How It Works

TubeTraps, the original, archetypal bass trap, dating back to 1984, are set up in the corners of the room where they act like sonic shock absorbers. TubeTraps eliminate excessive build-up of bass energy in the room while their built-in diffusers minimize flutter echo by horizontally scattering mid-high frequency sounds to provide fine grained lateral ambience.

The TubeTrap was developed using acoustical engineering principles and voiced by the consensus of "golden ear" audiophiles and engineers.  It was the first full bandwidth sound absorber/diffuser (abfuser) and has become synonymous with quality listening and performing spaces.  TubeTraps quickly became the worldwide defining icon of high performance audio room acoustics, and remain so to this day.

TubeTraps are used to make music from the beginning to the end of the audio chain.  In the recording studio, TubeTraps are used to control the acoustics that surround the talent and mic during the creation of audio tracks.  Next in the process, TubeTraps work to create crystal clear mixing environments.  After that, TubeTraps are used to create the perfectly translatable acoustic environment needed for song and album mastering.

Finally, TubeTraps are used to create reference listening rooms for the manufacturers of audio equipment, great demo rooms for the equipment dealers and fantastic playback rooms for the audiophile listener...amazing rooms which help audio gear turn great recordings into great sounding music. TubeTraps are involved with music from creation to consumption.

TubeTraps are very busy at work, from the making of music to the playback of music...or as we like to say.....from music to music.

Room Acoustics & TubeTrap Bass Traps

The loudspeakers and subwoofers in today's high performance audio playback settings produce tremendous amounts of bass energy.  Professional recording studios have long used speakers powerful in the bass range, and traditionally have used built-in bass traps to balance the sound in the room and prevent unwanted buildup.  On the other hand, rooms constructed for residential or retail demonstration use have no accommodation to handle the build-up of excess bass energy. And so the uncontrolled sound pressure builds up inside the room, which not only is unpleasant for the listener, but it additionally shakes the walls, floor and ceiling, windows and doors of the room.

These shaking surfaces act like giant uncontrolled loudspeakers that bother the neighbors and additionally ruin the quality of sound in the room. High power audio playback at home or in commercial spaces is no different than what goes on in recording studios. Bass trapping, combined with treble range absorption/ diffusion, is needed for quality sound to be heard, regardless of how expensive the speakers and amps may be. The TubeTrap is a self-contained, broadband bass trap, utilizing a reactive acoustical circuit that is energized by and works off of the presence of sound pressure.  It performs best when placed at locations in the room where the sound pressure is the highest, which are typically in the corners and against the walls of the room.

Because the TubeTrap only reacts to sound pressure it is sometimes referred to as a pressure-zone bass trap. Although the TubeTrap is a broadband sound trap, it can be modified by adding additional acoustic circuitry to give it an enhanced narrow band range of sound absorption in addition to its broadband bass trap properties. However, this is not to be confused with a "tuned bass trap" which is exclusively a narrow band bass trap and has no broad band properties. 

For the most part, the "tuning" of the TubeTrap is actually not done with internal circuitry, but done by the room itself.  When a room resonance is stimulated, the sound pressure is always the highest in the corners of the room and in select locations along the walls.  Placing TubeTraps in the corners and at certain wall locations puts them in the high pressure zones of the room modes. The higher the pressure, the more efficiently the TubeTrap absorbs energy.  For tones that are not room modes, the energy in the room is diffuse and sound pressure is more uniformly distributed.   Properly placed TubeTraps ensure that loud, long lingering modes will be more highly damped than the more quickly decaying diffuse sounds in the room.  This gives any room in which TubeTraps are used a much more tonally balanced reverberant field.

Acoustic Circuitry

The bass trap component of the TubeTrap is an acoustic circuit. It acts just like a series RC circuit in electronics, a high-pass filter. The R part is the acoustical resistor, the wall of the 

TubeTrap, whose DC flow resistance equals the acoustic impedance of air, 410 Rayls.  This is similar to what happens when a video technician terminates the unused leg of a video cable system. A 75 ohm terminal resistor is used to cap off the open ends of a 75 ohm coax cable transmission line. The C part of the acoustic circuit is an acoustical capacitor, the air cavity inside the TubeTrap. The larger the volume, the lower the roll off frequency in the response curve.

Covering half of the surface curved surface of the TubeTrap, end to end, is a perforated sheet of soft plastic, a limp mass. High frequency sound bounces and scatters from the surface of the reflecting sheet while low frequency sound passes right through the holes in the reflecting sheet. This is another acoustic circuit element, in effect it creates acoustic inertia, which is comparable to an electronic inductor, L.  An inductor is a low pass filter.   The other half of the TubeTrap is fully absorptive, with broad-band effectiveness.

TubeTrap - Treble Diffusion and Absorption

These three acoustic circuit elements are connected in series which produces the effect of a bandpass sound absorber. The lower cutoff frequency is determined by the diameter of the TubeTrap, not its length.  The upper cutoff frequency of the bandpass is determined by the hole pattern in the treble reflecting perforated sheet.  Rotating the TubeTrap on axis changes the % of treble diffusion facing into the room between 0 and 100%.  Rotating a 

TubeTrap is equivalent to adjusting the volume control for "laterally scattered treble". Tuned resonators can be installed inside TubeTraps to provide enhanced absorption at a particular frequency. Active TubeTrap bass traps are also available and they provide a very wide bandwidth of deep bass absorption.