High definition acoustic playback requires great equipment and great room acoustics. The equipment produces one kind of sound, the direct sound while the room produces another kind of sound, reflections and reverberation. These two kinds of sounds, the direct and the reflections are acoustically mixed at the listening position into one composite signal, the perceived sound of the system at the listening position.
Why It Sounds The Way It Sounds…
We Control The Impact Zones!
The acoustic setup for the Crestone Peak Room was designed by ASC using only the floor plan for the room along with manufacture’s estimate for speaker position and a few photos. The room will initially be setup as shown and then “tweaked” until the best sound is achieved. The room is divided into 5 basic zones, as shown in the floorplan. What happens in each zone is different. It happens at different times and at different stages of the evolution of the wavefront from the speaker which is why the acoustic setup in each zone is different.
ASC supplied all the acoustics for this room. We are using our new patent pending IsoThermal TubeTrap which provides extended bass, literally twice the absorbing power compared to the standard TubeTrap below 60 Hz, in the sub bass region.
1) Speaker Plane Traps:
Trapping the walls in the plane of the speaker defeats the otherwise powerful buildup of lateral and vertical bass early reverberation, which greatly improves musical clarity, punch and overall dynamic response. It also softens the hard wall reflection which otherwise imposes a phase add/cancel effect onto the speakers and results in a more smooth speaker frequency response curve.
2) Front Wall Traps:
The front of the room experiences two kinds of bass wave front impacts. The first is the direct reflection of the wave off the front wall, back down the length of the room. If left untrapped, these waves creates phase add/cancel problems for the speaker and again at the listening position. It also begins to buildup reverberation and modes along the length of the room. Bass is mixed mono so the playback equipment can deliver the required bass power to the room without overdriving most speakers or amps, which means we have identical wave fronts expanding out of each speaker.
These wave fronts crash together along the midline between the speakers. At the midpoint of the front wall the sound pressure becomes quite high, just as loud as in the other two front corners. This midpoint “virtual corner” gets the same TubeTrap as the other two real corners in the front of the room.
The second kind of wave impacts in the front of the room is the buildup of lateral, side to side reverberation and as well vertical reverberation. The front corner traps are very powerful in damping down this “head end ringing” or storage of sound in the front 1/3rd of the room.
3) Mid Wall Traps:
Mid–wall traps deal primarily in the treble range do clean up the sonic image, stage, ambience and spaciousness effects. Here the “early reflections “ are processed, of which there are two types. The least well known and yet the most serious is the LR cross talk reflection, which is when the left speaker signal reflects off the right wall into the right ear, and visa versa. This cross talk signal bleed ruins stereophonic perception process and converts stage imaging into a sonic fog bank. The more commonly known and less worrisome early reflection, the near wall reflection, acts to widen and distort the sonic stage.
In this room we have the racks of electronics lined up along the left wall which act as treble range diffusers. They block the hard left wall reflections and replace then with multiple lower level diffusive reflections. We use StudioTraps to add similar sounding diffusive reflections from the right wall. Now we have achieved a LR balance in the strength and nature of the low level lateral reflections.
4) Rear Wall Traps:
The rear wall is split in half, one side has the back doors which are kept ajar. The other side is a hard walled cavity. The bass air pressures near the doorway are vented out of the room, which minimizes their bass buildup. The hard walled cavity on the other side of the room is not vented and so stacks of bass traps have been added to balance with the bass venting at the door. Again, the treble diffusing panels are rotated so they backscatter sound into the room, as does the angled door set.
5) Stage Detailing Trap:
In some cases adding traps up close, in the nearfield of the speakers, can absorb and diffuse sound long before it expands out into the room. With Martin Logans, a tradition has developed where a trap is positioned just to the outside of the focal point of the curved diaphragm. This absorbs compressed rearward moving bass energy while the reflector is rotated into the focal point to side scatter the treble backwave. By moving this stage trap left and right, back and forward the right balance of front wall reflection (stage depth) and lateral diffusion (ambience) can be setup.
