Originally Posted by Sam Schulz
Are spike feet available for the f12?
I used spikes for years, but there is now a better way to go---isolation. Spikes couple the sub enclosure to the floor, which has it's benefits. Coupling is the opposite of isolation---vibrations from the floor can travel up the spikes as well as down them. When you isolate the sub's enclosure from the floor, you prevent vibrations from coming up into it from below.
The way to isolate is to place a mechanical "filter" between two objects, in this case the sub enclosure and the floor. It has long been considered common wisdom that a speaker enclosure should be held firmly in place (such as with spikes), to prevent it from moving in reaction to it's cone's travel---as the cone pumps forward and backward, the enclosure moves in the opposite direction, resulting in a loss of information, and "smearing".
But audio designer Max Townshend in England has some fascinating videos posted on You Tube showing measurements of speaker cabinets with and without his isolation feet, which he has named the Seismic Pod. It is a spring enclosed in a rubber sleeve, with a small hole in the cap that seals each end of the spring/sleeve assembly. They work great, both theoretically and in practice. They are, unfortunately, rather expensive (if you have to ask how much.....;-).
A much cheaper way to get a good portion of the Pods benefits is to use a set of roller bearings, available from a number of companies, the most well known being Symposium Acoustics. SA named theirs Roller Blocks, and it works just as the foundations in Los Angeles high-rises do (to deal with seismic activity---earthquakes!): two shallow cups are separated by a ball bearing, which allows the top and bottom cups to move independently of each other. When vibrations enter the bottom cup, rather than traveling up through the ball bearing into the top cup and then into the sub enclosure, the ball simply rolls ever so slightly, the ball disposing of the energy (vibration) by trying to "climb" up the wall of the cup. And it actually works!
The Roller Block Jr, is priced at $190 for a set of three, and is designed to be used with both the top and bottom cup in place. But some users prefer using just the bottom cup, the bottom of the sub enclosure sitting on the ball bearing itself, rather than on a top cup. Used thusly, the resonant frequency of the bearing is lowered, down to around 3Hz it is claimed. A single set of three Roller Blocks is therefore enough for a pair of subs, only three extra ball bearings needing to be purchased separately. $190 (plus the cost of the three extra balls) for excellent isolation of a pair of subs---a great deal in my book!