why spikes under speakers???


could you guys educate me about the use or need for spikes under speakers, it seems to me that putting an air pocket under a speaker would be the last thing you want to do, isnt bas about pressure? and if you put a gap of air between speakers and floor arent you losing some of what makes bass work? I am not claiming this to be bad, I simply want to pose my questions about this concept and get educated on why this is a good idea, and when it may not be a good idea...thanks
chadnliz
Pbowne: Correct, but totally off-base. You are right that 1-3 inches of space won't do anything to affect the transmission of low bass sound waves. Unfortunately, that's not the transmission that's in play here. What spikes help with is reduction of the transmission of vibrational energy from cabinet resonance due to a reduction in contact surface area between speaker cabinet and floor. Cabinet resonance isn't only caused by low frequency waves...any frequency can cause it. Which frequency does cause it in a particular speaker is determined solely by that speaker's cabinet design and construction.

To answer your question, the answer is no. Think of it this way...your ear canal/eardrum is only about 3/8ths of an inch across, does that mean we can't hear any frequency with a wavelength longer than that? Low frequency waves, as you correctly point out, have huge wavelengths. Unlike higher frequency waves, these suckers don't care about walls, or even our heads and simply pass right through. You will still hear them just fine, provided they are still in the audible range, that is. It is standing waves that are affected by room size, not sound waves coming directly from the speaker. Hope that helps...
Eldartford is correct. No decently made cabinet is going to be moved by a lightweight little driver. Vibrated/resonated, yes, but pumped back and forth by a driver...no way. Eldartford's experiment is the perfect way to prove that and to clarify what he said: Idiots who don't know why they sell spikes disagree.

S7horton, that cell phone on vibrate isn't moving in response to a driver since in vibrate mode it isn't connected to one. It's moving in response to a small electric motor with its driveshaft connected to one side of a small weight, purposely creating an unbalanced rotation. Take one apart, if you doubt me. Ever had sore muscles? It's the exact same system used to make a massager.
Some spikes are more cone shaped than others. Cones run one way when it comes to vibration. They 'drain' vibration from the speaker cabinet and dont permit vibration from traveling up from the floor. Thats why with cones under components and stands you get less vibration.
As for speakers moving, I have seen speakers and subs "walk". Its the vibration of the cabinet that you are trying to reduce. A drivers motion will be more precise if its 'working against' a solid stationary baffle to start and stop from , as opposed to a vibrating baffle. Spikes ususally improve the sound by giving the drivers a less resonant platform so they work better and also by reducing the sound you may hear from the cabinet itself.
Blkadr...The notion that a mechanical structure (cone) can transmit vibration one way, and not the other has no basis in fact. Vibration, by its nature, is a back-and-forth motion.

Vibration of enclosure walls can be a significant sound source. It is minimized by solid construction, with internal braces, curved panels, and damping material. Except for the bottom panel of the enclosure, where the spikes/floor may serve as a brace, spikes don't help.