Lessons in Acoustic Treatment: 101


As newbies to home recording…

Virtually everyone underestimates the importance of acoustic treatment…

Instead spending all their money on gear, thinking its the higher priority.

Then after a month or two of unsuccessful projects, they stumble upon the realcause of their frustrations in some online forum…

And think to themselves…

So THAT’S why my recordings sound so crappy!

And while that realization is a big first step…there’s still the problem of what to do NEXT…

Because actually getting the acoustic treatment in your room requires:

  • creating a plan

  • budgeting/shopping

  • putting it all together

…all of which, can turn into a huge hassle if done incorrectly.

Which is why for today’s post, I’ve created an in-depth guide to walk you through the entire process, step by step.

First up…

Soundproofing vs. Acoustic Treatment

Very often, musicians will use these two terms interchangeably, mistaking ONE for the OTHER…

When really, each one is completely different.

Soundproofing is intended minimize the level of sound that passes through the walls, by blocking them with heavy, dense building material.

The benefit is…you can record whenever you wish, without worrying about you or your neighbors disturbing each other.

Acoustic treatment on the other hand, aims ONLY to control sound reflections WITHIN the room, to make better sounding recordings.

BOTH are valuable, but NEITHER does the job of the other. So if soundproofing is what you really need…check out this article instead:

Otherwise, let’s continue…

Evaluating Your Bare Room

Too often, when novices first hear of the supposed benefits of acoustic treatment…

They immediately go out and buy stuff, without first diagnosing and evaluating the extent of their problem.

So…to find out how bad the acoustics in your room really are, here’s what you do:

Walk around the room, clap your hands as loud as you can from every spot, and listen closely to the reverberations that follow.

  1. In the WORST case scenario – you’ll hear a harsh metallic ringing sound, which typically occurs in small cubical rooms.

  2. In the BEST case scenario – you’ll hear a pleasant reverb, which typically occurs in larger rooms with high ceilings and lots of complex diffusive surfaces.

But most likely, the sound you hear will be somewhere in-between. Now…

  • The closer it is to #1, the more absorption you will need to make the room sound as dry as possible.

  • The closer it is to #2, the less acoustic treatment you will need in general, although virtually any room will still benefit from a little.

If you need some reference points to hear the difference between good and bad acoustics, perform the clap test in a wide variety of different rooms, and take notice of which types tend to sound best.

Then later on, when you begin installing acoustic treatment in your room, use the clap test constantly throughout the process to observe how the sound changes.

With each new addition, that nasty ringing should be becoming less prominent, until it disappears completely.

Moving on…

The 3 Elements of Acoustic Treatment

Getting your room to sound great with acoustic treatment requires of a combination of 3 items:

  1. Bass Traps – to absorb the low frequencies

  2. Acoustic Panels – to absorb the mid/high frequencies

  3. Diffusers – to scatter the remaining frequencies

Now let’s learn more about each one…

1. Bass Traps

The first and most important element of acoustic treatment to add to your room is bass traps.

If you can only afford 1 thing now, get these.

And here’s why:

Though commonly thought of as specialized tools for absorbing bass frequencies…

Porous bass traps actually are actually broadband absorbers, meaning they’re good at absorbing mid/high frequencies as well.

Which is why sometimes…bass traps alone can be enough to get the job done.

In small home studio rooms especially, where bass frequencies can be particularly problematic, bass traps are a MUST-HAVE.

To find out which ones I recommend, and get detailed instructions on how to set them up, check out this post:

2. Acoustic Panels

While many people think of acoustic panels as the primary “go-to” weapons to combat problems with studio acoustics…

The truth is, they’re almost completely ineffective at absorbing the lowest bass frequencies…

And should therefore be used as a supplemental tool…AFTER the bass traps are taken care of.

But here’s what they can do that bass traps can’t:

Because they’re thinner, and offer more surface area with less material, acoustic panels can provide greater wall coverage, for less money.

What that does is kill any standing waves that may exist between opposite parallel walls. Which is the one thing that bass traps can’t really do, since they’re primarily located in the corners of the room.

3. Diffusers

Most folks today believe that for smaller rooms…

Like those of most home studios…

The effectiveness of diffusion is greatly reduced, if not neutralized.

For project studios, that’s good news, because it eliminates the need for expensive diffusers.

Many people don’t use them at all. Yet others disagree completely, and use tons of them.

