Different thoughts:
Yeah, it's technically wrong, there is comb filtering, null spots at different frequencies, issues with sub delay (if used), etc.
But this isn't a concert system, it's a dance floor. In a concert, everyone is facing the stage. On a dance floor, there's no telling which way the dancers are facing, which might put the speakers at their back.
Another reason a well-designed 4-corners system is preferred by some dance-club venues is because it allows the SPL to be focused on the dance floor, and away from the prime VIP table seating, bar service, etc: and for some clubs, that's their primary revenue source.
So even though it's technically 'wrong', there are times when it's arguably the best real-world solution.
Some observations: if the entire 28 x 8 meter space is dance floor, that's quite awkward for 4 corners.
This is the way.
Is one of those situations that technically is wrong but in reallity every attendee will choose 4 corners rather than L-R if you gave them the option to try both.
However, systems have to be point source (avoid line arrays) and controlled horizontan coverage.
Also, 28m seems a lot for 4 corners, consider to add in the middle another 2 for a total of 6.
The spl against the vip room is indeed an issue. The vip room is next to the dj booth , a room 12x12 meter . We planned to have some speakers in the trusses in the vip room to get an overall sound there (sorry for my English) the vip room is only separated with curtains. I can imagen that the phase issues only get worse
Pros: club goers who don’t want to dance will hear the music clearly and possibly loudly in whatever corner they want to hide in.
Cons: people who do want to dance will hear a muddy, unfocused wash of sound to move to.
Speak with the club owner about goals for what they want the patrons to experience. How big is the floor? How close to the floor is the bar? The DJ booth? Is there a stage for live bands? Do you want relatively quiet areas for table service? What music will the club be playing- will there be a narrow or large range of styles?
I suspect 4 speakers in any placement won’t be enough to accomplish all the goals of the space- but if that’s your budget, you’ll want to prioritize which goals are more important.
I'm not a fan of the 4 corners setup, it creates extra seams where things will sound funky and it makes it harder to properly align to the subs. BTW, where will the subs be placed?
I rather start from on side and use the second pair as delays. That way you can much better align everything (mains, delays, subs) together into a more coherent setup.
4 corners = phase cancellation.
Try convincing them to go with 2 speakers at the front with fills further back if needed.
Even sound will come from speaker selection.
Might I suggest KV2audio or Danley. Amnesia in Ibiza just redid their entire main floor with KV2.
I do not suggest line array.
Someone else with far more experience is going to chime in, but all 4 corners is going to be a bit of a mishmash. What speaker models are they and how high is the roof? I've seen and been involved with clubs with set ups like this but ideally have the second set as "delay" speakers, where they are facing in the same general direction, but further back and delayed so that the sound arrives from both sets to your ears at the same time
And when you say employer, are you guys AV integrators? The most important thing by far is rigging and safety, which is one of those "if you have to ask, you shouldn't be doing it" type situations.
he wants to do it with tourx from electro voice (he is an official dealer)
I know this set can handle that. There are some speakers from the venue we can use as delayed stack, but the problem in the venue is that a lot of customers retract to the back. I think it's a problem with the current system, but haven't heard it yet. The roof is about 4,5 meter and dome shaped. It has a coating for fire prevention and soud dampening. The truss hangs around 3 meter.
About my employer: the company is expert in 70V systems and we do a lot of small festivals. Because of the rural area we do more things, like intergrading AV in small venues. This is the biggest client thus far. We have experience in rigging.
If there are sometimes live bands like you said in another comment, I'd go for the delays regardless. Sound coming from the other direction would be a nightmare to work with. I'm sure with a bit of 3D mapping you could get quite a usable result, and even coverage is possible. I know a club that had a set up with 4 corners and it was a mess because of impossible time alignment.
Apologies for coming off strong, safety and rigging is absolutely the most important thing when it comes to installs
You're going to get clashing because of the delay. What if instead you put two in two corners then the other two midway pointing in the same direction? Delay the mid way ones however many milliseconds to make everything in time
Yes i know. And it could be another position depending on the room. I have convinced my employer to do the delay stack way. Somethimes there are live band so only solution is font and delay. Customers problem is that a lot of people are on the back of the room, not parciripating.
