Karaoke Forums

On the same idea that I am working towards doing some outdoor events, some ideas have popped into my head. One idea is building a speaker array, using 6 smaller full range speaker, most likely 12", put into a hexigon configuration. The speakers would be mounted or hung on a six sided bracket that would suspend them in the air about 8-9 feet. This would allow sound to go in all directions. Total weight of the array should not be more than 200 pounds.The speakers need to be smallish to be able to be handled easily. Passive speakers I think would be the way to go, with one amp .

I have 2 different questions for the techies in here. First question is what do you recommend for the speakers? I would like the cost of each speaker to be under $200, but might go slightly higher if warranted. The sound coming out of the array would have to be fairly loud, since it is outdoors, but clarity is the biggest factor. I am planning on putting this array on top of a scaffolding system which I have alreay built. Under the platform of the scaffold (on the ground actually) I am going to place 4 subwoofers, one pointed in each direction, inside the scaffolding area. The second question is, if I only use one amp to push this array, what power rating should I use for the 6 speaker? Lets say the speakers are rated for 400 watt each, what would the amp need to be? Also, using only one amp, would it be better to put the amp on mono and daisy chain all six speakers? or would it be better to split into the two sides, daisy chaining only 3 per side? or is there a better way that I don't know of.

Your suggestions are greatly appreciated.

Really good questions, mrscott!

First of all, expanding the coverage beam of your PA to be wider, 360 degrees in this case, is usually cheaper and easier than covering a deeper area; but it will still be easier to do, and sound better, with quality speakers that have good pattern control. I do not think you will be happy with any $200 boxes.

To hear an example of the reason why, take 2 speakers and place them side-by-side with no "splay," so they are both pointing the same direction. Send them the same signal and walk horizontally across the sound field. You will hear a harsh, audible effect at higher frequencies called "comb filtering" (see Wikipedia on comb filtering.) This is why you see very expensive speaker systems at large concerts instead of clusters of cheap speakers.

By changing the direction the speakers are aiming, you will change the amount of horizontal area affected by this, and eventually you may find a good balance between even volume and sound quality. Try it with three speakers and you will get a pretty good idea if the speakers you are using are practical for this, and determine how much area each box can cover, so you know if you need 4 or 6 or whatever to wrap around 360 degrees.

Note that there will also be a low-frequency cancellation effect with a circle of speakers. You may find that there is very little output below 300Hz (depending on the radius of the speaker circle and the speakers' directivity) if you stand further than a few feet away from it, and this will not be correctable with EQ. Don't try to fix it with EQ because the speakers will be working against each-other, and turning up the low-end power will only waste energy and add heat to the speakers.

With your subwoofers, you should not aim them in different directions. Subwoofers are almost omni-directional anyway, and so a normal cluster of subs all pointed the same way will basically work. They will fight some of the top speakers around the crossover point, and work with other ones, so there will be a little bit of bass steering as a result of this, and you will hear a bit more bass on one side of the circle than on the opposite side. But that is due to interactions with the top speakers, more so than the direction the subs are pointed. If you aim the subs in different directions, the sound field may become more even (and maybe this is desirable) but output will most likely go down dramatically. Instead of having a "power alley" or area with a lot of bass, you will have significantly less bass in all directions.

As far as the top speakers, if you use six 8 ohm cabinets, then three of them on each amplifier channel will present a 2.6 ohm load to the amp. Do not try to run six speakers off a single amplifier channel, and definitely not on a bridged amplifier channel, as the amp will be badly current-limited, clip easily, and be prone to over-heating.

If I had to do what you are describing, I would consider medium-quality wedges, such as the MRX512M, which costs about $500ea. Anything cheaper will probably not deliver a good "even coverage" to "comb filtering" balance no matter how many you buy to complete your circle.

Are you doing karaoke with this, or just DJing? Note that 360 degrees coverage means there is no area that is not being hit with a really loud PA signal, so no matter where the karaoke singers stand, it will be very important that they close-mic, and the microphones may require significant EQ to avoid feedback when there are no objects between the mics and the PA speakers. Due to the comb filtering, walking sideways across the coverage field may dramatically change the GBF.

The visual you are describing seems awesome and quick to deploy, but there are a number of practical problems to solve.

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Jeff Wheeler, moonlight DJ/KJ

Oh yeah, and note the MRX512M is NOT rated for flying, in fact, most cheap speakers aren't. So never let anyone stand under the speakers, even if you build a really great and safe mounting system. If one ever falls for any reason, and an injured person sues you, their ambulance-chasing personal-injury lawyer will find out that most cheap speakers have a big warning in the instructions that say NOT SUITABLE FOR FLYING, and you will lose your case and a ton of money.

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Jeff Wheeler, moonlight DJ/KJ

You have good ideas operating on a swap meet budget.

$200 a speaker??????? Your crazy!!! Ok that's $600 a side still not even close. We use a Non- Array Speaker as and array for Small bands. We use a tri-mount and put 3 QSC K-12's on each side. We use 4 Powered 18" subs to mach up.