So it’s totally up to you. Just remember to get the absorption part handled first…then if you want to add some diffusers later, here are 3 great options I recommend:

  • Auralex Studiofoam T’Fusor

  • Auralex Sustain Bamboo Waveprism

  • Auralex Sustain Bamboo Peak Pyramid

Up next…

3 Great All-in-One Packages

If you haven’t figured it out by now…buying all this stuff individually can be a HUGE hassle.

Which is why companies like Auralex and Primacoustic offer complete “room packages” to simplify the process and eliminate ALL the guesswork.

For home studios, here are 3 great packages I recommend:

1. Primacoustic London 12

Known as one of the top brands in acoustic treatment…

Primacoustic offers a ton of great solutions for home studios…

Including their current line of room packages known as the London Series.

I recommend the mid-sized London 12, which as you can see in the picture, is a perfect solution for standard sized rooms.

Here’s what’s included:

  • Two 24″ x 48″ x 2″ Broadband Panels

  • Eight 12″ x 48″ x 2″ Columns

  • Twelve 12″ x 12″ x 1″ Scatter Blocks

  • various mounting hardware

Also check out the smaller London 10 package designed for 100 square foot rooms.

Up next…

2. Auralex Roominators Pro Plus Kit

The only brand more popular and trusted than Primacoustic…

Is of course…Auralex.

And the standard full package option they recommend for project studios is…

The Auralex Roominators Pro Plus Kit.

Include in this kit is:

  • 36 Studiofoam 2″ Wedge Panels

  • 12 LENRD Bass Trap

  • 8 T’Fusor 3D Sound Diffusors

  • EZ Stick Pro Adhesive Tabs for mounting

Click here to see the current price.

Also check out the smaller, more affordable Auralex Alpha-DST Roominators Kit containing:

  • 32 1’x1′ two fin panels

  • 32 1’x1′ four fin panels

  • 4 LENRD Bass Traps

  • EZ Stick Pro Adhesive Tabs for mounting

Up last, the best package of them all…

3. Auralex SFS-184 SonoFlat System

For those of you who don’t care much for the “traditional” look of acoustic foam…

Auralex also offers some sleek and sexy alternatives in the Auralex Sonoflat Series.

At the top of this series, is the Auralex SFS-184 System, which offers the MOST goodies of any package we’ve seen so far.

Included in this package are:

  • Thirty-Two 2′ x 2′ x 2″ SonoFlat Panels

  • Eight SonoCollars

  • Eight 12″ x 6″ x 28″ SonoColumns

  • Six Q’Fusors

  • Tubetak Pro for mounting

Click here to see the current price.

Also check out the cheaper Auralex SFS-112 SonoFlat System which includes:

  • Twenty-Four 2′ x 2′ x 2″ Sonoflat Panels

  • Four SonoCollars

  • Four 12″ x 6″ x 28″ SonoColumns

  • Tubetak Pro for Mounting

Up next…

The 3 KEY Points in Any Room

Once your acoustic treatment has arrived in the mail, you’re almost ready to start putting it up.

First though, there 3 key areas of the which we must define.

They are:

  1. Trihedral corners – shown in the diagram as the red dots

  2. Dihedral corners – shown in the diagram as the blue lines

  3. The Walls – shown as the flat white surface area

Common wisdom states that in any room:

  1. the trihedral corners get first priority for coverage

  2. the dihedral corners get next priority

  3. the walls get last priority

And here’s why:

For best results, it makes sense to place acoustic treatment in the areas which have the greatest impact, right?

Well at the trihedral corners…all 3 sets of parallel walls converge, and any absorption located here catches room modes from all 3 dimensions, essentially working 3x as effectively.

The dihedral corners get next priority, since they work on 2 dimensions. And finally there’s the walls, which only work on one.

Now…

How to Set Everything Up

The typical setup process consists of 4 basic steps which I’ll show you now.

Step 1:

Since bass traps offer the widest range of broadband absorption

It makes sense to put them in the areas where they can have the greatest impact.

Which is why the first step in setting up your acoustic treatment is to mount a bass trap at each of the tridhedral corners.

For more information on what else you can do here, check out to the following post:

Step 2:

Now that the most important corners are covered…

The next step is to fill in the remaining corners with acoustic panels.

To cover the dihedral corners, simply bend them around the edge as shown in the picture…

And be sure to leave an air gap for maximum low-end absorption.

While I recommend using some of your acoustic panels for this purpose, don’t use them all…

Because you still need most of them for the next task…

Step 3:

Whenever two opposing walls are parallel to each other…

Sound waves have a tendency to reflect back and forth in the same spot…

Causing some frequencies to be amplified, and others to be cancelled-out.

