FSP-ARRAY

Deadbeat, The MX system was calculated with the help of Mick Nash, who was MAN Flying Systems. He told me how the balance should be in free fall so that it would behave itself when flown and kelped back to the shape reqiured. The transformer system that it flew on, was the most elaborate system ever designed. All that changed when line array hit us. He never got involved in that, and neither did I.
All the flying components were engineered superbly, Mick and I were toolmakers together in a former life, so the ideas used to roll.

jsg,

I've also seen very short lines as well. I think that dB tech even encourage the use of 3 LA cabs actually, I found this gem on their website:


Note the curvature of the array, they recommend this is smaller groupings.
Anyway, less talk about LA, I'll make a new thread bout it.

From my limited knowledge of line array theory:

At the end of the day, you'll get noise out of a short line array and in the size of venue it's likely to be used, it'll probably sound fine. The drivers will all couple well, because they're configured as designed. However, you won't get proper pattern control at lower frequencies, since the line has to be a given length to achieve this. I can't find the figure at the moment - it's either 1 wavelength or 1/2 a wavelength. If I find/remember it, I'll edit this post!

Do we need a FSP-LINE ARRAY?

Sounds like an interesting project. I wouldn't build one personally, but still a great exercise.

What are your thoughts on using this section i designed as a as a 'lower mid'? You should get a bit of directivity at the higher end of it's playing range. I think a point source upper mid/top above this would make for a very nice 3-way cab.

www.speakerplans.com/forum/forum_posts.asp?TID=15864

I was experimenting with a trapezoid profile, but by going for something with parallel sides you could get rid of the awkward 'bulge'. (although a conical horn would still sit quite nicely above it)

Hi tommy,

That's a really nice response! (Well apart from the obvious peak...but better than a lot!)

How did it sound though? I've come to the conclusion that having an extended unity horn above tapped horns (a la the Synergy) would sound better than tapped horns playing up to a conical?

However, you won't get proper pattern control at lower frequencies, since the line has to be a given length to achieve this. I can't find the figure at the moment - it's either 1 wavelength or 1/2 a wavelength. If I find/remember it, I'll edit this post!

Its not pattern control, its the ability to function as a line rather than a point source (e.g. -3db per doubling rather than -6db per doubling)

Was looking at the D&B J system at the weekend and was with the system tech who was showing me the software. They have compensation for different length hangs at the frequency where it becomes line source.

Now I look at heathrow's original criteria:

Fully Hornloaded
Compact
70-250 khz
Long Throw

I see... a 15+10+1

The 10 would be on a straight horn no doubt, I think we can take a cue from the EAW KF850 and bung the compression driver in as a phase plug for added compactness.

The bass end could be a BPH or a short straight horn.

The cab would be trapezoidal.

After that, we can start considering the flying hardware, I know there's at least one engineer on this forum.

The compression driver really is the clue to designing a correctly operating LA. Its no use just bunging in any old waveguide just "to do". It needs to play pretty low and also be capable of very high SPL's. Obviously dispersion (usually around 120 x 10 degrees) is also of paramount importance.

IMO one of the reasons that they can sound so good is purely down to the fact that the upper bass/mid drivers are very often pretty small ( 5" - 10") and also of excellent quality. Putting in any design of band pass horn that also does lower mid would probably seriously compromise overall quality.

The hardware design is actually pretty simple and with the availability of inexpensive Laser profiles can be made to look very professional.

Tony

You know its funny but looking at forums where there are selections of line arrayable tops and regular hornloaded tops on offer, such as the Bill Fitzmaurice one, he has these fancy 2 way line arrayableish boxes called DR horns with built in splay angles and everything - but what are people building and using the most - Omnitop 12s!

Simple 2 way boxes, rectangular, no awkward trap or splay angles, horn loaded 12", ported rear chamber, melded Piezo array - I think its the most built box for PA over there recently. You can stack them 5-6 boxes high without scaffold if they are strapped together.

Obviously they wont go to 70Hz but a pair seem to cross over at 100Hz with no ill effects. I am sure DJK will come and post his burning 4560 picture now but nevertheless still a useful and popular box that you can use everyday.

Just a thought before you go trying to get a horn loaded 15" to get to 70Hz - I think Rosso Pico probably had the best idea there already, and look how big it is!!!

Stu