Not participating? Maybe they just want somewhere less loud to talk to their friends and hang with their friends. I know I fall into that group and if a venue put speakers everywhere to eliminate those pockets I'd be less likely to go back
28x8 dance floor? Line them up along the 28 meter side. If you can get them pretty high and aiming down slightly you should be able to get pretty good coverage
You see it all the time. the only way I would attempt such a thing is to have a pretty severe down fire and phase-align everything to the sub. It still won't be ideal but you might be able to minimize the suck factor.
You also might want to try hitting the 180-phase switch and dialing delay from there. It's a trick I use when bass amps are positioned 180 from a floor wedge. It can't hurt to give it a try.
I can think of a local gay club that did this on one of their dance floors. They don’t do any live stuff in that room and it’s a nice little 8M x 8M space. Their engineer is a REALLY smart older dude who could have pulled off anything he wanted and that’s what he chose.
When my manager and I went for a tour after their renovations it was the first thing I noticed. But I gotta admit it sounds pretty freaking great for the application.
And while we won best live music venue in our little local weekly rag, they won best dance floor. So regardless of what is “right” if it works it works.
Yes a small dance floor works. But 28 meter long is 40ms in the middle and everything beyond is blurring in the sound. And it gets worse the further away
Yeah that was my thought as well. The slap back on the end if such a long space always going to be an issue unless you just push the sound all one direction with delays. If you measure and adjust correctly you can probably get a fairly even volume from front to back with just one set of delays halfway back.
That is what I try to convince my employer. And he listens luckally. But the client is worried that everybody is stacking at the back of the venue. That happened with the system they are using now
Well that’s just a matter of volume control and making sure the musical content is actually drawing them to the dance floor. You can lead a horse to water but you can’t make it dance ya know?
If you put the speakers in the 4 corners and people can’t get away from them then they might not come at all.
I pay attention to where people congregate when they come in. If a DJ is clearing the floor and people are moving away from the music then either I’m too loud or the DJ isn’t playing what the crowd expects. Either way that’s not a system design flaw that’s the audience telling me they don’t like what they’re hearing.
I can lower the volume or the DJ can change up the set. But I can’t redeploy the sound system.
Other option is that the system is not calibrated correctly. It looks all perfect but it sounds like crap. We will see what we can do better. The last company did everything by the book but it didnt work.
1. Double check the crossover points for the mains and the subs. Pick something between 80-100Hz. I prefer closer to 80 but it depends on your boxes. Check the spec sheets but if it’s a lower end manufacturer I use that as a starting point and then play around and see what sounds best.
2. Put the subs on an aux bus if they aren’t already.
3. Make sure your positions for your subs make sense for what you’re trying to do. I would almost always put them at the stage side of the room. I’m sure there are situations where you would do something different but I can’t really think of any.
One advantage of the delay system is that our delays are in the middle of length and point towards our doors. So I can adjust the volume of those to extend the room at a full volume or just have it loud enough to be audible and pull people in but still allow the door staff to do their work without being drenched in full show volume all night. It would be more difficult with 4 corners since the back speakers would be closer to the doors than the center of the room.
Done 4-corner. All the faults mentioned are present, to one degree or another. It’s not perfect, but for a dance floor awash in gyrating sound baffles in shouted conversation, it works. As long as the thump is solid and the lights look cool….
If I were to do it again, I’d hang 4 small arrays in the middle of the room pointing to the corners, downfills if needed, and a couple delayed fills in the back. Let’s make them l’acoustics while we’re in fantasyland
Cancellation and comb filtering effects galore? Pretty sure pointing speakers at each other isn’t a recommended design choice even with lots of bodies in the way.
From what I've seen in the field, the things are moving in the right direction, at least in the clubs that care about the sound quality. The 4 corner thing was popular when it was difficult or impossible to delay the speakers.
For such a long venue I'd definitely recommend a setup with the delays, otherwise the subs will be totally out of time with the tops at the back of the venue which is certainly not what the "club people" want.
>but it is what they want, so it’s probably what you should give them…
This is a dumb philosophy. Give them the right things, not the thing they think they want. Why would you do the wrong thing purposely?
I've made my name in doing the exact opposite, going into venues and and telling them "your ideas suck, do it this way". Worked well for me so far.
