Primacoustic London Bass Trap

OVERVIEW

The Primacoustic London Bass Traps are designed to help control excessive low frequency build-up that cause room modes in studios and listening rooms. Acoustic energy naturally migrates to corners using the walls and ceiling as waveguides. This makes corner-mounting the bass trap the preferred location.

The London Bass Trap kit consists of two 24″x48″ (61 x 122cm) Broadband 2″ (5cm) thick absorption panels along with corner-mount Impalers, sheetrock anchors and screws. Each panel is constructed from high-density 6lb per cubic foot (96 kg/m³) glass wool with resin hardened edges and fully encapsulated with micromesh. The panel is hand wrapped with an acoustically transparent polyester fabric to create sharp, architecturally pleasing lines. Installation is just about as easy as hanging a picture! Once installed, the substantial surface area of the panel combined with the 17″ deep (43cm) air cavity created in behind delivers excellent absorption throughout the audio listening range and extends well down into the low bass region. This helps reduce troublesome room modes and hot spots by attenuating standing waves making it easier to record and produce music with greater confidence.

The London Bass Trap kit is the perfect add-on to the Primacoustic London 8 and 10 room kits or may be incorporated into any room where low frequency control is needed.

INSTALLING CORNER BASS TRAP PANELS

Primacoustic corner impalers make it easy to mount the 24” x 48” Broadband panels across room corners to form effective bass traps. Like the surface impaling clips, the corner impalers feature sharp tips that penetrate the panel and hold it securely in place.

Applications

Home Theater

Create an accurate listening environment for your room by controlling bass for your home theater or listening room.

Basstraps in Studio

Add London Bass Traps to your existing sound treatment or a London 8 Room Kit for extra low end absorption.

Basstraps in Studio

Primacoustic modular approach allows you to purchase the panels you need and add additional panels when you want.

Specifications

The London Bass Trap™ kit consists of two 24” x 48” (60.96 x 121.92 cm) panels that effectively absorb sound energy from 75Hz and up. Designed to be corner mounted at ear-height, or stacked floor to ceiling, the kit provides substantial surface area for broadband absorption with effective coverage down into the low bass region.

The London Bass Trap kit is constructed from fabric wrapped, high-density glass wool Broadway panels. When installed in the room corner, a 17” deep air space is formed behind the panel. This air space provides significant absorption in the problematic low-mid (100Hz – 200Hz) region while seamlessly integrating with other Broadway panel installations. Mounting is achieved using the included Primacoustic Corner Impalers. The Primacoustic London Bass Trap kit is available in black, beige or grey fabric or in Absolute White™ paintable finish. Sold in pairs.

Tests and Safety

Absorption Coefficients

London Bass Trap Science

It is well documented that the most difficult frequencies to control are in the deep low bass region. This is due to the long wavelengths that require a lot of energy to produce, and then tremendous effort to control. Once a room is overly excited with bass energy, room modes develop whereby sound bouncing off the walls will react with the direct sound from the loudspeaker and either cancel each other out – if out of phase – creating a lull or combine together – if in phase – to create a peak. These cause frequency bumps (modes) in the room that cause the sound to change depending on where you are positioned.

The solution is to integrate a bass trap into the room. Because low frequencies below 300Hz are considered to be omnidirectional, a bass trap can be positioned anywhere in the room to have effect. However, because sound travels within the confines of the walls, ceiling and floor, it tends to migrate into corners. This makes the corner the most efficient location for capturing sound energy.

There are several types of bass traps including Helmholtz resonators, diaphragmatic resonators, large masses of foam, and rigid panels with air cavities. They all work… albeit some are more effective than others. In all cases, their task is to reduce bass energy so that their effect on the direct sound is minimized and room modes are lessened.

Helmholtz Resonators

These are very effective. They employ an air cavity that is tuned to a specific frequency – like blowing into a Coke bottle. For the ultra-ambitious, one could measure the room modes and then build a bunch of these to pull out the problem frequencies. Helmholtz resonators are rarely used due to the complexity and high cost.

Diaphragmatic Resonators

These generally come in two forms – hard and limp. Hard resonators work like the Helmholtz device and are made to target very specific frequencies. Limp mass resonators like the Primacoustic MaxTraps vibrate as they automatically center where the room energy is greatest. These are very effective, but more expensive than foam or air cavity type bass traps.

Foam Bass Traps

These absorb bass by allowing bass energy to penetrate the foam and cayuse the soft membranes to vibrate. Using what is known as the ¼ wavelength calculation, one can estimate the low frequency cut-off. As a rule, the deeper the foam, the lower the bass they will absorb. A 12″ x 36″ (30.5cm x 91.4cm) foam trap will absorb energy down to about 125Hz – although this will vary significantly depending on the density of the foam and whether large areas have been cut out to create an anechoic wedge appearance. The higher the density, the better the bass absorption. Foam is losing popularity due to dusting, health concerns and lack of fire ratings.

Panel With Air Cavity

Primacoustic London Bass Traps employ a glass wool that is as much as 12 times more dense than the typical foam used in bass traps. The higher density creates a barrier that not only traps energy as it enters, but also does the same when the energy reflects into the air cavity behind and tries to escape. The 17″ air cavity dramatically intensifies the low frequency absorption point down to 100Hz when using the same ¼ wave calculations.

The other benefit of using large panels like the London Bass Traps is that they not only absorb bass, but absorb energy at all frequencies above the lowest point. This means that they also help tame flutter echo, standing waves and primary and or secondary reflections.