Monitoring and Room Acoustics

How to Improve the Room Acoustics in Your Home Studio

Monitoring and Room Acoustics (2)

How to Improve the Room Acoustics in Your Home Studio

In a classic bedroom studio, everything happens in one room: songwriting, recording, mixing, and mastering. That’s a cozy setup, if not exactly ideal in terms of room acoustics. Yet with some simple optimizations, you can improve your room acoustics drastically.

As we’ve seen in the previous episode, the acoustic requirements for recording and mixing are very different. Most instruments sound best when recorded in a live room with some ambience – “acoustic support”, as the legendary engineer Bruce Swedien calls it. However, for mixing, we want a room which adds no sound of its own, a room that is essentially dead, so we can judge the recorded signals without any coloration. The question is, how can we fulfill both requirements in one room?

Live End Dead End

A solution to this dilemma is the “live end dead end” concept (LEDE). This is a popular acoustic concept for control rooms, which is particularly attractive for home studios as it retains some degree of “acoustic support” in the rear part of the room. The basic idea is rather simple: one end of the room is treated with sound absorbing materials, while the other end of the room has reflective surfaces.

Assuming your computer setup is facing a wall and the monitor speakers are next to the wall, this half of the room will be your dead end zone. The other half of the room will be your live end. Of course, you won’t get the lush reverb of a big live room in a professional studio, but you do get a bit of room ambience, which enriches the sound of acoustic instruments, in particular. And if you’re going for a dry sound, e.g. for the lead vocal, all you have to do is move your mic to the dead end zone. The LEDE approach thus offers some flexibility in terms of room ambience.

DIY Broadband absorbers behind the speakers and suspended from the ceiling. The panel in the corner is a bass trap from EQ Acoustics.
DIY Broadband absorbers behind the speakers and suspended from the ceiling. The panel in the corner is a bass trap from EQ Acoustics.

Optimizing the Dead End

A lot of rooms that appear “dead” or “dry” really aren’t. Our ears are quite sensitive to sound reflections in the higher frequencies, while room ambience in the lower frequencies often goes unnoticed. Yet this low frequency build-up can be a big problem in the home studio. It makes recordings sound dull and boomy, and it makes it very hard to judge the mix balance.

So it’s not enough to kill sound reflections in the high frequencies by putting a thick carpet on the floor. We must reduce reflections at all frequencies to achieve a short decay time over the entire sound spectrum. We need so-called broadband absorbers. You can buy them ready-made from a number of manufacturers, or you can build them yourself. The most effective materials are mineral fibers, such as “Rockwool”, and melamine foam, such as “Basotect” from BASF. Rockwool is less expensive, but should be handled with great care because of potential health risks. Melamine foam is more expensive but very easy to work with.

A simple way to DIY a broadband absorber is to glue a piece of melamine foam to a wooden frame. A convenient size is about 50 x 100 cm (20 x 40 inches). Cover the front and sides with a piece of cloth to protect the foam (which breaks quite easily). Tack the cloth to the back of the wooden frame, and you’re done.

The minimum thickness for such broadband absorber is 10 cm (4 inches). 20 cm (8 inches) affords you more absorption in the low frequencies. 30 cm (12 inches) would be optimal, but is often unrealistic due to the high cost and/or the space you lose. If possible, install your absorbers 5 to 10 cm (2 to 4 inches) away from the wall, this will make them more effective in the lower frequencies.

Cover at least about 30% of your dead end wall with broadband absorbers. The area behind your speakers is particularly important. Two additional absorbers should go to the sidewalls left and right of your listening position.

Another area that should be treated is the ceiling above your listening position. You can either glue melamine foam to your ceiling, or build lightweight frames to suspend the foam from the ceiling. The latter version is both more effective and easier to remove.

A diffuser panel from HOFA for the live end.
A diffuser panel from HOFA for the live end.
Real-life solutions: guitars and keyboards aren’t as effective as dedicated diffuser panels, but much better than bare walls.
Real-life solutions: guitars and keyboards aren’t as effective as dedicated diffuser panels, but much better than bare walls.

Optimizing the Live End

The rear half of your home studio should have reflective surfaces. Bare walls, however, aren’t any good, as they’d produce irritating flutter echoes. What we want are irregular surfaces that scatter the sound waves randomly in all directions. There are dedicated acoustic elements for this, so-called diffusers. Diffusers are usually made of wood or other sound reflecting materials, shaped into a deliberately irregular surface.

Diffusers are quite hard to DIY. But if you can’t afford factory made diffuser panels, there are other means to create irregular surfaces. If you own a lot of books, you could place bookshelves at the rear walls of your home studio. However, you must arrange your books in a disordered manner, so they form a jagged surface. Or, if you own a lot of guitars, put them on the walls. Multiple keyboards on stands will also scatter sound reflections. Technically, such “life hack” solutions may not be as optimal as dedicated diffuser panels, but almost anything is better than bare walls. And hey, it’s inspiring to be surrounded by instruments! Whatever you do, don’t forget to have fun!

Two kinds of bass traps in a room corner: above, a bass trap from EQ Acoustics, below a different bass trap from HOFA.
Two kinds of bass traps in a room corner: above, a bass trap from EQ Acoustics, below a different bass trap from HOFA.

Taking Care of Bass

In almost any normal size room, there will be bass resonances. Usually, those so-called modes are too low to be treated with broadband absorbers, because you’d need extremely thick materials that would take up a lot of space. A more effective way to treat room modes are dedicated low frequency absorbers, so-called bass traps. There are different kinds of bass traps. Some work with absorbing materials; those are quite bulky but are effective over a relatively broad frequency range. Other kinds of bass traps work with materials that resonate at a certain bass frequency. The latter type is effective only in a relatively narrow frequency range and often must be tuned to the specific frequency it is supposed to absorb.

Bass traps are usually placed in room corners, where the bass energy is strongest. Bass traps are important for a transparent listening environment in your dead end, but you should also consider them for your live end, because you don’t want bass resonances in your recorded signals, either.

If you can’t afford professional bass traps, you could try an old couch, preferably a bulky one. Depending on its construction, a couch can absorb quite some bass energy. Move it to where your room sounds the most boomy.

Don’t overdo it!

Be careful not to overdamp your room with broadband absorbers. A very dead sounding room may be good for mixing, but it’s not a very pleasing environment in which to create music. Always make sure your home studio remains a place that is inspiring and gives you pleasure. Make sure your home studio is both: a home and a studio.