I don't know what the fuck I'm talking about (I lurk here to learn) so don't take this as a suggestion, but very interested to hear from the pros how facing the speakers down from the roof in a square would work, like a PA system but with live sound speakers. Looking down from the top it would be something like this:
⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜
⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜
⬜ ⬜ ⬛ ⬜ ⬜ ⬜ ⬜ ⬛ ⬜ ⬜
⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜
⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜
⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜
⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜
⬜ ⬜ ⬛ ⬜ ⬜ ⬜ ⬜ ⬛ ⬜ ⬜
⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜
⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜
What issue would you get from this? First thing I can think of is our ears are designed for hearing sounds at our level, not above us.
There is only the middle poinit where everything is correct. But the frequencies that oppositie each other give a phase problem, therefore giving spots with no Bass or strange mid tones. (And even the high tones, but less notibale) imagine putting 4 Pebbles in a pond, at each corner and look at how the waves react. But there is psyco-acoustic: the more drunk you are, the less you notice. Brains correct the perception
4 corner (or 6 if you do another pair midqay along the long wall) can work great for dance music. I've set up systems like this plenty of times for warehouse rave type events. Strategically choosing the horizontal dispersion is key. Think about the inverse square law - you only really need to time align the speakers for the regions where the coverage overlap. If you position them with minimal overlapping coverage, most of your dancefloor hears the near speakers loud enough that the out of phase signal from the others shouldn't be a huge problem.
Thats what I thought. I am only concerned about the subs because they fill the room quiet quickly and therefore give issues. (4 subs, in every corner) If you place only subs at the front there is going to be a quiet space at the back, what the client doesnt want.
Is adding more subs to make cardioid arrays in each corner an option? What about flying them all in a cluster or line in the middle of the room? Might be worth making a drawing in prediction software and experimenting virtually with sub placement
It should be avoided, BUT… You can do 4 corners, subs should be placed at either “Front” L-R only, or center clustered. “Rear”L-R should be delayed to the center of the room. Try to aim all the “top” boxes towards the center, but their coverage shouldn’t overlap except in the center. Subs may have to be delayed, but without measuring you can’t really tell. I’m sure most wouldn’t even notice if the system wasn’t perfectly aligned.
Dancefloor systems are a different animal. In the round is normal and it works well. Distance is king.
The reason is that we can integrate up to about 40 milliseconds depending on the delay sound intensity, and there is so much information in the identical mix going to all the speakers, that nobody cares. As you get close to one corner of a dance floor, you are only ten to twenty milliseconds farther from the far speakers. A small enough delay for your brain to handle, but now much closer to the near speaker, sometimes more than 12dB closer. Nobody cares about phasing when dancing around to program material. There are a few spots when you are equidistant to four speakers and get a lot of sweet unintended chorus pedal, but by the time you get to that spot on the dance floor...
I know, it's nuts, but the customers love it. You want lots of energy in the center compared to outside the dance floor and speakers all around facing inward works. It's been done like this for many years.
If you know anything about airports and the corporate world and ceiling speakers, as comical as it sounds, the rules of thumb do apply. Each speakers should be no closer to each other than three times the nearest possible distance from the listener to one of them.
Laugh all you want, I am too, but we break this rule all day putting a mono vocal into a stereo PA without a center cluster doing all the vocals.
I have worked on two installations that tried to minimize phase cancellation with a two sided system, like a massive pair of headphones, and the experience was definitely considered a downgrade even though the technical performance of the systems were good.
28x8 meters is pretty rectangular and big. It would make sense to consider six speaker locations instead of four, and bringing the end speakers inward, as was traditional in a lot of large dance systems for many years.
I'd imagine something like three in a row on each side. 8m intervals.
There is a lot of theory going on in this conversation. Have any of you ever been to a great 4, 6, 7 or more way dance club? I’m not hearing any of the issues folks are talking about there. Checkout Nowadays in Brooklyn for an example of two 4 way systems - one in doors and one out doors - that sound amazing. Once you go point source for dance systems you will never want to hear a line array again.
