Replacing the structural elements was trickier, and the quest for a replacement for aluminium or steel led first to the slightly bizarre and mildly Dali-esque ReVo stand which I reviewed for Hi-Fi+ way back in issue 68. I still use the modular version, the ReVo II and, out-dated as it now is, it’s still easily one of the better sounding stands I’ve come across. Eventually, the odyssey led to PEEK (polyethyl ethyl ketone), an engineering plastic stronger than (and ten times the price of) aluminium. The big surprise came with the discovery that the audible benefits of replacing metal structural elements with PEEK alternatives exceeded expectations. The difference was greater than could be attributed to simply removing the metal. PEEK has applications where vibration control is a potential problem and this happy/accidental discovery led to a tranche of support products and racks making judicious use of the material. Shelves, though, have remained a bit of an issue. PEEK as a raw material really doesn’t lend itself to the task. It is awkward to work in sheets, and not inexpensive, so in the short term, work continued with acrylic.
All mixed up…
Stop me if you’ve heard this before, but it turns out that a matrix of dissimilar materials can be effective in damping vibration. We see it in the constrained-layer damping of loudspeaker cabinets, turntable plinths, and, sometimes, hi-fi racks. We see it in matrix-based materials and the sandwich structures used in drive units. Vibrational energy is converted at the material boundaries into heat – or maybe light, X-rays or neutrinos for all I know – but whatever the ultimate destiny of the unwanted energy, the interaction between two different materials can be an effective way to manage it. Plenty of well-regarded products have exploited these broad principles over the years. Leak and Focal drivers are cases in point, as is the use of sandwich construction in Clearaudio or VPI turntable plinths. Panzerholtz is another example, a wood-based matrix that finds its way into turntables and cartridge bodies.
Bamboo has become popular in recent years. I know RG’s a fan of the cheap and cheerful IKEA bamboo chopping boards and they’re definitely a great way to explore support possibilities for very little outlay. Like Panzerholtz, the bamboo products consist of an organic material bound together to form a machine-workable substrate, but unlike Panzerholtz it’s (relatively) light in weight so designs that eschew mass, like the Quadraspire tables, are finding new ways to exploit its energy management potential. The Harmonic Resolution Systems racks use various sandwiches or constrained layers in their isolation bases and platform shelves. Grand Prix Audio, drawing on its motorsport expertise, was a pioneer in using carbon-fibre, which exhibits characteristics common to Panzerholtz or bamboo in being one material bound by another, but also adds lightness and tenability to the equation. Colin Chapman would doubtless have approved.
The best ingredients…
And there have been other products that use amorphous mixtures, like Clearlight Audio’s RDC material, found in support cones and occasionally as additional damping in equipment platforms. The important thing is that there should be an opportunity for energy transfer between the two materials so as to dissipate and control that energy and minimise any negative effects from it rattling around in your system. Whether that energy transfer happens at levels meaningful to our objectives and in ways relevant to what we want to achieve, is key to all this. Engineered solutions, like HRS or GPA, identify an issue and devise an engineering solution. And if the problem they’ve identified and managed is one your system suffers from, they can be astonishingly effective. Others, and the developers of AcouPlex will doubtless recognise this, are more like an educated version of trial and error, using careful listening tests to home in on an effective solution. You can’t just slap two dissimilar materials together and hope for the best – and sometimes throwing bleeding edge technology at it isn’t the solution either. Manchester happens to be the home of the Graphene Institute – the Nobel Prize for the discovery of Graphene went to a Manchester University team – and AudioWorks did some early experimentation with Graphene particles suspended in an acrylic medium, but listening tests quickly showed that this was barely any better than unadulterated acrylic. What was better though, and not just by a small amount, was PEEK particles suspended in acrylic; after further refining the mix and proportions, the best-performing combination was duly dubbed AcouPlex.
