Side by side on the floor.
The floor boundary slightly extends the horn
mouth. When they sit as designed.
Sounds like boom boom room.
And big cancellation from being
spread apart or 2 bass sources
far away.
1 bass source. 4 wide sitting
on the floor as designed.
Not vertical. pretty standard.
Side by side makes larger horn.
As does the floor.
Remove the grills. To check for rattles.
Otherwise temperature or previous owner
moved them a lot. Corner joints fail
reinforce the corners and baffle inside
the speaker rear chamber.
As for dead High frequency boxes.
The usual checks for grinding voice coils( dead)
Or fuses, blown light bulb limiters. or dead
padding resistors. which is repairable
The floor boundary slightly extends the horn
mouth. When they sit as designed.
Sounds like boom boom room.
And big cancellation from being
spread apart or 2 bass sources
far away.
1 bass source. 4 wide sitting
on the floor as designed.
Not vertical. pretty standard.
Side by side makes larger horn.
As does the floor.
Remove the grills. To check for rattles.
Otherwise temperature or previous owner
moved them a lot. Corner joints fail
reinforce the corners and baffle inside
the speaker rear chamber.
As for dead High frequency boxes.
The usual checks for grinding voice coils( dead)
Or fuses, blown light bulb limiters. or dead
padding resistors. which is repairable
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So the subs shouldn't be placed right in front of a wall, but should be flush mounted with the wall, right?
Now what if I were to do like some skating rinks and put one sub in each corner flush mounted with the wall?
I saw that done at two local rinks and the bass seemed to sound good, however they both used JBL 4520 cabinets which are more of a long throw design.
Maybe that's how they got away with one cabinet in each corner flush with the wall.
Unfortunately in this case with the small QSC two way 8" powered speakers (14 originally used) all but three have blown woofers which comes from using them to fill a 10,000 square foot skating rink with sound for several years. As a speaker blew it meant the others had to be pushed a little harder.
We got three Mackie 12" two way powered speakers and will eventually get two more. They do the job quite nicely and even integrate with the subs better.
No.. subs against boundaries is fine.
I don't know why you seem to be fixated on the old JBL scoops... they barely qualify as subwoofers and are more problematic to integrate.
8" 2 way tops are definitely not optimal for this application.. 12's are much better, but you need to find another brand than Mackie, thier PA speakers are very failure prone as of late. I had 4 Thump boxes and they all failed within a year, and I'm not alone.. online reviews show similar results.
Something else I just thought of, since you don't know the history of this gear you can't assume everything is configured 100% correct. It is particularly important with the subs that they are all wired for the same polarity.. if even 1 is reversed there will be heavy cancellations. Once you get them pulled out and side by side start by connecting 1 box and note the level of bass output, every time you add another box the bass level should get stronger, if it doesn't flip polarity on the cable to that box. If you find that produces better results then either the driver is wired incorrectly inside the box, the speaker cable is pinned incorrectly, or the amplifier is configured incorrectly.. for example it's set for bridged operation but speakers connected normally to L & R output terminals.
I don't know why you seem to be fixated on the old JBL scoops... they barely qualify as subwoofers and are more problematic to integrate.
8" 2 way tops are definitely not optimal for this application.. 12's are much better, but you need to find another brand than Mackie, thier PA speakers are very failure prone as of late. I had 4 Thump boxes and they all failed within a year, and I'm not alone.. online reviews show similar results.
Something else I just thought of, since you don't know the history of this gear you can't assume everything is configured 100% correct. It is particularly important with the subs that they are all wired for the same polarity.. if even 1 is reversed there will be heavy cancellations. Once you get them pulled out and side by side start by connecting 1 box and note the level of bass output, every time you add another box the bass level should get stronger, if it doesn't flip polarity on the cable to that box. If you find that produces better results then either the driver is wired incorrectly inside the box, the speaker cable is pinned incorrectly, or the amplifier is configured incorrectly.. for example it's set for bridged operation but speakers connected normally to L & R output terminals.
Far as I know the subs are all wired properly. At least the two pairs sound like they are.
Each pair of subs is wired to the bridge output on their respective amp.