With you budget the best you could do is buy a used set of a Better Dual 15" cabnet. or go Cheap and get 4 JBL JRX125's. I still suggest 2 dual 18" cabs under each side.

Jeff, thats pretty good information you are giving me. I do have some powered speakers that i can try you test with. I will give that a shot this weekend. The weight is a HUGE issue, so whatever I use for this array must be light. I have looked at some different speakers that only weigh about 33 pounds each, and this is in the range I am looking for. I do have other array options I can apply, so I am not stuck on this idea, but I agree that it would be simple to set up. I already have the scaffolding system and two of the subs, so I will be looking at all options.

No, it's not for karaoke application, not even DJ application, as such, but it will have music played at a medium decibel level. The vocal part, which is announcements by the host or other people, NEED to be heard clearly for longer distances, without blowing peoples ears that are near the main array and speakers. There will be satellite speakers placed at intervals away from the main area (see my other thread about wireless systems). This is for car show applications, so should always be in a park or parking lot situation. Great sound isn't an absolute, but clear vocals are. It would be nice however to achieve both great music and great clarity.

I know there is somebody on here that has done or currently provides sound for events like this, and I would be interested in hearing their point of view.

Thanks again
Scott

If you only needed announcements, paging horns would obviously be the easiest and cheapest solution to cover a huge area; but music with decent quality will take the kind of careful planning you are doing. Sounds like a really fun project.

35 pounds is certainly possible, in fact the MRX512M I mentioned weighs 33 pounds, and the Yamaha CM12V is around that, too. I would look for common wedge speakers that you might be able to rent when you need a lot of them.

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Jeff Wheeler, moonlight DJ/KJ

How important is the music quality in this situation. Most times you see something like that it is usually 70V horns. Now the problem is the frequency response of those horns is pretty narrow so music quality would suck. However to get that spread 360 degree coverage and the long throw you're talking about with serious vocal clarity, it is the best option. Otherwise, usually in a situation like that if you're going to use cone drivers, usually a perimeter system would be most common.

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DJ Tony
Let It Rip Karaoke

Sound is mildly important, but vocal clarity is more so. I know some of you will not like my own thought here, but I am considering the Behringer B212XL 12" passive speakers. They would not need to take a huge pounding from overpowering them, and with the addition of the subs below the array, I might be able to get something to sound decent. It is for car shows, honestly shouldn't have to be top of the line stuff for something as simple as that. I dunno tho, they might not even have the capability of doing what I want to do. What Jeff was trying to describe, "comb filtering", I might need to do something totally different altogether for an array. But these speakers do fall in the right price, the right weight and are flyable. I will toy with this idea some more.

It is possible instead of doing a six sided array, to just put one speaker in each corner of my scaffolding system, pointing in opposite directions. Would be simple to do as well, just not as cool looking . I plan to use some main speakers just outside the entire scaffolding/sub/array system about twenty to thirty feet in each way. As soon as I figure out what I am going to use, how to put it together, I will set it up in my front yard (poor neighbors) and see exactly what it sounds like before I put it into application.

If the Behringers don't cut it, then I will look at others as well. But back to one of the first questions I had, using these 4 or six speakers, am I understanding it correctly, that I should use both sides of the amp and split the signal to a balanced amount of speaker on each side? or daisy chaining them all on mono would not be good on the amp? right? I haven't decided on the amp yet. It will all depend on the speakers I get and the configuration I put them in.

Again, thanks for all you input! Very useful info and much appreciated.

How much power are you going to feed them? The Peavey PR-10 might be an option. They are light (18pounds), push OK with 200-400w, and are $149 apiece.

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[color=#ffff55]Mickey J.[/color]
Alas for those who never sing, but die with all their music in them.
-- Oliver Wendell Holmes, Sr.

mckyj57, I would consider those Peavey as well. I'm not a big Peavey fan at all, and those Behringers might be undesirable too, but both are worth a look.

I think they sound surprisingly good, but you had said it was really speech work and I think they are fine for that. They aren't the most efficient speaker, though, and want some power.

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[color=#ffff55]Mickey J.[/color]
Alas for those who never sing, but die with all their music in them.
-- Oliver Wendell Holmes, Sr.

The issue with cheaper speakers will be pattern control. It's likely that the "array" will sound pretty bad up close but "smooth out" as you step further away, and that is probably fine for an application like this. There are always compromises when doing audio like this, and you just have to balance cost and complexity with coverage area and volume in a way that will make your customers happy and stay within their budget.

As far as amplifiers go, bridging an amp is often a good idea when you have one or two high-powered speakers and a low-powered amp than is able to do 4Ω bridged, which is essentially the same as 2Ω per channel.

In your case, you have several low-powered speakers, so you are better off keeping the channels separate. The 212XL is a 200w RMS 8Ω speaker, and two to four of them per channel of an EP2500/EP4000 or EPX3000 should work fine. If you find yourself driving the amplifiers into clipping, reduce the number of speakers per channel.

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Jeff Wheeler, moonlight DJ/KJ