Acoustic Treatment for the Small Studio

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Broadband bass traps are available from a variety of specialty manufacturers like RealTraps, Primacoustic, and ATS Acoustics, and there are even some companies, like ReadyAcoustics that specialize in making affordable DIY kits. If you’re really handy, you can even build your own from scratch.

Step 3: Controlling Reflections

Once you’ve got your low end is in a workable place, many acousticians will recommend that you focus on high and mid-frequency absorption to create a “reflection-free zone” in the listening position of a control room.

The idea here is to use absorption panels that are just like the broadband absorbers already discussed, only thinner, as to lower the cost and gain more coverage.

White Mark “Fast Studio” acoustic system installed in Peregrine Andrews’ London studio.

Instead of going with rigid fiberglass panels up to 6” thick, you might opt for panels that are 2′ x 4′ or so and only 1” to 4” thick. 2” seems to be a pretty common choice, especially if you’ve already done a good job controlling low-frequency resonances.

The first goal is to eliminate first-order reflections – that is, sound waves from the speakers that bounce one off the walls, and then make a beeline straight for your ears. A small handful of strategically placed panels can help accomplish this quite well: one or two panels each on the walls adjacent to your listening position, on the ceiling above it, and behind the speakers themselves.

There are a couple of ways to figure out exactly where to place these absorbers. The ones you place on the side walls should be around ear level, naturally, and you might want to ask a friend to walk around with a mirror up against the wall. Any point along the wall where you can see the speakers in the mirror from the mix position is a potential place to put a panel.

Another way to figure this is to calculate a distance halfway between you and the speakers, and put absorbers there.

This is the first, and most essential step to controlling high and mid frequency reflections. If you want even more control, you can add additional panels from there, but even this alone can make the most reflective rooms into workable environments.

A similar approach can be taken in a live room. It’s never a bad idea to throw up some evenly spaced 2”-4” panels in a rectangular room, in addition to a few broadband absorbers.

If you continue to have problems with flutter echo, you can now add in 1” panels in problem areas to clean up any high-frequency slapback.

Step 4: Diffusion

Once you’ve treated your low end, created a largely reflection-free zone in your listening position, and cleaned up any significant flutter echo, you can think about adding diffusion.

Usually, diffusors are place on the back wall of a control room to scatter reflections, making the back wall practically “disappear.” All the companies mentioned earlier offer diffusion solutions, and some companies like RPG, Delta H Designs and Carl Tatz Design specialize in making custom, sometime breathtaking options.

But diffusion isn’t just for control rooms. A small live room can be made to sound larger, more open and less “boxy” thanks to a few well-placed diffusors. They can also be incorporated into a “live end/dead end” type of design, where one side of the live room is surrounded in thick absorption panels, and the other is accented by wood diffusors to help scatter the sound.

And once again, for the handy studio owners among us, there’s always the DIY route. All that takes is some wood, a good saw, a ruler, and plenty of patience.

Justin Colletti is a Brooklyn-based audio engineer, college professor, and journalist. He records and mixes all over NYC, masters at JLM, teaches at CUNY, is a regular contributor to SonicScoop, and edits the music blog Trust Me, I’m A Scientist.

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  • ott0bot

    thanks for organizing this material in a informative and concise article.

  • Mike Sorensen

    Hey Justin,

    Speaker placement and low frequency management in today’s physically small project studios is a large issue and must be placed one and two.. Broadband absorbers do provide a smooth, in most cases, absorption curve and are good performing units for frequencies above 80 – 90 cycles up through 400Hz.

    Smaller project studio rooms have absorption needs above 90 Hz. but also have what I think is a larger need below 90 Hz. Just the room volume in our smaller project studios dictates we address this area This frequency range below 90 and down into 30 cycles requires a certain treatment type. This frequency range requires a more powerful sponge.

    Diaphragmatic absorbers, as you point out, are readily available in a new construction scenario, where they have the space and the location to build them into. However, they can be built to be portable units that can be easily placed into positions required within the room.

    Diaphragmatic absorbers can be designed to go to 30 cycles and this rate and level of absorption will give more definition to the attack and decay of low frequency energy In our smaller rooms Yes, they are heavy, but that issue seems to resolve itself when one first hears how well they perform below 90 cycles. More bass definition is always welcome within our recordings and musical rooms.

    Regards,
    Mike

  • Sure thing Mike! If a studio is having a lot of low-end trouble particularly at one low frequency area, then a tuned membrane absorber can be a superb addition.

    What we tried to outline here was a great and effective place to start. From there, there’s a lot you can still do to get closer and closer to perfection — and yours is a fine recommendation in my book.

  • Acoustic Panels

    Decorative wall panel art are usually installed for commercial use like in Hotels, Office lobbies, Retail outlets, Restaurants, Trade show exhibits and the likes. One interesting use is to install on ceilings.
    http://mixmasteredacoustics.com

  • Ken

    A good starter’s article, but I found this misleading “A really effective broadband absorber might be as much as 6” thick, capable of dampening major resonances well below 100Hz” Based on 1/4 wavelength theory, 6″ would not offer significant absorption below 100Hz. Mike Sorensen makes a similar point.

  • Justin Colletti

    Interesting theory, but I’m not sure the evidence backs up your suggestion: Even 4″ panels can be reasonably effective down to 50Hz, as long as they’re mounted in corners. 6″ can do a lot below 100Hz as well, especially when placed in corners.

    There are plenty of real world measurements to back that up, readily available on the web. Can you point me to any real-world testing data to the contrary?

    That’s not to say that frequency-specific absorbers can’t be even more powerful in their narrow range. But corner-mounted 6″ rigid fiberglass can definitely be quite effective, well below 100Hz.

  • would it work well to only use wood diffusion panels in a room? I have a bedroom studio which occupies approximately a quarter of the entire room and my monitors are not typically placed. they are on separate walls and my studio space takes up half of the half (of which side it’s n equalling roughly a quarter of the room) with a sole window on my right side. it’s tough to explain with just but in addition to the monitor placement not being ideal, I have. ery little funds to put towards acoustic treatment. so I need to maximize my effectiveness for the cost.
    that’s why i thought having two diffusers – one on the long wall behind me, and one on the short wall that’s to the far left of me.
    an additional question: what happens if you place diffuser panels in the room’s corners?