Improving Your Recordings: DIY Acoustic Panels

Acoustic treatment for your studio is probably the least expensive way to improve your studio’s sound; seriously! For the same price as a Shure ’57, you can build a half-dozen broadband absorbers and improve your monitoring accuracy significantly, leading to better tracking and mixing quality. Read on for pics and a description of how to do it.<!–more–>

The biggest problem in any room are the low frequencies, which is why “bass traps” are so important. Basically, a bass trap is just a huge wad of sound absorbing material. You could just use a package of Rockwool insulation, no need for overpriced pre-fab bass traps from big name acoustic foam salesmen. You can just plop a bale of rockwool in each corner of the room (stack ’em two high for even better coverage), and you’ve got $20-a-shot bass traps that will be quite effective.

A couch or loveseat will absorb some low frequency energy, and add a comfortable relaxing spot to the room – that’s usually a freebie, and if you can spare the space in the room it’s a multi-functional addition to the studio.

I’d say that for $300 total you could get a medium-sized room into pretty good acoustic shape. Do it! It will improve your sound more than any gear will. I like to think of the “heirarchy of recording” as:

1) The source – great performance and instrument tone are irreplaceable.

2) The room – the acoustic space in which you are recording should be treated to reduce direct reflections and resonant problems.

3) The engineer – the person positioning the mics and listening carefully to adjust the tone of the recording is key to capturing a solid sound.

4) The gear – believe it or not, this is last on the list. Why? Because an experienced engineer recording a great performance will ALWAYS sound great, whereas even the best gear can’t make a lousy performance sound good!

My newest book “Big Studio Secrets for Home Recording and Production” is coming soon (published by Cengage Learning), and goes into depth about each step of the process. Look it up on Amazon, or you can find it in any Borders Books or Barnes and Nobles. I’ve created a CD-Rom to go with the book, so very much like the “Pro Techniques for Home Recording” ebook, there are loads of audio examples to guide you.

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One of the easiest studio projects – and one that brings the most obvious, audible benefits – is to build yourself a bunch of broadband absorbers.

The wood frames (pictured above) are easy and inexpensive to build. I think that the cost per absorber came to about $10, not including the value of my time and labor, of course!

Click on “next” for a step-by-step description of how to do this. You’ll need:

– Wood for the frames (next step for measurements)

– Sound absorbing material (Owens-Corning 703 or Rockwool Sonorock. Fiberglass insulation is not heavy enough for effective absorption)

– Wood glue and heavy staples, staplegun

-Fabric of your choice to wrap ’em up.

Building the wood frames is really quite simple. Have the wood cut to size at the hardware store based on the dimensions of your sound-absorbing material. In the USA you’ll probably want to use Owens-Corning 703, whereas in Europe Rockwool “Sonorock” is the right stuff.

In my case I used Rockwool, and the sheets are 100cm x 62.5 cm, and 5cm thick. So I chose 10cm wide wood, to create absorbers using 2 panels of Rockwool each. By making the frame inside measurements 100cm x 62.5 cm I didn’t have to cut any Rockwool at all, which would create itchy dust.

Keep in mind that the wood has a thickness of it’s own, and this affects the cutting measurements. I had to add 22mm board thickness at each side to the short ends, giving me 66.9cm length for those pieces. The long sides were 100cm each.

Shown in the picture is how to join the frames. Don’t screw them, as they’re likely to crack. Glue and staple them – it makes for a very strong frame. They dried in about an hour and were ready to fill and wrap.

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With the frame ready to go, lay them out on the fabric for wrapping. I used some basic beige-colored cotton/synthetic material I bought fairly cheap at a market.

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In the next step, you just lay in the absorptive material (Rockwool) which fits snugly due to the measurements being the same as the size of the Rockwool sheets.

This is really a very simple project!

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Laying in the sheets of rockwool.

Be sure to wear gloves – they’re dusty and itch even when not cut.

The sheets of Rockwool need a bit of coaxing into the frames. This is fine, since a snug fit will keep the insulation from falling out; you don’t need to tape/glue/etc. the rockwool into the frames unless you wanted to mount them on a ceiling. I wouldn’t recommend mounting these frames over your gear and your head anyway unless you have some experience in building; they could come loose and seriously hurt you.

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With the Rockwool in the frames, fold over the cloth and secure it with staples.

I left an opening on the back so that I can hang them on the wall without puncturing the cloth. If you are concerned about dust from the Rockwool coming out, then just use more cloth and close the backs completely.

You can see the package of Rockwool on the left in the picture – the sheets are relatively firm, and I can’t imaging any dust coming out unless someone starts pounding on them.

Pull the cloth snug before stapling. The first couple I made were somewhat uneven, but with practice they started to look very even and professional.

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A closeup of securing the corners.

It’s more important to make neat folds than to use a lot of staples.

None of this affects how they absorb sound, but avoiding big wrinkles and bunches of fabric keeps the absorbers, and therefore your studio, looking professional.

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Here are some of the finished absorbers, ready to be mounted in the studio.

I also made a few 15cm thick absorbers (three sheets of Sonorock), but it’s just as effective to stack a few of these in front of each other. With a lot of 10cm absorbers I can treat the corners with 20- or even 30cm of absorption, making for effective bass traps. If needed, I can steal a couple from the corners when tracking, and then put them back for more bass-control when mixing.

These things are so cheap and easy to build, you should make a whole bunch at once. Stack them 2- or 3- deep as bass traps – it’s very important to treat the corners of your room.

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Here’s a shot of the absorbers in place. The studio was still in disorder at this point, but I had to work on a few mixes right away, so I divided up what I had built and stacked half to the left and half to the right of my mix position. It’s hard to see in the picture, but the monitors are not placed up against the wall – there’s about 4 feet from the backs of the monitors to the wall, and the absorbers are heavily focused on the corners with a few set to stop reflections between the left and right walls (not pictured).

I had the monitors up in the bare room before I brought in the panels, and it’s amazing how clear the stereo image became afterward! EQ and effects  effects and EQ adjustments were not just a guessing game that sounded different in various parts of the room, and the mix translated very well to other systems. I can also work longer without ear fatigue. I’ve since added more bass traps to the corners and a “cloud” overhead out of extremely light-weight “Basotect” (melamine-foam) material, which has further improved the room.

All this acoustic treatment effects every aspect of the recordings – the tone of each track is clearly represented, making mic positioning for tracking a breeze. Sounds come clear very quickly. When mixing, everything falls into place with less guesswork. The small monitors let me switch to a “consumer stereo” kind of sound to check mixes. Bass levels are much easier to set now, and that kind of “hollowness” or “boominess” that sometimes happened to mixes is a thing of the past.

I recommend you take on this project ASAP!

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