'Practical' Home Studio Construction in the Nashville Area

Scott H. Hawley, Ph.D.

A work in progress. Last update 06/29/14, 9:08:18 PM.

Process / Algorithm:

  1. Background Information

    1. Acoustics:

      1. Recommended: A course like Physics for AET is a good start, of course ;-). Books like Everest. Free utilities like Room EQ Wizard and SHAART. You can check Auralex's website, which actually offers lots of useful info, e.g. their "Auralex University" and "Acoustics 101" pages. . For $25, you can get Rod Gervais' Build It Like the Pros, a guide for home-studio-building. Or for only $11, you can get Mitch Gallagher's Acoustic Design for the Home Studio.

      2. Not recommended: GearSlutz forums – those guys are presumably brilliant, but advice can range from bizarre to questionable to (often) extreme-overkill and is likely to confuse mere mortals like you and me. Recommended instead: I've found a much more accessible group to be the home theater enthusiasts at AVS Forums; there's a lot of crossover, content-wise.

    2. Electrical: A course like Electronics & Circuit Theory is a good start, and Belmont's Studio Maintenance classes are strongly (and highly!) recommended. When in doubt, hire an electrician.

    3. Real Estate: “The Swimming Pool Analogy”: Hard to believe, but adding a home studio (in a non-removable way) makes it harder to resell your home. It's like adding an in-ground swimming pool: most people have no interest – even in Nashville – and thus do not want to deal with a home with one in it. Thus, all design and construction considerations should be based on the use of low-impact, non-permanent, removable components. Plus, you may move in a few years and ideally you'd likely prefer to take as much of your improvement(s) as you can with you when you move.

    4. Saving money: “The Baby Clothes Analogy”: Just as people who have children can save money by inheriting or buying-used from forerunners who no longer need their 'gear', Nashville has a steady flux of people offloading gear – e.g., absorbing panels, power conditioners – and it may not be necessary to build-from-scratch or buy-new everything on your list.

    5. Every project is unique. Every room is different, each location unique, each person's set of circumstances and resources will differ somewhat. Not everyone desires the same outcomes, nor is willing to make the same compromises. (Corollary: What worked for others may not work for you, given these differences!) This is where expertise comes in: the ability to adapt and make choices to effect a particular end. Nevertheless, we will attempt to emphasize some common tasks.

    6. "What if I'm a renter?" At this time, and given the number of modifications to the home that are necessary, this guide doesn't contain a whole lot that renters can implement and expect to get much of a return from. (e.g. you can hang absorbent panels but if you don't isolate, what have you really gained?) I hope in the future to tailor more information that renters can implement, but for now, this document is really an organized/generalized history of me-learning-how-to-build-my-home-studio. There's always the option to ask your landlord if they'd mind you making some improvements! Perhaps they'd even assist with some of them, e.g. for electrical upgrades if they are needed.

  2. Specifications (Intended Use & “When's Good Enough”)

    1. What will you use the room for? (Mixing, mastering, recording, …?)

    2. You're probably not going to be able to do much about the low end...more later

    3. Very rough ballpark of budget: do you have hundreds, thousands, or tens of thousands of dollars to spend? You may not actually want to know what this is going to end up costing you ;-). Much of this work can be done progressively over weeks/months/years, and thus the total cost can be spread out.

  3. Assessment (Measuring Existing Space)

    1. Physical Dimensions

      1. Tape Measure

      2. MagicPlan App (e.g., LifeHacker article.)

    2. Acoustical Measurements

      1. Room Eq Wizard

      2. SPL meter

    3. Identify problems -- this section is brief because I already know and teach this stuff ;-)

      1. Frequency domain: Modal frequencies

      2. Temporal domain: Impulse response, early reflections

      3. Spatial domain: Locations of nodes & antinodes

  4. Design

    1. Speaker Placement

      Where do you prefer to sit? That's the main question.

      It's best to space the speakers away from the walls by a couple feet. Will add more later.

    2. Room Shape & Dimensions

      Boxy ain't bad. Actually the “build walls at wonky angles” design method is not only unfeasible for resale reasons, but also many acousticians are actually favoring rectangular rooms nowadays. Reason is, they allow for easy calculation of acoustical behavior and methods of treatment. Thus if you have an L-shape or an extra-space coming off on some side, consider walling it off – either partially to create a “leaky wall” for bass trapping, or completely with a heavy door – and turning the extra space into a utility closet or vocal booth.

      It may be that actually shortening one of the room dimensions will produce better distribution of modal resonances (ala the Bolt Area and/or Bonello Criterion). Here are a few useful room mode calculators...

