What do personal studio owners need to know about speaker placement?
Manzella: Speaker placement is the single biggest thing you can change in your room to address problems, especially bass problems. There’s a couple of factors that come into play, and the biggest one is speaker boundary interference, especially in a small space.
The distance that the low-frequency speaker is from all those boundaries—the walls, the floor, the ceiling—creates a series of potential cancellations at the mix position, and the closer you put the speaker to the corner, the more bass you get. You’re shortening a couple of those path lengths to the two sidewalls, so those two reflections cause higher frequency cancellations and they don’t cause low-frequency cancellations. In a corner, that speaker gets reinforcement from all the modal energy in the corner. And this is the most common call I get: “The bass isn’t right. I’m having trouble translating my bass. I’m having trouble hearing the bass.”
One of the biggest things they can do is experiment with speaker placement, and the best way to facilitate that is to get the speakers off your furniture and get them onto some stands. Whether you’re listening on 6-inch two-ways or 10-inch three-ways, getting them onto stands gives you the flexibility to move things around more without necessarily having to move your whole rig.
When somebody hires us, obviously, we measure everything, and we will experiment with different speaker placement to try to find the flattest low-frequency response, but this can be done by ear, too. If you’ve got a good ear, you can move the speakers around and find a pleasing amount of bass that sounds even. What I discourage people from doing is trying to do this with sine waves and an SPL meter. You play any pure sine wave, and you’re going to walk through nulls, peaks and valleys. Any room does that. The key is not having a whole bunch of valleys at the same place. You don’t want to have a dip at 60 and 80 and at 100 all in the same place.
Another thing that’s good to have is one of these inexpensive realtime analyzers that are available for iPad or iPhone these days. Of course, their weakness is always low-frequency [information]; if you try to use the built-in mic on an iPhone or iPad, you’ve got a lot of roll-off below 60Hz, so if you’re trying to get information down in those lower couple of octaves, you’re going to have problems. But I just got a really neat interface for my iPad called an iAudio Interface 2, and it allows me to plug my measurement microphone directly into the iPad.
Pelonis: Moving things around without having something to tell you what’s happening as a result of the movement is a big mistake. You want to get a microphone that is reasonably accurate and software like Fuzz Measure or Smaart Live, for example. You’ve got to start with a really solid barometer of tools.
Boundary interference is really important for people to understand. Low frequencies are somewhat omnidirectional; they don’t just fire out with a trajectory from the front of the speaker the way the other frequencies in the spectrum do. They fold out and go around the sides and back—they go everywhere. So, if you have a speaker that’s standing somewhere in the middle of the room, or not flush with the wall, the low-frequency energy goes behind the speaker and to the sides of the speaker, and then it regenerates off of the surface of the boundaries, and it arrives at the listener at a different time interval. That causes a deviation in the frequency response as a result of that phase information.
Grueneisen: In many cases, proper speaker placement just comes down to some basic ground rules. Maybe the most important thing is that there is symmetry to the room, so that the speakers are set up along an axis that is as symmetrical as it can be, and that means that the distance to the walls is the same on both sides, that the room itself has symmetry to it so it doesn’t, for example, open up to a very large area on one end and is really confined on the other end.
If the room is not arranged symmetrically, it will distort the information you get from the speaker, because the room interacts with the information so much. The bass response can be very different in that case, and on a higher-frequency level, you would have very different reflections; you would have very different room modes. The distance to the wall affects the time that the sound takes to be reflected back, so if it’s not symmetrical that time will be different to different walls and different elements.
Are there any prefab or DIY solutions you would recommend to correct acoustical issues in a room?
Manzella: We work a lot with RPG, so I tend to default to their products. They make a selection of off-the-shelf low-frequency absorber products, including their Modex series, which are membrane absorbers that are covered in fabric. They make triangular-shaped ones for corners. They will tune them at specific frequencies, so if I measure the room and notice that there’s a particular buildup at 63Hz, we can buy traps tuned for 63Hz. They will also build them in flat boxes; the depth depends on what frequency you’re talking about, but it’s the kind of thing we can hide in ceilings, so I end up recommending their products quite a bit.
One thing I think that everybody needs in their small room as well is broadband bass trapping—not just tuned bass trapping. This is also on every DIY site out there: Put a bunch of rigid Fiberglas behind fabric in a framing system, and put that in a corner. There’s a lot of low-frequency information congregating in the corners of every room. So if you put in some Fiberglas and porous absorption, you’ll turn a lot of that energy—through molecular friction—into heat, and you’ll calm down a lot of that low-frequency information that’s bouncing around in and building up at the boundaries and corners. That will always help; you can’t have too much of it. A popular misconception is that if there’s not enough bass in my room, I have too much bass trapping. No. If there’s not enough bass in my room, I don’t have enough bass trapping.
Pelonis: If you look at those Modex Edge products on RPG’s website, you can download their brochure, and you’ll see the performance specs. The results that are plotted on graphs are actually of a room that I did. This product isn’t super cheap, but you can see how it very gradually transitions from reflection to absorption as it gets into the lower frequencies, and you don’t have a bunch of big dips and peaks and valleys. Most low-frequency devices don’t do that. They’re peaky, or they have big holes and they’re not gradual, and the idea is that, because this thing is faceted, it causes dispersion, say, on the back wall; it very gradually transitions from low-frequency absorption and high-frequency dispersion, and you get really natural responses.
