[Guy 13]

Hi all Audio Circle members.

By curiosity and to satisfy my appetite for learning about audio,
what is the main advantage or the difference to go with line array speakers, in comparison to bass reflex, horn, transmission line, etc…

The only thing I can say and know about the line array is that it loads the room.

As you can see and read, I am pretty ignorant, therefore,
please educate me.

Thank you.

Guy 13
 

[navin]

Hi all Audio Circle members.

By curiosity and to satisfy my appetite for learning about audio,
what is the main advantage or the difference to go with line array speakers, in comparison to bass reflex, horn, transmission line, etc…

The only thing I can say and know about the line array is that it loads the room.

As you can see and read, I am pretty ignorant, therefore,
please educate me.

Thank you.

Guy 13

The best person to ask this is Don Keele.
http://www.xlrtechs.com/dbkeele.com/CBT.php
http://www.almainternational.org/assets/Documents/WinterSymposia/InvitedPapersWS2011/keele%20-%20intro%20to%20cbt%20loudspeaker%20arrays%20pt.%202%20of%203.pdf

Yes I understand it IS the way the room interacts with the array. As long I can remember I have seen arrays used in Stadium environments and very well i should add; but not the way Don Keele has done his.

It WAF is not a concern I would have built one myself.

[G Georgopoulos]

Here is a link about various speakers ...

http://en.wikipedia.org/wiki/Loudspeaker_enclosure

 

[JLM]

Frankly I'm not impressed with vertical arrays:

To be effective as promoted (in room loading) they must extend literally floor to ceiling.

Drivers usually aren't spaced close enough together.

They cannot image vertically (unless you go with a back curved array and get into complicated delay systems).

(Refer to Floyd Toole's book "Sound Reproduction" to explain the above comments.)


Requires dozens of drivers per speaker that if high quality would increase cost by about 50 fold versus building the speaker from just one of each type (woofer/tweeter).

The amplifier does not "see" a simple/direct driver load, so has poor synergy.

[Guy 13]

Hi all Audio Circle members.
Thanks all.
I never had intention of buying or building a line array speaker,
but now, I am even more convinced that it will never happen.

Guy 13

[JLM]

Most designers push horns too hard (to gain efficiency) resulting in coloration (high pressure compression resulting in non-linear response).

Another dirty secret of speaker design is the back wave: 

Equal energy goes forward and behind the driver (into the room and the cabinet).  Cabinet pressures are very high, waves bounce around and "look" for a way out.  In a typical squarish cabinet it bounces off the back cabinet wall and straight back towards the highly acoustically translucent cone, causing smearing (phase delays).  Cabinet backs (or internal baffles) slanted relative to the front baffle direct waves away from the driver, thus reducing smear.

Sealed designs are inefficient and thus suffer dynamic response.  Ported designs must be carefully designed to avoid port noises and response peaks.

In dipole/open baffle designs (which are typically vertical) the back wave goes directly into the room, mimicking a distribution pattern of almost no known acoustical (real) music source except a gong.

There is no perfect speaker.

[Rick Craig]

Frankly I'm not impressed with vertical arrays:

To be effective as promoted (in room loading) they must extend literally floor to ceiling.

Drivers usually aren't spaced close enough together.

They cannot image vertically (unless you go with a back curved array and get into complicated delay systems).

(Refer to Floyd Toole's book "Sound Reproduction" to explain the above comments.)


Requires dozens of drivers per speaker that if high quality would increase cost by about 50 fold versus building the speaker from just one of each type (woofer/tweeter).

The amplifier does not "see" a simple/direct driver load, so has poor synergy.

Wrong,wrong,wrong...

Floor to ceiling isn't needed (see Keele's CBT designs). Driver spacing does matter but with attention to the design integration can be excellent. Vertical imaging is possible with both straight and curved systems and no additional delay is needed for the curved CBT's. A straight array with no delays will have a more narrow vertical beam but it still can be acceptable. Multiple drivers are taxed less so there's less need for expensive drivers like you might prefer in a conventional speaker. The amp / speaker synergy is not an issue unless the amp has its' own problems (high out impedance,etc).

[JohnR]

I never had intention of buying or building a line array speaker,
but now, I am even more convinced that it will never happen.

I think you're a little quick to dismiss them... With regard to your original question, "line array speakers, in comparison to bass reflex, horn, transmission line, etc…" - the latter three are types of loading of the drivers and are not related to the line array configuration.

[G Georgopoulos]

Now it got me started, which is the best line arrays or single driver speakers,I say this because both are extremes to what is the norm...

 

[AJinFLA]

Hi all Audio Circle members.

