What is vibration isolation for?

Pbb, it does take time and patience to become aware of some changes in sound quality. If you walk into a new room, it takes time to notice the flaws, even if first impressions are great. If you were at my place for a few days, listened to my system a lot, I am sure you would notice a degradation in sound quality if I removed my isolation stand under my CD player and you would also notice the improvement upon its return. Not being a scientist I can't offer measurements, but my positive results are enough to satisfy me at the moment.

Once I am settled into my new place and I have a more controlled listening environment... I herebye solemnly plege to invest the time and funds (2.25$) to invest in some bubble pack (maybe even some other freebies) in order to try to discern differences resulting from vibration isolation. (though logic and common sense STILL tells me stands ARE NOT ISOLATION when the room is filled with vibrations - but I will cast aside common sense ;-) and give it a shot.

My perspective going into this is as follows:

- that isolation for speakers is a given (though differences may be very subtle depending on set-up)

- isolation for turntables? Naturally. - well, according to Ivor (at Linn) and REGA - a lightweight wooden IKEA table is perfect. But that is because the engineers have already solved isolation issues in the design of the table itself.

- isolation for CD player? - Well.., theoretically I guess because things are moving in there.

- amplifiers/ preamplifiers? Ha! - er, I mean, I'll find out for myself when I do the test.

I do admit that I used to be skeptical about speaker stands for bookshelf speakers - until I tried them. They did (he says sheepishly) make a noticeable difference - but the concept behind speaker stands is much easier for me to get my head around. They stabilize the speaker as well as place it in the best location in the sound field - away from sound refracting objects and things that will resonate. Basic stuff.

My present place is cluttered because I'm getting ready to move. I also have an nearly-finished pair of floorstanding speakers that I am building that are standing next to my Keilidhs. They look a bit like frankenstein in their present state - wires and crossovers hanging out all over the place. I think this is not the best scenario for doing an experiment such as this - not that I would be doing this test using my homemade speakers, but they say passive transducers muck up the sound quite a bit. - this too, is a concept I can believe.

Despite the occasional mud-slinging I think this is a very good thread. Toodles.

In my opinion, vibration isolation offers probably the largest improvement per dollar that one can make to a sound system. Start with speakers first, especially subwoofers. And proceed from there.

What we would like is for only the transducers to vibrate (loudspeaker drivers, cartridge stylus) - and of course the air - but nothing else. Every other bit of vibration will in one way or another add "grunge" or coloration which obscures or masks the music we wish to hear. Many of these effects are well described above, by Audiofile9, Albertporter, and others.

If you live in a wood frame house, the likelyhood is that you will have a lot of vibration of floor and walls which originates from the motion (desireable vibration) of the drivers in the speakers. Maybe Pbb listens in a basement with concrete floor and walls? A simple, fun way to learn about this is to explore your listening room with your hands. Feel your speakers, the floor, walls, equipment racks, and components.

Start with your speakers. You need something soft (and preferably linear - but that is a refinement...) under you speakers. The bubblewrap is a great way to start. When you are successful, the floor near your speakers (and as a result - all the rest of your room) will have no perceptible vibration due to mechanical contact with the speakers. Now what do you hear? In my case the improvement in sound quality is almost shocking (since I have flexible floors, etc). Some times it is helpful to add mass to speaker boxes to reduce motion (reaction mass). Speakers, when isolated on soft "springs", should be bouncy like a turntable (rigid body modes of around 8-10Hz) when you push on them by hand.

Remember that floors and walls have thousands of times the radiating surface area as a speaker driver, and they sound terrible, so the above should not be surprising.

Next, you can sense the need for or effectiveness of equipment isolation racks or platforms the same way: feel with your hands. In some cases, vibration of cables and interconnects can make a difference.

So why do people use pointed feet under speakers? Maybe they have concrete floors, and the vibration of the speaker boxes is reduced. We don't want speaker boxes to vibrate either...

So try it if you like, and share your success with us. What approaches work best? What materials? Has anyone compared metal springs vs sorbothane?

Crp raises some very legitimate issues; I'll share my experiences in that regard.
My floors are concrete & outer walls are cinderblock - very "dead" stuff indeed. Previously when I used a soft / flexible base under the speakers, there was enhancement of perceived bass but at the expense of articulation (some call this 'sloppy' or 'loose' bass; an accurate description.
Changing to spikes atop the concrete actually enhanced deep bass extension, improved articulation across the full frequency band, & reduced some resonance issues.