Problem and Solution
Small rooms like Project Studios often suffer from low frequency modal problems.
Absorption at these
frequencies requires a high absorption efficiency and significant surface area. Since
small rooms do
not offer the needed space, the absorption efficiency must be optimized.
This product solves the problem by optimizing the absorption efficiency using a unique
internally damped membrane absorber that provides ideal absorption in the modal
Sound (1) strikes the membrane (2) which sympathetically vibrates, converting the sound pressure to air (3) motion. The air
loses velocity (4) as it moves through the internal absorber and air cavity.
Now you absorb more bass in less space!
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 Bass Trap 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 Bass Trap to absorb the fundamental and higher harmonic modes that are
often problematic in small rooms.
While membrane absorbers can be designed for a specific frequency and offer a high absorption efficiency, their
bandwidth or range of frequencies over which they are effective is limited.
One can broaden the Q of the system by
introducing damping in the air cavity, but this is accompanied by lowering the maximum absorption efficiency.
RPG has taken a different approach to provide absorption in the modal range. By systematic impedance tube testing,
RPG has optimized the membrane mass, compliance and cavity depths that offer maximum absorption efficiency at the
third octave center frequencies of 40, 50, 63 and 80 Hz. To cover the 40-80 Hz frequency range, one can simply
combine Modex modules, thus providing 100% efficiency. Specific modal problem frequencies can also be addressed
with individually tuned modules.
The Modex Bass Trap can be simply mounted, directly onto walls or ceilings, using the supplied split battens. The split batten is screwed
onto the wall and the unit is simply hung on the batten.
A modfied version is also available for ceiling mounting with side 'wings' for screw fixings. This unit can also be
used for wall mounting if the whole array is to be fabric covered complete on site.
Please Note: These units only have a 0.36m² surface area per unit. Generally this is very small in relation to the overall surface area within a small room.
We have found that a pair of traps in the optimum placement will give a 1-2dB dip so generally at least 6 units are needed.
- The Modex Module's proprietary internally - damped membrane converts any available wall or ceiling into a highly absorptive low frequency absorber
- The Modex Bass Trap provides useful low frequency absorption in wall-wall and
wall-ceiling corners that are often unused and available for acoustical treatment
- Bass management in the sub-woofer region is now simply a matter of attaching Modex to walls, ceilings or corners
- Modex modules can be upholstered and visibly installed or concealed behind ceiling clouds, soffits or stretch fabric
- Modex Plus Modules (12& iquot; depth) offer absorptive chevrons between the room
and the membrane to extend absorption to cover the 40- 10,000 Hz frequency range
- All Modex modules are modular and can be added as needed. The modules simply stack on top of one another and offer
unlimited opportunity for experimentation and modification
- Recording studios
- Post production studios
- Listening rooms
- Home theaters
- Quality control rooms
- CD mastering
- Film mix and dubbing stages
- Music practice rooms
600mm (W) x 600mm (H) x 200mm (D)
- Weight varies with the membrane (call for details)
- Standard fabric finish is Cara/Premier. Custom colours are also