Greetings speaker Gods (and Goddesses?),

I'm Keith from Cincinnati, Ohio. My guess is that I know enough to be dangerous and am ignorant enough to irritate. I'll try to limit both.

A small group of musician friends and I (I'm enough of a musician to recognize a good one when I hear one) have begun hosting very small music festivals. As I am the music tech geek of us, I have been tasked with the venue's PA (and DMX lighting as I was a professional photog for many years). The venue is a psuedo outdoor teepee. Imagine a 30 foot diameter teepee frame, half covered or skinned with metal roof sheets. It makes for kind of an amphitheater effect and has a very cool vibe for live shows. I'm sure the sheet metal could be improved upon greatly, however this parameter is outside my scope of influence. The open side of the teepee looks out on a "yard" that gently slopes up and measures about 30' wide and 60' to 70' long. Musical styles range from Blue Grass to Blues to Cowboy Junkies to James Gang type stuff. I'm not trying to push hip hop or Dub step. Volume level usually falls to where I need to mic the kick (and sometimes the snare a bit) of the drum kit but the cymbals mix well without amplification.

I'm currently using plastic speakers in my rig. (I know, I know. But that's why I'm here.) I have 2 used EV Sx200s and 2 of the matching "bass modules" (EV can't even get themselves to call them subs) the Sb120s. I also have 2 more Sx200s with blown HF drivers someone recently gifted me. I do not care for the standard pole mounted cabs on either side of the stage. I have been flying the whole rig in a poor man's single point set up directly over center stage. Well, as close to single point as I can create so far.

I've always been a tinkerer (even have a patent for one idea) and I'm way too obsessive to leave well enough alone. That is what brings me here.

Ideally I would like (or think I would anyway) a single point speaker that can cover 120 degrees to 180 degrees. Distance is not as important. Flying a home brew will be safe as one of our group is an engineer with professional rigging experience.

So, has anyone come up with a sphere that can expand and contract at a rate of 20-20k times a sec.? No? Oh well...

Thoughts?

As the frequency rises, the dispersion becomes more narrow, so getting a single speaker to do hi mids and treble at 180 degrees is not really going to happen unless there are multiple HF horns arranged to your desired coverage. The best bet would be to have multiple mid top speakers splayed so that they cover the area appropriately. The bass should be pretty much omnidirectional-ish.

Thanks for the quick reply. I would very much like to read up on directivity, especially where it relates to frequency and reflectability. Any good reading you might suggest?

Is there ever a situation where a HF driver, fired upward at an upside-down conical reflector, is appropriate?

Also, I recently read about a slot loaded, open back design. Can a slot load design be enclosed and still work?

I would never recommend using room reflection as a method of delivering high frequencies. Your suggestion would get some sound splashing around, but it would have no definition, would be full of cancellations and nodes, really distorted and out of timing with the speakers you can hear directly. I don't even like my high frequencies to hit the back wall and reflect back. I place my tops at about 7 feet, try to angle my high frequencies down toward head height near the middle of the room. Proper HF drivers and horn combos are always more efficient than the cone drivers anyhow. It will not take much before the treble has to be turned down in order for the rest of the system to keep up. People do use corner loading and reflection to get more out of their subs sometimes, but I would not do that for anything over like 150 hz personally.

As for reading, I would just recommend doing a search for the terms you wish to understand better. DIY forums are often a wealth of knowledge. There are several white papers on speaker building and theory. You can really geek out on it all, but having done that myself, I think it is more efficient to follow your own custom trail and experiment as you go or the theories will mean nothing when you read them. Here is some basic PA theory for starters. here

Right. I wouldn't want to use the room either. I was thinking of some outdoor speakers I've seen that fire a "full range" speaker immediately into a reflector that looks like an upside-down Hershey Kiss or a kind of curved cone with the point right at the speaker.

So, all of my audio experience has been in my own recording studio. There, I have grown to hear the comb filtering induced be multiple transducers. Now, tasked with providing sound reinforcement for an outside venue, I am probably too fixated on creating as close to a single point source speaker as I can. When I hang a speaker above the front center of the stage, I get the sound I'm looking for (given the speakers I currently have). I need about 120 degree of dispersion to cover the audience. The best I've achieved so far is placing my 2 EV Sx200 speakers next to each other and splay them out away from each other. What kind of HF dispersion can be obtained with a HF driver fired through the center of a coaxial? I'm thinking maybe an enclosure with two 10" coaxials firing 60 degrees from each other (or 3 at a lesser angle if needed). Could this be made to cover the desired 120 degrees? I really dislike that the center line of the audience area is THE area the gets the multi speaker effect, though. BTW, I haven't mentioned the subwoofer as I'm not as anal about its proximity.

How would you approach this?

Am I worried too much about this? Flying the speakers in mono above the stage has amazed everyone else involved with the production. They are shocked at how much better the rig sounds in mono than it did in stereo, on stands at the sides of the stage. Should I leave well enough alone and learn to live with it?

This leads me to another question... Isn't the entire benefit of a line array compromised when two arrays are used and placed on either side of the stage?

Alright, I'll stop now.

Thanks for helping me wrap my head around the challenges of sound reinforcement. The studio is a different animal for sure.

Take care, Keith