At the end of this chapter I have a link to a step by step guide for building simple, beautiful, and yet affordable acoustic panels and traps. And because my designs employ all of the basic features of way more expensive, professionally manufactured treatments like depth, density, durability, etc., they are highly effective.
In a home studio, you cannot simply mix in headphones 100%. Fact is, we need reference speakers, and we need our rooms to work with the sound coming from our speakers, not damage it. Managing sound reflection is both a critical skill you must understand and one you must afford to implement.
When you first encounter an acoustically treated room, it’s a very satisfying experience. All of the echo that you hear everyday, everywhere, is stripped away, and you are left with the pure sound itself. Some describe this effect as dead, it feels like you are in a space vacuum. In any case, your studio should give-off that impression.
You may find in some rooms this happens more organically than others. Room shape, furniture, wall covering, carpet, etc. all play a part in sound reflection and absorption. But you can't also just fill-up your room with foam or blankets and achieve a professional studio level of acoustic treatment.
If you do any type of research on acoustic treatment, you will also quickly find much of the guidance is somewhat confusing and appears to be somewhat of an art form. There are a few hard and fast rules, which we will cover below, but many other factors are involved which I will not explore here. This is because two rooms are rarely the same. Suffice to say if you cover the basics, you can manage about 70-80% of the acoustic control more expensive studios achieve.
The Crowe Traps account for all of the fundamental design requirements found in professional panels including size, density, and depth. Here are some specs right from the Rockwool website:
While the density of the insulation is a contributing factor to the effectiveness of the sound absorption, Safe and Sound is rated at 2.4lbs / CuFt, it is the actual thickness of the Rockwool installation that will determine the overall absorption. At 3", Safe and Sound Rockwool will absorb 50% of frequencies @ 125hz, and 100% from 250-20khz. At 6", it will absorb 100% of frequencies from 125-20khz.
This is why the wall-mounted Crowe Traps are designed in thicknesses of 3" and 6". Even at 3", they are very effective at managing low-midrange. To gain even more absorption over frequencies lower than 125hz, we recommend you employ Corner Traps.
There are basically three things you need to worry about in your room: Bass Build-up, First Reflection Points, Back Wall and Ceiling absorption.
BASS BUILD-UP
Even if you don’t employ a sub woofer, you will experience bass build-up, especially in the corners of your room. I cannot stress enough that bass is the number one problem in home studios. So it should be treated first.
Lower frequencies have a lot of energy, you can actually feel them. And when they hit a corner, they tend to retain their energy. The longer the waveform retains its energy, the longer it persists. As new bass frequencies arrive, and old ones remain, this build-up starts to blur your sound. Instead of a crisp kick or bass string pluck, you will find the lower frequencies tend to give-off a rumbling effect, like thunder that persists for a long time, much longer than the original waveform. It is very easy to spot, and very easy to fix.
Thankfully, you don’t need to stuff all of your corners with treatment to solve this problem, but you will need to have a strategy. Since you are building your own traps, you can start with just two, and then continue as needed. In my studio, I employ only two Crowe Corner Traps.
The first place I would treat is the corners behind your monitors. If you employ a sub woofer, it should be placed somewhere between your monitors, on the floor, at the front of your room. So it is safe to say the front of your room experiences the most energy and bass build-up. Placing a corner bass trap in each corner at the front of your room should fix a majority of the build-up. You can also add them at the back of your room, but start with the front. Once you get them installed, you will be able to hear any remaining build-up much more easily.
FIRST REFLECTION
When your monitors project sound waves into your room, they should hit your ears first, then likely hit a reflective surface like a side wall. If you have things like pictures or shelves on your walls, chances are the sound will be somewhat scattered, but it will still bounce. This is the first point of reflection, and is a great place to reduce the energy of those sound waves since you know exactly where they are going to land.
If you are going to treat these target areas, it is safe to assume the size of the treatment is important. This is because your speakers tend to spray sound waves in a pattern that increases in width the further it travels from the monitor. This is why many acousticians like to treat rooms that are much deeper than wide. The wider your room, the more first reflection you will have to consider.
Start your plan by imagining a straight line from the center of your monitors to the wall where they are aimed. At this center point on the wall, you should employ at least a single 3” panel on one side of that center point and 6” panel on the other. They should be positioned at your normal listening height, centered vertically on your ear. This means they will be 2-3 feet off the floor, basically in the middle of the wall.
I prefer to place the 3” panel at the front of the room and the 6” panel toward the rear. This is because lower frequency sound waves are larger and tend to travel further. They also require deeper materials to absorb.
If you have space for it, you should install 4 panels, 2-3” and 2-6”. Since most walls are 8 feet high, the Crowe Traps are 48” tall which allows you to stack them one on top of the other. This will provide maximum suppression of first reflection points.
BACK WALLS AND CEILINGS
Once you have your corners and first reflection points covered, settle-in and get to know your room. You may find additional treatment is needed at your back wall and ceiling.
