Acoustic Treatment for Club/Bar/Restaurant

I wasn't sure if I should post here or in "Acoustics" but... I'm playing in the house band for a new supper club that will open in the next couple of weeks. This place will be an upscale, fine dining and dancing establishment. The band has rehearsed in the club a few times and there are concerns about us being too loud. I don't think we are playing very loud but the place is nothing but hard, reflective surfaces all around and parallel walls. I'm sure just having people in the place is going to help quite a bit but I thought it might be a good opportunity to do some acoustic treatment. The owner wants to do it but he really doesn't know the much about this stuff. I'm no expert but I know this is the place to start. I'd like to help him come up with a plan because as of now he is thinking of just buying "some foam or something off of eBay". I explained to him we could make some absorption panels that would look good, be effective in controlling the sound, and not cost a fortune. I'm thinking some broadband absorbers all around the room and some sort of cloud above the band which could also house some lights would be helpful. Not sure if bass traps would be needed. I need to show the owner some examples of the type of treatments I'm suggesting because he seems uncertain about my ideas. He thinks a cloud would not look good. I plan to show him the Buddha Bar pics from this thread: viewtopic.php?f=3&t=12354 I would really appreciate some input from the folks here regarding how to approach treating this space and maybe some links to examples of good looking panels/treatments in general I can show him. I don't have details on the space yet. I know I need them and I'll get that stuff very soon I just thought I could get the ball rolling with this video which gives some idea of the space and the sound in the room: http://www.youtube.com/watch?v=3kOfDFPPvwM

The treatments that John used in the link are not a broad band type cloud, but is a hard faced diffuser with absorption in the back. Maybe targeted at a specific frequency. Does this room you are in have an acoustical tile ceiling?

...as of now he is thinking of just buying "some foam or something off of eBay".

:shock: :ahh: :!: :cen: :cop: Whew!

I'm thinking some broadband absorbers all around the room and some sort of cloud above the band which could also house some lights would be helpful. Not sure if bass traps would be needed.

For that kind of problem, I'd start by doing a proper analysis of the room as it is right now, with REW or something similar, to find out where your real issues are, before you start treating things that might not need it, and not treating things that do. That said, just putting panels on the wall wont necessarily make you guys any quieter! It will only help if there is an acoustic issue with the room itself, but not if the underlying problem is that you are too loud. The only thing that will tell you that for sure, is to measure yourselves with a real sound level meter, to see how loud you are. There might also be structural issues going on, in the sense that the drums and bass are pumping vibration directly into the building itself. It's hard to see from the video, but it looks like the drums are on a riser of some sort? If so, is it an properly designed fully decoupled acoustic riser? Or just some bits of stuff thrown together to lift the drums a bit higher? A good drum riser and a pad for the bass cab could do wonders to keep that kind of flanking issue out of the picture. But I'd start by measuring: both yourselves, to see how loud you are, and the room, to see where the problems lie. - Stuart -

Thanks for the responses guys.

xSpace wrote:

The treatments that John used in the link are not a broad band type cloud, but is a hard faced diffuser with absorption in the back. Maybe targeted at a specific frequency. Does this room you are in have an acoustical tile ceiling?

Yes, those hard faced diffuser/absorption panels are a different beast and too complicated I think for what we can do here. I would just like to find some pictures of the type of treatments I'm thinking of to show him. I'm not sure if there are acoustic tiles but I will find out tomorrow.

Soundman2020 wrote:

I'm thinking some broadband absorbers all around the room and some sort of cloud above the band which could also house some lights would be helpful. Not sure if bass traps would be needed.

For that kind of problem, I'd start by doing a proper analysis of the room as it is right now, with REW or something similar, to find out where your real issues are, before you start treating things that might not need it, and not treating things that do. That said, just putting panels on the wall wont necessarily make you guys any quieter! It will only help if there is an acoustic issue with the room itself, but not if the underlying problem is that you are too loud. The only thing that will tell you that for sure, is to measure yourselves with a real sound level meter, to see how loud you are. There might also be structural issues going on, in the sense that the drums and bass are pumping vibration directly into the building itself. It's hard to see from the video, but it looks like the drums are on a riser of some sort? If so, is it an properly designed fully decoupled acoustic riser? Or just some bits of stuff thrown together to lift the drums a bit higher? A good drum riser and a pad for the bass cab could do wonders to keep that kind of flanking issue out of the picture. But I'd start by measuring: both yourselves, to see how loud you are, and the room, to see where the problems lie. - Stuart -

