[SergeyDove]

Has anybody tried to put speakers inside circle (not along line)? Would get shortest distances between all speakers.
Sorry for the picture quality:

Sorry, don't know how to attach image.

[JoshK]

I've seen it done before.  Just to be clear, it works (equal distance to all drivers) for precisely one point in space.  So the arc needs to be calculated based on the exact location of your listening position relative to your speakers.  I'd call it an arc array. 

[SergeyDove]

We get less distortion I think. But ofcourse we lose in stereo. Whole speaker will look like one big driver.
Can't find any similar projects on the Web.

BRGS,
Sergey.

[JoshK]

Ooh...with the picture I see I misunderstood what you meant.  Kinda reminds me of the mid array of the Legacy Whisper.  Another diy speaker forum junkie I know has used a 4 mid driver cluster in a narrow dispersion speaker he built.  It has some benefits, but needs to be thought through carefully if you are serious about the outcome.

[FredT300B]

Wouldn't the circle array behave like a single large coaxial driver instead of a line source?   

[JLM]

Yes, it would behave like a large coaxial, but with comb effects.

Why not look at the 15 inch diameter Hawthorne Silver Iris coaxial driver ($150 each, well built, 96 dB/w/m, rated down to 40 Hz, and can be easily used in a small open baffle)?

[SergeyDove]

Ok, next question - what is the main idea of line arrays: number of drivers and as the result good SPL and depth or shape of the speaker cabinet (line). I think that the idea is a number of drivers regardles of cabinet shape. Whenever I read about arrays I read about line arrays but why only line? Also I have found spherical array but it is not the case. And as I know the ideal speaker is a speaker wiht one ideal full range driver. I think that "circle array" is closer to "ideal" than line array with the same SPL. I see that line is more convinient for small room than big circle. But now I tell about idea.

[samplesj]

Ok, next question - what is the main idea of line arrays: number of drivers and as the result good SPL and depth or shape of the speaker cabinet (line). I think that the idea is a number of drivers regardles of cabinet shape. Whenever I read about arrays I read about line arrays but why only line? Also I have found spherical array but it is not the case. And as I know the ideal speaker is a speaker wiht one ideal full range driver. I think that "circle array" is closer to "ideal" than line array with the same SPL. I see that line is more convinient for small room than big circle. But now I tell about idea.

The reason you are only seeing line array vs other type is it isn't about the eff, but rather the ability to approximate a line source.  In other words its all about the dispersion pattern.

[KCI-JohnP]

I think these guys are "similar" to what you are thinking;

http://cls.audiogon.com/cgi-bin/cls.pl?spkrfull&1197669182

John

[SergeyDove]

No, definitely no.
The similar is only the shape but not principle.

[Greggo]

Interesting topic.... I was thinking of the same thing when looking for an original project last year that would lead to some new lessons learned but I cheaped out.  I was thinking about a DDS ENG-1 waveguide surrounded by 6 or 8 of the Extremis 7inch mid-bass drivers, crossed around 1.5kHz (which IMHO is as low as you should cross that particular waveguide).  Anyways, as I see it, here are the key issues:

1)  For me personally, a big attraction regarding line arrays is the limited driver excursion and lower levels of distortion created by distributing the music power load across multiple drivers.  This principle would still hold true in your circle array as it would in any configuration of multiple drivers grouped together in some fashion to share the drive responsbilities

2)  Another, albeit not clearly proven, princicple is the cylinder like wave launch of multiple drivers in a vertical line, thus giving the line array some unique imaging and spacial properties that appeal to some listerners and not to others.  Talk to Rick Craig about his experience here and also note the fact that he seems to put as much if not more so efforts into his point source designs as his line arrays, though both are extremely impressive IMHO.  Your circle array would not benefit from this potential.

3)  Focused field array - I believe there is a paten on this from Legacy audio but I am not sure, anyways, the 64,000 dollar question here is that we seem to understand the affect of placing two drivers along a vertical access and as an alternative what happens if they are place together along a horizontal access, but not a lot of information on using four drivers to apply both at once.  Even less information about more than four in various symetical geometries around a shared focal point.  I say "information" meaning just what I find around the forums as I am not a truly dedicated audio engineer going through the tombs of research available to those with such passion and discipline.

