You’ve seen pictures of bass traps in recording studios. Audiophiles brag about bass traps and other acoustic treatments in their listening rooms. But do bass traps make a difference?
Bass traps can make an enormous positive difference in your listening experience. Every listening room has acoustic qualities which affect the sound. Properly placed bass traps improve sound quality dramatically and are a relatively inexpensive way of upgrading your home audio system.
Whether your listening area is a basement, a garage, or a family room, you might benefit from some carefully placed bass traps. Read on, and I will explain what bass traps can do for your audio system.
The Basics of Bass in Your Listening Room
Bass notes pressurize the whole room. You feel the twanging double bass, the swelling organ, the thundering explosion. Your walls play a critical role in reproducing bass notes. But unlike cathedrals and concert halls, our homes were not built with acoustics in mind.
Every listening room has a different size and layout. Here are just a few of the variables that can change your room’s sonic signature:
- Brick, paneled, or plasterboard walls.
- Glass patio doors or big windows.
- Low or high ceilings.
- Carpeted, wood, or tiled floors.
- Bare walls or bookcases.
- Heavy upholstered furniture or open floors.
- Small vs. large enclosed area.
All these can play a role in how your audio system sounds. And one of the biggest improvement opportunities in most home audio systems sits on the lowest end.
Lots of people own subwoofers. Few know how to install and use them properly. Bass traps can treat the three biggest problems commonly found in subwoofer installations:
As bass notes reflect around your room, some frequencies get boosted and stand out above the others. This boost produces a boomy, distorted bass that quickly becomes a painful one-note thump as the volume increases.
Today, many judge an audio system’s bass by its ability to rattle windows and teeth. But the most impressive subwoofer installations give you detail along with gut-wrenching power. You don’t just feel the monster’s steps. You hear the difference as the monster moves from a dry road to swampy terrain.
Bass traps can tame some of those boomy frequencies. By absorbing sound that would otherwise reflect, your room’s sound becomes more accurate. What you hear is more like what the sound engineer intended you to hear.
Reflections can give you too much bass, but they can also give you too little. If you check your system’s bass performance with test tones, you may find that certain frequencies sound much quieter or are even suppressed altogether.
When a sound wave hits a wall, it reflects. If the distance between the speaker and the wall is 1/4 the sound wavelength, the reflection will be out of phase with the original signal. This out-of-phase echo results in the cancellation of both the echo and the sound wave.
If you’ve ever used headphones with noise cancellation, you’ve seen phase cancellation at work. The acoustic principle which lets you listen undisturbed on a crowded plane can also cause sudden valleys in your bass response. Bass traps dampen the out-of-phase reflection.
Ringing and Resonance Modes
If you’ve ever tapped a glass, you’ve heard ringing. Hard surfaces ring or resonate at different frequencies. When struck with sound waves at its resonant frequency, that surface vibrates. This vibration blurs the room’s sound and makes other frequencies less distinct.
Windows and glass surfaces can be highly resonant, as can unfinished plasterboard walls, tile, and thin wood paneling. But the dimensions of your listening room will also create resonance nodes that cause standing waves.
A standing wave is like a ripple striking a rock. As the sound flows back, pressure builds up, and the wave crests then recede. The turbulence causes unexpected peaks and valleys amongst different frequencies, boosting some and suppressing others.
Bass traps placed in troublesome areas can tame these ringing surfaces and standing waves. These traps not only increase the accuracy and clarity of your bass but they also improve your system’s sound across the entire audio spectrum.
How Do Bass Traps Work?
As their name suggests, bass traps trap bass. Low frequencies check into the bass trap, but they don’t check out. Bass traps absorb sound that would otherwise echo back toward the listener. They do that using several different technologies.
Foam Bass Traps
When a sound wave hits foam, it must travel through a labyrinth of tiny holes and entangled polymers. Much of the sound wave dissipates before it reaches the wall. The wave which echoes back must go back through the foam before making its way back to the listener.
Foam bass traps are generally best for handling midrange and higher frequencies. It takes an awful lot of foam to slow down a powerful low-frequency sound wave. However, as you will soon see, the proper placement makes all the difference in creating foam bass traps.
Helmholtz Resonator Bass Traps
Helmholtz resonator bass traps like the Vicoustic VariBass counter suck-outs caused by room nodes. When the node frequency hits the Helmholtz resonator, a membrane within the bass trap vibrates. This vibration is amplified through a small hole in the resonator and sent out into the room, where it makes up for the decibel drop caused by the suck-out.
A bad room node can drop a frequency over 20 decibels—the difference between a shout and a quiet conversation! A Helmholtz resonator trap can dissipate much of the sonic energy that would otherwise cause problems.
Diffuser panels absorb some of the excess sonic energy. They then spread the rest of the soundwave out, so it’s not so concentrated. This diffusion blunts much of the effect of room-related bass issues and results in more accurate sound.
Unless they’re very large and deep, diffuser panels don’t help a great deal with the lowest frequencies. But they can clean up reflections and unwanted echoes in the upper bass and low midrange. These frequencies carry the information that allows you to distinguish between a bassoon and a tuba and are very important to a good audio experience.
Do I Need Bass Traps With My Equalizer?
Today software and hardware equalizers can go a long way toward smoothing out your room’s sonic flaws. But some room issues go beyond an equalizer’s power. Room nodes are particularly challenging. When you boost the frequency to counter the node’s effects, the out-of-phase reflection gets louder along with the signal!
Bass traps can bring those problems down to manageable levels. Equalization works best as part of a total package. It can cover up issues, but equalization really shines when used to bring out a room’s best sound.
Where Do You Put Bass Traps?
Two of the more common locations for bass traps are in corners and on the rear wall.
Corner Bass Traps
Low-frequency pressure builds up in corners. The walls push the soundwaves toward their intersection, and the corner becomes like a horn projecting the wave back into the room. Placing bass traps in a corner helps diffuse that pressure.
Corner bass traps like the JBER 8-Pack Acoustic Foam Bass Trap from Amazon can be the most efficient use of your space. While bass traps can be large and unwieldy, putting acoustic foam in the corners takes up less room and is less intrusive than enormous padded mats.
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Last update on 2023-05-30 / Affiliate links / Images from Amazon Product Advertising API
Rear Wall Diffuser Panels
The reflections coming from behind the listener are generally the ones that cause the most problems. Putting diffuser panels on the rear wall will give you clearer dialogue when watching movies and better instrument separation when listening to music.
The Acoustimac DMD Stagger Acoustic Panel 8-pack found on Amazon will take care of your rear wall deflections and clear up many of your room’s acoustic issues. Acoustimac panels come with installation hardware and give your room a chic mid-century modern look along with vastly improved sound.
- High NRC Rated Core .95 or higher avg.
- Sturdy Cabinet grade wood Inner-frame and backing
- ASTM E84 Class A Fire Rated
Last update on 2023-05-30 / Affiliate links / Images from Amazon Product Advertising API
Getting your home audio system dialed in just right can be a lengthy, nerve-wracking and costly process. For considerably less than the cost of a new subwoofer, you can improve your sound with bass traps. This upgrade will actually make a difference in your listening pleasure.
- Georgia State University: Standing Waves
- GIK Acoustics: How Bass Traps Work
- Ethan Winer: Bass Trap Myths
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