Line array for complete dribbling idiots

[pritch]

Can someone explain what line array is, please? I've found mentions of it on the BR and on websites further afield, but they all assume that I have sort of idea about sound in the first place, which I don't really.

 

I'm well aware that it's the sort of thing I'm never going to encounter up close in my life ever (unless my career plans change dramatically), so just a quick two liner will be fine, I'm just curious!

[Simon Lyall]

Can someone explain what line array is, please? I've found mentions of it on the BR and on websites further afield, but they all assume that I have sort of idea about sound in the first place, which I don't really.

 

I'm well aware that it's the sort of thing I'm never going to encounter up close in my life ever (unless my career plans change dramatically), so just a quick two liner will be fine, I'm just curious!

 

 

sticking line array into google images gives this:

 

line array thingy

 

I always think that pictures speak a thousand words!

 

its basically a set of flown speakers, I could probably go into more detail, but perhaps thats all you want to know, and someone with far better knowledge will give you better details and I can save anyone that hassle of having to correct any mistakes of what I think one is!

 

 

Simon

[Bobbsy]

OT aside: Does the rigging in the link above look dodgy to anyone else? Rigging and flying speakers is not my area of expertise, but using webbing straps wrapped around a relatively sharp-edged metal fork doesn't strike me as good practice.

 

Anyway, line arrays:

 

By definition, a line array is a group of sound-radiating devices that have been arrayed, or “stacked up” in the vertical plane. The individual boxes use a mixture of techniques including constructive and destructive interference at low and mid frequencies and (usually) wave guides coupled to compression drivers at higher frequencies to achieve extremely directional patterns of coverage, allowing them to be aimed at specific parts of an auditorium to achieve (in theory at least) very even coverage without the use of extra delayed speakers. This makes them particularly suitable where long throws are required.

 

THIS PAPER on the Meyer site gives as clear an explanation of line array theory as I've found. Another reference that might be useful is this AES Paper. Get ready for some detailed reading!

 

Bob

[StevieR]

Line array...

 

Essentially, an alternative approach to a cluster for larger events utilitising the 'coupling' effects of multiple cabinets to produce a single source which has a wide horizontal dispersion with a variable vertical dispersion based on the number/alignment of the cabinets used. Normally employed in venues with a wide horizontal coverage and a combination of short to long-throw requirements.

 

Steve

[jim b]

Depending on the level of your maths/physics knowledge or comfort going to pretty much any advanced book about fields (electrostatics, fluid dynamics, acoustics) and finding the section on line sources will give you the mathematical knowledge for a theoretical version. These theoretical workings are obviously not accomplishable in real life (trucking an infinite line of speakers does tend to blow the budget somewhat) but designs derived from these principles do have many advantages. WARNING this does involve calculus.

 

Bobbsy rightly points out the real life compromises. Most major line array companies have some form of document about how they arrived at their design and what compromises this entails. Meyer, Martin, L'Acoustics all have at least a general description.

 

Hope this was useful to you.

 

Jim

[Rob_Beech]

Sadly a 2 line response isn't going to sum anything up, no matter how long the lines are.

 

<pedant>

a line array doesn't have to be flown

</pedant>

 

Bobbsy has covered the basics of it, and the documents he's linked to will give you ALOT more information, its very technical stuff and is much more than sticking speakers together, although the result of some I've heard recently I think that is all they did.

 

more and more manufacturers are making a line array nowadays, IMO this is often just a WE CAN DO THIS TOO thing and some of the "cheap" ones are really not worth wasting the time and effort on. Certain manufacturers are well known for their line arrays more than anything else, such as L'acoustic. Martin Audio's W8L cabinets are also very popular, particularly the new W8L Longbow which IMO is an absolutely stunning box. Martin also do 2 more Line arrays, a slightly more compact version and a mini version. Sadly the mini version is competing against D&B's offering of the Q1 which is a fantastic system.

 

SFL Group in Reading do a training day on Line Array theory, I have been to this and it is a very good course indeed (as are all of the offerings from SFL). It does help to have a good understanding of sound as its not a course that starts at the most basic level. PM Mark Payne or check the SFL website.

 

 

Rob

 

 

Edit : another couple of good posts whilst I was typing, although that doesn't change anything.

 

2nd edit : Yes Bobbsy, there's no doubt about it, it looks dodgy to me too. Fancy taking them to each gig with you, with their maximum speed you'd have to set off 4 days before :D

[pritch]

Cheers, all! As I said, I'm never actually going to encounter one in the flesh (overkill for a 100 seat amateur theatre, I think), I've just seen mention of them and wondered what that was all about.

 

That should stop me feeling quite so confused next time I encounter the term.

