Advice on speaker placement an qty of KSubs

K, KW, and KLA Series loudspeakers

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  • Hello,

    I'm doing sound for a relatively odd outdoor venue and would like input on speaker placement for optimum coverage as well as a recommendation on the number of KSubs we should run.

    The current equipment on hand is/are two K12's,one KSub, and the Behringer XR18 wireless mixer.

    It's a 4 piece band, switching instruments throughout the show, consisting of electric drums, electric bass, lead electric guitar, Rhythm guitar (Electric/acoustic), nylon string guitar (electric/acoustic), and banjo (electric/acoustic). Music genres ranging from folk to classic rock.

    The venue is the back of a boat as a stage, the audience will be in their small dinghy's (boats) over an area of roughly 100' x 100'. I will be running the sound from about 50' off the stage and proposed main speaker mounting location.

    Image

    We're planning on mounting the K12's, one on each of the rear corners of the boat/stage, which would put them roughly 14' apart, about 5-6' above the audience, and maybe 8-10' from the closest audience members. With the K12's 75º coverage, would I get better/more even coverage if I cross fire them? What do you recommend?

    Also, we're looking for ample, however well balanced sound and it will get EQ's with a calibrated mic. How many KSubs will we need to keep up with the K12's outdoors without room reinforcement or boundary loading? 2? 4? Solid impactful kick from the electric drums, warm rich bass guitar... again not looking to overwhelm the k12's, just keep up with flat EQing. We haven't decided weather we'll be able to have the subs directly aimed at the audience, or if for practicality to just put them in with the band which would eliminate direct line of site.

    Kind of a preliminary plan, and by all means correct any errors and make recommendations... but if we can run 100db mid audience, 50' off stage, that should require 125db at 1m and put the front listeners at roughly 116db (maybe even a little less if they're cross fired). Is that too loud? Either for the speakers (noted the peak rating to be 131db) or the audience up front?

    Any help is greatly appreciated.
    SethU
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  • Is one of those boats depicted going to be the stage?

    It's easy for low frequency sound from a sub to get somewhat lost outdoors when there is no wall to reflect the sound waves. Subwoofers are largely omnidirectional, so much of the sound energy will be going in non-useful directions. Depending on how bass-heavy the music is, you might want to use more than one sub. I would suggest that if you use multiple subs, you group them together as close as possible so they act like one big sub.

    For the two K12 loudspeakers, I'd suggest that you run your system in mono, not stereo. If the audience is mostly centered between them, try aiming them slightly inward. If they're a little more spread out, aim them straight ahead. If the audience is arranged even more widely, splay the loudspeakers a little.
    Bob Lee
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    Bob Lee
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  • Thank you for the response Bob.

    Bob Lee wrote:Is one of those boats depicted going to be the stage?


    Yes, that is a picture of last years event. We expect twice the attendance this year. The pic got chopped off in the forum, here's another try. The "stage" is the power boat at the top.

    Image

    Here's a profile shot.

    Image

    Bob Lee wrote:It's easy for low frequency sound from a sub to get somewhat lost outdoors when there is no wall to reflect the sound waves. Subwoofers are largely omnidirectional, so much of the sound energy will be going in non-useful directions. Depending on how bass-heavy the music is, you might want to use more than one sub. I would suggest that if you use multiple subs, you group them together as close as possible so they act like one big sub.


    Some of the music is bass-forward (in the mix) and I'd like the electric kick to come through strong and concussive. However, I don't consider the songs to be bass-heavy compared to current pop and EDM.

    We currently have 1 KSub and intend on renting additional unit/s. How many do you suppose we need. I was thinking 4 might be optimal. However, there are transport and stowage concerns too. Would 2 KSubs be too few?

    Additionally, the bass player has a 4 x 10 SVT amp combo he'd love to use... I'm trying my best not to have him use it and DI everything through the FOH. Is this a mistake? At rehearsals, indoors, it's a pain in the butt (impossible at the level he's used to) to mix around it, especially since the song choices call for different presence of bass. If it would be more of an asset to the quality of FOH sound than a detriment, it is an option. What's your opinion?

    Bob Lee wrote:For the two K12 loudspeakers, I'd suggest that you run your system in mono, not stereo. If the audience is mostly centered between them, try aiming them slightly inward. If they're a little more spread out, aim them straight ahead. If the audience is arranged even more widely, splay the loudspeakers a little.


    Looking at the pictures from last year, I estimate the audience was 30' deep, 50' left, and 50'' right... 100' total width, pretty much right off the stage. 180º coverage would be optimal. The last option you mentioned, "splayed" makes the most sense. What angle do you recommend? If I splay them for 150º coverage, might there be a low spot up the middle? Something less than that I suppose.

    Would comb filtering eliminate cross firing as an option? I read somewhere that it becomes more of an issue at higher volumes. Whatever "higher" means...

    I appreciate your input and guidance Bob. Thank you.
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    SethU
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  • A couple additional things...

    It may also be an option to put the K12's on top of the boat too. Clustered and splayed, which may help with coverage.

    However, I'm not sure if feedback would be an issue with them essentially shooting over the mics. Thoughts?

    Image


    One other thing, there is a sheer cliff 150'-200' from the boat, that the sound will essentially be aimed at. It's not flat and the surface is not smooth. Whether sound is reflected or diffused is a point of debate. Just thought I'd mention it.
    SethU
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  • Having loudspeakers behind the mics could cause feedback if the mics pick up enough sound from them. You would have to be careful in how you set this up and use it.

    Cross-firing tops doesn't make sense, but aiming them inward so they cover the same area makes sense if that's where your audience is.

    There are many variables in your situation, and it's not possible to reliably predict how many subs you'll need. It would be good to base your decision on prior experience. Keep in mind a rule of thumb about the K12 and any other top loudspeaker you might use: You have to point them where you want the sound to cover. The K12 loudspeaker has about a 75-degree coverage angle.
    Bob Lee
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  • I'd aim the K12s inwards, maybe at quite an angle. They'd both be covering the area immediately in front of the stage, but each one would cover "out the other side", so people to the outside of the left speaker would hear more of the right speaker etc.

    I'd go 2 KSubs a side. Outdoors on the ground, I'd probably go one per side. Water is not the same as concrete - its almost like running your subs suspended in the air, which loses you 6dB immediately. To get that back, you'll need to double up the cabinets.

    FWIW, I always try to DI or mic any amps, and keep stage volume low. PA speakers have much wider dispersion than guitar amps, so everyone gets to hear everything, rather than the people standing in-line with the guitar amp getting hit by the laser-beam of destruction, and everyone else being unable to hear what's going on. Bass amps are a bit better for this, since lower frequencies are pretty omnidirectional. In order to keep control of the FOH mix, I'd ask them (politely, at least at first) to keep their amp at a sensible volume.

    Chris
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