Treating a room for mixing isn’t a straightforward matter. However, it’s something you can’t pass on if you don’t want distortions and echoes making your job harder.
Here are 5 essential things you should do to treat your room for mixing:
- Understand how sound travels in a room.
- Get speaker placement right.
- Install acoustic panels.
- Add diffusers.
- Install bass traps.
If you’ve dabbled into acoustic treatment before, then you’ve noticed that there’s a lot of science involved. But don’t worry: this article will break down all the important concepts and leave you with practical steps you can apply right now to your home studio.
1. Understand How Sound Travels in a Room
If you are familiar with acoustics, you can skip to the next section. But if you need a refresher or this is your first time treating a room for mixing, then you might want to keep reading.
Rooms have walls – there’s not much more to say about that. We call the way sound travels inside rooms “acoustics.”
Sound is made of tiny air oscillations, or waves, that travel through space. These sound waves will bounce off surfaces, like the walls in your room.
The problem comes when different sound waves reach your ears at different times, creating “time smears.”
Directional waves travel straight from speakers to your ears. You can picture them as a straight line. However, other sound waves travel towards a wall, bounce off them, and then get to your ears.
This means that those indirect sound waves will arrive at your ears a little after the direct sound waves arrive. This resonance will cause reverberation and distort your sound.
In this explanation, we pictured only one wall and one bounce. However, rooms have at least six walls (taking into account both the floor and ceiling), and soundwaves bounce several times. If you also take into account the fact that many rooms have irregular shapes, things become even more complicated.
If you would like a more visual representation of acoustics, take a look at this video by Acoustic Engineering:
It’s nearly impossible to have a room with 100% neutral acoustics.
Luckily, however, you don’t need one.
Placing a few dampeners and diffusers in key places will make a huge difference, more than enough to let you mix accurately.
Besides, if you completely kill the echo in a room, you’re left with an unnatural sound that humans just don’t like.
2. Get Speaker Placement Right
The first step in treating your room for mixing is knowing where you’ll place your speakers.
This is one of the most crucial steps on this list. The music won’t sound clear if your speakers (or you) are in the wrong place, even if you have a perfectly treated room.
Find Your Listening Spot
The first thing you should do is locate where your listening spot will be.
Your speakers shouldn’t be close to any walls or corners, but the same goes for your back.
Producer Wes Lachot says that you should have a listening position that’s about 35%-40% of your room’s length from the front wall. There are two reasons for this:
- You should have more empty space behind you than in front of you. Unless your back wall is extremely insulated with acoustic panels, you will have to deal with undesired wave cancelation and harmonic distortion.
- Due to how sound waves bounce in a room, certain places will become “nodal points” where reflected waves intersect. These nodal points are usually at 50% and 25% from the front wall.
Keep in mind that the 35%-40% suggestion is just a rule of thumb, and you can try sitting at different positions to determine what works best for you. However, it does give you a good starting point.
One more thing: if your mixing room is relatively big, then it’s probably a bad idea to have your speakers right up against the front wall. However, for small rooms, the opposite is usually true.
Place Your Speakers
Ideally, you should create an equilateral triangle where the three corners are the speakers and your reference point.
What is this “reference point” exactly? Some guidelines, like those offered by Dolby, place the reference point as the place you’re sitting, or, rather, your head.
However, many mixers prefer to place the reference point slightly behind their heads, usually around 16 inches (40.64 cm). This allows better sound imaging for stereo listening.
After determining your reference point, each speaker should be placed facing toward you at 30 degrees to the left or right, respectively. The result should be an equilateral triangle.
If you find that hard to visualize, imagine there’s a circle with your head (or, rather, your reference point) at the center.
If you’re looking at the front wall, the right speaker will be placed 30 degrees to your right along the line of that circle, facing you. The same goes with the left speakers, but 30 degrees to the left.
You can play around with those measurements depending on the shape of your room and your own preferences, but this should be a good way to start.
3. Install Acoustic Panels
Here we get to the first and most common form of acoustic treatment: absorption.
Acoustic panels are made of foam or some other material that absorbs sound.
This “absorption” doesn’t just make sound disappear. When soundwaves come in contact with the panel, friction is created. This friction transforms the motion energy of the soundwave into heat energy.
Foam is the material of choice for acoustic panels, but be aware that not all foams are the same. Professional acoustic treatment companies use thicker, more resistant materials. But if you’re on a budget, you can buy common foam and make a panel yourself.
So, should you just cover every surface of the room with foam and attempt to eliminate all echoes?
This might sound logical at first, but it’s actually a bad idea. If you create a completely anechoic chamber, the music will have an unnatural sound. For music to sound natural, it should have a little reverberation.
Start by covering key places with acoustic panels. Depending on the size and shape of your room, you can consider adding more foam later.
Early Reflection Points
The first places you should treat in your room are the early reflection points. This is where soundwaves will reflect first before bouncing into the rest of the room.
Mid and high frequencies lose energy each time they bounce, which is why these first reflections are stronger and cause the most interference. Treating early reflection points should mitigate most of the echoes that get in the way of your critical listening.
There are three early reflection points you should worry about: the points on each side, as well as the point above you. Here is a simple method to find the early reflection points at your sides:
- Sit in your listening spot.
- Have a friend hold a hand mirror flat against the wall at the height of your speakers.
- Ask your friend to move through one of the walls until you can see your speaker in the mirror.
