DIY: Building Acoustic Treatment for a Piano Room

The following is a step-by-step explanation about how to build acoustic treatments that are easy, economical and quite beautiful.

Why We Needed the Treatment in the First Place
At our wedding, my wife and I were given by our friends and family contributions toward buying a Yamaha U-3 upright acoustic piano. We fell in love with one at East Cambridge Piano (which is actually in Somerville now!). A couple of months after the wedding when the dust had settled we paid for the piano and had it delivered to our home. We were both so excited about it coming, but when it got to its new home the instrument sounded really different. The tone was still very good, but the rooms reverberations made the piano really loud and at times unpleasant sounding. An acoustic guitar could never play with the piano because the piano would take over the sound in the room.

Laura, my wife, plays piano and performs in a Latin American fusion group called Son del Sur (Song of the South). The group has a minimum of 4 women singers, 1 male singer, 2 percussionists, 2 guitars and assorted other musical snacks. To be frank, they sounded absolutely awful in the room. The sounds were all competing with each other: the voices covered the guitars, the percussion had no where to go but louder and louder. The musicians couldn’t hear themselves or the people they were playing with. Something needed to be done:

This is what the room looked like when we started:

As you can see from the photos, the room is bare except for the piano and the table. The bay window breaks up the parallel walls from front to back and the closet door and the bed room door create a nice diffusion to break up the side walls. The natural reverb is really quite lovely and for a solo instrument (like a violin, vocal or acoustic guitar) the room sounds great. Unfortunately, anything louder than that and the ambiance turns in a noisy, brassy screech.

Based on the shape of the room I calculated that the most important walls to treat were largest flat wall (opposite bottom photo) and the wall above the piano. The goal would be to start with a minimal acoustic treatment and add more later if necessary. The plan was to build 4 panels, 4 inches thick in frames 2 feet by 4 feet. The acoustic absorptive material is Owens & Corning 703 Rigid Fiberglass Insulation. We would then stretch fabric over the frame and the fiberglass to keep the fiberglass from getting in the air and then getting into people.

Here’s how we did it:

The following 2 photos show the wood stock and 703 Fiberglass that we used to build the acoustic panels. The wood is 3/4″ furniture grade plywood from Home Depot which was $26 for a 4′ x 8′ sheet. We ripped in into 4″ strips with my trusty Makita portable table saw. (very dangerous…don’t try this at home kids…we’re professionals…) The 703 stock is 2″ thick 2′ x 4 panels. I bought them at Kamco in Woburn, MA for $80 for 12 sheets or 83 cents per square foot. This is about HALF the price that you pay when you buy it on the web. Do yourself a favor and find a good insulation supply house! (Eat you heart out Auralex! ($3.75/sq. ft)

Here we are setting up our first 45 degree cut for where the corners of the frame are joined together.

Ty Smith cutting the 45’s with earplugs in but without a dust mask:

Ty with earplugs AND a dust mask…Sawdust makes a bad lunch.

Squirting glue on the joint:

Spreading glue with the glue spreader that mother earth gave us:

Using 90 degree corner clamps to hold the corner while we nail the frame together and wait for the glue to dry:

More clamping:

Popping in a couple of 8 Penny finishing nails for over kill at the joint:

Waiting for the glue to dry:

This is what a frame looks like after it has been assembled:

Ty stacking the frames so they can dry completely:

A Jecklin Disk was used to record the ambiance of the room before the treatment went up. Look for the actual before and after sound files in a later post…

Recording the bare room:

Assembling the acoustic panels on the table. The 703 fiberglass was pressure fit into the frames and the material was held in place with friction:

These are some panels that have been assembled but the material hasn’t yet been glued down:

The first panel has been hung, one glued panel is drying against the wall and another panel is being glued closed:

Three panels mounted on the wall in their final locations:

An additional panel mounted above the piano to absorb reflections from the top of the piano:

I hope that this post has helps some people control the acoustic in their music spaces. Please feel free to post links to your own DIY acoustic treatment projects.

-Hendrik

12 Responses to “DIY: Building Acoustic Treatment for a Piano Room”

  1. marty Says:

    looks great and truly easy to follow step by step instructions
    it will be your plan i use so thank you

    marty STP-studios

  2. Bias Says:

    What sort of material did you use to cover the insulation? Did you have to pay attention to how reflective the material itself is to stop high frequency reflection?
    Great step by step post by the way.