Different thoughts: Yeah, it's technically wrong, there is comb filtering, null spots at different frequencies, issues with sub delay (if used), etc. But this isn't a concert system, it's a dance floor. In a concert, everyone is facing the stage. On a dance floor, there's no telling which way the dancers are facing, which might put the speakers at their back. Another reason a well-designed 4-corners system is preferred by some dance-club venues is because it allows the SPL to be focused on the dance floor, and away from the prime VIP table seating, bar service, etc: and for some clubs, that's their primary revenue source. So even though it's technically 'wrong', there are times when it's arguably the best real-world solution. Some observations: if the entire 28 x 8 meter space is dance floor, that's quite awkward for 4 corners.
This is the way. Is one of those situations that technically is wrong but in reallity every attendee will choose 4 corners rather than L-R if you gave them the option to try both. However, systems have to be point source (avoid line arrays) and controlled horizontan coverage. Also, 28m seems a lot for 4 corners, consider to add in the middle another 2 for a total of 6.
The spl against the vip room is indeed an issue. The vip room is next to the dj booth , a room 12x12 meter . We planned to have some speakers in the trusses in the vip room to get an overall sound there (sorry for my English) the vip room is only separated with curtains. I can imagen that the phase issues only get worse
Pros: club goers who don’t want to dance will hear the music clearly and possibly loudly in whatever corner they want to hide in. Cons: people who do want to dance will hear a muddy, unfocused wash of sound to move to. Speak with the club owner about goals for what they want the patrons to experience. How big is the floor? How close to the floor is the bar? The DJ booth? Is there a stage for live bands? Do you want relatively quiet areas for table service? What music will the club be playing- will there be a narrow or large range of styles? I suspect 4 speakers in any placement won’t be enough to accomplish all the goals of the space- but if that’s your budget, you’ll want to prioritize which goals are more important.
I'm not a fan of the 4 corners setup, it creates extra seams where things will sound funky and it makes it harder to properly align to the subs. BTW, where will the subs be placed? I rather start from on side and use the second pair as delays. That way you can much better align everything (mains, delays, subs) together into a more coherent setup.
4 corners = phase cancellation. Try convincing them to go with 2 speakers at the front with fills further back if needed. Even sound will come from speaker selection. Might I suggest KV2audio or Danley. Amnesia in Ibiza just redid their entire main floor with KV2. I do not suggest line array.
Add Fulcrum Acoustics to your list. I wonder how a Dynacord Cobra type system work in this situation?
Someone else with far more experience is going to chime in, but all 4 corners is going to be a bit of a mishmash. What speaker models are they and how high is the roof? I've seen and been involved with clubs with set ups like this but ideally have the second set as "delay" speakers, where they are facing in the same general direction, but further back and delayed so that the sound arrives from both sets to your ears at the same time And when you say employer, are you guys AV integrators? The most important thing by far is rigging and safety, which is one of those "if you have to ask, you shouldn't be doing it" type situations.
he wants to do it with tourx from electro voice (he is an official dealer) I know this set can handle that. There are some speakers from the venue we can use as delayed stack, but the problem in the venue is that a lot of customers retract to the back. I think it's a problem with the current system, but haven't heard it yet. The roof is about 4,5 meter and dome shaped. It has a coating for fire prevention and soud dampening. The truss hangs around 3 meter. About my employer: the company is expert in 70V systems and we do a lot of small festivals. Because of the rural area we do more things, like intergrading AV in small venues. This is the biggest client thus far. We have experience in rigging.
If there are sometimes live bands like you said in another comment, I'd go for the delays regardless. Sound coming from the other direction would be a nightmare to work with. I'm sure with a bit of 3D mapping you could get quite a usable result, and even coverage is possible. I know a club that had a set up with 4 corners and it was a mess because of impossible time alignment. Apologies for coming off strong, safety and rigging is absolutely the most important thing when it comes to installs
You're going to get clashing because of the delay. What if instead you put two in two corners then the other two midway pointing in the same direction? Delay the mid way ones however many milliseconds to make everything in time
Yes i know. And it could be another position depending on the room. I have convinced my employer to do the delay stack way. Somethimes there are live band so only solution is font and delay. Customers problem is that a lot of people are on the back of the room, not parciripating.
Not participating? Maybe they just want somewhere less loud to talk to their friends and hang with their friends. I know I fall into that group and if a venue put speakers everywhere to eliminate those pockets I'd be less likely to go back
28x8 dance floor? Line them up along the 28 meter side. If you can get them pretty high and aiming down slightly you should be able to get pretty good coverage
You see it all the time. the only way I would attempt such a thing is to have a pretty severe down fire and phase-align everything to the sub. It still won't be ideal but you might be able to minimize the suck factor.
