By Wilde Becker. Speaker Stands. At Tuesday, July 30th 2019, 19:04:30 PM.
An isolation platform works in a similar way to a car’s suspension, and comprises three mechanical components: a spring, a mass supported by the spring, and some form of damping to prevent the sprung mass from continuing to bounce around. In a car you have the springs between the axles and the car body: the car body provides the mass and the shock absorbers provide the damping, to stop you having a bouncy ride.
The theory is that the mass and spring characteristics are chosen so that the resonant frequency of the combination is well below that of any frequency they’re likely to be asked to isolate. For example, if the lowest note a speaker can reproduce is 30Hz, then the resonant frequency of the supporting platform needs to be well below that — perhaps just a few Hertz or less.
A speaker platform is designed primarily to provide a degree of mechanical isolation between the speaker and the surface upon which it is placed, while keeping the speaker firmly in place. This is particularly important when siting speakers on lightweight desks or shelves, as these can easily be set into vibration if in direct contact with a speaker cabinet.
Many stands come with a compartment dedicated to sand and similarly heavy and well-damped materials. And there’s method in the madness. You see, the speaker plays music by moving its drive unit in and out to create sound pressure: when the drive unit pushes outwards, it creates sound pressure, but when it moves inwards it pushes the entire speaker backwards.
No, it’s not because we don’t like your bookshelf. It’s probably really good looking. But, bookshelves, sideboards, TV-boards and tables all share a common drawback: surfaces. You don’t want surfaces close to your speakers, as surfaces can cause early reflections that colour and distort the sound image – that’s also why we recommend getting your speakers away from corners and walls.
A cheap DIY option is to build a couple of towers by stacking concrete blocks or bricks. This low–cost approach really works — we’ve used it successfully on more than one Studio SOS visit — and because of the high mass, very little vibrational energy makes it through to the floor. Some people like the rugged appearance of bricks, but if it’s not to your taste you can always disguise them with cloth drapes, or even spray them gold if you like that kind of thing!