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Old 20th June 2007, 05:37 PM   #1
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Default line-array vs conventional point-source/ distorsions issues

Hello,

Beside other issues like directivity, efficiency, shape of waves, it is commonly admited that because of their multiple drivers, line-arrays allow reducted distorsions.
So my question: if I use very good drivers (I think about accuton for exemple) well filtered in a conventional speaker, listened at average spl level (I would say 80-85dbs with 110dbs peaks...that's what was once mesured in my room), DOES a line-array let less distorsions to be heard?

Thanks.

Hubert
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Old 20th June 2007, 08:26 PM   #2
adason is offline adason  United States
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I would say most likely yes, just consider the distortion of one midrange driver at few watts (assuming average sensitivity), than use ten of those drivers, each at 1/10 of power to produce the same spl...I believe distiortion will be noticably lower

offcourse the higher the spl, the bigger the difference in distortion between one driver and line array
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Old 22nd June 2007, 12:03 AM   #3
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Thanks adason for your comments. My feeling is that there are certainly other main issues than the amount of distortions in this matter of line-arrrays vs point sources...so it must be very difficult to answer to my initial question.

Cheers.
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Old 22nd June 2007, 12:54 AM   #4
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Default Re: line-array vs conventional point-source/ distorsions issues

Quote:
Originally posted by crazyhub
DOES a line-array let less distorsions to be heard?
It would probably be educational to look at both line array and linesource:
line array = closely spaced line of point source speakers
linesource = ribbon like continuous source. It possible to construct a midrange linesouce ribbon down to say 100Hz and a tweeter linesource ribbon up to 30Khz

It would probably be educational to look at both the distortion measured at say 0.5m and the distortion measured at say 4m.

Many distortion agruments against line arrays and linesources come from the difference in signal arrival time from the top of the array(line), the center of the array(line), and the bottom of the array/(line) to one single listening point 3-4m away. Some consider this a "smearing" distortion, others consider it creating a rich ambience.

Line array and linesource speakers have won several "best of show sound" awards, but also seem to create love/hate polarized opinions.
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Old 22nd June 2007, 01:44 PM   #5
Zarathu is offline Zarathu  United States
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Are you interested in actually building a line array, or are you just exploring topics?

As the owner of a line array, I have to say that comparisons to point source systems are flawed. The operation and the experience is simply very different than a PS system. If you want a big point source, buy or build a point source.

Many of the stuff that might be hearable on paper in a point source, are not noticable in a line array. The smearing that was spoken of may sound good on paper but doesn't exist in listening experience. I have 30 tweeters per side. Each one only handles 3.3% of th total tweeter load. I have 17 mid ranges per side. Eac h o f these handles only 5.8 % of the total midrange load. Distortion? It cannot be heard.

Zarathu
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Old 22nd June 2007, 10:58 PM   #6
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Linesource wrote:
Quote:
line array = closely spaced line of point source speakers
Obviously I had linesources in mind, sorry for my mistake.
Quote:
It would probably be educational to look at both the distortion measured at say 0.5m and the distortion measured at say 4m.
Room will add a lot of bounces but regarding reduced spl losses I suppose less distortions as a result here too...
Quote:
Many distortion arguments against line arrays and linesources come from the difference in signal arrival time from the top of the array(line), the center of the array(line), and the bottom of the array/(line) to one single listening point 3-4m away.
Curved shape can cancel these different time arrivals if drivers symmetrically placed from ears height, or?

Zarathu wrote:
Quote:
Are you interested in actually building a line array, or are you just exploring topics?
I'm asking myself about the best choice for my next project...Why I thought about linesources?: because I want to keep the same clean and undistorded sound at high spl that I hear at average spl with my present 2.5-way (Modulus from Tony Gee + a big subwoofer). I very rarely heard such clean sounds from point-sources, almost always becoming relatively harsh at high spl. However, it's a difficult matter to know where come distortion from: room acoustic or drivers stress? If I had both systems in my room, it would be easy to know about!!!
Quote:
As the owner of a line array, I have to say that comparisons to point source systems are flawed. The operation and the experience is simply very different than a PS system.
Can you please point the differences out? Particularly: does image remain accurate in its size, growing with spl level? Also, do you get beautiful
soundstages in width and deepness? Could a linesource be adapted to a relatively small room? (my room is in an attic, under the roof with two slopes, so a good area but less volume than an average (in the height) room of the same area.