4)  In relation to the point above, you have lobing and combing artifacts that may or may not be desirable depending on where they occur and how the may relate to driver response, crossover points (when using asymetrical slopes), and desired voicing.  The key here is "center to center" driver spacing and the realtion between this distance and the wavelength of the upper frequency limit you are calling on those multiple drivers to reproduce.  In my opinion, once you go around in a circle, the c-t-c is not the drivers beside each other but the drivers across the focal point from one another.  This is a large distance and now forces you to break all the rules regarding this relationship (best explanation in the world AFAIK is Dr. Jim Griffins white paper on line arrays).  There is also enough anecdotal evidence to conclude that these artifacts may or may not be as noticeable as the engineers think and that people respond differently to them, and that both points are heavily driven by usage, i.e. - do you like to sit in one place, do you want everyone on the couch to get a decent image, do you want everyone mingling about the room in either standing or sitting positions to at least here a balanced frequency response regardless of image specificity.  All of these preferences make power reponse, frequency response, lobing and combing artifacts more or less important to each speaker designer (again all IMHO, and I am just a hack that is addicted to reading four of five well known audio forums on very regular basis)

My own conclusion, if you were to set a circle array system up like a near field studio monitor, where each driver is pretty darn close to be of equal distance to your ears, then you may achieve a great result due to lack of distortion and power compression in a group of share frequecy spectrum drivers, especially if they were mid-bass drivers and you had a very capable tweeter in the middle, preferrably a pro compression driver or horn loaded tweeter of some sort.  For general use it is wide open and I don't think there is much confidence in anything other than trial and error, knowing that the odds are a bit stacked against you as the power response of such a system is bound to be all over the place on both horizontal and vertical listening axis.

Regards,

Greggo

[JohninCR]

To me the attraction of line arrays isn't about the efficiency of multiple drivers-  There are other ways to get good efficiency and dynamics.
It's not about lower distortion with the so little work done by each driver-  Significant levels of distortion are needed to become audible.
It's not about looking cool, though well done arrays can be quite impressive.
It's not even about the dispersion pattern, though the limited vertical dispersion can be a significant benefit.

From my perspective, arrays are about 2 things:
Imaging and soundstage-  The sense they provide is quite different from typical speakers, and rather than bringing the performance into your room, they transport you to the venue of the performance with an up front center stage seat.
Filling a room more evenly with sound- Within the nearfield operation of a line array the SPL decreases by 3db each time distance doubles vs 6db for typical speakers.  This advantage is tremendous.  Not only can you move around in the room without experiencing a huge change in volume, but the sweet spot is so much larger with arrays that it becomes a sweet area.  This is because the difference in distance from you to each speaker as you move away from dead center has greatly reduced effect.

Unfortunately, the circle array concept will enjoy neither of these 2 primary line array benefits.

John

[samplesj]

It's not even about the dispersion pattern, though the limited vertical dispersion can be a significant benefit.

...

Filling a room more evenly with sound[/u]- Within the nearfield operation of a line array the SPL decreases by 3db each time distance doubles vs 6db for typical speakers.  This advantage is tremendous.  Not only can you move around in the room without experiencing a huge change in volume, but the sweet spot is so much larger with arrays that it becomes a sweet area.  This is because the difference in distance from you to each speaker as you move away from dead center has greatly reduced effect.

But the 3 vs 6 drop is because of the dispersion pattern

[SergeyDove]

Thank you all guys for your opinions and thoughts. Now I am more clear in mind than whenever before about what I want from array.

With best regards,
Sergey.

[JohninCR]

It's not even about the dispersion pattern, though the limited vertical dispersion can be a significant benefit.

...

Filling a room more evenly with sound[/u]- Within the nearfield operation of a line array the SPL decreases by 3db each time distance doubles vs 6db for typical speakers.  This advantage is tremendous.  Not only can you move around in the room without experiencing a huge change in volume, but the sweet spot is so much larger with arrays that it becomes a sweet area.  This is because the difference in distance from you to each speaker as you move away from dead center has greatly reduced effect.

But the 3 vs 6 drop is because of the dispersion pattern

True, but ribbon tweeters typically have limited vertical dispersion too, but don't have the same SPL/distance relationship, and electricity makes speaker cones move, but how they sound is what should be discussed.  My point was that talking about the limited vertical dispersion of line arrays tends to get people stuck on the reduction in floor and ceiling reflections.  Sure that's a benefit, but not one of the 2 things that IMO really set arrays apart from all other speakers.

John

[scorpion]

Here is a picture of one channel of what is essentially an IB that the Swedish audioprofile Josef Svalander had. He was very satisfied with its performance:



By the way he used the same SW-12 bassunits that I have employed in my topless U-baffle, see OB circle, then 6 Monacor SPH30X (the small yellow units between the bass elements, the inner circle of midrangers was abandoned in favour of the Monacors) and in the middle a Decca Ribbon copy of Bulgarian origins. All actively driven of course.

/Erling