If you can’t afford to buy RPG products, you can build your own makeshift Home Depot low-frequency absorbers. One of the best ways to do this so that it’s not lumpy is to get a product like Bonded Logic; it’s nontoxic cotton insulation [bondedlogic.com]. You can just sort of stuff that in the corners a couple of layers deep and put a piece of stretch fabric across the front of it, and although it’s not going to transition into diffusion the way the Modex Edge product does, it will settle down the low-frequency modes considerably.
Grueneisen: There are a lot of manufactured acoustical products now, and I think that’s been getting better over the years. Magazines like Mix and Electronic Musician are actually a great resource, as well as the Internet—look at the ads and articles and see what’s out there. You have to be careful, though, because with these manufacturers, their one main goal is not necessarily to give balanced advice—they’re primarily selling products.
What about low-cost solutions for isolation issues?
Manzella: When it comes to low-frequency isolation, the long and short of it is, it’s mass and airspace. If you don’t build another room inside the room, the question becomes: Can I double the mass of all these walls? Because looking at it really simply, if you double the mass, you cut the amount of sound transmission in half. But doubling the mass of an existing wall is often not that easy. I look at a lot of older apartments in New York City, and a lot of them are plaster and masonry walls—you can’t double the mass of it without building another wall. So what can you do?
You can hang a ceiling if the ceiling height allows for it. That will certainly partly address transmission to above and transmission from above. Other than that, the only thing you can practically do is to address the openings—the windows and the doors. You could put a better door on. You can put door seals around the perimeter and the bottom of the door; that costs about $500 a door opening, so it’s not outlandish. As far as the windows go, if it’s your place, you can upgrade the windows to newer windows, which generally use better-insulated glass. You can also consider putting in a secondary set of windows, particularly in a city, where you have more of a problem with outside noise getting in.
There are a couple of companies selling secondary window systems that we often recommend. The one we most use in New York is called Cityproof (cityproof.com). They build to order what are basically miniature sliding-glass doors on a 1-inch track. They’ll put up to half-inch glazing on it, so when properly installed and sealed, it makes quite a bit of difference.
Pelonis: Quiet Rock [soundproofing drywall; quietrock.com] is very good. Green Glue [noiseproofing compound; greengluecompany.com] works. RPG and Kinetics [kineticsnoise.com] and Mason [mason-industries.com] have some different types of channel clips that work nicely. I’ve been using RPG’s CDM system a lot lately, and it’s very good; that can help you with your wall isolation.
There are a few different isolation matt materials that you can lay down on a floor—put down a couple layers of something dense like cement board and MDF over that. Then there are the spring or puck isolators that end up giving you a 4- or 5-inch-thick floor, and those work pretty well. Or you can go so far as to actually pour a concrete slab over the isolator so that you have multiple layers of isolation and density and mass, but that’s an expensive solution.
As far as doors and windows, Pemko [pemko.com] makes acoustical hardware that seals the door much better. You can also take matt to that door on both sides, like barium-loaded vinyl or even drywall; just putting more mass on that door will help. I’ve also taken those barium-coated vinyl to create flaps around the perimeter of the door, so when the door closes you’ve got this flap going over the seal. It’s not going to seal it, but it is going to put a barrier in front of the source.
On windows, you want to use laminated glass, not dual-pane. A dual-pane window does a lot for thermal, but it doesn’t do a lot for sound.
Grueneisen: I think the isolation is always the biggest issue for a personal studio because it’s usually more costly to do something really effective about isolation problems if you are too close to a neighbor or a bedroom. Room selection is really the most effective tool to help with that, to put something in the right space can save a lot of money in the long run.
Your doors and windows—anything that’s a weak spot—are the first things that should be treated. Put seals around the doors, so there’s as little as possible air exchange when it’s closed. And in addition to that, create intermediate spaces—what would be called a sound lock. If you could have a hallway with doors on both ends, that is very effective rather than just having one door. If you just have one door and somebody opens it, it’s no longer there.
Other openings that are sometimes ignored are where you have your air conditioning. The ducts connect to other rooms, and the sound can travel through those ducts. Ideally you would have a separate air-conditioning unit for that space. And even here in L.A., you sometimes need to heat the space, but the equipment will need cooling all year round, so you can’t actually use the same piece of equipment to do both at the same time. To really solve it, for a single space you might need two units.
Speaking of isolation, what do you suggest to clients who want to track drums in a smallish personal studio?
Manzella: Go to a big space. Often, I tell people, “Just don’t do it.” If you’re going to maintain your situation—whether it’s residential or commercial—with your neighbors, and you’re not going to spend a couple hundred thousand dollars on isolation, you’re going to cause anxiety with your neighbors and you probably won’t be that happy with the results.
Pelonis: You would definitely need more professional advice in this case, but I’ve personally recorded drums in rooms that were 250 or 300 square feet, and they sounded great, but the rooms were well treated. Again when you get in those spaces, the low-frequency control is going to be pretty important, and then achieving the sound you’re going for—the right amount of diffusion, absorption, reflection. It really would be best to hire somebody to help with that, because you could spend a lot of time and money building things and tearing them out, and that’s not necessarily what you want to do, right?
Grueneisen: I would say, be really nice to the neighbors! [Laughs.] You know, it can be tricky when you’re being really loud next to other people. The first thing is definitely going to be isolation, and I think all the other things we talked about apply here except even moreso: how to seal your openings, how to position your space, how to schedule when you’re recording or playing—it’s just a more extreme version of everything else. But like with everything else, people are very resourceful in the industry these days and they do things that awhile ago wouldn’t have been possible.
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