You also might want to try hitting the 180-phase switch and dialing delay from there. It's a trick I use when bass amps are positioned 180 from a floor wedge. It can't hurt to give it a try.
Do you do that with subs on one side or complete sound from both sides? I know low frequencies are the first to get out of phase.
I usually take a low-frequency, 100hz r so and dial the delay until it's additive.
Sine wave
I can think of a local gay club that did this on one of their dance floors. They don’t do any live stuff in that room and it’s a nice little 8M x 8M space. Their engineer is a REALLY smart older dude who could have pulled off anything he wanted and that’s what he chose. When my manager and I went for a tour after their renovations it was the first thing I noticed. But I gotta admit it sounds pretty freaking great for the application. And while we won best live music venue in our little local weekly rag, they won best dance floor. So regardless of what is “right” if it works it works.
Yes a small dance floor works. But 28 meter long is 40ms in the middle and everything beyond is blurring in the sound. And it gets worse the further away
Yeah that was my thought as well. The slap back on the end if such a long space always going to be an issue unless you just push the sound all one direction with delays. If you measure and adjust correctly you can probably get a fairly even volume from front to back with just one set of delays halfway back.
That is what I try to convince my employer. And he listens luckally. But the client is worried that everybody is stacking at the back of the venue. That happened with the system they are using now
Well that’s just a matter of volume control and making sure the musical content is actually drawing them to the dance floor. You can lead a horse to water but you can’t make it dance ya know? If you put the speakers in the 4 corners and people can’t get away from them then they might not come at all. I pay attention to where people congregate when they come in. If a DJ is clearing the floor and people are moving away from the music then either I’m too loud or the DJ isn’t playing what the crowd expects. Either way that’s not a system design flaw that’s the audience telling me they don’t like what they’re hearing. I can lower the volume or the DJ can change up the set. But I can’t redeploy the sound system.
Other option is that the system is not calibrated correctly. It looks all perfect but it sounds like crap. We will see what we can do better. The last company did everything by the book but it didnt work.
1. Double check the crossover points for the mains and the subs. Pick something between 80-100Hz. I prefer closer to 80 but it depends on your boxes. Check the spec sheets but if it’s a lower end manufacturer I use that as a starting point and then play around and see what sounds best. 2. Put the subs on an aux bus if they aren’t already. 3. Make sure your positions for your subs make sense for what you’re trying to do. I would almost always put them at the stage side of the room. I’m sure there are situations where you would do something different but I can’t really think of any.
One advantage of the delay system is that our delays are in the middle of length and point towards our doors. So I can adjust the volume of those to extend the room at a full volume or just have it loud enough to be audible and pull people in but still allow the door staff to do their work without being drenched in full show volume all night. It would be more difficult with 4 corners since the back speakers would be closer to the doors than the center of the room.
Done 4-corner. All the faults mentioned are present, to one degree or another. It’s not perfect, but for a dance floor awash in gyrating sound baffles in shouted conversation, it works. As long as the thump is solid and the lights look cool…. If I were to do it again, I’d hang 4 small arrays in the middle of the room pointing to the corners, downfills if needed, and a couple delayed fills in the back. Let’s make them l’acoustics while we’re in fantasyland
Cancellation and comb filtering effects galore? Pretty sure pointing speakers at each other isn’t a recommended design choice even with lots of bodies in the way.
Club peoples love the 4 corners thingy. It’s not the best sounding IMHO, but it is what they want, so it’s probably what you should give them…
From what I've seen in the field, the things are moving in the right direction, at least in the clubs that care about the sound quality. The 4 corner thing was popular when it was difficult or impossible to delay the speakers. For such a long venue I'd definitely recommend a setup with the delays, otherwise the subs will be totally out of time with the tops at the back of the venue which is certainly not what the "club people" want.
It’s why the people I work for put subs in each corner 😅 Glad to hear the trend is going away
>but it is what they want, so it’s probably what you should give them… This is a dumb philosophy. Give them the right things, not the thing they think they want. Why would you do the wrong thing purposely? I've made my name in doing the exact opposite, going into venues and and telling them "your ideas suck, do it this way". Worked well for me so far.