  3. Hendrik Gideonse Says:

    The material that I used is a nice cotton material that is pretty breathable. The thread count is low enough so that you can breath air through the material, but not so loose as to visually seem open. If this was a commercial space you would have to use a fire-rated material like the material from Guilford of Maine. http://www.guilfordofmaine.com/. They make the material for most of the commercial acoustic panel companies out there. The material in this case was about $9/yard and looks really great, but I have had really good luck with raw burlap which can be as cheap as $2/yard. You can buy sprays to fire-retardant-ize the material if you want to be careful.

    Hendrik

  4. Cloudy Knuckles Says:

    Hey Hendrix, really great website, pictures, and instructions

    I was hoping you could explain the “pressure fitting” of the insulation in place, is that just fitting a slightly bigger piece of 703 into the smaller frame?

    And do you happen to know what your frames measure to on the inside? I.E. how much smaller are your frames then the 703?

    Thanks alot

  5. Hendrik Gideonse Says:

    What’s up Cloudy Knuckles?

    I made the inside dimensions of the boxes exactly 2′ x 4,’ the same dimensions as the 703. Then when you lay the cloth material on the 703 and push the box onto the 703 w/ the material. The pressure holds it in place because the material makes the 703 slightly bigger than 2’x4′.

    The only problem with having inside dimensions of 2’x4′ is that the plywood stock for the outside has to be longer by 1.5″ which means that you have to cut them lengthwise out of sheets of 4’x8′ plywood.

    Let me know if you have any other questions!

    Best,

    Hendrik

  6. Bart de Wit Says:

    Hi Hendrik,

    First off, great website, really liking the detailed information.
    I’ve been looking into exactly this for when me and the missus move next year.

    I was first attended to this method by the UK’s Sound On Sound.

    Just to verify, if I understand correct, the outside of the frame now measures 2ft 1,5in x 4ft 1,5in? (just so I don’t mess it up…)

    Also, I’ve got two choises of rockwool for use here in the UK. The first is 30mm thick high density rockwool the second being 50mm normal density rockwool. I believe the 50mm version has sort of the same denisty as the material you used. Sound On Sound however recommends the 30mm high density because it would damp down to 300Hz. Have you got an opionion on this?
    Thanks in advance!

    Bart

  7. Hendrik Gideonse Says:

    Hi Bart de Wit,
    My understanding of the rockwool equivalent of 703 is that normal density is like 703 and the high density is like 705. 6″ or 15 cm thick (3 layers of the 50mm) should go down into the bass range pretty easily. I’ve had pretty good results in the 80-120Hz range with 6″ (15 cm). You might be able to get even lower results even with 4 layers of the 50 mm.
    Hope this helps!
    Hendrik

  8. Bart de Wit Says:

    Hi Hendrik,

    I get what you’re saying but there is a version of rockwool on the market here, which is a compressed one, the high density one, which the sound boys seem to use a lot. I was wondering if you know if there are any specific advantages to using the thinner (30mm) high density over the thicker (50mm) normal density in the trap like you built?

  9. Hendrik Gideonse Says:

    My understanding is that the more dense material may offer slightly better control of certain low frequencies but that the control isn’t as even as with the lower density material in a thicker configuration. My acoustics professor preferred the lower density material as being a better all-around absorber, that was cheaper and at least in the states much easier to get.
    I hope this helps!
    H

  10. rajshree Says:

    It is vey nice tips it will stop out site noise it is very help full in sound studio.
    I am what you say, but there is a version of the mineral market here, with a high density compressed audio that children seem to use the circle. Would you be interested to know that there are certain advantages to using a thin (30 mm) thick high density (50 mm), current density in the trap after you’ve built it

    Hendricks Hey, very good, photographs and addresses

    I was hoping that the determination of the delay is explained in isolation, it’s just a bit to little more than 703 small frame
    Thank for sharing

  11. Bert Says:

    Thanks for the very useful article, Hendrik. I hope you’ll take it as a compliment when I say that I’ve very glad to see a black man engaging in a hands-on project. I read many DIY, hobby, and science types of magazines every month and it is rare to ever see blacks engaging in furniture building, home renovation, auto racing, model building (airplanes, rockets, cars, boats, etc.), landscaping, or other activities that requires a high level of innovation and motivation. I know the editors go out of their way to encourage submissions by minorities, but almost none are ever seen. Please encourage fellow blacks to make an effort to obtain coverage in the major magazines.

  12. amaurythewarrior Says:

    they look great !
    how is the glue holding ? i’m pretty bad with screws, i might try that !

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