OK Gonk, get your head our of the duct and listen up. Why did I get a pair of spikes with my speakers? I can see where it significantly reduces the surface area of the bottom of the speaker in touch with the floor but ...? By the way, how does it feel to really know what duct tape is for? Take care buddy!

(Crawling out of some last-minute background updates for a slightly deranged deadline, pausing before finishing review of an operating and maintenance manual...)

There are a few different cases offered for spikes. The one that I'd call most straightforward is stability on carpet - a flat surface or even rubber feet will still allow some motion (rocking, tipping) when resting on a soft surface like carpet, but spikes can penetrate to the floor beneath and let the speaker be supported separately from the carpet. There are other reasons offered (isolation to prevent transmission of vibration), but how effective that isolation actually is becomes a less clear-cut matter - the energy produced by the movement of the speaker drivers still has to go somewhere.

Sorry, gotta disagree with gonk. The main reason is isolation. No speaker should be on a flat surface, be it a shelf, speaker stand, or floor. Vibrations and coupling between the speaker and whatever it's on need to be minimized. My speakers (Hales Transcendence 5) would be solid on the floor, but they are on cinder block and then tiptoes. The difference, especially in the bass, is night and day.

Hmmm.

Consider the acoustic guitar. There are strings held and suspended at one end by the bridge and saddle. The bridge is firmly attached to the top of the body. Via firm contact with both the strings and the bridge, the mostly rigid saddle transfers the kinetic energy from the strings to the bridge and on to the guitar body. ( image and diagram ) The physical movement of the strings at points away from the nut and bridge would cause the strings to strike the neck or body and cause extraneous, mostly unwanted sound except that the strings are suspended above the neck and body of the guitar – the transfer of energy from strings to guitar body takes place in a controlled manner because of the saddle and bridge.

Imagine that I replace the saddle and bridge with a large enough piece of sponge or cloth to support the strings. Because this material is not rigid, the vibration of the strings would mostly be absorbed by the spongy action and not transferred to the body of the guitar. One could say that such sponge or cloth, to a large degree, acts as an isolator of vibration.

Now consider the loudspeaker enclosure and the surface that supports it. During operation, and usually unwanted, the loudspeaker enclosure vibrates to some degree. To the degree that the bottom of the enclosure is not perfectly rigid, it is like the guitar string. Placing the enclosure on rigid spikes, like putting a saddle between the bridge and strings, means that kinetic energy will be transferred in a controlled manner from the loudspeaker enclosure to the surface that supports it. To the degree that the supporting surface is not perfectly rigid, it becomes a radiator of acoustic energy like the body of the guitar. The loudspeaker enclosure itself vibrates less because kinetic energy is drained away via the spikes to whatever surface is under the spikes. Strictly speaking, from an energy transfer point of view, the spikes do not isolate the loudspeaker from the supporting surface, spikes help couple the enclosure to the supporting surface.

An item like the Auralex Gramma behaves like a varied spongy layer. Such devices behave as vibration isolators.

Consider a Newton’s Cradle . Rigid balls = effective energy transfer. What would happen if one or more of the central rigid balls were replaced with rolled cloth?

So what about spikes (couplers) and spongy layers (isolators)? First, how much vibration does your ‘full-range’ enclosure undergo anyway? How about your subwoofer? Pick each one up while playing something at a moderately loud volume. If you want to experiment with what some consider the best method, you’ll need to couple your enclosure to one or more somethings that have high mass compared to surface area – spikes, bolts, whatever and cement blocks, steel bricks, whatever – then put some form of isolating materials between the massive assembly and the supporting surface.

If I’m not mistaken, there are some specialty spikes that have two or more rigid portions that are separated by materials that have some ‘give.’ These can function as isolators, but solid spikes, no matter what you read from sellers, perform controlled coupling, not true isolation.

Because my enclosures already have a rigid and high mass-to-surface-area ratio, I just use ‘vibration absorbing isolation layers with give.’

There have been plenty of arguments made in favor of spikes as vibration isolators. Heck, I use spikes under my Studio 60's. I think that having a speaker on some sort of supports so that the bottom of the enclosure isn't flat on a floor surface is a wise decision.

But... There's one aspect of the arguments for spiking as vibration isolation that I've had a hard time with, and it's at the root of what bestbang4thebuck has so well addressed. If we look at the way we handle vibration isolation with rotating machinery (fans, pumps, compressors) and the one thing that we always see is flexibility: either springs or rubber isolation pads. A small point of contact will still transmit energy without that flexibility. A more optimal mix would probably be something like the spikes that bestbang4thebuck describes: a reasonably small point of contact with the floor for "controlled coupling" (I like that term) plus an absorber component between the point of contact and the body of the speaker to handle the vibration isolation.

Paradigm uses isolation mounts on their drivers at least in the signature series.I found that my subs sound much tighter when they were laged to the floor.They have two Ascendant audio avalanche 15's with 1.2kw per channel.Each box is about 150 pounds and 5 cubic feet.Without laging the enclousures would move over a quarter of an inch back and forth.What do you want,to move the box or move air?