- Mark that place. That’s the early reflection point on that side.
- Repeat the process with the other side.
Regarding the early reflection point above you, just place an acoustic panel above your listening spot. Ideally, it should be hanging a few inches from the ceiling.
If you’re in a small room and you can’t have enough space between your speakers and the front wall, consider putting an acoustic panel in the middle point behind them.
How Thick Your Acoustic Panels Should Be
The thicker a panel is, the wider the range of frequencies it will absorb. Panels with a small width (3 inches or 7.62 cm less) tend to absorb only high frequencies, so using them profusely will make for dead-sounding music.
Thicker materials will also absorb mid and low-mid frequencies. If you’re only placing panels in strategic places, go with thick, 6-8 inches (15.24-20.32 cm) panels.
If you can only find thin foam, placing them a few inches away from the wall will help it absorb some mid frequencies and improve its effectiveness.
4. Add Diffusers
We just saw how to deal with early reflections, which are the ones that distort your signal in the most obvious manner.
But what about late reflections?
These are the reflections that bounce between parallel walls and into the back wall.
You could spread out a lot of acoustic panels across your room, especially if your mixing room is large. However, if you do this, you also run the risk of dampening and killing your sound, especially if you’re in a small home studio.
A more sensitive approach is adding diffusers. Diffusers don’t remove sound energy from the room. Instead, they scatter it.
It’s not like they split it in a few different directions. Diffusers, as their name implies, diffuse sound energy evenly in all directions. If properly placed, they won’t concentrate sound in one area over others.
But what happens to those diffused soundwaves? Aren’t they just a new problem?
Quite the opposite.
When they are scattered, soundwaves change their direction, time, and intensity. That means that your brain won’t be able to identify where they’re coming from.
This will give you a pleasant, subtle reverberation that won’t cause any destructive interference with your signal.
Where To Place Diffusers
You can place diffusers throughout other key reflection points, like in the middle of the back wall. Spreading them across your walls can work great. In fact, some professionals like to use only diffusers instead of acoustic panels.
Making a Diffuser
The preferred material for diffusers is wood. If you have the skill and materials to work with wood, you can certainly make one yourself.
There are plenty of blueprints out there, like the ones offered by Arquen.
Some people use homemade methods like libraries randomly filled with books. However, these won’t be as effective since books tend to be more absorbent than reflective.
Of course, the best way to make sure you’re getting a great diffuser is to buy a professionally made one. If you’re on a budget, get some acoustic panels first.
5. Install Bass Traps
How Bass Works In Rooms
Bass can be one of the trickiest parts of treating a room for mixing. Mid and high frequencies bounce around inside your room until they decay. The wavelengths of lower frequencies are longer, so they “stretch” as the frequency decreases.
This means that, at some point, the wavelength will match the dimensions of the room. Below that point, instead of decaying, frequencies will be amplified.
And that’s the extra challenge imposed by bass: it gets amplified, and the point at which this happens varies from room to room.
It gets even trickier thanks to something called room modes. We won’t go into detail since it’s a rather complicated subject. In a nutshell, some frequencies will be amplified or dampened depending on the shape and size of the room. For example, bass might be very loud in one part of the room and quiet in another.
There’s one more thing about bass (don’t worry, that’s the last one we’ll talk about here).
Monitor speakers are directional, so most frequencies travel in the direction they’re oriented.
However, lower frequencies can travel omnidirectionally. They will spread in all directions, bouncing against the front wall and the front corners.
Now that we understand why bass is a special challenge, let’s take a look at the solutions.
Bass traps work in a similar way to normal acoustic panels. During this process, peaks are lowered, and valleys are raised. In other words, the amplitude is reduced, and so is the volume.
The most efficient place to put bass traps is in the corners. Low-frequency pressure builds up when it encounters a surface, so, naturally, corners are where it will build up the most. By installing bass trap panels across corners, you’ll get the most bang for your buck.
For small mixing rooms, there are other key places you should consider:
- The sides of the wall. This is mostly necessary for very small rooms.
- The ceiling. In rooms with small ceilings, a lot of energy is located close to the ceiling. A bass trap can mitigate this effect.
- Behind the monitors. In small rooms, speakers tend to be close to the wall. As we saw before, bass will also reflect off the back wall. Adding some bass traps there will make a difference.
If you want your mixes to sound as you intend them to, then you need acoustic treatment.
Sound works in rather complex ways when it’s inside a closed room. The music can be louder in some places than others, and some frequencies could be dampened or overpower others. In that case, what you hear won’t be the same as what people hear on their devices.
To have as much control as possible in your mixes, make sure to add a few acoustic panels, diffuse echoes, and set up some bass traps.
- GIK Acoustics: How Bass Traps Work
- GIK Acoustics: Basics of Room Setup
- YouTube: GIK Acoustics: How to Treat a Room with Acoustic Panels – First Reflection Points
- YouTube: Acoustic Geometry: How Sound Works (In Rooms)
- Acoustic Frontiers: THE SCHROEDER / TRANSITION FREQUENCY EXPLAINED
- Arquen: How to Place Acoustic Panels and Sound Absorbing Material for High Fidelity Listening and Mixing
- GIK Acoustics: Early or First Reflection Points
- Arquen: Sound Diffusers 101: Free DIY Diffuser Designs
- Dolby: Dolby Atmos® Home Theater Installation Guidelines
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