They vary. Most speaker spike threads are M12, M8 or 1/4” 20 but there are exceptions for sure. You can print off a thread chart from the internet or just take a spike into a hardware store to confirm your size.
9 responses Add your response
Dill....I put Herbies soft something or other things under my spiked speakers on a Travertine tile floor. Absolutely ruined the sound. Herbie took back the things, and my system returned. All of these things depend on everything....they have to be tried to hear the results. Sometimes better, sometimes worse, sometimes no difference.
It is only my opinion, but I would be concerned about a speaker over an HVAC vent. Lying over a vent will produce very dry, hot air in winter, and in summer the cold air will definitely cause condensation on the speaker base as it hits the warmer air in the house. I feel you will certainly cause deterioration of the box, if not stress the electrical innards as well (dying out, increased heat/cool and condensation in the unit also. I hope their is a way to move the speaker a foot or two in any direction (or if a not yet complete addition, placing the vent itself a few feet away.)
dseltz is partially correct. Heating the speaker deferentially (expand and contract) may cause the enclosure to crack eventually. Water will not condense on the speaker unless your are refrigerating it for some reason. You can get registers that have deflectors on them that will exhaust the heat out from under the speaker but you would have to get the speaker up high enough to get over it and heat rises so the speaker is still likely to get warm. I had the same problem once and the solution was simple. I blocked off the register. The air flow will simply be sent to other registers in the house and as long as you do not block off to many of them you will be fine.
@dmk_hifi, the Townshend Audio Seismic Pods are available in different weight capacity versions (4-8lbs, 8-16, 16-32, 32-64, 64-132 each), yet all retail for the same amount. More economically-priced mass-on-spring isolators are available from Machina Dynamica, and are listed right here on Audiogon.