Subwoofer Placement in Large Room (30x50x14)

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I am about to purchase 4 18" subwoofers for my shop stereo. They will be powered by 2 iNuke NU6000DSP amplifiers. My high end consists of 4 Pioneer SP-FS52 Andrew Jones Designed Floor standing Loudspeakers powered by a single iNuke NU4-6000. My question is, hopefully, a simple one.

I read the white paper by Harman, and most of it was over my head... by a lot. However, I am smart enough to understand the conclusion, either put them directly across from each other centered on walls, or in the corners facing each other.

Being that my room is so long, I was curious what everyone thinks would be better

A. Have the subwoofers facing each other with 50 ft between them

B. Have the subwoofers facing each other with 30 ft between them
 
50 feet, as that is about 2 times the wavelength of the lowest frequency playing. But I would chose the short side of a room instead of the long side to set up your audio. (frontwall reflections)
This is no longer a small room (Geddes), but if you play low volumes it will work and will spread the bass evenly.
At higher volumes I recommend this:
Corners and the back wall are prefered locations to get the least reflections (tight bass). As a first try I would put them all against the back (short) wall, one sub 1 foot from a corner next one 3 feet in between the subs, 3rd one 3 feet/phi (1.61 golden ratio) 1.86 foot from the 2nd sub and 1.86/phi = 1.15 feet in between sub 3 and 4.
As it is best to place drivers within 1/4 of the wavelenght of further then 2x wavelenght of frequencies being played. Then they couple well (play together) or are not playing against each other.
The phi number is the best to use because those distances are not multiples of each other. Often is putting them symetrical left and right the worst thing to do.
 
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Thanks for all the help! A lot of it is over my head, I'll have to read it a few times and see if it sinks in. I'm not sure if I'll be able to move the speakers to test them in multiple locations, they will be very large and heavy boxes.

Keep ideas and information coming if you have more! I've got some time before I build everything, hope to have it designed perfectly.
 
Thanks for all the help! A lot of it is over my head, I'll have to read it a few times and see if it sinks in. I'm not sure if I'll be able to move the speakers to test them in multiple locations, they will be very large and heavy boxes.

Keep ideas and information coming if you have more! I've got some time before I build everything, hope to have it designed perfectly.
You don't have to move large speakers, you can do location testing with your full range speakers:
Reciprocity Theorem in practice

Your mains speakers are only capable of around 107 dB at one meter, 4) 18" may be overkill depending on what SPL you like to listen to, and the program material.

For a shop set up where you are likely going to be listening from a variety of locations, I'd suggest flying your main speakers to reduce the inverse distance level variations (and sound obstruction by cars, etc.) experienced if you "floor stand" them.

Depending on the crossover frequency you decide upon, you may also want to co-locate the mains and subs once you determine the best locations.

Stay warm, have fun!
Art
 
I'm going to agree with Walter on one point... four 18" subs are going to be overkill and will create some new problems for you like audible structure vibrations, and disagree with the Geddes approach to speaker distribution. I think this approach produces much lower inteligibility as it focuses more on consistent sound levels throughout the listening area much like big scale audio production does these days by using as much soundwave interference(constructive and desctructive) as possible. IMO a single point source or cluster works better in larger rooms, it sounds more natural to have the sound level drop off as you get further away from the source and inteligibility is higher. I do audio production in a wide range of room sizes from relatively small community centers to large conference and banquet centers and spreading speakers out never sounds better.
 
Conanski,
It may sound more natural to have the sound level drop as I get further away from the source, but I'm more concerned with consistant sound despite where I am. I have the shop set up as 3 stalls, so I may be in, literally, every square yard at one point or another throughout the work day. If I have everything set up equally, then I don't have to constantly adjust volume depending on where I am at, and I bounce around a lot. I may be adding filler on a car, then blocking a different one while filler dries, then tearing apart an engine in another corner... I really move around. That's what's killing me right now, in my center stall it's dead, you almost can't tell there is 2 12" subwoofers with roughly 2000 watts rms each. Go south a stall, and it shakes your clothing.

I understand that the 18's are overkill, but honestly I adjust my subwoofers per what music I'm listening to. Sometimes I just want to feel the bass shake me, probably going to be rap and I don't really care if I hear the lyrics because, mostly, they leave a bit to be desired anyways. If I'm listening to rock, the subwoofers will be turned down a bit, although often the bass isn't nearly as overwhelming with rock anyways. Sometimes I chill out and listen to calmer music.... well, you get the idea.

Structural vibrations... yes, I will have some of those, but since the building is concrete block and most things are bolted down near the walls, I haven't had too many issues, aside from occasionally shaking something off a place it probably shouldn't have been set anyways.

Maybe I'm misinterpreting your reply, if so feel free to straighten me out.

Flying the speakers does make sense, I have 2 up quite high as it is, but the other 2 are floor standing. I have to work around 2 large garage doors on the 30' sides, but otherwise I have some room to hang. The subwoofers are currently hanging about 8 ft up, mounted to a concrete support pillar, but the 18s will probably end up floor mounted as they are going to be obscenely heavy, and anchoring to a concrete floor should keep them from inducing vibrations into other objects.

I should mention that in the future, I do plan on studding and spray foaming the entirety of the room. That's when the placement will probably be finalized. It would be nice to have it figured out ahead of time.
 
I have the shop set up as 3 stalls,
Are those stalls separated by walls or is it still one big space? If you have separate "rooms" you may want to consider separate speaker systems for each stall.. all fed by the same source.


That's what's killing me right now, in my center stall it's dead, you almost can't tell there is 2 12" subwoofers with roughly 2000 watts rms each. Go south a stall, and it shakes your clothing.
That is a perfect example of the sound cancellations that happen in large rooms, so guess what.. you install 18" subs in the same locations and you will still have the same problem. If that happens then you will have to explore other placement options, nobody can say for sure what will work best but you definitely should experiment with a few options including a center cluster.. subs on the floor, mains suspended overhead.
 
The stalls are open, so that isn't an issue. Currently the subwoofers are 1/3 the way on the same 50 foot wall facing the opposite 50 ft wall. So 15ft from the 30 ft wall and 15 feet between each other. The 18s will, maybe, go in each of the 4 corners, possibly facing each other with 50 ft between them.

Lot of maybes, still planning and learning!
 
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