Swiss Army Recording Rooms
Acoustic treatment for multi-purpose studio spaces
This article on acoustic treatment first appeared in Recording Magazine. I reprint it here with permission, and I encourage you to subscribe to that publication, as they are a stand up bunch of folk! Also, you may see affiliate links here, and I may make a commission from sales there.
Not everybody has the luxury of a multi-room studio complete with control room, recording space, and booths. Many great recordists make do with one room which serves all these purposes and more. Some people even prefer it that way. After all, who wants to run back and forth between two rooms every take? Other than fitness buffs, that is.
Still, while it may be true that a most recordists work in one room, when we talk about acoustic treatment, we usually talk about specialized rooms such as mix rooms or live rooms.
So, we thought it’d be good to talk about acoustic treatment for multi-purpose spaces – the kind of space most people actually record in.
One thing that doesn’t change if your room serves multiple purposes is the potential issues low frequency reflections pose. So, as with any room, deal with the low frequencies first. Owing to large wavelengths, absorption is best here, but one-inch absorbing panels or Auralex style foam on the walls won’t cut it.
If you have enough room to use 4-inch panels, spaced 4 inches away from the wall all over the room, go for it, but most likely you’ll need to use other strategies such as corner traps and broadband panel traps.
Start by treating the corners where lows build up. A great solution is the super chunk (figure 1), which is easy to build, and consists of corner pieces of rigid fiberglass or rockwool, enclosed by breathable fabric. You can stack an entire corner this way or you can build them in small modular chunks (figure 2) for flexibility.
Panel traps (figure 3) are broadband absorbers using a resonating membrane principle. They’re reflective at high frequencies – handy if you don’t want the room too dead. Space panel traps around the room for an even distribution of low frequency absorption.
It’s probably wise here to go for an even distribution of low frequency absorption, leaving no spot in the room with any major nulls or peaks.
When it comes to high frequencies, various rooms are treated differently. Vocal booths may be entirely dead, whereas recording rooms may be live, using diffusion to randomize reflections. Mix rooms use reflection free zones (RFZs) to the sides and above the mix position, sometimes leaving the back wall live or diffused.
If you mix in the room, you’ll want an RFZ, but you might deal with the rest of the room differently.
Diffusion is a great way to give a multi-purpose space an even high frequency response, but unless your room is pretty big, it won’t do much. Smaller absorptive panels, usually two inches thick, can be distributed throughout the room to create a kind of pseudo diffusion, evening out reflections, but keeping the room from being overly dead.
Consider small, light panels which can be rearranged to create different acoustic environments. You can even use a light frame and artful fabric covering, hanging these acoustic art pieces like you would any painting (figure 4).
In addition to moveable panels, solutions like absorbing curtains that can be rolled up or gobos that can be stored away let you change the space to your advantage. For example, you can cover your reflective panel traps with a curtain or blanket to transform the room into a dead space for vocals or acoustic guitars. (Just be sure your temporary absorber doesn’t touch the front of the trap, lest it lose its low frequency absorption properties).
Similarly, you could remove absorbing panels to create a live space or use gobos to create a temporary booth. Double points if your hangable treatment can come off and stack. Listen to the results of changes so you don’t just recreate the boxy sound you were trying to fix.
We often forget about the ceiling as a source of problematic reflections. The ceiling can also be thought of as a treasure trove of surface area to place low or high frequency absorption. Mix rooms usually have some treatment above the mix position, but in a multi-purpose room, you may want to have a go at the entire ceiling.
You can deal with the ceiling in a variety of ways, including alternating panel traps with high frequency absorbers or spreading absorbers around and creating a pseudo drop ceiling. Again, you can use movable panels for flexibility, but it’s a little more of a hassle to move overhead panels. Either way, ceiling treatment light so it’s easy to hang (figure 5).
If you can, give some space between the ceiling and the panel itself. Ideally this distance is equal to the thickness of the panel (ie: 2 inches for 2-inch panels). This increases the effectiveness of the absorber.
You can strategically place ceiling panels to create zones, or simply go to town on the ceiling to create a kind of acoustic foundation, as it were.
Flexibility and Planning
At the end of the day, your multipurpose room is still unique to you. Think about what you plan to do in there – ie: you don’t need to treat for drums if you never record drums. And think about flexibility. Keep things modular and light, and you’ll be able to adjust your room as needed. Finally, think about evenness first, because a room with a good foundation is already most of the way toward super useful.
Here’s to the bedroom recordists! May we all win Grammys in our jammies.
I’ve built out home studios from Oakland to Albuquerque to Austin to Houston, and hold a master’s degree from Stanford University, where I had the distinct privilege of learning acoustic science from the author of the textbook. 🙂 Talk acoustics with me on Facebook @AaronJTrumm or Instagram @AaronJTrumm