AES Section Meeting Reports

Melbourne - April 11, 2022

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On Monday April 11th a small cohort gathered in person for the first time in over two years for a Section Meeting. We visited the Involve Audio facility at Mentone, where Charlie Van Dongen demonstrated his designs for the complete surround sound chain with improved soundstage imaging - decoding, amplifier, loudspeaker processing, as well as electrostatic loudspeakers.

Charlie started by introducing his colleagues David Alexandrou - head of electronics, Ron Berger -electronics and software development, and Wayne Cary - mechanical and process audio consultant, who would assist him with the demonstrations.

He then described their Sound Master product, a 2-channel to surround decoder, and the Y4 System - a complete Surround system comprising a 10 Channel amplifier driving 4 dual electrostatic speakers and dual woofers. Then Charlie previewed their new products to be released soon — the Amp Master, a compact six-channel Class D amplifier for imminent release followed a few months later by a companion preamplifier fitted with MM and MC phono inputs as well as a built-in vinyl de-click and de-pop feature.
He briefly spoke on their supply difficulties across a range of materials like cases, wood, and semiconductor chips. He described how this was affecting their ability to deliver product, and in some cases forcing redesign to use more available parts.

Following this introduction, we were broken up into two groups with a small group going into Dave's office for a session with the Sound Master decoder and the larger group going into the main demonstration room for a more wide-ranging demonstration session.

For us in the larger group, Charlie first demonstrated an effect present in traditional "box" speaker cabinets where imaging and focus can be significantly affected by changing the driver configuration from normal to either coaxial or dipole.
He used a pair of speaker boxes configured to be able to operate in any of these three modes.
As he switched modes, the effect was clearly audible to the "golden ears" amongst us — a test facilitated by the well-synchronized mode-switching of Charlie and Wayne. Charlie suggested that the biggest improvement was with the dipole configuration, but that the concentric also improves the focus.
A truly fascinating demonstration.
He then moved on to their hardware designs, describing the evolution of their surround decoder and the psychoacoustic effects involved to achieve a quite believable surround effect from stereo sources. He showed examples of design prototypes from the first generation to the current DSP iteration of the decoder, and the various current and future companion amplifier products.
Charlie then moved on to describe, and then demonstrate their Y4 system.
This is a system of eight electrostatic speakers (configured as four pairs front&rear/left&right) plus two woofers. They are driven by a ten-channel amplifier with integrated stereo->surround decoder and their patented "sweet-spot" technology.
He explained that each speaker in a pair is driven by a slightly differently-timed signal to minimize the usual sweet-spot limitations.

A listening session followed where we all could experience the quality of the system, and the absence of the dreaded sweet-spot.
In smaller groups, we then moved to Dave's space where he explained the Sound Master decoder and demonstrated it on the new 6 channel amplifier system, 4 x bookshelf electrostatics, and a woofer. Dave then discussed their experiences of the surround effect that can be achieved on the Stereo Master with standard stereo recordings, commenting that quite significant surround effects can be recovered from many stereo recordings. This was suggested to be a product of the microphone techniques used in the original recordings.

He then played some examples of stereo tracks being decoded into surround and described some projects their technology had been used on.

We thank Charlie, Wayne, Ron, and Dave for their hospitality and for the most interesting demonstration sessions.

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