To avoid this problem, mount your acoustic panels flat on the walls, and be sure to spread them evenly thoughout the entire room.

To get maximum effectiveness from a limited number of panels, avoiding placing panels on BOTH points of opposing walls…and instead, stagger their positions as shown in the above picture.

And finally…

Step 4:

The commonly accepted theory when it comes to diffusion is…it’s far more effective in larger rooms compared to smallerrooms.

Add to that, the fact that commercially-made diffusers are expensive, and it’s no surprise that most home studios skip it entirely. And that’s totally fine.

However, if you do use them… even better. In which case, the standard locations to put them are:

the ceiling/the upper portion of the walls in rooms with high ceilings. everything head level or below is absorption to kill those initial reflections.

Up next…

Control Room vs Live Room Strategies

In pro studios, where control rooms are used for mixing and live rooms are used for recording…different acoustic treatment strategies exist for each purpose.

The strategies we just covered are what you would typically use for a live room, to get a nice sound from virtually anywhere in the room.

However, in the control room, where the main goal is to maximize the accuracy of your studio monitors from the seated mixing position…

Specific acoustic treatment strategies exist, which I reveal in this post:

If your studio (like most home studios), is one that uses one room as both the control room AND live room…

Your acoustic treatment setup will need to blend elements from both strategies into a single “hybrid” plan.

Up next…

What to Do if the Money’s Already Spent

When setting a budget your studio, you should ideally set-aside a BIG chunk of the money (possibly as high as 50%), for acoustic treatment alone.

The problem is…most of us don’t figure this out until after the money has already been spent.

And while you can always save up more for the future, there’s still the problem of what to do right now.

Typically, people try various DIY methods of acoustic treatment including:

  1. Carpeting

  2. Cup holders

  3. Egg Crate Foam

The problem is…they DON’T work, and can actually worsen the situation by absorbing the high-frequencies, while ignoring the low-frequencies (where the real problems exist).

So here 5 effective DIY solutions that I suggest trying instead:

1. Close-miking

In rooms with poor acoustics…

The close-miking is one technique you can use to get decent sound from a less-than-ideal situation.

Here’s how it works:

By positioning the mic as close to the instrument as you can (without ruining the tone)…

You increase the portion of direct sound from the instrument, while decreasing the portion of reflected sound from the room…thus minimizing the impact of the acoustics on the recording.

To take this concept one step further, you can also try…

2. Using dynamic mics

Since dynamic mics are typically “less-sensitive” than condenser mics…

They also tend to pick up less ambience, which is good in rooms with poor acoustics.

Which is why, in untreated rooms, you should use dynamic mics whenever possible…especially on vocals, where the difference is often enormous.

You won’t get the sparkling highs of a condenser mic, but it will still sound much better overall.

Up next…

3. Household Absorbers

While acoustic foam manufacturers would prefer you believe that theirs is the onlymaterial that works…

It simply isn’t true.

Because really, any type of soft porous material such as pillows, blankets, couches, or even clothes, can offer similar absorption.

And since you already have plenty of that stuff lying around your house, it won’t cost a dime to simply store some of it in your studio.

While it might not look as professional as “real” acoustic treatment, it does help a lot…as long as you remember to stack everything as thick as possible, so all frequencies absorb evenly.

Up next…

4. The “Mattress Vocal Booth”

Even better than pillows and blankets…

Often times, the best natural sound absorber in your house is a mattress.

Which is why the most popular DIY method of recording vocals is to prop an old mattress against your wall so its directly behind the singers back as he performs.

Remember though, that making this technique work requires effective broadband absorption. And to do that:

  1. You MUST use a heavy solid-core mattress, and NOT a light inner-spring mattress.

  2. The most sensitive side of the mic should face TOWARD the mattress, to shield it from incoming reflections.

5. Reflection Filters

If commercial acoustic foam is currently beyond your budget…

But you think mattress and blankets are a little bit too ghetto…

A great “in-between” solution many project studios use is a reflection filter.

Rather than the absorbing reflections scattered about the room, reflection filters work by absorbing them before they even enter the room…

Using a semi-circle absorption panel which mounts to your mic stand and wraps neatly around the mic.

And while they may not work quite as well as proper acoustic treatment…

  • they still work decently.

  • there’s virtually no set up.

  • they’re about 1/10th the cost of a stand room package.

Even though they make not work as well as “proper acoustic treatment”…

By using your reflection filter in combination with the previous 4 techniques we covered, your recordings will sound 1000x better than they otherwise would in a completely bare room.

And they’re a great temporary solution until you can afford something better. To see which ones I recommend, check out this post:


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