What you say makes sense and has made me realize that perhaps this would not be the job for me to take on. I don't think I have time in my life right now for learning how to perform then performing acoustic analysis of this room. I just thought there should be some benefit to adding some absorption to the space, even if it wasn't done in a very scientific manner. I do see what you mean about the absorption not making us quieter but what I can tell just from listening in the room is that there are plenty of noticeable reflections and I'm sure that has something to do with the owners wife saying how loud it sounds to her. I'm certainly not as experienced or knowledgeable as you guys when it comes to acoustics and I know it's not intuitive stuff but I have been around live music my whole life and I know this band is not excessively loud. I could take the SPL measurements but would that really be of much use? I mean, we can bring it down a little but basically the band is gonna play how it's gonna play. I did try to explain to him how that drum riser could possibly be causing problems as you describe but I don't think I was able to get through to him. See, he's planning on getting rid of that and building a different stage. I told him how we might need to think about the design of that stage and consider filling it with sand for dampening to avoid the "drum head effect". I'm not even sure that is a good approach but that is another thing I was planning on researching. At any rate, I don't think I convinced him because he was kind of looking at me like I had two heads. I guess that's my fault because I know very little about these topics, just enough to know they must be considered, but not enough to properly explain them. Not only that but there are building code considerations that would make it difficult to build a "fully decoupled acoustic riser". The stage must be less than 6 inches high or he has to make it handicap accessible. He does not want to do that because it would then take up too much space. I can really only suggest basic, easy to build and install options to him because anything beyond that I don't think he will consider. Also, I really need to find some pictures, plans, and any other visual aides available of anything I suggest because I think that is the only way he will get it.

what I can tell just from listening in the room is that there are plenty of noticeable reflections and I'm sure that has something to do with the owners wife saying how loud it sounds to her.

OK, that makes sense: If you can hear echoes, reverb and resonance, then you do have acoustic issues in there, and even though adding people will help to some extent, you'd need to put an awful lot of people in there to make a big difference! (Most of them would have to be standing on the stage, too... ) I'm gonna go out on a limb here, and suggest stuff without having seen any analysis of what the room is actually doing, but what the hell, I'm feeling lucky tonight! :) (And because I like your music...) So lets look at your options: The drum riser and base cab pad: Easy and cheap. A basic, very simple drum riser can just be something as easy as a 4 inch layer of semi-rigid fiberglass insulation laid on the floor, with a sheet of plywood on top. OK that's not too safe, but you get the idea. Use the "search" feature on the forum for "drum riser" and you should find a few simple, cheap designs. Ditto for the bass cab: some manufacturers of acoustic products sell read-made pads for that (some also sell drum riser kits), but once again you can make your own, exactly like a small drum riser. Where is the bass cab, by the way? I but don't see it in there... Do that, and you will at least be sure that you are not pouring energy into the building structure itself. That takes care of structure-borne sound, leaving only air-borne sound. From the video, it looks like you guys are up close to a wall: What is that wall made of? I'm betting it is hard and reflective. If so, I'd start by putting some thick absorption over that. Maybe 6" of the same semi-rigid fiberglass panels (commonly called "Owens Corning 703", available at most good construction supply stores)., and space it away from the wall by several inches. Put it in wooden frames, covered with pretty much any kind of thin cloth that you happen to like. Speaker grill cloth would be great (but not cheap!). Cover as much of that wall as you can afford to. You could make a few modules and angle them a bit (bigger air gap behind on one side than the other) for aesthetics. Next, you seem to have a window over to the right: hang heavy drapes in front of that. Shine psychedelic lights on it artistically (and also on the modules behind you), to make it look pretty: make a nice backdrop! Also, get that speaker out of the corner! I'm guess that's for the keyboard? Vocals too? The corner is NOT a good place for it: All room modes end in corners, and with the speaker right there, you are probably exciting all of them: Figure out a way to keep the speaker far from corners and walls. That way, you won't be triggering the natural response of the room itself so much. What about the ceiling? What is that made of? If that too is hard and reflective, then follow the same procedure as for the rear wall: thick 703, spaced away from it a bit. The rest of the room isn't visible in that video, so hard to say what to do about it, but at least with that basic treatment you'll be controlling some of the sound at its sources. If you want to convince the owner (and his wife) that this will work, just go "borrow" a dozen or so panels of 703 from your local building supply store, and lean them up against the rear wall and window, at an angle. Bring a sheet of thick plywood too, and do the "el cheapo" drum riser, too. If it doesn't work, take it all back to the store for a refund, and you lost nothing. :) If it DOES work (it will) then you can talk to the boss from a more authoritative position, and get him to splurge to build a proper drum riser, frames for the panels, and also money for the rest of the treatment. This "dozen panels of 703" won't make a huge difference, but it should be enough to be noticeable and make your point. Worth a try, I reckon! - Stuart -