The reason I am fixated on the old JBL scoops is because even though they don't go all that low, what bass they do produce was some of the most natural I've ever heard.
Unfortunately mackie is what the guy who handles all the tech went with. They are the model 212 powered speakers.
Each pair of subs is wired to the bridge output on their respective amp.
The reason I am fixated on the old JBL scoops is because even though they don't go all that low, what bass they do produce was some of the most natural I've ever heard.
Unfortunately mackie is what the guy who handles all the tech went with. They are the model 212 powered speakers.
Concerning the subs, farther away they sound ok.
Up close I can hear the air moved by the drivers and it doesn't sound pretty. At least that's what I think I'm hearing up close.
That's why I wanted to replace them with something like the JBL 4520 which sounds good close and far away.
EDIT:
Here's where the EQ was set when using the subs with the 8" powered speakers.
Had to do that to make the subs sound decent.
I put the EQ back flat and the subs seem to sound not as bad up close.
Up close I can hear the air moved by the drivers and it doesn't sound pretty. At least that's what I think I'm hearing up close.
That's why I wanted to replace them with something like the JBL 4520 which sounds good close and far away.
EDIT:
Here's where the EQ was set when using the subs with the 8" powered speakers.
Had to do that to make the subs sound decent.
I put the EQ back flat and the subs seem to sound not as bad up close.
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You should have the low cut(subsonic) filter set at around 30-35hz so those boosts weren't doing anything productive.
The 40 did something as it doesnt sound as bad with the 40Hz set to flat.
The QSC amps have a built in 30Hz high pass I have switched on.
I think another reason the subs sound bad is because they are sitting a few inches off the floor.
The QSC amps have a built in 30Hz high pass I have switched on.
I think another reason the subs sound bad is because they are sitting a few inches off the floor.
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The issue with the one rattling sub was this.
Pulled the casters and the sub sounds fine now.
Gonna see if they will turn two up vertical and sit them on the floor to see how they sound.
If they sound good I'll have them modify the walls and put the subs flush with the walls.
Pulled the casters and the sub sounds fine now.
Gonna see if they will turn two up vertical and sit them on the floor to see how they sound.
If they sound good I'll have them modify the walls and put the subs flush with the walls.
To maximize low bass, place cabinets all together on the floor and in a corner. Flying subs makes for good punchy impact around 100Hz, but anything below 60 will suffer and require more power to get the same SPL to the listener/feeler. A few inches off the floor shouldn't matter but as soon as they have enough room to place another cabinet under, you'll start loosing lows. Also, pull the crossover between tops and subs down to 80Hz if possible to allow more head room for sub bass. An 80Hz crossover essentially splits the kick drum evenly between subs and mids, so special attention needs to be paid to time alignment and placement or the kick starts sounding hollow and muddy.
When shopping for subs for low bass performance, look up the specs on the driver. Displacement is what ultimately matters. Sd*Xmax=displacement where Sd=surface area and Xmax=how far the coil can move without loosing control.
Something like this is what you need; https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=201070150
If the Xmax is less than 12mm, hang up and try again. I've seen way too many "pro" subs with Xmax of 5-6mm. These work great for putting the kick drum mallet right on your chest, but even if they can handle 3000 watts, will start sounding like a## at 30-40Hz because the cone is moving outside it's Xmax. A smaller Xmax means a tighter magnetic gap with stronger flux but it also means less control with more movement. Half the frequency requires four times linear motion to achieve the same SPL. As soon as the coil moves outside the Xmax, it becomes non-linear and introduces compression/distortion. I assume that this is what you're talking about when you reference car audio. With lower frequencies, Xmax becomes just as important as power. If the speakers are getting sloppy, they're only going to get worse with more power.
I would also tend to steer you away from horn subs for this purpose. I am a huge fan of horn loading speakers and even subs. I have designed and built my own horn subs. What I can tell you is that unless the horn is 30ft. long, it's not going to give you much if anything extra under 40Hz. The ones I designed are a 9ft. horn with a single 18". A single cabinet has 4x output per watt than a bass reflex double 18" at kick drum frequencies, but at 30Hz, it takes two of my cabinets that are the same size each as a double 18" to keep up. Just get some good bass reflex double 18"s, push them together in a corner, and give them some solid power and you'll be swimming in bass.
