Silent Speakers Great Soundstage
In a poorly set-up room it is easy to know that the speakers are playing. You can hear them, you can point to where the sound is coming from…and it will be coming from the speakers. In a well set-up room, it’s hard to actually know that the speakers are even playing, they seem to be silent.
And when you point to where the music is coming from, it’s not the speakers, it’s up and ahead of you, between the speakers, behind the speakers and out to the sides of the speakers. The music seems to come from a large sound stage floating in space in the front part of the room. The better the room setup is, the more the soundstage wraps around the listening area.
The ultimate listening room was coined around 1990 by Bruce Brisson of MIT Cables: 2C3D, 2-channel 3-dimensional soundstage. It was developed by a collaborative effort between 4 manufacturers: ASC TubeTraps, MIT Cables, Spectral Audio and Avalon Acoustics. Once the system was developed, other high-end components were combined to produce a similar holographic audio performance.
In the traditional Hifi setup the soundstage appears as a crescent shape space in which various instruments or combinations of instruments, including vocal of course, seem to be floating in space and projecting sound from their location. We can’t really see the visual image of each instrument but we can see where they are located on the sound stage, and we can point out right where they are located.
What is interesting to observe is that in the well set-up room you can get up and walk left and right, and the sound stage moves left or right with you. In a poorly set-up room you might enjoy a reasonable sound stage but when you get up and move to the left the stage collapses onto the left speaker or right speaker if you move to the right.
Non-Room Early Reflections
HiFi gear back in the 70’s used to be piled up in the front of the room between the speakers, the “golden calf” era in audio. It made a great visual presentation and included turntables, reel to reel players, preamps, equalizers, amps and the stands to support them.
Suddenly in the mid 80’s that gear setup literally disappeared.
Audiophiles had discovered that early reflections off all that equipment stacked between the speakers was causing the stereo image to be limited to a ball of fuzz between the speakers.
Where did all that gear go? It was moved down the two side walls and the interconnect cables became longer and longer. There was nothing but clean air surrounding and between the speakers. Today the gear setup has changed again. The amps are back near the speakers and preamps not far away but instead of being up on stands they are down low, near the floor, then set back behind the plane of the speakers. Turntables were moves far away from the speakers to distance the record player from the wave impact from the speaker.
This compromise position minimized the strength of the treble range reflections off the equipment. It was far enough away and behind the speakers so the wave strength that hit it was weak and the reflections were cast away from the listener. Also, some equipment was removed from the audio chain. No equalizers were to be found. The only signal processed was the original unadulterated signal. We used a “linear audio chain” and no accessories.
Effects of Reflections
We have a direct signal that is recorded along with numerous early and late reflections. These reflections in the recording have an effect on the listeners impression of the timbre of the sound and the location of the image of the sound.
In Hifi playback the goal is generally for the listener to have a listening environment which allows the original timbre and image to be perceived. Otherwise, the early and late reflections in the room additionally change the timbre and image of the recorded signal.
Below is a graph, based on tests, which outlines the effects caused by early and late reflections. The graph shows the various types of effects one will hear based on the time delay and loudness of the reflections. A multiplicity of reflections creates a multiplicity of effects.
Very early reflections, within 5ms, cause changes in the position of the image. Early reflections between 5ms and 35ms delayed cause image shift and tone coloration. This is because very and early reflections are sound fusion reflections, they become part of the direct signal.
Late reflections between 40ms and 70ms create the effect of space in which the direct sound was created. Very late reflections, beyond 70ms, create a confusion of noise being added to the music which compromises the clarity in the hearing of the music which degrades the appreciation for the quality of the music. These reflections will come up again and again as we review the imaging of musical playback.