I like the drum riser and bass cab pad ideas. The problem is he is planning to build a small stage that is 5 inches high. He wants the whole band on this stage. We won't be taking up as much space as we are in that video. When he told me about his plan to build this stage I was concerned because I've played on stages have the drum head effect and I did not like it. That's when I suggested filling it with sand and he didn't like that idea because for some reason he wants to be able to move it. I guess I could try to get the drum riser and bass cab pad on top of this stage or would the drum riser idea you suggest apply to an entire stage? My concern is the stage will be built with no consideration of how it affects the sound. To answer your question about where the bass cab was, I think it was right behind the bass player (also the owner, BTW) but he was only using a small practice amp. He will have a big Acoustic head & cab rig from the late sixties I believe for the real setup and a similar looking Acoustic head & cab for my guitar rig. He likes the way they look & sound. I haven't heard the guitar rig yet. He mentioned a few different cabinet options for guitar and bass so I'm not sure if they will be 15's, 10's, 12's or combinations of those, but they will be big. These are solid state amps. As for the walls, yes they are hard and reflective and there are big windows to the side and all around - all the way down that wall and behind the camera where you can't see. He was/is planning to put curtains behind the band but I like your idea to put 703 behind and use the curtains for the windows. I do need to try and get that speaker out of the corner. That is one of the main P.A. speakers. I haven't seen all of the P.A. gear yet and I'm not sure if he plans to hang stuff or use stands. I'm not sure about the ceiling. I will check that out at tonight's rehearsal. I like the idea about "borrowing" some 703 to test things out. I might suggest that and see if it's possible. I wish I could pull that off for tonight but there's not enough time to make it happen.

I guess I could try to get the drum riser and bass cab pad on top of this stage or would the drum riser idea you suggest apply to an entire stage?

Sure! Same basic principle: Just scale it up to the size you need. (but do take into account the total load that it has to support). - Stuart -

Soundman2020 wrote:

From the video, it looks like you guys are up close to a wall: What is that wall made of? I'm betting it is hard and reflective. If so, I'd start by putting some thick absorption over that. Maybe 6" of the same semi-rigid fiberglass panels (commonly called "Owens Corning 703", available at most good construction supply stores)., and space it away from the wall by several inches. Put it in wooden frames, covered with pretty much any kind of thin cloth that you happen to like. Speaker grill cloth would be great (but not cheap!). Cover as much of that wall as you can afford to. You could make a few modules and angle them a bit (bigger air gap behind on one side than the other) for aesthetics. - Stuart -

I know you are suggesting 6" of insulation here but I don't know if that will be possible because of space and money concerns. Actually, I'm not sure about the money part - I think he could spend as much as he wants to but I don't know yet how much he's willing to put into this. Anyway, do you think 4" of 703 (or similar) with a 4" space behind it would be effective behind the band? Can we get away with less space behind the panels? Let me put it another way. What would be the most efficient approach to treat the area behind the band, in terms of saving space and maybe money? Also, with wall panels for the rest of the room - I was thinking 2" 703 with no space behind. Good enough? Or have I not provided enough information to determine that? I wanted to post the details of the room already but the rehearsal planned for Wednesday got rescheduled for tonight so hopefully I'll have that by tomorrow.

Anyway, do you think 4" of 703 (or similar) with a 4" space behind it would be effective behind the band?

Well, it's better than nothing at all! If that's what you can do, then that's what you can do. You might want to build these things as movable "panels", kind of like a gobo. Just a frame with the insulation inside and cloth across the front. Build several of them, and set them up across the back of the stage, but angle some of them just a bit (artistically!) so that the depth of the gap behind them varies. For example, set them up in a kind of "sawtooth" pattern, where one panel angles out slightly, and the next angles back in again- The exact depth behind isn't that important, as long as it is at least 4". So you could angle one panel to get 4" depth behind the left edge, and 8" behind the right edge, and angle the next panel the other way. Or some such. Or even "double-up" in places: put some panels in FRONT of other panels, for even greater depth (especially behind the drums, for example!). If you do build them as movable panels, just make sure that they have firm, steady bases: you don't want them falling over on top of you during the performance! :)

Can we get away with less space behind the panels? Let me put it another way. What would be the most efficient approach to treat the area behind the band, in terms of saving space and maybe money?

