Basic Concepts for Listening Rooms2023-11-28T12:20:15-08:00

Basic Concepts for High End Listening Rooms

Room Setup

To understand basic concepts for listening rooms we realize that each room is different and the equipment to be setup in the room can also vary. Still there are fundamental features in most all audiophile playback rooms. The orientation of the equipment in the room is fundamentally based on protecting the expanding sphere of bass pressure which is centered on the woofer of the loudspeaker.

The front of the room is where the loudspeakers are located. It should be symmetrical with respect to the speakers and have fairly hard surfaces with no open doorway or hallways, no acoustic venting to unload the pressure wave of one speaker differently than for the other speaker. The speakers are set wide apart, typically 8 to 10 feet apart and the width of the room also needs to be wide, typically at least 16 wide, otherwise the speakers experience some degree of acoustic loading, the megaphone effect, which changes the efficiency of the speaker in the lower range, hence its tambour becomes bass heavy.

The vents, the openings into the room work best for listening if they are located behind the listener. The kitchen break out, hallways and stairwell allow the bass wave once heard to continue on, out of the room, expanding into the rest of the volume of the house. This adds a desirable reverberance while minimizing bass wavefront reflection off the back wall and the accompanying standing wave and resonant mode effects.

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Although most HiFi rooms are existing rooms in a home that have been renovated to some degree, some audiophiles have the means to build dedicated audiophile listening rooms from the ground up. In these cases the desired room performance can be built into the design and construction of the room. Audiophile rooms are dedicated to supporting a particular kind of listening experience. They are unlike normal residential rooms. Without proper room conditioning the high end audio equipment cannot achieve its potential in performance.

  1. Setup equipment and listener with respect to room geometry
  2. Damp sympathetic acoustic and structural vibrations of room.
  3. Damp reverberant acoustic and structural vibrations of room.
  4. Damp treble range reflections
  5. Diffuse treble range reflections
  6. Add discrete reflections.
  7. Soundproofing

With basic concepts for listening rooms, the primary goal in these rooms is to hear the loudspeaker recreate music without room acoustic induced distortions and sound masking effects. The secondary goal is to cultivate the acoustic ambience suitable for listening, an envelopment by a blend of discrete reflections and directional reverberation. A third goal, which indirectly supports the audiophile experience, is to develop some sense of privacy. This manifests itself as keeping sound from bothering other people and keeping sounds by others from bothering the listener, essentially soundproofing.

Acoustic Damping

The air in the room, like the surfaces of the room, is flexible and is set into motion by the movements of the loudspeaker. The listener is very interested in listening to the sound made by the speaker but not very interested in listening to the stored energy of those sounds. Reflections, buildup, modes, standing waves and reverberations are all residual effects that are caused by the room intercepting and redirecting the expanding wavefront from the loudspeaker

The primary system for acoustic damping are corner loaded bass traps. Corners act like two-way megaphones. They funnel sound into the corners where it becomes very loud and then rebroadcast the sound back into the room using the walls on either side of the corner as a megaphone. Adding bass traps into the corners of the room dramatically damps the excessive storage of sound in the room, much more than adding the same damping material anywhere else in the room.

The first, most important set of corners to add bass traps into are the front two corners, those behind the speaker. These clean up the very rapid buildup of reverberation in the front of the room, something which dramatically obscures or sound masks the lower sound level details of the direct signal

The second set will be along the back wall, so as to depressurize the strength of the bounce of sound off the back wall. However, if the back wall has numerous openings, which vents and depressurizes the back wall bounce, then corner bass traps are not needed in the back of the room.

Reflection Control

Illustration of a stage 2 hifi room with tubetrap bass traps and soundplanks from acoustic sciences. Basic Concepts for Listening Rooms, 2c3dReflections, called early reflections in the audiophile environment, are treble range sound waves that bounce off nearby walls, floor and ceiling, and which arrive at the listener within the Haas Effect Time Window. This time window is within the first 30 to 40 ms following the arrival of the direct signal from the speaker.

These reflection points are found mainly scattered around on the walls, floor and ceiling surfaces that lie between the speaker and the listener. Treble range sound panels are usually applied in this area of the room to get rid of most of the early reflections. Early reflections generally defocus and stretch the sonic stage and the imaging detail on the stage, which is why they are not popular with the audiophile set.

Once the early reflections have been erased, the listening ear hears a vacuum space, a black hole in the listening room. This is also not agreeable and so two sections of the back wall, one for each speaker, is kept flat and clear from any absorption or diffusion. This section acts like a mirror which beams sound back up along the side walls. On the side walls are sound absorbers/diffusers. They absorb sound coming at them from the speaker but side scatter reflections coming off the reflecting panel zones at the back of the room.

These very time delayed low level reflections trick the ear-brain into thinking the room is very wide, quiet and spacious. This feeling of lateral ambience, an undefined but still palpable perception of sound coming from some distant objects off to the side is very desirable lateral ambience effect. (TubeTraps: Full Rounds and Half Rounds, Offset Reflectors)


When soundproofing is needed, a number of steps can be taken. Basically the damped flexible interior surface of the room cannot be altered. Any soundproofing efforts must take place on the other side of this damped flexible interior surface.

For the most part, soundproofing means bass range soundproofing. The soundproofing equation has 4 separate terms, a density term, a mass term, a damping term and lastly a strength term. Bass range soundproofing belongs exclusively to the strength term and so to soundproof a high power audio playback room, it needs to be surrounded with a very strong and therefore immovable wall.

Structural Damping

isowall cross section illustration from acoustic sciences for soundproofing and Basic Concepts for Listening Rooms

Regarding basic concepts for listening rooms, generally, the surfaces of rooms are flexible. Flexible surfaces are displaced and set into motion by the sound pressures developed by the loudspeakers. The audiophile is not interested in listening to the shuddering of walls, floor and ceilings. Structural damping is added between the elements of the structure, between studs or ceiling joists and sheetrock that covers them, between the first and second layers of sheetrock and between floor joists and the subfloor.

By structurally damping the surfaces of the room, both sympathetic and reverberant vibrations of the surfaces of the room and the accompanying sounds they make will be minimized. Additionally, structural damping acts like a huge membrane bass trap. The entire surface of the room dissipates the buildup of bass energy, hence the structural induced sustain of bass sounds. Basic concepts for listening rooms is our specialty. Contact us today to learn more.


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