My studio has a lot of reflective surface both on the back wall and ceiling. And since I could not address my first reflection points, challenges I won’t go into here, I needed a way to deal reflection from these surfaces.
Chances are sound will bounce off your first reflection points and hit both of these surfaces looking for another place to go. So I treated nearly 100% of my back wall with 3” and 6” panels in a checkerboard design. Since my back wall is 10 feet wide, I was able to install a row of four panels at nearly ceiling height. Below those panels I have a long couch which is the primary listening area. So much of the sound is absorbed by either the panels or the couch.
My ceiling was another challenge. I am not a big fan of hanging a bunch of 2’x4’ panels from a ceiling. My first experience doing this in a studio left me wanting a better solution. So instead, I built a 6’x8’ cloud out of 2x4 studs and a lot of Rockwool. Suspending this thing was a challenge, I left about an 8” air gap from the ceiling, and it all but removed the ceiling as a reflective surface. I also hung it lower toward the front of the room.
But let me warn you, a panel this size is not walk in the park to hang. Neither is it inexpensive. I put about two bails of Rockwool into it, and at approx. $70 a bail, it cost me about $200 to build. Due to its size and weight, about 100 pounds, you must ensure you tie it into the ceiling rafters and employ heavy chain to hold it. I couldn’t believe my eyes after it was hung. I put some cheap LED lights from Amazon on top of it so it was back-lit. Made my studio look and sound super pro! And the absorption it produced was magical!
PANEL DESIGNS
If you click this link: Crowe Traps, you can access my step by step panel designs. I include a 2’x4’x3” Wall Trap primarily for high mids and high frequencies, a 2'x4'x6” Wall Trap for low mids and bass frequencies, and a Corner Trap for low and sub-low frequencies. Each of them look totally professional, not lumpy or cheap. They are fully covered in an inexpensive neutral colored fabric and compliment your walls; they don't stick-out like sore thumbs.
I recommend supplies that can be purchased at just about any big box hardware store. And I don’t recommend expensive, “acoustically permeable” fabric, which in my experience is just a waste of money. Instead, I recommend covering your panels with sturdy, cheap, canvas drop cloths. These not only look really sharp, the material is tough, and you can modify it before or after installation to make the panel more artistic. I provide some ideas in the last section.
Finally, hanging panels on walls can be a real challenge. I have seen some pretty ugly designs that just make your studio look amateur. Instead, I recommend Z-Clips. These are completely hidden and super easy to install.
You are on your own if you hang panels from the ceiling. I have seen a few designs that employ hook screws and chain that work well, they are just a pain to install.
OTHER THOUGHTS ON TREATMENT
Furniture is a great way to diffuse or absorb sound waves. The more stuff in your room the less likely reflective surfaces will impact your sound. That said, keeping a clean room is also necessary to maintain a professional look.
A lot of acousticians recommend you create dead space behind your wall or ceiling panels. This tends to make the panel more effective, and I won’t argue there. But suspending a panel off a wall is a real challenge. I have yet to come across a hanging method that I trust and looks fairly professional. As such, I recommend air gaps but do not employ them in my design.
Floors tend to be a major area of reflectivity if not covered. In my studio, I have cement floors. Placing a rug on the floor, and covering a majority of the surface, is all you need. I chose a cow skin for mine. If your floor has carpet, check this one off the list.
Windows are especially reflective surfaces. But they also make the room appear more open and provide creative distraction. Don’t cover your windows unless you are dealing with huge sliding glass doors. Instead, treat other parts of the room to make-up for the reflectivity you will no doubt receive from glass surfaces. If you have large glass surfaces, however, I would recommend partially covering them with an acoustic drape that can be opened or closed depending on your needs.
Same goes for rooms without a door or large openings to other rooms. You can treat these with an acoustic drape as well. Unless you have an issue with others complaining about the sound, however, I would not worry about covering openings. They act as a natural non-reflective surface, allowing the sound to escape your room instead of bouncing around.
ARTISTIC PANELS
My wife and I are both artists, so we have a lot of ideas we like to incorporate into our spaces that make sitting there for hours a more pleasurable experience. My panel designs incorporate unbleached canvas cloth, usually made from cotton. Canvas is also a surface commonly used for art canvas because it is generally a very flat and absorbent surface. I do not recommend actually painting your panels, this will reduce the ability of the fabric to allow sound waves through it and make it more reflective. Instead, you can use a number of other media like spray paint, ink, or stain to make your panels one of a kind!
In my art work, I generally use black ink as my primary "paint". You can buy black ink, or really any color, in bulk on Amazon. A 16oz bottle will run you under $20. Experiment on a spare piece of canvas. Use a paint brush, sponge, or splash the ink against it. I think you will find the contrast of black ink over the natural canvas background can be quite pleasing.
An advanced technique is to spray the ink with rubbing alcohol once it is applied. This makes the ink spread like water color and can soften the brush strokes or drops of ink. You can also place masking tape over parts of the canvas where you don't want the ink to absorb. Once the ink is applied, remove the tape immediately.
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