      Bob Gold's Room Mode Calculator
      AMROC Mode Calculator

    3. Placement of Absorption

      Early reflections: Get a mirror, get a friend...

      Corners...

      How dead/live do you want it? This goes back to Specifications. If it's for mixing & mastering, dead is great. If it's for recording vocals or acoustic instruments, do you want any natural reverb, or will all reverb be applied in post via reverb plugins? Incidentally, convolution reverb technology has become phenomenally good.

    4. Mock-Up

      SketchUp is a great tool for 3D design. Via the “3D Warehouse” feature, you can search for others' studio designs and copy & paste into your own. Here are some examples. SketchUp can also export into more industry-standard CAD formats for use with Simulation (below).

    5. Simulation

      Low freqs: Boundary Element Method. AcouSTO.

      High freqs: Ray Tracing. Check out the 3dB Realtime 2D Raytracer. Also, this Blender Plugin: http://www.explauralisation.org/

    6. Aesthetics (or “Making it Look Cool”)

      I'm including this because I know almost nothing about interior design. Having a space which is visually appealing and inspiring is important for the creative process – pro engineers recognize this. How to get this without hiring a designer? One suggestion is “get a feel for what you like,” which I break down thusly:

      1. Look at others' designs. Use the internet to look at other home studio designs. Google Image Search and the aforementioned SketchUp 3D Warehouse are good sources. Even those ancient devices known as magazines.

      2. Inspiration while shopping. Again, you're just looking around and seeing what grabs you. This can be done online or in stores. A few recommendations:

        1. IKEA. Nashville has no IKEA, but the catalog is online. Also, Atlanta and more importantly Austin have IKEAs. (Walking into the lamp section at IKEA was awesome. I could buy every lamp they sell.) Nashville also has the store ModernNash, which is essentially a they-go-to-IKEA-and-get-it-for-you service.

        2. Pottery Barn Kids. No joke, a multi-Grammy-winning producer said this was one of his best sources. (Not necessarily creepy?) YMMV.

        3. West Elm (across from Whole Foods in Green Hills) is overpriced but may give you some ideas.

      3. Colors. Again, feel free to skip this if you have a clue; I did not. Lots of studios incorporate red, often via red walls or red panel absorbers. Is it overused? Maybe, you be the judge. Is it effective at producing a cool vibe? Hells yea.

        Note:When you put in absorbers, it is not necessary to use the stock gunmetal-black. You can buy fabric in a variety of colors, or even use fabric with artwork on it. Check out this great thread on using an image-printing service to produce designer fabric screens for DIY absorbent panels.

      4. Leverage friends. Turns out some people just love to decorate, especially if they're not spending the money. A pro interior designer friend may give you some free tips or feedback if you're cool about it, however you may have other friends – and dare I say, particularly it seems, females – who would love to help you figure this **** out and tell you what to do. For free.

  5. Construction

    1. Electrical

      Often this work is done DIY, without licensed electricians. There is, however, no substitute to having someone who actually knows what they're doing, when it comes to the future of your safety and your equipment's integrity. Do not be afraid to hire out this work -- preferably someone who has experience (/a clue) when it comes to home studio installation; asking fellow engineers to suggest electricians is a good way to choose.

      Must have: actual grounded outlets, preferably on dedicated circuit(s) for the studio.

      Do not want: GFCIs, dimmers, multiple grounds.

      Nice to have (“If you're doing all that work anyway...”): Surge-protected breakers, acoustical deadening clay & caulk around the outlet-boxes for sound isolation.

      Probably don't need: Fancy grounding schemes, power conditioning, transformers, TVSS, etc. Such arcana are fascinating and intimidating, however... Consider these on an as-needed basis, should problems arise, but most users will not find them necessary. If you just have to have a power conditioner, check used resources (Craigslist, Ebay) as these units hold up well over time; for new, Furman products from Sweetwater are a popular choice.


    2. Isolation (i.e. “Soundproofing”) – Reducing Transmission

      "For sound isolation there is no substitute for heavy, airtight construction, regardless of how you finish it." -- Richard Schrag, Broadcast Engineering, March 1992

      Assessment & spec questions: a) What external sources do we need to isolate from, and are these outside the home (cars, lawnmowers, airplanes) or inside (spouses, children, pets)? b) What external listeners do we need to protect from the noises we'll be making in the studio, and what are those sources (drums, electric guitars, loud speakers)?