It may also be worth mentioning that mid-bass is often overlooked. If the mid-bass from your' top cabinets is lacking and you have to make up for it by raising the crossover point betweeen them and the subs in order to get good punch, then the subs are going to suffer in the bottom half octave. If the low bass isn't an absolute imperitive, consider improvements in mid-bass (not subs) so that the crossover can be lowered. If this is in fact the weak spot in the system, it will improve the dynamics of everything under the tweeter frequencies.
When shopping for subs for low bass performance, look up the specs on the driver. Displacement is what ultimately matters. Sd*Xmax=displacement where Sd=surface area and Xmax=how far the coil can move without loosing control.
Something like this is what you need; https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=201070150
If the Xmax is less than 12mm, hang up and try again. I've seen way too many "pro" subs with Xmax of 5-6mm. These work great for putting the kick drum mallet right on your chest, but even if they can handle 3000 watts, will start sounding like a## at 30-40Hz because the cone is moving outside it's Xmax. A smaller Xmax means a tighter magnetic gap with stronger flux but it also means less control with more movement. Half the frequency requires four times linear motion to achieve the same SPL. As soon as the coil moves outside the Xmax, it becomes non-linear and introduces compression/distortion. I assume that this is what you're talking about when you reference car audio. With lower frequencies, Xmax becomes just as important as power. If the speakers are getting sloppy, they're only going to get worse with more power.
I would also tend to steer you away from horn subs for this purpose. I am a huge fan of horn loading speakers and even subs. I have designed and built my own horn subs. What I can tell you is that unless the horn is 30ft. long, it's not going to give you much if anything extra under 40Hz. The ones I designed are a 9ft. horn with a single 18". A single cabinet has 4x output per watt than a bass reflex double 18" at kick drum frequencies, but at 30Hz, it takes two of my cabinets that are the same size each as a double 18" to keep up. Just get some good bass reflex double 18"s, push them together in a corner, and give them some solid power and you'll be swimming in bass.
It may also be worth mentioning that mid-bass is often overlooked. If the mid-bass from your' top cabinets is lacking and you have to make up for it by raising the crossover point betweeen them and the subs in order to get good punch, then the subs are going to suffer in the bottom half octave. If the low bass isn't an absolute imperitive, consider improvements in mid-bass (not subs) so that the crossover can be lowered. If this is in fact the weak spot in the system, it will improve the dynamics of everything under the tweeter frequencies.
Thanks for that explanation. It helps me understand things much better.
First I'm gonna try two of the Yorkvilles standing upright on the floor side by side just to see if they sound better.
Now if I putt he four Yorkvilles in a row at one end of the rink, will the bass reach the other end of the rink properly or will the bass be stronger by the subs?
I've determined that ultimate below 40Hz low frequency performance isn't going to happen with normal subs.
OAP still makes a W bin that when stacked 8 high is a true 40Hz horn, however that would be a 15' high stack. I'd only stack four though.
Now if I for instance use a ported sub such as the JBL SRX828SP, Will that provide bass across the whole rink?
https://jblpro.com/products/srx828sp
I could always go the expensive route and get a Bassboss sub, but I know they won't go for spending that much on speakers.
That's why they got three Mackie speakers versus the Yamaha DZR315 three way actively amplified powered speakers I wanted them to get. The owner couldn't see spending $1,800 per speaker.
First I'm gonna try two of the Yorkvilles standing upright on the floor side by side just to see if they sound better.
Now if I putt he four Yorkvilles in a row at one end of the rink, will the bass reach the other end of the rink properly or will the bass be stronger by the subs?
I've determined that ultimate below 40Hz low frequency performance isn't going to happen with normal subs.
OAP still makes a W bin that when stacked 8 high is a true 40Hz horn, however that would be a 15' high stack. I'd only stack four though.
Now if I for instance use a ported sub such as the JBL SRX828SP, Will that provide bass across the whole rink?
https://jblpro.com/products/srx828sp
I could always go the expensive route and get a Bassboss sub, but I know they won't go for spending that much on speakers.