By curiosity and to satisfy my appetite for learning about audio,
what is the main advantage or the difference to go with line array speakers, in comparison to bass reflex, horn, transmission line, etc…

The only thing I can say and know about the line array is that it loads the room.

As you can see and read, I am pretty ignorant, therefore,
please educate me.

Thank you.

Guy 13

Hi Guy,

First, a "line array" is the arrangement of the drivers, in a "line" as the name implies. "Bass reflex, horn, transmission line, etc…" is the type of bass loading employed by the enclosure that the drivers will be mounted in.
IOW, you could have a line array bass reflex enclosure, line array horn, line array TL, etc, etc.
In terms of effect on bass (re)production, a line array interacts with the room as multiple sources, the height of the line of bass drivers. Whether this beneficial or not is another question, though multiple sources do tend to spatially average to smoother response than singular or dual ones. There are a lot of "it depends" associated with the format (as any).

cheers,

AJ

[navin]

Most designers push horns too hard (to gain efficiency) resulting in coloration (high pressure compression resulting in non-linear response).

Another dirty secret of speaker design is the back wave: 

Equal energy goes forward and behind the driver (into the room and the cabinet).  Cabinet pressures are very high, waves bounce around and "look" for a way out.  In a typical squarish cabinet it bounces off the back cabinet wall and straight back towards the highly acoustically translucent cone, causing smearing (phase delays).  Cabinet backs (or internal baffles) slanted relative to the front baffle direct waves away from the driver, thus reducing smear.

Sealed designs are inefficient and thus suffer dynamic response.  Ported designs must be carefully designed to avoid port noises and response peaks.

In dipole/open baffle designs (which are typically vertical) the back wave goes directly into the room, mimicking a distribution pattern of almost no known acoustical (real) music source except a gong.

There is no perfect speaker.

Actually in my opinion the best way to 'treat' the back wave is a transmission line. A tapered line reduces the volume of box required and also standing waves inside the box.

Now back to line sources. They are not all bad. The 4 driver arrays touted by Ed Jordan and his ex-wife Doreen are quite good and are WAF friendly. One of my other ideas was to mate 4 JX6R drivers with a pair of TLed 8" woofers. Crossover would be 250-300Hz using an active XO with 2 stereo power amps (or 4 channels of. 5 channel amp).

I have not tried a curved array but I did try a 16 driver (3" full ranges) line array and the sweet spot was very small. As one stood up and walked around we got some funny effects. Georgeopoulos, I would start with a simple 4 driver array and take it from there.

[JLM]

Guy, my previous post was meant to help balance out some of the pros and cons of various speaker designs.  I responded to start with because most audiophiles want to listen to the best drivers they can afford and applying that to vertical arrays gets super expensive, so inevitably folks compromise on the driver quality.  And at the end of the day isn't the drivers selected the #1 factor in how your system sounds?  (My single drivers would currently cost over $700 each in a $8000 MSRP system).

Rick, I respectably disagree with every point you made (except for the the CBT, which I had already pointed out).

John et al, yes we are discussing two different aspects of speaker design (sorry to extend any confusion).

AJ, to clarify my point, for a line array to really function as a line source it must extend floor to ceiling, otherwise it's some sort of point source/line source hybrid.

Navin, I agree regarding transmission lines 100% but didn't want to add my bias into such an off topic discussion.

[navin]

Guy, my previous post was meant to help balance out some of the pros and cons of various speaker designs.  I responded to start with because most audiophiles want to listen to the best drivers they can afford and applying that to vertical arrays gets super expensive, so inevitably folks compromise on the driver quality.  And at the end of the day isn't the drivers selected the #1 factor in how your system sounds?  (My single drivers would currently cost over $700 each in a $8000 MSRP system).

AJ, to clarify my point, for a line array to really function as a line source it must extend floor to ceiling, otherwise it's some sort of point source/line source hybrid.

Navin, I agree regarding transmission lines 100% but didn't want to add my bias into such an off topic discussion.

I have very very limited experience with line arrays which is why in my earlier posts I refered Guy 13 to Don Keele.

JLM, I think what Rick was trying to say is that if one is using 16 or 32 drivers in a line array that is say 60-120" tall then each driver need not be as expensive as say a single Lowther. After all one would be hearing the averaged response of multiple drivers and each driver is operating in a very linear manner as each driver has to move little.

I believe what Don Keele did was by curving the array in a manner he did reduced or eliminated the "point-source-ness" of typical line arrays. Some of the theory Don used was developed by the US Navy (I read his papers  ).

After hearing a Fried G/3 and Ted Jordan's 4 driver array I figured why not try to marry the best of both.  Never got around to executing this idea (like I never got around to executing a good OB using Hawthorne's Silver Iris drivers or a 95db speaker based arond Fountek's NeoPro5i - all ideas I have kept for when I retire).