line array with full range drivers?

[leadbelly]

So I'm trying to come up with a line array design using one of the inexpensive FR drivers out there.

I've found some good threads and great links on the subject here, but not too much detail on FR drivers specifically.

So what should I be looking at for an enclosure type and design for FR drivers?

[Brendon]

Hi Leadbelly,

Probably not a good idea from a polar responce perspective. It's generally recommended that the center to center spacing between drivers be kept small enough that at the crossover point, the spacing is lower than the corresponding wavelength of the highest frequency that a driver is 'asked' to reproduce.

With a full range speaker, of course this would be ~20kHz. This is a very small wavelength and you couldn't find drivers small enough such that their center to center spacing is less than 13,500/20,000=0.675".

Jim Griffin has written a paper on line array design that you should look at. If you can't find reference here, check the Madisound forum or the fullrange driver forum at melhuish.org.


Brendon

[kelticwizard]

Brendon:

I checked the full range driver forum at melhish.org. Is this the Jim Griffin article, (actually, a lengthy post), that you were referring to?
http://f18.parsimony.net/forum31999/messages/39607.htm

If not, where can we find his article?

[leadbelly]

Thanks.

While I see that < 1.5" c2c spacing is the design goal for the tweeter portion, hence the use of ribbon tweeters, I understood the paper to acknowledge that < 1.5" spacing between the radiating surfaces of adjacent drivers is a viable compromise. It's mentioned in the section titled "What is the impact of gaps..."

Am I too optimistic?

[ryoshu]

http://www.prism.gatech.edu/~gte929u/LinusWP.pdf

That's the white paper. You want a 1.5" or less center to center spacing for your tweeters to avoid comb filtering in the higher frequency ranges. At least that's my take on it.

[leadbelly]

This is an excellent link on exactly what I was thinking:

http://www.partsexpress.com/projects.../Kuze3201.html

But since active eq is beyond the scope of what I was thinking of doing, I think I'm at a dead end.

[ryoshu]

Those are nice looking speakers, but he mentions the comb filtering is quite noticeable. Jim Griffin's paper is a very good read on line array theory that explains that.

If you search the PE message board for line arrays you'll find alot of discussion about them. I just ordered 32 of the $.90 drivers (instead of Tang Bands) from PE to start playing around with some line arrays. For ~$45 it is cheap enough to go wrong. The system is going to need a line of tweeters to avoid comb filtering though.

Your best bet is to probably try a 2 way design. Unless you know of a 1.5" driver that goes down to 100hz

[kelticwizard]

You might try downloading Vertical Polar Line Array program here:
http://www.pvconsultants.com/audio/frdgroup.htm

Maybe you can come up with a combo of drivers.

[leadbelly]

You got it, I'm now researching 2-way line arrays. I've seen some links, but so far no complete designs.

[jmiyake]

How much are you interested in spending?
How much speaker building experience do you have?