That's why they got three Mackie speakers versus the Yamaha DZR315 three way actively amplified powered speakers I wanted them to get. The owner couldn't see spending $1,800 per speaker.
Interesting that you mention BassBoss. I used to work with/for David back when it was BassMaxx . This discussion is one of the primary reasons he decided to move away from horn subs. I would highly recommend the BassBoss double 18" if they can fit it in their budget. They are expensive but worth every penny. Two of them would likely be plenty for the application. ...I mean, you don't want to be disorienting people while their doing 30mph on skates.
Since this is a DIY forum, you're on a budget, and they are going to be a permanent install, I would suggest getting raw drivers and building an enclosure from 3/4" MDF. Minimum tools needed would be dust mask, Skilsaw, jigsaw, drill, drywall screws, and wood glue. If you have access to a table saw, router, and clamps, even better. If you need help with design, I'm sure there are plenty who could help including myself. After designing horn cabinets, bass reflex is beyond simple. I would recommend something like this for drivers; https://www.parts-express.com/B-C-1...Neodymium-Subwoofer-8-Ohm-294-6026?quantity=1
Unless you want to double the amount of drivers, this is about as good as it gets balancing price, displacement, and quality.
To answer your other questions, coverage is always an issue with PA speakers. To maximize bass, it's always a good idea to place all subs together. Although in some situations, it's often a good solution for coverage to separate the subs, sacrificing some of the low end for good coverage. As long as the distance from listener to box A is close to that between listener and box B, it's not an issue. With the traditional setup of two stacks in front of a stage, it's only an issue on the sides of the stage or very far out where there's no audience. With larger stages, it can quickly become an issue and the solution is often a row of subs centered in front of the stage. In your situation, I would try to find a central location. Where would you put it if you only had one sub? Ideally, all subs would be in this location. This is why you often see a cluster of speakers hanging right over the arena for things like sporting events. Point source is often the easiest way of acheiving coverage with minimal sacrifice.
Obviously, the closer one is to the subs, the louder it will be but it should always be in relation to the mains. If you have great bass coverage everywhere, but some places are lacking in mids or highs, then it's not going to sound good there. You also have the issue of lining up the phase at the crossover point. It's all about distance from ear to speaker. If there is a significant difference in relation to frequency/wavelength, that changes as the listener moves around the venue, you WILL get comb filtering.
Ideal situation here is the mains and subs are close together. I have worked many non-ideal venues and someone is usually upset that I can't bend the rules of physics around the awful acoustics of the venue. People think that you can just get more speakers and place them around the venue for coverage and although there is some truth to this, it comes with some serious drawbacks in sound quality via comb filtering and time alignment. There was a local venue here that has since shut down that had four Turbosound stacks, one in each corner of the room. The only places it sounded good was either directly in front of one of the stacks or in the very center of the room. With all this said, I would start thinking about where can you and/or should you compromise for frequency, volume, coverage, and sound quality. (audio triage) Personally, I think that if you have good solid bass with adequate power, placing subs and tops at one end of the rink would most likely be your best bet. It won't be as loud at the other end, but will otherwise sound just as good. The bass will most likely carry over the distance just fine. If anything, I would think that you may want to hang an additional pair of small full range fill cabs (facing the same direction as the others) so that they fill the area that's lacking. If you do this, you'll want to measure the distance between mains and fills and put that much delay on the fills so that by the time the main wave hits the fills, they are in phase and not fighting or making horrible echo. The other advantage to this approach is that you don't have to blast the mids from the mains, ripping heads off, in order to get good coverage to the back of the venue.
As for JBL (and EAW), I can't in good faith say that it's worth the money. They will usually be a safe bet in that it's going to be fairly dependable and get the job done. To me, they are adequate and reasonably dependable like an F-150 (meh). I tried to look up the driver specs for that JBL cabinet and it doesn't look like they publish that information which is a huge warning sign. If asked why, they would likely say that they are protecting their IP, but that's a BS answer because if someone wanted to reverse engineer it, it would be easy enough to pull a driver out of a cabinet and measure it. To me, it screams that they are hiding a weak spot that saves money, but would otherwise be embarrasing to publish. Probably has an Xmax of 2mm...
