Recording - April 2012 - 26

Soundproofing calls for remedies large and small. Brian Gadson first introduced us to Green Glue (October 2010), and this month he offers more hands-on advice on keeping noises from entering and leaving your studio.—LzR

By Brian Gadson You’ve spent many hours, even days, putting in layers of drywall, insulation, and anything else your budget allowed, to stop sound from escaping and—just as importantly—from entering your studio. But, maddeningly, you keep asking yourself, “Where is that sound coming from?” And, just as maddeningly, your neighbors tell you, “We can hear you...” (and that’s how the nice neighbors put it). Three items that get overlooked In my line of work, I am often the one who gets calls from folks suffering exactly those problems. I go and check on the callers’ soundproofing issues, and more often than not I find the problems in one or more of these three areas: Doors and window seals, electrical outlet and switch boxes, and air conditioning/heating vents and ducts. They either were overlooked altogether, or not adequately addressed. Many of you are trying to get that perfect studio room in your house to work, and some may be fortunate enough to have a separate structure in the backyard. Either way, there is hope here, with a budget in mind. I would like to touch on these three problem areas, in hopes of helping the next person celebrate their hard work instead of going into a mantra of newly thoughtup expletives. Doors and windows For perfect sound control there should be no doors or windows—but you and I know that is not a reality in a studio. I don’t care how good a door or double door, and window— dual glazed or triple glazed—you have: if you don’t have a good seal all the way around you’ll have a big problem. A standard 36" wide by 80" high door has a perimeter of approximately 19', so if you have a 1/32" gap leaking sound all the way around the door, you have the equivalent of a hole in the wall that is 7 square inches (2" x 3.5"), or picture a round hole that is 3" in diameter. Need I say more? Q-lon door seals work well—they come on most pre-hung exterior doors, or you can get their products and retrofit them on top of the door stop with a little carpentry prowess. Products from Q-lon come with a T-nail fin that fits in a precut slot in the door stop. When they wear out, simply pull them out and replace them. You have to install great-fitting door bottoms with this style. Make sure you see no light. (For more, see q-lon.net.) Another good product I have used for retrofit seals is by Zero International. Their Sound Trap Acoustical Gasketing system is a kit which can be retrofitted to the existing door jamb; it is a two-piece design where the actual piece that has the rubber seal on it can be adjusted in and out, to get the perfect compression
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to the door after you have attached it. This is great—as time goes on you can re-adjust the seal to the door to fit as needed. They also have an automatic door bottom that seals as it closes. With door and window seals, don’t fit them too tightly to the point where they over-compress to the door or window, because if you check the specs on these products there is actually a point where going too tight reduces their sound reduction properties. (For more, see zerointernational.com.) Electrical wall boxes Look at a metal electrical box that sits in your wall and see how many holes are on the back and sides. Even if you took the time to caulk around each box to the drywall, once sound leaks through your plastic switch or outlet cover plate (which has no sealing properties) and makes it to those holes, there is all manner of sound leaking through the walls. I looked at a standard electrical outlet box and calculated almost a square inch of a hole that is left open going through the wall if left untreated. Multiply that times several outlets and switches in your walls, and once again—need I say more? Fortunately there are Acoustical Putty Pads (from a number of manufacturers) that make a big difference in this area. A putty pad can be formed around the backside of electrical boxes. These pads are almost like Silly Putty rolled into a flat sheet, and they can be molded tightly to the shape of the box. They stay pliable and are fire-rated for safety. Pieces of these pads can be used for all kinds of little soundproofing details in sealing your various items in your studio setup. (Search the web for Acoustical Putty Pads.) HVAC The air conditioning and heating system is a bit more involved than the previous items we looked at. If the room that serves as your studio is one of several rooms in your house, it is most likely already connected to those other rooms via all the existing duct work. Many duct runs feed multiple rooms, through a main duct branching off into smaller tributaries, so no matter what you have just done to all your door and window seals and wall boxes, you still have an 8" round megaphone sending sound from room to room. The other unwanted side effect of HVAC systems is air noise from the actual air supply blowing into the room through the vents. What to do? There are solutions, and your budget will play a large role in the success rate. One is adapting a conventional HVAC system; the other is installing a newer type, the mini-split system. ~ Conventional HVAC: The best way, from the ventilation, heating and cooling standpoint, is also the most costly (surprise, surprise). If you can afford several thousand dollars, you can

http://www.zerointernational.com http://www.q-lon.net

Recording - April 2012

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