Low Frequency Control

Basic broadband bass traps rely on thick porous absorption, with an air gap between the absorber and the wall. However, for very low frequencies this is an inefficient use of space. This is because porous absorbers act on the particle velocity of a sound wave, which is zero right against the wall and maximum at ¼ of a wavelength away from the wall. That means for porous absorption to be efficient at 80 Hz (wavelength of 14 feet), you would need absorbent material 3 ½ feet from your wall.

In contrast, Vicoustic’s Super Bass Extreme has excellent absorption at 80 Hz, and it fits snug in the corner of your room. It achieves this because unlike porous absorbers (which act on the particle velocity), it uses a membrane that responds to the sound pressure, which is maximum in the corners of the room.

The membrane (or diaphragm) is tuned to 75-85 Hz and vibrates over that frequency range, converting pressure fluctuations into air motion. The moving air is forced to pass through high-density acoustic foam inside the Super Bass Extreme. This resistance causes acoustic energy to be absorbed and converted to heat. The system behaves like a damped spring, absorbing low frequencies down to 60 Hz.

But, Super Base Extreme traps are not simply membrane / diaphragmatic absorbers. To further take advantage of the high pressure in the corners of your room they integrate another method of absorption: The panel at the back of the bass trap is micro-perforated with 1 mm holes, making it behave as a tuned Helmholtz resonator. Through testing, Vicoustic found that these perforations caused a 20% increase in low frequency absorption efficiency. The back panel Helmholtz resonator in the Super Bass Extreme is a simple enhancement that makes a big payoff in performance.

Mid-High Frequency Control

The Wavewood panel front of the Vicoustic Super Bass Extreme features a sequence of cavities with absorption underneath. This patterned wood surface (which looks like an audio wave form) functions as a hybrid absorber / diffuser. As the frequency increases, the front surface acts less like an absorber and more like a diffuser, scattering mid-to-high frequencies to improve the sense of spaciousness in your room. This way, low frequencies are absorbed while precious high frequency energy is preserved. In other words, these bass traps help retain liveliness so your room does not sound overly dead.

Optional Super Bass Extreme Stackers (Sold Seperately)

The modular design of Vicoustic Super Bass Extreme traps allows mounting flexibility and portability. The default mounting method for permanent installations is to use adhesive flexi glue. For non-glue installation, consider the optional Stacker Levels and Stacker Bases (sold separately). The Stacker Base anchors to the bottom bass trap, giving a stable platform for building the stack, while Stacker Levels sit between traps so they can be stacked on top of each other.

This system lets you safely stack multiple Super Bass Extreme traps in the corner without the need to permanently fix them to the walls.

Why do I need Bass Traps?

Small and midsize rooms such as control rooms, mastering rooms, tracking rooms, listening rooms and home theaters naturally have a problematic, uneven low frequency response. This is caused by resonant room modes, standing waves, random wave interference and speaker boundary interference response (SBIR).

Room modes are natural resonances caused by the geometry of your room. They cause problematic peaks and nulls (dips) in the frequency response. In other words, the loudness at a particular modal frequency will vary depending where you are in the room. At locations in your room where sound waves are in phase with each other at a specific frequency, a peak occurs in the response (this is what causes the infamous “one note bass”). At locations where bass waves are out of phase (called nodes), you’ll get a null in the response.

Speaker boundary interference response (SBIR) causes deep dips in the bass response below a certain frequency. This is caused by destructive interference between the source sound wave coming out of your speaker, and the reflected sound wave bouncing off a nearby boundary (such as a wall). When the direct and reflected sound waves are out of phase with one another, cancellation occurs, causing a dip, or null.

The simplest way to tackle these problems is to mount bass traps, like the Super Bass Extreme by Vicoustic, in as many corners of your room as possible. Then, you’ll be able to clearly hear the frequency balance in your music and enjoy numerous benefits: You will be able to make better mixes, trust your ears when mastering or critical listening, hear nuances you never new existed and enhance the pleasure of your listening experience.

Applications for Vicoustic Bass Traps

Any domestic-sized room used for music will benefit hugely from bass traps. In general, start with broadband control, then use tuned bass traps like the Vicoustic Super Bass Extreme to target problematic low frequencies where broadband absorption is inefficient. Use in small to medium sized rooms including control / mixing rooms, post production rooms, mastering rooms, live recording rooms, hi-fi listening rooms, home cinema rooms and small rehearsal spaces.

If you’re looking to treat your whole room, click here for your personalized Vicoustic room treatment plan. We can assess your room and design a custom-fit acoustic treatment kit just for you.

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Room modes distort your low frequency response. Modes cause peaks at some frequencies (making them sound louder), nulls or dips at other frequencies (making them sound quieter), and modal ringing (where some frequencies take much longer to decay than others). This reduces listening clarity and creates problems like “one note bass”, where all bass frequencies sound basically the same regardless of pitch.

Room modes and other bass problems below 100 Hz require special tuned bass traps to treat effectively. Unless you want to dramatically shrink your room, you can’t treat a 50 Hz room mode using only porous broadband absorption (like fiberglass, rockwool or acoustic foam). To treat these deep bass problems you need tuned bass traps. These include tuned membrane / panel absorbers, and Helmholtz resonators like the Vicoustic Vari Bass.