As you move the panels closer to the wall they become less effective: Move them away from the wall, and they become MORE effective, and treat down to lower frequencies. Think about what happens when a sound wave hits a wall and bounces back: OK, better: think about how a soccer ball hits a wall and bounces back, in slow-motion: As the first edge of the ball just touches the wall, the ball is still moving at its original speed, but as it "squashes up" to the wall, it both flattens out and slows down very fast. As it flattens out, the air pressure inside the ball rises very fast, and the speed of the ball drops very fast. At some point the speed is zero, the pressure is maximum, and things start going backwards. The pressure gets converted back to speed as the ball starts "unflattening" and accelerating away again. As the ball returns to its original shape, the air pressure drops back down to normal again, and the ball speeds up back to its original speed again. Sound waves kind of do the same thing: as they approach the wall they slow down and their pressure increases. Right at they wall the pressure component is maximum, and the speed is zero. Then as they move away from the wall again, the pressure drops and the speed increases. Insulation works on the speed component of the wave, NOT the pressure component. So since the speed is zero right at the wall, there is nothing for it to work on! So insulation up tight against the wall isn't much use. It has to be spaced away from the wall, where it can work on the speed of the wave, not the pressure of the wave. So the question is: how far away? Well, sound waves are also unlike soccer balls, because they come in different sizes, or rather different "frequencies". Soccer balls only come in one size, but sound waves come in various "sizes". You probably know that there is a direct relationship between frequency and wavelength: high frequencies are short, lows are long. So at one end of the spectrum, you have waves less than an inch long, and at the other end you have waves more than 50 feet long: So you have tiny soccer balls the size or marbles, and huge ones that you couldn't even fit in your whole house. Obviously, for the little tiny (high frequency) waves, they are smaller than the thickness of your insulation, so it doesn't matter for them: even with the insulation right up against the wall, they still feel the full effect, because they are so small in relation to the size of the treatment. But those 50-foot waves? Well, clearly they are HUGE in comparison to the 4" thickness of the treatment, so they won't even see it up against the wall: to them, it just isn't there. Doesn't even exist. It turns out that the important measurement here is 1/4 wavelength: That's where the speed is highest and the pressure lowest, for any given wave so that's the best place to put the treatment. So for a 50 foot wave that makes... umm... about 12 feet! Not gonna happen! that's why it's really hard to treat a room for very low frequencies with absopriton alone... If you put your treatment 4 inches from the wall, you have effective treatment for wavelengths of 16 inches and shorter, which is about 800 Hz. Put it at 6" and you cover down to 500 Hz. 8" takes you down to about 400 Hz: etc. So there you have your answer: move it closer to the wall, and you stop treating low frequencies. Put it right against the wall, and all you are doing is taking the edge off some highs (above 4 kHz.).

I was thinking 2" 703 with no space behind. Good enough?

See above! :) OK, it isn't totally as drastic as it sounds from above: that assumes that all waves hit the panel head-on, at a 90° angle. Most don't. As the angle gets smaller, and they hit it more of a grazing trajectory, the effective distance to the wall is LONGER, which is good. So lower frequencies do get treated, if they hit at a sloping angle, instead of head on. In fact, in realty it turns out that if you space it roughly 10% of the wavelength from the wall then you get decent effect. But a spacing of zero is still not much use! - Stuart -

Did I miss any dimensions being posted? L, W and H of the room. What is the floor and what is the ceiling. Where does he want the stage to go? How about a drawing?

I've been reading about this stuff off and on for several years now but that is the first I've heard of the soccer ball analogy. I like it. Thanks. With the 2", no space panels I was suggesting I was thinking of them only as mid/high frequency absorbers. I don't know how to do the math like you did to determine what frequencies they would affect. These would not be for behind the stage but in other locations around the room where space is at even more of a premium because it affects where tables and chairs and people can be. I believe the mids & highs bouncing around the room are what contribute most to the perception of the band being too loud. I could be wrong though - wouldn't be the first time! :D Eric Best - no, you didn't miss anything; I have yet to provide that info. I hope to post it by tomorrow. The stage will be roughly where the band is in the video I posted but farther back toward the wall behind us, meaning we will be taking up less space than we are in the video.

that is the first I've heard of the soccer ball analogy.

Most likely that's because I just thought it up, in the spur of the moment! :) I was trying to think of an easy way to explain it, and my daughter is playing in a soccer match this afternoon, so I guess some kind of association going on in my subconscious! As with all analogies, it only holds up to a certain extent. Sound waves don't really behave like soccer balls, but it gives you the basic concept.

I don't know how to do the math like you did to determine what frequencies they would affect.

Easy: Frequency x wavelength = speed of sound. So for metric measurements, F x W = 343, or for imperial measurements, F x W = 1125.

but farther back toward the wall behind us, meaning we will be taking up less space than we are in the video.

:shock: But you are ALREADY pretty close to that wall in the video! - Stuart -

No news on this project. The owner didn't seem terribly interested in what I was suggesting and if it's not important to him what's the point? I guess he can only focus on getting the place open right now so maybe we'll do something later. I just thought an update was in order even though no progress has been made.

Thanks for the update! I was wondering what happened here... Maybe his wife (who doesn't like the "loud" part) could be an ally in getting this done right... :) - Stuart -

Yes, she might be but I think we'll have to wait another week or 2 until the place is up and running. Then if it is a problem I think he'll be more interested in hearing what I have to say.