Spikes
couple the speaker to the floor so there is no isolation at all and placing a heavy slab between spikes and floor will only alter the character of the sound transmission, not prevent it, but every little helps. Isolation, in varying degrees, can be achieved by:
- Spring systems which when carefully specified can provide total isolation (Townshend Seismic products are the Gold Standard but you can go DIY at modest cost). The challenging bit of designing a spring system is to get the correct spring rate, with optimum damping, and (most importantly) having something that's stable in use.
- Elastomer systems where good isolation can be achieved at mid-high frequencies, but compared to a sprung system low frequency isolation is often poor. Gaia do some good ones.
- Foam pads like the Auralex products used in studios are the cheapest and most convenient way to achieve some isolation and decoupling, but in truth not much.
Moving from a 'hard coupled' mindset to one that accepts speakers can be quite softly supported is quite liberating in terms of sound reproduction, but much more liberating for anyone living in a house or flat where transmitted sound to other rooms and/or neighbours is a problem (that's pretty much all properties, and even those supposedly constructed in accordance with Building Regulations Part E).