      "Heavy": Mass stops sound, empty space also stops sound. Is this a paradox? I'll add more here later... (Related: Solid things can stop sound, but solid things can also conduct sound really well... )

      "Airtight": Sound isolation is tough because, the fact is, even a tiny hole can (and will!) let through enormous amounts of sound. (Yes, the frequency content depends on the size of the hole, but this is immaterial at present.) Obviously, one needs to plug holes and cracks that exist, and not allow subsequent modifications (e.g., utility work like HVAC ductwork or electrical) to introduce new holes, but this fact has two other important practical implications:
      1. It may not be possible to evaluate independently the effectiveness of individual isolation components; i.e. each piece of isolation work will have a "bypass path" available around it until all measures are in place and all such paths have been cut off.
      2. 'Awesome' isolation products may be rendered no better than 'inferior' products (including "nothing") if meticulous attention is not given both to the details of that product's implementation (e.g., seals, cracks) and to the 'big picture' of other 'vulnerabilities' affecting the room elsewhere. In plain English, one can easily waste money and effort on ineffective piecemeal-overkill.

      Places to add isolation: (note to self, reorder these as per Flowchart below.)

      1. Windows

        It's not necessary to fill in the windows with opaque material. Adding another pane can help immensely. New actual-windows are expensive, but a removable sheet of some material works well. Recommended to get clear mass-loaded vinyl, and mount that in addition to existing windows. Here's the cheapest I've found so far. Don't forget to get some mounting hardware.

      2. Doors

        Heavier is better, with all air gaps sealed via weatherstripping and/or caulk. (Again, plenty of websites & videos on how to do the sealing.) Solid wood or solid-core doors, 1 3/8” at least, preferably 2”. Word on the street is that a simple flat door beats a sectional/paneled aesthetic door, chiefly because these panels occur in the form of indentations which decrease the thickness of the door in those places, thereby reducing its effectiveness for isolation.

        Problems: Heavy doors are expensive, solid / solid-core doors are not sold anymore at Home Depot or Lowe's, and hanging your own door is hard compared to using a pre-hung door.

        Solution: The Habitat for Humanity Store: “ReStore” in the Gulch! There you can find & buy a used heavy door, on the cheap. You will still need to learn how to hang your own door ;-). Check YouTube again.

        908 Division St
        Nashville, TN 37203
        (615) 942-1292
        http://www.habitatnashville.org/restore

        One other solution: In case Habitat ain't happenin' for you, some people have had success “building up” the thickness of an existing door by attaching layers of drywall or MDF. This can work. Just be sure the hinges/frames will support the new weight, because it will be significant. (Do NOT: try to fill a hollow door with sand; the sand will exert pressure which will break the door apart from the inside, and you'll end up with sand everywhere.)

        Update: As a bit of an experiment, I just bought a Masonite "SoliDoor" pre-hung, noise-attenuating door from Home Depot for $99, for another part of my house, because they had it in stock and I didn't want to wait around to have a door shipped. Unfortunately, the door had to go in in a bit of a hurry, and I didn't have any insulation materials on hand to place (or extrude) inside the door frame -- it's just empty space in there. I will still run weather stripping and caulk and let you know how that works (if at all, lol). Given that "the devil is in the details" when it comes to isolation, it may be that such a door, properly sealed, would be adequate for many home studio applications, i.e., given the other 'gaping' isolation problems that are likely to exist with other aspects of the home studio, perhaps maxing out on a giant oak door would not offer much improvement over the "SoliDoor." To be continued...
        Regarding the Masonite Solidoor, one user has said "...those doors are on every interior door in my house. When I did my basement I ordered them to match. They are durable value solid core doors. From a pure soundproofing evaluation I would rate them as 5-6 on a 10 point scale" (from AVS Forums). Not sure what constitutes a 10 in that author's mind, but...there you go.

        Another update: For my studio, we ended up buying a solid 2" slab from Home Depot, and cutting it to size -- putting Bondo(tm) to seal and harden the side that was cut, since it's exposed particleboard -- and hanging it on heavy hinges within a pre-fab exterior door framing kit that came with weatherstripping pre-installed.

      3. Walls

        Building new walls is generally not recommended for homeowners who might wish to resell. But adding layers of drywall is ok. :-)

        Add one or two additional layers of 5/8" drywall, with Green Glue acoustical isolation glue in between the layers. (This combination is so common for home acoustical isolation, you'll often see it referred to by the abbreviation "DD+GG" or "DD/GG," short for "double drywall plus green glue.") The layers of drywall should not share the same seams, so either rotate each successive layer by 90 degrees, or else stagger the locations of the seams for different layers. Install each layer first before moving on to the next (i.e., don't green-glue two layers together first and then put them on the wall).

