Unlike watching an image on a large TV screen. Producing a believable, correctly positioned sonic image in front of the listener whilst listening to a stereo recording through conventional loudspeakers can only be achieved from a seat equidistant from each speaker. This is, surprisingly, rarely mentioned by speaker manufacturers.
The reason that this problem exists is to be found in how conventional speakers emit sound. Speakers using cones and tweeters produce a stream of spherical wavefronts. Each corresponds in size directly to the frequencies handled by each of the drivers in the front panel if the loudspeaker.
Like dropping a pebble into a pond these almost bubble-shaped waves rapidly expand and in doing so rapidly lose energy which translates directly to loss of volume. This is made worse by the fact that this decay in volume decreases exponentially with distance from the speaker.
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This means that a listener only has to move a little left or right, to have a large effect on the volume from the speaker nearest and the one furthest away.
The position and stability of sonic images in the soundstage rely on the accurate arrival to each ear of the listener of sound at the correct volume from each speaker.
If this fine balance is upset, chaos ensues with the suspension of disbelief, vital in recreating a believable image, being destroyed.
Below is an example of what can happen to an image in a conventional speaker set-up.
With a listener is sat in a central position, a centrally positioned sound image in the recording is placed correctly for the listener in the sound stage, as the sound’s volume is the same in each ear.
If the listener moves slightly left, the image will appear to come from the left-hand speaker because the left-hand speaker appears much louder.
If what should be a centrally placed image moves to its left, what should be heard is the image moving from the centre to the right-hand speaker seamlessly and smoothly with no change of shape. In reality, with the listener off-centre, this is what happens to the sonic image.
Decades ago amplifiers came fitted with ‘Ballance’ controls to some degree counter this. The listener could sit where they wanted and adjust the sound for them. However, still only one person could get the best sound.
The patented William Eikos Aurigen technology places all the sonic images in their correct positions and allows them to move without distortion for anyone seated in the room.
Like each side of the pyramid stage at Glastonbury, and in the Royal Albert Hall in London (and for the same reason) our array of identical speakers do not pump bubbles into the room but a flat coherent wave of sound containing far more energy and decaying much less.
An additional advantage is that, unlike conventional loudspeakers, due to the shape of the sounds produced there are far fewer reflections from the floor or ceiling of the listening room. This greatly improves the coherence of what arrives at the listener, further enhancing the believability of the sound.
For this explanation, we have kept things simple, by only using one sonic image.
Imagine what happens with more than one… and they move?
The added bonus here in AV applications is that not only is a central channel now completely redundant but in installations with larger screens, as sound sources move on screen, so will their position for the listener, making the experience much more believable.
This does not happen with a mono-centre channel speaker. There is an additional advantage which we have not represented in our graphics.
As most conventional speakers shift phase with frequency due to the vagaries of their crossover filters (see our paper on crossover filters). The spatial cues and harmonics captured in the recording and vital to have any hope of sounding like the original, are damaged. This creates a more two-dimensional almost blurred image adding to the destruction of the fine detail captured at the recording. All leading to knowing immediately that we are listening to loudspeakers.
At William Eikos we have chosen to take a far more technically challenging route to preserve the subtle structure of the original signal with the result that images are very three-dimensional and coherent, with the sound of air and space of the original venue represented in amazing detail.
This places the listener in the original acoustic making engagement with the artist and emotional involvement almost instantaneous.
At William Eikos we like to explain features of our products that solve issues that have dogged conventional loudspeakers for decades. These explanations can be technical and are perhaps not for everyone, but if you decide to read on, we hope they will enlighten you as to why our products are special and represent a major technical leap forward in bringing you closer to your music and therefore aid you in making an informed decision.
There are four papers in our series:
Please feel free to contact us if you require any further information.