If using an off the shelf 2x18", personally I would be looking at EV or Yamaha where Yamaha is a little lower quality but has better low bass, claiming a bottom end of 30Hz for a couple models of 2x18".
Since this is a DIY forum, you're on a budget, and they are going to be a permanent install, I would suggest getting raw drivers and building an enclosure from 3/4" MDF. Minimum tools needed would be dust mask, Skilsaw, jigsaw, drill, drywall screws, and wood glue. If you have access to a table saw, router, and clamps, even better. If you need help with design, I'm sure there are plenty who could help including myself. After designing horn cabinets, bass reflex is beyond simple. I would recommend something like this for drivers; https://www.parts-express.com/B-C-1...Neodymium-Subwoofer-8-Ohm-294-6026?quantity=1
Unless you want to double the amount of drivers, this is about as good as it gets balancing price, displacement, and quality.
To answer your other questions, coverage is always an issue with PA speakers. To maximize bass, it's always a good idea to place all subs together. Although in some situations, it's often a good solution for coverage to separate the subs, sacrificing some of the low end for good coverage. As long as the distance from listener to box A is close to that between listener and box B, it's not an issue. With the traditional setup of two stacks in front of a stage, it's only an issue on the sides of the stage or very far out where there's no audience. With larger stages, it can quickly become an issue and the solution is often a row of subs centered in front of the stage. In your situation, I would try to find a central location. Where would you put it if you only had one sub? Ideally, all subs would be in this location. This is why you often see a cluster of speakers hanging right over the arena for things like sporting events. Point source is often the easiest way of acheiving coverage with minimal sacrifice.
Obviously, the closer one is to the subs, the louder it will be but it should always be in relation to the mains. If you have great bass coverage everywhere, but some places are lacking in mids or highs, then it's not going to sound good there. You also have the issue of lining up the phase at the crossover point. It's all about distance from ear to speaker. If there is a significant difference in relation to frequency/wavelength, that changes as the listener moves around the venue, you WILL get comb filtering.
As for JBL (and EAW), I can't in good faith say that it's worth the money. They will usually be a safe bet in that it's going to be fairly dependable and get the job done. To me, they are adequate and reasonably dependable like an F-150 (meh). I tried to look up the driver specs for that JBL cabinet and it doesn't look like they publish that information which is a huge warning sign. If asked why, they would likely say that they are protecting their IP, but that's a BS answer because if someone wanted to reverse engineer it, it would be easy enough to pull a driver out of a cabinet and measure it. To me, it screams that they are hiding a weak spot that saves money, but would otherwise be embarrasing to publish. Probably has an Xmax of 2mm...
If using an off the shelf 2x18", personally I would be looking at EV or Yamaha where Yamaha is a little lower quality but has better low bass, claiming a bottom end of 30Hz for a couple models of 2x18".
The way the mains are there's three along one long side wall and will be three along the other long side wall.
The rink is an oval.
One rink I went to uses several speakers along both long sides of the rink floor and just one sub.
Honestly the clearest, cleanest system I've ever heard at any rink and the one sub (not sure what it is or the number of cabinets) surprisingly filled the rink with bass.
I have been to a rink that had a JBL 4520 cabinet in each corner and what bass it could reproduce sounded good throughout the rink.
Now if the owner goes for one of the bassboss subs, would it be best to put one at one end of the oval and another at the other end of the oval or should both be stacked on top of each other at one end of the oval.
The goal I'd like to try and achieve is fairly even bass throughout the rink floor.
The rink is an oval.
One rink I went to uses several speakers along both long sides of the rink floor and just one sub.
Honestly the clearest, cleanest system I've ever heard at any rink and the one sub (not sure what it is or the number of cabinets) surprisingly filled the rink with bass.
I have been to a rink that had a JBL 4520 cabinet in each corner and what bass it could reproduce sounded good throughout the rink.
Now if the owner goes for one of the bassboss subs, would it be best to put one at one end of the oval and another at the other end of the oval or should both be stacked on top of each other at one end of the oval.
The goal I'd like to try and achieve is fairly even bass throughout the rink floor.