        You can buy 5-gallon buckets of Green Glue from Wallboard & Supply on Charlotte:


        1619 Charlotte Ave
        Nashville, TN 37203
        615-320-7900
        www.wallboardsupply.com
        Update: Nah, you can't. They'll say they can only special-order it for you, BY THE PALLET-FULL. Whereas Insulation Supply Co. are awesome and a joy to work with, the guys in the office at Wallboard Supply are notoriously unhelpful in general. :-( Green Glue buckets will ship for free from Amazon, so....

        To be clear: At this point, advice from experienced, Grammy- and Dove-winning engineer friends is that they have found fully adequate performance just via DD+GG, without building a whole "box within a box" as is commonly viewed as a requirement. YMMV. Remember, circumstances are different...

      4. Ceiling

        You probably won't have high enough ceilings to drop them much and add insulation. But as with walls, a couple layers of drywall (rotated 90 degrees or staggered) with Green Glue, can work well. Note that the ceiling can also be used for low-frequency absorption. See Mitch Gallagher's interview with Sweetwater (see References) on making the ceiling “bouncy”.

        When adding drywall for a ceiling, do not try to do this without renting a drywall press for this job or else just hiring a pro. Otherwise you will go crazy.

      5. Floor

        "If your customer has a vented crawlspace with insulated ducts and no pipes, they likely have noticed their cold and noisy floors. The best solution for both the thermal and acoustical problems is to insulate the floor above the crawlspace." -- Owens Corning website

        Many engineers and artists have not found the need to do anything to their floors. My floor will probably need something, however, so expect more text here in the future...

      6. Edges/Cracks -- "Airtight"

        It is astonishing how much sound will go through even a tiny hole! This will render valiant isolation attempts nearly worthless. Cracks need to be sealed if you want your other soundproofing efforts to not be in vain. Caulk. Lots of caulk -- and "caulk" here really means USG Acoustical Sealant, or OSI SC-175, or Green Glue's caulk or the like, something which will stay supple and not harden over time, not just regular general purpose silicone caulk (which WILL harden). Whatever you can find a good deal on, e.g. $3 to $6 per tube (NOT $15/tube for QuietSeal Pro), probably at Nashville's Wallboard & Supply. Any type of edge where one thing meets another thing? Yea, “caulk that shit.”

        Electrical boxes are a source of noise leakage. You'll hear about putting clay or putty around the boxes, which is nice if you can actually get behind the boxes. When it comes to existing electrical boxes where you don't have easy access without ripping out walls, caulk around them as best you can using acoustical caulk. These gaskets may also prove helpful but I have no information on their effectiveness. Similar rubbery gaskets are sold for waterproofing, e.g. at Home Depot, and may be adequate as well.

      7. Ventilation - HVAC

        If your room is primarily for recording and some light mixing, just turn off the HVAC when you record, get anyone on connecting vents to temporarily quit making noise, and save gobs of money. Seriously, "you don't want to have to go there."

        If you're going to be mastering and doing lots of mixing -- i.e. spending lots of time in the room, where noise reduction is crucial, then you may need to do some ventilation upgrades, either to quiet the existing ventilation or running new, quiet, ventilation. Let's put a pin in that...

        Here's a “common sense” note which is often overlooked: once your room is airtight, the only way air will circulate is via the vents – both the blower and the return vent. The air will literally not get replenished as it naturally might in other 'regular' rooms. Oh, your room doesn't come with a return? Guess that blower's not going to work so great anymore -- but hey, you were going to have to turn off the HVAC while recording anyway. Just remember to open the door from time to time in order to get oxygen to breathe. A small quiet fan may also be in your future.

        If you would like to build new ventilation,...stay tuned. (I'm hoping not to have to do that!!)

      8. Resources re Soundproofing

        Now go read the entire four-page article by Richard Schrag from the March 1992 issue of Broadcast Engineering. (Note that this was written before Green Glue products became popular; it is true, as he says, that direct-coupling added layers of drywall will actually reduce the STC of the wall. This is not what we are going to do.)

        Now check out Matt Risinger's YouTube Video: "Cheap Soundproofing Tricks.

      9. Prioritized Flowchart for Conserving Effort/Money
        1. Listen and Look. Can you identify where then sound is getting in/out? If so, skip down to the item that applies. Or else just move on to step 2.
        2. Cracks. Seal/treat doorframes, window frames, drywall, moulding, etc. Then return to step 1.
        3. Windows. Then return to step 1.
        4. Doors. Then return to step 1.
        5. Walls. Then return to step 1.
        6. Ventilation. Then return to step 1.
        7. Floor. Then return to step 1.

