Like many things associated with Max Townshend, how the Seismic Speaker Bars work sounds eminently sensible when it’s Max explaining things, and complete gobbledegook when that explanation is passed on to someone else. Here’s the best we can do: Although they are too weak to feel, we are shaken by an almost constant series of earthquakes at Magnitude 2.0 and below. The horizontal displacement of such quakes is in the order of microns, but when you consider that a loudspeaker cone only needs to move 0.01 microns to emit sound, and that localised displacement caused by traffic has its own effect, it’s perhaps not much of a jump to conclude that vibration transmitted from the ground and through the structure of a building can easily undermine that being created by the cone. So much for having a speaker physically spiked to the floor!
Townshend’s Seismic Speaker Bars are designed to decouple speakers from the floor, so that all save for the lowest frequencies (as in, those below three hertz) cannot travel between floor and speaker. Until this geophysical explanation came to light, I was under the impression that the bars helped reduce energy travelling from the speaker to the source and amp: but it’s very likely a much bigger issue than that.
Townshend’s Speaker Bars are available in four widths, from 250mm to 550mm, and seven spring ratings, for speakers weighing anywhere between two and 256 kilos. Each steel cradle sits on two Seismic load cells, which are essentially damped springs supported by flat, felt covered bases. It’s a simple but smart solution that doesn’t look too out of place, even under a serious loudspeaker.
Installation of the Seismic Speaker Bars requires any spikes or feet be removed and the cradles placed such that the speaker is balanced in a vertical position. This can take a bit of experimentation and can be quite tricky with larger floorstanders; I used them with 20kg PMC Fact.8s and 17kg Cambridge Aeromax 6s, and both required precise positioning of the bars to balance properly.