to achieve comparable bass response. Earl Geddes recommends multiple subs to provide uniform in-room bass response. I have two.

The Orion is designed to be listened to at only moderate volumes, and the open baffle woofers will max out on movies played at reference volumes - hence the addition of two subwoofers in the Orion+. The Abbeys, on the other hand, can be listened to at any desired volume without significant distortion.

The imaging of both designs, properly set up, is superb. However, the sweet spot provided by the Abbeys is much wider. The Orion sounds echo-y when listened to off axis (e.g., from a side position in a typical living room). The Abbey does not. The in-room placement of the Abbeys is more forgiving in terms of distance from the front wall (the Orions must be at least 3-4 ft away in order to achieve sufficient delay between the direct sound and reflected sound from the rear).

The Orion requires multiple amps and a dedicated ASP. The Abbeys, with their 95 db sensitivity, can be easily driven by any conventional receiver or amplifier.

The place where the Abbey really shines is in the dynamics. Their ability to accurately reproduce live sound at reference volumes is unparalleled.

There are a number of former Orion owners who switched to Earl's speakers (Abbeys or Summas) and have never looked back. They provide clean, uncolored sound with rich bass, smooth mids and accurate highs. They image like a speaker of much smaller size, and provide amazing dynamics. They also perform very well in minimally treated rooms (like mine) due to the constrained radiation. They perform great for all kinds of music, including classical played at moderate volumes. They are fairly large, but so are the Orions. I would definitely make the same choice again.

- Doug
post #54 of 141
Thread Starter 
Doug,

Have you heard the Orion's with the new x-over? They are now in version 3.1, and Linkwitz suggests that is virtually a different speaker from the perspective of transparency and SPL capability.

John Ks NaO Note also looks very intriguing, but his still in the process of developing that speaker. To some extent his design is a hybrid of OB and Waveguides.
post #55 of 141
Quote:
Originally Posted by catapult View Post

I see constant directivity as a subset of controlled directivity, not the other way around. Earls speakers aren't constant D because they go from 90 degrees coverage to 360 as the frequency changes. But they are controlled because they have the polar response he wants.

About dipoles having more reflections, not true compared to an omnidirectional woofer. A dipole or a cardioid will have a summed power response (average of measurements around a sphere) 4.8dB lower than an omni. A horn drops that even more of course but the big question is whether the mismatch in power response between the low end and the high end is a problem are not. Dipole fans say it's a big problem, horn fans say it isn't.

All this design theory aside, a good power response test is how does it sound from down the hall or in the next room? If it sounds like there are live musicians in the other room, the power response is pretty good. If it sounds like there are speakers playing in the other room, it isn't.

THere is NO definition to controlled directivity. Have not found one yet so please show me how constant directivity is a subset. Opinion is meaningless, we need facts from viable sources.

Constant directivity was defined way back. Controlled directivity is more marketing spin then anything.

If anything constant directivity is the REAL term and has definition and value to you and controlled directivity is what some people want to spin to create a unique product (ie. Geddes).
post #56 of 141
Quote:
Originally Posted by soho54 View Post

That is it. It just means there was an attempt to alter the polar directivity in some manor. There is nothing else to it.

Sure controlled means controlled...we should move past the grade school word associations. Well all understand that point, we want the research level discussion on "Controlled directivity" and we both know it does not exist, we both know that controlled directivity is a marketing term and nothing else. We should not even continue using it since constant directivity is a real defined audio term.

Constant directivity is defined by the polar directivity so if you are saying controlled directivity is an attempt to alter it then controlled directivity is altering constant directivity. Conclusion, it has to be a subset of constant directivity to alter it.

You defined what I have been posting. You just do not understand what I have been posting. I posted already that we are arguing the same thing but do let that stop anyone

I asked before but I will ask again post a speaker that has controlled directivity but no constant directivity.
post #57 of 141
Quote:
Originally Posted by Raul GS View Post

Doug,

Have you heard the Orion's with the new x-over? They are now in version 3.1, and Linkwitz suggests that is virtually a different speaker from the perspective of transparency and SPL capability.

John Ks NaO Note also looks very intriguing, but his still in the process of developing that speaker. To some extent his design is a hybrid of OB and Waveguides.

No, I haven't. I saw those comments, though, so it would be interesting to hear what the new version sounds like.
post #58 of 141
Quote:
Originally Posted by penngray View Post

THere is NO definition to controlled directivity. Have not found one yet so please show me how constant directivity is a subset. Opinion is meaningless, we need facts from viable sources.

Constant directivity was defined way back. Controlled directivity is more marketing spin then anything.

If anything constant directivity is the REAL term and has definition and value to you and controlled directivity is what some people want to spin to create a unique product (ie. Geddes).

Constant directivity is indeed the correct term to use. Geddes speakers do that, I'm not sure if the Orion does - I have never seen a plot of the actual polar response.
post #59 of 141
I will have to say that Dr. Geddes idea of controlled directivity makes sense to me. There may not be any white papers on it, but that does not mean that there will not be any papers in the future.
post #60 of 141
Directivity is quantified as DI or "Q"; Directivity Index = 10logQ.

Constant directivity is, by definition, a flat DI, the value being inversely proportional to the conical section subtended by the -6dB dispersion pattern.

Any narrow reading of the definition reveals that nobody does it; practical implementations are imperfect and rarely encompass the entire audible spectrum.

While Keele is generally credited with first use of the term to describe the design objective of his early CD horns for EV, constant directivity as a SYSTEM design is clearly evident in Allison & Berkovitz's ca. 1970 AES presentation describing AR3a. Fortunately, they never achieved their 180° goal:

http://www.classicspeakerpages.net/l...d_in_home_lis/

The paper is also published in the AES "Loudspeakers" anthology, Volume 1.

My own exchange with Geddes regarding whether his products have constant directivity or not appears on diyAudio forum:

http://www.diyaudio.com/forums/multi...ml#post1862626

His oblate spheroid implementations are not constant directitvity by strict definition of the term, and are also less constant than other designs. Forum member Patick Bateman posted a further adulterated viewpoint that Geddes's imperfect OS defined constant directivity (much as Earl claims "Waveguide"), and I was awarded a 48-hour sabbatical for my contentious assertion to the contrary:

http://www.diyaudio.com/forums/multi...ml#post1841022

Quote:


That's the problem in the horizontal axis of this waveguide; all the curves are nearly identical to the on-axis response.



In any case, to whatever extent we accept that Geddes and other designs having quasi-constant directivity horns/waveguides qualify, as SYSTEMS, they do not, as directivity control is limited to the higher frequencies only.

Orion and similar designs strive to extend directivity control to lower frequencies by taking advantage of dipole effect, with some success, but a wider pattern than achievable using waveguides. To whatever extent we accept that they also satisfy the definition, they are not constant directivity across the entire spectrum, either.

Here are polar maps by Geddes of Geddes Nathan, Linkwitz Orion, and a conventional cone/dome 2-way loudspeaker:
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