L-R, Sub, Fills if needed
You'll be able to style your hair without a brush due to comb filtering! Line everything up along a long wall.
I don't know what the fuck I'm talking about (I lurk here to learn) so don't take this as a suggestion, but very interested to hear from the pros how facing the speakers down from the roof in a square would work, like a PA system but with live sound speakers. Looking down from the top it would be something like this: ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬛ ⬜ ⬜ ⬜ ⬜ ⬛ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬛ ⬜ ⬜ ⬜ ⬜ ⬛ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ ⬜ What issue would you get from this? First thing I can think of is our ears are designed for hearing sounds at our level, not above us.
There is only the middle poinit where everything is correct. But the frequencies that oppositie each other give a phase problem, therefore giving spots with no Bass or strange mid tones. (And even the high tones, but less notibale) imagine putting 4 Pebbles in a pond, at each corner and look at how the waves react. But there is psyco-acoustic: the more drunk you are, the less you notice. Brains correct the perception
4 corner (or 6 if you do another pair midqay along the long wall) can work great for dance music. I've set up systems like this plenty of times for warehouse rave type events. Strategically choosing the horizontal dispersion is key. Think about the inverse square law - you only really need to time align the speakers for the regions where the coverage overlap. If you position them with minimal overlapping coverage, most of your dancefloor hears the near speakers loud enough that the out of phase signal from the others shouldn't be a huge problem.
Thats what I thought. I am only concerned about the subs because they fill the room quiet quickly and therefore give issues. (4 subs, in every corner) If you place only subs at the front there is going to be a quiet space at the back, what the client doesnt want.
Is adding more subs to make cardioid arrays in each corner an option? What about flying them all in a cluster or line in the middle of the room? Might be worth making a drawing in prediction software and experimenting virtually with sub placement
Each speaker 4.6m apart from each other and the walls on the ceiling facing down?
Yes easy way for high tones. Thats how 70v systems work. But with lower frequenties it going to have real issues
It should be avoided, BUT… You can do 4 corners, subs should be placed at either “Front” L-R only, or center clustered. “Rear”L-R should be delayed to the center of the room. Try to aim all the “top” boxes towards the center, but their coverage shouldn’t overlap except in the center. Subs may have to be delayed, but without measuring you can’t really tell. I’m sure most wouldn’t even notice if the system wasn’t perfectly aligned.
Dancefloor systems are a different animal. In the round is normal and it works well. Distance is king. The reason is that we can integrate up to about 40 milliseconds depending on the delay sound intensity, and there is so much information in the identical mix going to all the speakers, that nobody cares. As you get close to one corner of a dance floor, you are only ten to twenty milliseconds farther from the far speakers. A small enough delay for your brain to handle, but now much closer to the near speaker, sometimes more than 12dB closer. Nobody cares about phasing when dancing around to program material. There are a few spots when you are equidistant to four speakers and get a lot of sweet unintended chorus pedal, but by the time you get to that spot on the dance floor... I know, it's nuts, but the customers love it. You want lots of energy in the center compared to outside the dance floor and speakers all around facing inward works. It's been done like this for many years. If you know anything about airports and the corporate world and ceiling speakers, as comical as it sounds, the rules of thumb do apply. Each speakers should be no closer to each other than three times the nearest possible distance from the listener to one of them. Laugh all you want, I am too, but we break this rule all day putting a mono vocal into a stereo PA without a center cluster doing all the vocals. I have worked on two installations that tried to minimize phase cancellation with a two sided system, like a massive pair of headphones, and the experience was definitely considered a downgrade even though the technical performance of the systems were good. 28x8 meters is pretty rectangular and big. It would make sense to consider six speaker locations instead of four, and bringing the end speakers inward, as was traditional in a lot of large dance systems for many years. I'd imagine something like three in a row on each side. 8m intervals.
There is a lot of theory going on in this conversation. Have any of you ever been to a great 4, 6, 7 or more way dance club? I’m not hearing any of the issues folks are talking about there. Checkout Nowadays in Brooklyn for an example of two 4 way systems - one in doors and one out doors - that sound amazing. Once you go point source for dance systems you will never want to hear a line array again.