Place the subs together in a place as close as possible to equal distance to all boundaries that you want equal volume in and as close as possible to the mains.
From what you have said, I assume this would be along the wall with the mains and under the center of the three mains.
From what you have said, I assume this would be along the wall with the mains and under the center of the three mains.
Not sure that would be possible unless some seating was removed along the rear long wall or some area along the front long wall (wall is a little higher than barstool height as stools are there for people to sit and watch or eat or drink) is removed which would have to be removed on the rink side of the wall.
The only real place for the subs would be by the booth which is in one corner of the oval and we plan on expanding the booth anyways to give a little more room so the wall for the booth could be brought out to give room for the subs to sit there in the middle end of the oval.
So here's the two current options we are exploring with the mains.
Speakers will be turned slightly right facing the direction of travel so that no speaker is directly facing another speaker.
Here's what we might do to the booth.
Here's where I was thinking of putting the subs.
The only real place for the subs would be by the booth which is in one corner of the oval and we plan on expanding the booth anyways to give a little more room so the wall for the booth could be brought out to give room for the subs to sit there in the middle end of the oval.
So here's the two current options we are exploring with the mains.
Speakers will be turned slightly right facing the direction of travel so that no speaker is directly facing another speaker.
Here's what we might do to the booth.
Here's where I was thinking of putting the subs.
I understand the intention of not facing any speaker towards another, but the problem with this is that they aren't laser beams. Most PA speakers have a dispersion of at least 90 degrees and when you're anywhere near 100Hz, likely at least 180 degrees. All of these scenarios will have tons of comb filtering.
The sub placement in the last two is where I would start. Having the subs separated will give you a more even coverage but at the cost of comb filtering. This will have the effect of certain frequencies being summed and others canceling where ideally you only want summing. If you were to feed them with say a 60Hz signal and move around the rink, you'll notice some places louder and some quieter. Playing a different frequency will have the same effect, but with different places being loud/quiet. Where there is a difference of 9.5ft. (half wavelength), 60 Hz will be muffled if not completely cancelled. Granted, some of this will be mitigated by the fact that it's low frequencies in an enclosed space, but the same concept makes the actual placement less important. Where it does become important is at the crossover frequency where the subs need to play nice with the mains.
In the following image, I have included a listener in a random position represented by a red filled circle. Green/blue lines representing the sound travel from speakers to listener. Take note that the lines are all different distances. Now imagine moving the listener around the rink with either end of the lines tethered to the listener and speakers. If you take a snapshot of that travel at any given moment, you get large variations in line lengths. Those variations in distance will create comb filtering at various frequencies. This is something that is to some degree unavoidable but can be minimized.
Because high frequencies are more directional, much more care should be taken to avoid overlap of sound from different sources. I would also be very concerned in this scenario about your crossover frequency between subs and mains. This is often right at or near the kick drum frequencies which is usually the foundation (metronome) of a song that all the rhythm and melody of a song is built on. Most crossovers aren't a hard cut at any frequency and the ones that are have to be used very carefully as they can otherwise impart large phase problems. No matter what delay you put on any speaker, you will get frequencies near the crossover point that are muffled, but only in particular places that correspond to the difference in travel representing a half wavelength. For instance, where the difference in travel is 7ft., you will have cancellation at 80Hz, and any punch from the kick drum fizzles out.
The next image is my suggestion for placement, but with the caveat that the middle and front speakers need to be delayed (time aligned) or it will sound no better than the above image. If shopping for a DSP/amp with delay, make sure that it is capable of what you need as many of them can only achieve 20-30ft and you'll need something around 2/3 the length of the rink with a little extra so you have room for adjustment.
I would start by setting up and playing some music through only the subs and mains near the subs. Balance the output of subs and mains so that it sounds good only with concern to near field. (10-20ft.) With music playing walk away from the mains until it sounds like you should turn the subs down to balance with the mains. At this location put a piece of masking tape or other marker on the floor. Repeat this until you have something that represents the usable boundary of the system. If you find that this boundary doesn't cover at least a third of rink, you should turn up the mains until it does and find the new boundary.
