By Wilde Becker. Speaker Stands. At Tuesday, July 30th 2019, 19:05:14 PM.
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.
Fortunately, we don’t need to balance the speaker on actual springs, as a suitably dense piece of acoustic foam can act as both spring and damper. The speaker cabinet provides mass — so sitting a speaker cabinet directly onto a piece of foam, such as an Auralex MoPad, will bring about an improvement in the amount of vibrational energy getting through to the desk. However, foam isn’t particularly rigid, so the cabinet may still tend to move back and forth slightly as the speaker cones move, especially if the speaker cabinet isn’t particularly heavy.
Furthermore, in accordance with Newton’s third law of motion (each action has an equal and opposite reaction), whenever the speaker cone moves in one direction it will try to push the speaker cabinet the other way.
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.
To sum up, the platforms with a heavy plate of some type on top are the most effective, though you can add mass very easily to any type of support by using floor tiles. Similarly, the more massive and better damped a speaker stand, the less vibrational energy is likely to make it through to the floor and less the stand itself will vibrate. Compared with the cost of speakers, adding suitable stands or platforms is relatively inexpensive, yet it can make a very worthwhile improvement to the overall sound quality!
That’s where you need to put the sub. If your sub has a phase adjustment knob, or a polarity–invert switch, adjust this until you hear the loudest result from frequencies around the crossover point, typically 80 to 120 Hz.