Line array information

A friend of mine is thinking about getting a V-DOSC line array after christmas and has asked me if i want to help him run it. Thing is, as i've been a point source man all my life i've not had any need or want to look into the basic fundamentals of the design and how to, in theory of course, set up an ''X amount'' of box hang using the correct splay angles on the boxes etc.

Does anyone know of any online literature i can get stuck into to at least give me a heads up on what seems quite a fun project?

I see L-acoustics do a training course but i've emailed them and they said v-dosc owners get priority and at the moment all there are alot of companys who already own the equipment sending their tech guys through, so i'm going to have to wait until my friend enters the buying process at the beginning of next year

thanks in advance

Here ya go....

http://yu-ra.tripod.com/array.htm#advantages

http://www.prosoundweb.com/sr/tech_corner/

http://www.jblpro.com/vertec1/VerTec%20WP%202.3.pdf

http://mixonline.com/mag/audio_truth_loudspeaker_arrays_2/

http://mixonline.com/mag/audio_truth_loudspeaker_arrays/

http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/auditcon.html

have fun!

.p.

Dave Rat ( www.ratsound.com ) has loads of nice info on the sub bass setup they use with the Chilipeppers.. On top of that, he definately knows his stuff when it comes to V-Dosc etc. and is usually happy to answer any questions that might pop up:

Thanks everyone, that lots gonna keep me busy for the time being.

Its all well and good having the pc programs but its reassuring knowing whats actually going on in the array, its a bit like sat nav, just follow the pictures on the screen and get to your destination but you always have an air of disorientation to you about where exactly you are (if you know what i mean)

been reading the threads about Cardiod bass arrays but am still learning, got along way to go with that one

thanks again

i ain't selling my void kit pete, thats my toy

only reason i put my stasys 3 up for sale was because i wanted to replace them with the latest version of the cab with the stacking point feet on the bottom that will locate into the top of the X and the new syko rig 

vanity was also playing a part in it too mind

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Jody,

is there a copy of Danley's article on the web?

Rambling mode on.

Given that I have read where Danley states that he is a designer not a mathematician I'm surprised he has made such a comment. OK I'm not that surprised because he has a none line array product to sell and, based on word in the discussion boards, the major selling point is the fact that the products are designed by Danley, who is a genius, rather than on the merit of the product. I'll come back to this later.

Although I've not read the article, I am guessing that he stated that except for at zero distance or infinity the listener will be a different distance from each source and the signal will be time smeared between closest and most distant source. At zero distance you would only hear a single element of the array and at infinity you would be equal distance from each element. Theoretically they are only the two places where there would be no time smearing. The fact that this is theoretically true is irrelevant. The main concern is, when does it become objectionable to the human ear? Also in reverberant environments how do you distinguish which is the time smear caused by the room?

One could argue that all compression drivers are rubbish because they can't reproduce 30KHz. While the fact is true it is not really relevant. Most people can't hear that high and when I've done a spectral analysis of the signal coming out of the mixer (live band situation) the amount of signal above 10KHz was negligible.

If you consider a conventional array – none of them are point sources because a point source is small relative to the wavelength produced and radiates omni-directionally, not large and highly directive- and if you are in a situation where one cabinet is not loud enough what do you do? If the advertising is to believed the answer is nothing. One of the selling points of conventional arrays is that the cabinets integrate with no overlap, eliminating comb-filtering effects and a time smeared signal. If there is no overlap the maximum SPL any point is limited by the capability of an individual cabinet.

This is easy to try. Set up two cabinets side by side as you would for one normal stack. Power them from the left and right channels and stand in front of one of the cabinets. Turn up the volume and listen. Now turn up the other channel. If you hear any change in level or tone then the output from each cabinet is combining and you will get comb-filtering and time smear. If you can't hear any difference, then why didn't the team at Glastonbury just turn down the offending cabinet that was pointing in the direction of the complainers rather than the whole rig.

Yes I am aware of all the ifs and buts. Even in practical acoustic theory a lot of assumptions are made. In real life large quantities of salt are required. My comments about Glastonbury are also based on what I have read so I don't make any authoritative claims about that. I just used the problem as an example.

I briefly mentioned promoting products by association with their designer. This in my opinion bad for the advancement of design. The main problem is that it is turning engineering into a religion or belief system. Any criticism, constructive or not, about the product becomes a criticism of the person rather than the product. I used to post on a discussion board run by a gentleman who sells speaker plans for a modest sum. I gave up because even when quoting standard acoustic text, if it didn't agree with the opinion of the plan originator then it was heresy and I'd get loads of abusive mail.

From his personal posts at places like Audio Asylum, Mr Danley comes across as a knowledgeable person who is generous at sharing his knowledge with others. That he comes up with some nifty designs does not make him some sort of genius or god like person. < ="-" ="text/; =utf-8"> < name="GENERATOR" ="Office.org 2.4 Linux"> < ="text/"> Engineering solutions always have compromises. The compromises that any particular designer makes depends on their view of the problem. No doubt if they made themselves more visible the designers at JBL would come across as quite knowledgeable too.

Consider the recent furore over the tapped horn. Have a look at the picture below and note the date that the patent was granted. Hopefully it will require no comment.

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Apologies for the topic swerve. To bring it back slightly, why does everyone assume that it is mandatory to fly line arrays? In large scale settings both line and conventional arrays are flown. In both cases it improves coverage and sight lines. In fact if the advertising claims about conventional arrays are true, they are less scalable than line arrays. The number of cabinets required is dictated simply by the coverage angle.

p.s. when I preview the post a couple of lines of code appear. I'm not sure if it will show up when I finally post, but I can't get rid of it so please ignore