    3. Absorption – Reducing Reflection

      Recall "intended use": If you want any physical reverberation at all in a small room, you may not want to go guns-blazing into building a set of absorbers. This author is likely to be recording lots of acoustic guitar, but is unlikely to be mastering or mixing bass-heavy hip-hop. Reverb plugins have come along way, though, so perhaps resigning oneself to always playing in a dead room and using reverb effects will be the way to go...

      1. Porous, Panel Absorbers:

        Any number of YouTube videos and websites will instruct you on how to build 2'x4' panel absorbers using mineral wool / "rock wool" or else Owens Corning 703 fiberglass. See, e.g. HomeStudioDAWG's video: HomeStudioDAWg: roxul, video. Try Google for more. When it comes to purchasing the insulation, go to

        Insulation Supply Company
        1400 Davidson St.
        Nashville, TN 37206
        615-425-2700
        http://insulationsupplycompanynashville.com/

        (Only two types of people shop there: pro builders/contractors, and DIY audio engineers. The people working at the store will identify you on sight.)

        One question that gets asked: “Which should I use – mineral wool or 703?” Their acoustical properties are pretty similar. Typical mineral wool is “messy” in that it crumbles somewhat while you're trying to work with it, whereas fiberglass is “itchy” in that you better cover up good but it offers easier rigidity than mineral wool. Mineral wool can be quite a bit cheaper than 703, e.g. by a factor of two for Roxul AFB, but superior grades of rock wool are available which cost about the same as 703. Roxul Safe'n'Sound insulation is available at Home Depot, in a pack of twelve 16"x47" pieces. Typically people build panels using the 2'x4' form factor, but there's no reason not to use the narrower insulation. A couple friends have said rock wool is "not that messy", and despite being nowhere near as rigid as 703, still is easy to work with and won't make you itch. So, the answer is: Whatever you want.

        Note: thicker is 'better'. Meaning: Adding thickness will not add to high-frequency absorption, but will allow greater reach into the lower end of the frequency spectrum. 4 inches is a great thickness to use. Also, adding an air gap between the wall and the porous absorber is recommended. How much? See Everest, or just try a couple inches.

      2. The Cloud. This is a just a small set of (typically absorptive) panels hung (typically at an angle) above the console and/or mix position. Put some hooks in the ceiling, and and then hang the cloud from these.

        Note: The cloud will probably now be blocking and obscuring whatever ceiling light fixture you had originally. Solutions: Install track lights in the cloud itself or in the air gaps between cloud panels. Might as well remove the original ceiling fixture and wire up your new cloud-lighting to where the ceiling fixture was, that way you can operate the lighting from the wall switch. Also put lamps around the room and on/near the console.

      3. Bass Absorbers...to be added later. For now, see Everest.


    4. Diffusion – Scattering Reflections (at the price of Time-Domain spreading)

      Do not try to kill yourself building a 3D (hemispherical) DIY lots-of-little-pieces-of-wood quadratic residue or primitive root diffusor. It will be heavy and take forever. But you are arguably going to want diffusion. Plastic or foam products can work for high-mids and up, are relatively inexpensive and are easily transportable when you move. See for example the Auralex diffusion products.

      What about the low end? Repeat to yourself, “I are not going to be able to do much about the low end.” There are designs out there for “bass diffusors.” Use at your own risk.

      If you want to build, start with a 2D (cylindrical) primitive root diffusor.

  6. Post-treatment Assessment

  7. Case Study: My Home Studio

  8. References / Resources

    1. absorbers: HomeStudioDAWg: roxul, video. poplar strips, roxul rock wool, broadcloth fabric

    2. video: mitch gallgher, sweetwater project studio build

  9. Acknowledgements

    Everything in this guide comes from someone else. Nothing should be regarded as original, except perhaps the synthesis itself. Most of this work was assembled through interactions with Justin Dowse, Luke Gilfeather and Sal Greco.

    Apologies in advance if I leave anyone else out. I've received helpful input from so many: Sam Neff, Shane Wilson, John Strickland, Alison Moore, Mike Janas, Mike Poston, Scott Glasel, Steve Allen, Lance Alvis, Stacy Scruggs-Gilfeather, Drew Ramsey, Rex Paul Schnelle, Dave Tough, Greg Bieck, Mark Covert, Matthew Burgess, Beverly Wilson, Marshal Myhan