Now you can place the second set of speakers so that they fill the area outside this boundary. (5-6 ft. in front of the boundary) At this point, you'll measure distance A in the image and place that much delay on the amps driving them. You will want to play a tone at the crossover point and fine tune the delay so that it has the loudest output. It should be a fairly minimal adjustment. (a couple feet max, otherwise you will end up aligning a wavelength off and other frequencies will suffer) Then play a tone one octave up (double Hz) and do the same. You'll want to split the difference between the two as this represents a compromise of sub to main vs. main to main. Now set the gain on the second set of speakers so that it's balanced with the sub output.
Repeat the procedure above for finding the second boundary line and setting up the third set of mains according to distance B.
It's not absolutely necessary but ideally, all the mains in this scenario would be hung from the ceiling (tweeters down) with a small angle. If you know the vertical dispersion of the tweeter horn, cut it in half and add 2-3 degrees. The idea is to minimize any waves from the tweeter from bouncing off the ceiling.
Another option that may or may not fit your goals better would be to place four of the mains near the subs, stacking them two high, bottom cabinet tweeters up and top cabinet tweeters down. This would be your main system and the extra two speakers would be roughly half way down the rink with appropriate delay. This would be a much simpler setup, only requiring one stereo delay but being noticably louder at one end of the rink.
The sub placement in the last two is where I would start. Having the subs separated will give you a more even coverage but at the cost of comb filtering. This will have the effect of certain frequencies being summed and others canceling where ideally you only want summing. If you were to feed them with say a 60Hz signal and move around the rink, you'll notice some places louder and some quieter. Playing a different frequency will have the same effect, but with different places being loud/quiet. Where there is a difference of 9.5ft. (half wavelength), 60 Hz will be muffled if not completely cancelled. Granted, some of this will be mitigated by the fact that it's low frequencies in an enclosed space, but the same concept makes the actual placement less important. Where it does become important is at the crossover frequency where the subs need to play nice with the mains.
In the following image, I have included a listener in a random position represented by a red filled circle. Green/blue lines representing the sound travel from speakers to listener. Take note that the lines are all different distances. Now imagine moving the listener around the rink with either end of the lines tethered to the listener and speakers. If you take a snapshot of that travel at any given moment, you get large variations in line lengths. Those variations in distance will create comb filtering at various frequencies. This is something that is to some degree unavoidable but can be minimized.
Because high frequencies are more directional, much more care should be taken to avoid overlap of sound from different sources. I would also be very concerned in this scenario about your crossover frequency between subs and mains. This is often right at or near the kick drum frequencies which is usually the foundation (metronome) of a song that all the rhythm and melody of a song is built on. Most crossovers aren't a hard cut at any frequency and the ones that are have to be used very carefully as they can otherwise impart large phase problems. No matter what delay you put on any speaker, you will get frequencies near the crossover point that are muffled, but only in particular places that correspond to the difference in travel representing a half wavelength. For instance, where the difference in travel is 7ft., you will have cancellation at 80Hz, and any punch from the kick drum fizzles out.
The next image is my suggestion for placement, but with the caveat that the middle and front speakers need to be delayed (time aligned) or it will sound no better than the above image. If shopping for a DSP/amp with delay, make sure that it is capable of what you need as many of them can only achieve 20-30ft and you'll need something around 2/3 the length of the rink with a little extra so you have room for adjustment.
I would start by setting up and playing some music through only the subs and mains near the subs. Balance the output of subs and mains so that it sounds good only with concern to near field. (10-20ft.) With music playing walk away from the mains until it sounds like you should turn the subs down to balance with the mains. At this location put a piece of masking tape or other marker on the floor. Repeat this until you have something that represents the usable boundary of the system. If you find that this boundary doesn't cover at least a third of rink, you should turn up the mains until it does and find the new boundary.
Now you can place the second set of speakers so that they fill the area outside this boundary. (5-6 ft. in front of the boundary) At this point, you'll measure distance A in the image and place that much delay on the amps driving them. You will want to play a tone at the crossover point and fine tune the delay so that it has the loudest output. It should be a fairly minimal adjustment. (a couple feet max, otherwise you will end up aligning a wavelength off and other frequencies will suffer) Then play a tone one octave up (double Hz) and do the same. You'll want to split the difference between the two as this represents a compromise of sub to main vs. main to main. Now set the gain on the second set of speakers so that it's balanced with the sub output.