Thanks.
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Old 23rd June 2007, 01:20 AM   #7
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Although I'm not really a big fan of line arrays from a conceptual point of view (I prefer the KISS principle, and: optimize, optimize, Optimize!), I've just noticed one major advantage that linear arrays may have...

The 'dominant' wavefront is not just the on-axis response at 0 degrees, which is usually the one drawn on driver FR plots. It's an average of the sounds produced at a variety of angles between say: 0 and +-30 degrees. So, when the speakers are crossed over and equalized for a flat response, the acoustic power radiated into the room at other angles also has a much more even FR.

So-called point-source speakers can't be equalized in the same way because there's often very little correlation between the on-axis and off-axis responses.

Edit: ...which means that line arrays tend to be more cheap-speaker-friendly , unlike point-source designs that rely on the frequency response being consistent across a variety of angles (difficult to do).
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Old 24th June 2007, 02:24 PM   #8
Zarathu is offline Zarathu  United States
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Crazy hub

I think the slope of your attic room would prevent the wonderfullness of a line array from working for you.
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Old 24th June 2007, 09:24 PM   #9
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ceramicMan wrote:
Quote:
I've just noticed one major advantage that linear arrays may have...The 'dominant' wavefront is not just the on-axis response at 0 degrees, which is usually the one drawn on driver FR plots. It's an average of the sounds produced at a variety of angles between say: 0 and +-30 degrees. So, when the speakers are crossed over and equalized for a flat response, the acoustic power radiated into the room at other angles also has a much more even FR.
yes, sure that the main difference between point-sources and linesources or line arrays is in this matter of directivity and amount of diffused energy in the room. However, even if difficult, a nice off-axis energy can be obtained on a point source with well choose drivers and correctly designed x-over.
Quote:
Although I'm not really a big fan of line arrays from a conceptual point of view (I prefer the KISS principle, and: optimize, optimize, Optimize!),
I'm OK about the KISS principle (when possible), but can you explain what you reproach to line arrays or line-sources in a conceptual point of view?
Zarathu wrote:
Quote:
I think the slope of your attic room would prevent the wonderfullness of a line array from working for you.
why please?
edit: you didn't answer my previous question: what are the main listening (heard) differences between point sources and linesources in image and soundstages?

As you see, I want to learn, not only to know without understanding.
Thanks.
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Old 24th June 2007, 09:43 PM   #10
Zarathu is offline Zarathu  United States
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Line arrays are usually 6-8 feet tall. You have a sloping ceiling that goes to the floor. They radiate togetyher in a cylinder pattern. No studies have been done as to what they would sound like put in a slope. and since your room isn't square.......

As to the characteristics of arrays:

The major benefits are as follows:

1. Frequency response dips and bumps tend to smooth out. And because there are some many of the speakers, each speaker may have limited output in the upper treble or the lower bass, but all speakers put out something in those areas. If you put enough of them together you can actually get some decent response in the areas even if the individual speakers don't have much to give.

2. All arrays whether with really cheap speakers(49 cent for example) or expensive($49 for example) have decreased distortion. Decreased distortion increases airiness, openness etc. Power handling goes up dramatically. 32 dome tweeters might give you a 450 rms watt per channel protection.

3. All arrays have vastly increased dynamic range and increase sensitivity.

4. Size: One of the benefits of an array is the coupling of the speaker to the ceiling and floor.

5. They may not need a sub woofer, or even a woofer to play deep. A combination of 12 7 inch mid woofs have a huge amount of bass, with very low distortion.

6. Sound dispersion and sound stage. Arrays produce a level of sound stage and sound dispersion that just has to be heard to appreciated. Array sound presents in the near field

7. Because array sound represents in the nearfield(as opposed to the far field for all point source speakers), the concept of reflections from walls and floor is almost non-existent

8. Baffle compensation distortion is reduced to less than 1 db when the numbers of speakers in a line exceed 15.

Disadvantages.

1. They can be expensive. Even an inexpensive array is going to cost around $500 - 700 for the speakers, plus the building. An expensive one might cost as much as $2000 just for the multiple speakers, and the whole system a lot more when you add the amplification

2. They often require extra amplification and electronic crossovers since its hard enough to build a quality passive cross for a point source. Its harder for a passive design due to the high power that goes through them, and because if you are going to go to all this expense and time you might as well get the benefits of electronic crosses and not waste have of it on a passive.

3. The cabinetry is long and can often be a nightmare with the number of enclosures and holes that have to be cut.
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