But most tuned bass traps have a fatal flaw. Because room modes are governed by the geometry of your room, tuned bass traps usually have to be custom specified to target a modal frequency with maximum efficiency.

The tunable Vari Bass trap solves this problem.

How to use the Vari Bass Helmholtz resonator

The simplest way to treat a problematic low frequency in your room is to place a Vari Bass in the corner, then rotate the wooden top until you hear it start to affect the frequency you’re targeting.

If you want to be more scientific, you can use acoustic measurements to find the exact frequency that’s causing you grief. Then, tune the Vari Bass to target it. You can accurately target frequencies from 50 Hz to 100 Hz.

A visual scale is included so you can see which frequencies the Vari Bass trap is absorbing as you tune it.

Unlike broadband porous absorbers, which need to be placed a distance from the wall to absorb low frequencies, Helmholtz resonators act on the pressure component of the sound wave. This means you should place Vicoustic Vari Bass traps where the sound pressure is maximum (right against the edges of your room). Corner placement is ideal, especially in the tri-corners where your floor and walls (or ceiling and walls) meet.

How the Vari Bass trap works

The Vari Bass Helmholtz trap operates using three main principles:

1. Variable frequency absorption by Helmholtz resonance (tunable).
2. Absorption by a piston system through the interaction of the air chamber and rubber isolation in the device.
3. Porous absorption (broadband acoustic foam) to widen the bandwidth and absorb harmonic frequencies.

Helmholtz resonance simply means air resonance in a cavity. It’s the same thing that happens when you blow across the opening of an empty bottle.

Like all Helmholtz resonator absorbers, the basic form of the Vari Bass is a resonant air cavity with narrow openings. During resonance, energy is absorbed through friction when high velocity sound particles are forced through the openings (the five tubes in the Vari Bass).

The top section of the Vari Bass contains five tube cavities surrounded by absorption (high density acoustic foam). Connected to the tubes is a larger air cavity, which shrinks or expands as you tune the resonant bass trap.

The cavity of a Helmholtz resonator can be accurately tuned to a specific resonance. While most Helmholtz traps are built with a fixed resonant frequency, the Vari Bass lets you tune it by adjusting the size of the resonant cavity.

Helmholtz resonators provide high efficiency absorption over a relatively narrow frequency range, so they are ideal for targeting low frequencies that are impractical to tame using porous absorption.

However, the bandwidth of a Helmholtz resonator can be widened by adding porous absorption inside the resonant air chamber. This is the purpose of the sound absorbing foam in the Vari Bass. The acoustic foam is also important for absorbing frequencies over 100 Hz, helping reduce the energy of harmonic modes. While the fundamental frequency of the Vari Bass (which you can tune) is absorbed by Helmholtz resonance, the harmonics of the fundamental frequency are absorbed by the acoustic foam.

The combination of these absorption methods means the Vari Bass does not only absorb energy of the acoustic mode it’s targeting. Acoustic testing done by Vicoustic and Salford University demonstrated that the Vari Bass actually distributes low frequency energy to other frequencies nearby, modifying the Q factor of the room mode it’s tuned to [1]. Vicoustic found that the amplitude (sound pressure) difference between peaks and nulls was reduced when the Vari Bass was added to a test room, resulting in an overall flatter low frequency response (a tighter, more even sound in the low end).

Vicoustic Vari Bass traps are especially useful in critical listening rooms where the low frequency response affects your ability to accurately monitor and mix. This applies to mixing rooms, mastering studios and recording studio control rooms.

The Vari Bass Helmholtz resonator can also be put to great use in your hi-fi room or home theater. If your goal is to optimize your room for high fidelity audio playback, targeted bass absorption is often the critical finishing touch. If certain room modes are causing your grief, tunable bass traps like the Vari Bass can take your listening experience to the next level.

If you’re looking to treat your whole room, click here for your personalized Vicoustic room treatment plan. We can assess your room and design a custom-fit acoustic treatment kit just for you.

[1] J. Castro, T. Silva, B. Fazenda, “Vari Bass – Vicoustic Research & Development”, Vicoustic press article, 2012

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Absorption Characteristics

Surface or corner applied porous materials lose efficiency at low frequencies, because the particle velocity or air movement associated with long wavelengths is low.  The sound pressure, conversely, is at its maximum.  The internally damped membrane in the Modex Corner exploits this high pressure by converting the pressure fluctuations into air motion.  As the membrane sympathetically vibrates over a selective low frequency range, determined by its mass and stiffness, it pushes air through an internal porous layer producing low frequency absorption.  This innovative approach makes it possible for the Modex Corner to absorb the fundamental and higher harmonic modes that are often problematic in small rooms.

Installation

The Modex Corner can be mounted in any 90° corner between two walls or a wall and a ceiling.  It can be attached directly to the surfaces using the supplied hook and loop or metal screw fasteners.  If there is no 90° corner available, or if the corner is not suitable, the Modex Corner can be stacked in a free standing configuration.

Features:

 
Benefits:

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