Repeat the procedure above for finding the second boundary line and setting up the third set of mains according to distance B.
It's not absolutely necessary but ideally, all the mains in this scenario would be hung from the ceiling (tweeters down) with a small angle. If you know the vertical dispersion of the tweeter horn, cut it in half and add 2-3 degrees. The idea is to minimize any waves from the tweeter from bouncing off the ceiling.
Another option that may or may not fit your goals better would be to place four of the mains near the subs, stacking them two high, bottom cabinet tweeters up and top cabinet tweeters down. This would be your main system and the extra two speakers would be roughly half way down the rink with appropriate delay. This would be a much simpler setup, only requiring one stereo delay but being noticably louder at one end of the rink.
Not sure why I never replied to this.
We now have three Behringer 12" two way powered speakers along one long wall and plan on putting three more along the other long wall. I'd have chosen a different brand myself, but that's what the IT guy who is over all the tech bought. At least they are better than the QSC 8" two way powered speakers we had.
One of the Yorkville LS1208 subs was making a rattle so I unplugged it maybe two years ago. The one right next to it is starting to make a similar sound.
So it's time to replace the subs.
I have two QSC RMX2450A amps that can do 1200 WPC into 2 ohms or 2400 watts bridged into 4 ohms.
What 18" sub would be the best choice at a reasonable cost that has a -3dB point of lower than 35Hz?
I'd use four subs stacked on top of each other. Each Yorkville LS1208 has a SPL of 136dB continuous so the new subs would need to be at least that or greater.
We now have three Behringer 12" two way powered speakers along one long wall and plan on putting three more along the other long wall. I'd have chosen a different brand myself, but that's what the IT guy who is over all the tech bought. At least they are better than the QSC 8" two way powered speakers we had.
One of the Yorkville LS1208 subs was making a rattle so I unplugged it maybe two years ago. The one right next to it is starting to make a similar sound.
So it's time to replace the subs.
I have two QSC RMX2450A amps that can do 1200 WPC into 2 ohms or 2400 watts bridged into 4 ohms.
What 18" sub would be the best choice at a reasonable cost that has a -3dB point of lower than 35Hz?
I'd use four subs stacked on top of each other. Each Yorkville LS1208 has a SPL of 136dB continuous so the new subs would need to be at least that or greater.
That fixed the rattle you had been hearing for a few years..
Maybe try fixing the rattling hardware rather than replacing the subs 😉
A -3dB point of lower than 35Hz (what the LS1208 are rated) for PA subs is a niche market, cost goes up considerably over the subs you have, and would require more power to get as loud.
The rattle had come back.
Took the grill off and didn't see anything loose. Couldn't see any easy way to further disassemble the cabinet.
Is there a way to disassemble the cabinet further?
Is the -3dB point of 35Hz with one sub or several side by side?
Also if I stack four side by side will that lower the F3.
Never really liked those subs as they never seemed to go real low, but that was with 8" two way powered tops.
The subs do sound better with the 12" two way tops though.
The way they are is two are on their side with the horn mouths end to end. That is on one end of the rink in one corner with an identical setup on the same wall in the other corner.
Likely that's why they don't seem to sound as good as they should.
Took the grill off and didn't see anything loose. Couldn't see any easy way to further disassemble the cabinet.
Is there a way to disassemble the cabinet further?
Is the -3dB point of 35Hz with one sub or several side by side?
Also if I stack four side by side will that lower the F3.
Never really liked those subs as they never seemed to go real low, but that was with 8" two way powered tops.
The subs do sound better with the 12" two way tops though.
The way they are is two are on their side with the horn mouths end to end. That is on one end of the rink in one corner with an identical setup on the same wall in the other corner.
Likely that's why they don't seem to sound as good as they should.
I don't know.
Have you determined with a sine wave sweep that the rattle is inside the cabinet?
It's the stated point on the spec sheet, no mention of several side by side.
Not more than 1 or 2 Hz, the low corner is determined by the cabinet design.