[paulears]

Well, actually, you have seen one - in fact you've probably seen hundreds. Those long thin column speaker cabinets found in churches, factories, railways stations. Line source loudspeaker columns. The main reason for their popularity was the fact the dispersion was very wide, and quiite flat, vertically. Just a product of lots of conical radiators in a row. Some were a bit clever - reducing the power to the top and bottom units in an attempt to control the beam even more. They got kind of tarnished because in general, they were being used for speech, and could use smaller and smaller drivers, making them physically very narrow - great for hiding away - but pretty bad at reproducing bass! Then in the '70s, along came people like Watkins (WEM) who stuck 10 and 12 inch drivers in a bigger box, ran them from a 100 (or 40) Watt amp and bands loved 'em. Then they stuck in a horn and introduced people to HF, horrid though it was. These columns were big and heavy, so they did smaller versions, with just 2 drivers and a horn. Then more appeared with just a single driver and horn. Nobody seemed to notice the dispersion pattern from the single driver had gone back to wide and tall - the column advantage simply vanishing. Nobody seemed to notice. Then the big PA players suddenlt re-remembered columns, re-remembered the 'line source' tag, and realised that they could sell smallish boxes, that when connected together and flown above, could produce wide and flat dispersion patterns. Fair enough, they also introduced variable coupling between the cabs with fancy brackets - but what they've done is re-invent the column. Much cleverer, better sounding, vastly more expensive - but a column! No doubt all their patents are valid, especially with the rather clever ways they've found to squeeze in massive power handling and wide frequency response - but it isn't really a new idea. I suppose a pile of them, ground mounted, do give the game away a bit!

 

It just occured to me that you could do great things with Tannoy dual-concentric drivers? Speaker plans for these don't need to be that complicated to get good results, the boxes would be fairly compact, and you could stack them up into a array fairly easily. 10" would make a sensible size, and still handle a reasonable amount of power. Perhaps a little too expensive to experiment with?

[Simon Lewis]

Do bear in mind that for a vertical array, the horizontal pattern is not affected by the number of elements in the array.

 

Furthermore, although the horizontal dispersion is considered to be "wide" it also frequency dependant. The larger coned column loudspeakers simply beamed and lobed, offering very poor directivity control in the mid to high frequencies.

 

Lastly, the distance to the border condition where the change from line source to point source behaviour occurs is also frequency dependant.

[Seano]

OT aside: Does the rigging in the link above look dodgy to anyone else?

 

Yep. It's not *desperately* dangerous, though I certainly wouldn't want to see that at a gig.

As an advert for the company, what it says to me (rightly or wrongly) is "We've got some nice kit, but we can't be trusted to rig it safely in unusual circumstances." Not so much because of the way its been done, but because it could have been much better without any additional kit.

[dan slv-tech]

Hi

 

With regards to the pic that people are dubious about, this was a system on demo to synergy audio, the system was the axiom line array and it was the 1st system in the UK that was actually purchased by synergy- great system by all acounts, and im reliably informed the fork lifts were just to raise the system up

 

 

 

Dan

[Animal]

Can someone explain what line array is, please? I've found mentions of it on the BR and on websites further afield, but they all assume that I have sort of idea about sound in the first place, which I don't really.

 

I'm well aware that it's the sort of thing I'm never going to encounter up close in my life ever (unless my career plans change dramatically), so just a quick two liner will be fine, I'm just curious!

 

 

Line array = Choice of the fashion victims.

 

See link - Click on 'Extremists Perspective'

 

Moderation: not quite sure what this means, but maybe this link is better - relates to line v spherical, or did I miss some kind of irony?

[Rob_Beech]

An interesting read.

 

Not sure about their inefficiency, with some mid and hi sections having a sensitivity of 120+db 1w/1m. But I see the overall point made.

 

Rob

[Chris Hinds]

It is interesting that the main detraction from Line Arrays comes from companies that don't have them in their product range i.e. Turbo and Funktion One. Mind you I should admit that F1 and me aren't very sonically compatible anyway.

 

I would suggest anyone who is looking for some more advanced reasoning should read Bob McCarthy's Sound Systems: Design and Optimization. In that he makes the case for both the Point Source and the Line Source array and explains how a true line array does not exist at all frequencies. The nature of what is used is more of a switch from the horizontal array to the vertical, shifting the plane of comb filtering to a perspective we are less sensitive. It's well worth the read anyway.

 

Regards

 

Chris

[andyc]

To break it town it to really simple terms, you need to realise what an array is. Basically it is a collection of objects grouped together in a regular order.

Here is an array of the number 1.

 

1 1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1 1

 

Thats an array!

Then you have different types of arrays! Radial / Horizontal / vertical

As the names suggest radial would be an array in a circular pattern, vertical in a vertical pattern, and I probably think you've guessed the last one!!

 

So what is a line array, simply put it is an array of objects in a line!

And in sound terms, a line array, is an array of speakers arranged in a vertical line!

 

 

Here is a very simple drawing of a side view of a line array! (Yes I know it looks dodgey! ** laughs out loud **)

http://www.andy-coates.com/misc/simple-array.jpg

This line array is made up of 4 elements (speakers) and each element has a very narrow throw, so each element can "cover" each part of the audience, E.G. 1 covers front of stage, 2 covers next section (more power needed) 3 covers next section (more power needed) and 4 covers the back audience section (even more power needed to cover the long throw!)

 

This is the very basic opperation of a line array, each element can cover a different section/zone of the audence with (hopefully) seemles intergration between zones! Meaning you cant tel the difference when you walk out of the path of one element and into the path of the other!!

 

Hope that helps!!

 

P.S..the rigging looks ok, theres quite a radius on tele-handelers forks plus thats probably only holding under 1.5 ton. Though without seeing a closer pic its hard to tell!!

 

 

Andy