Isolation Questions

Hi to all,

Being a true believer in vibration control, I purchased a BDR Shelf for Source here on Audiogon (thanks Sam) for an AA Capitole mk 11 CDP, equipped with BDR cones affixed to the bottom of the chassis.

My very limited understanding of the principles involved seem to indicate that the CDP, when placed on this shelf, will likely be more resonant than the shelf. Subsequently, shouldn't the point end of the BDR cones be in contact with the chassis of the CDP? If that's the case, reversal of the cones won't be an option, but I think rollerblocks might be more helpful in draining internal CDP vibrations. Any thoughts on that?
If the consensus is that the cones are fine where they are, can anyone advocate for rollerblocks under the BDR shelf, or is that like killing a mosquito with a shotgun?

Brimac, you raise some good questions and unfortunately no one can give you a real definitive answer except to say you need to try a lot of different combinations and go with what sounds best to your ears.

I have gotten some very good results using small blocks of hardwoods between components and shelves; and the Source Shelf that I have my turntable sitting on sounds good with a combination of Sorbothane pucks at the rear and one small hardwood block at center front. I'm using the Sorbothane because I'm on a suspended floor, otherwise I'd use hard materials (either wood blocks or BDR cones) all the way around.

In some applications I find the hardwood blocks are preferable to BDR cones, with the woodblocks sounding very similar through the bass and midrange, but less tizzy in the high frequencies. VanEvers used to sell a woodblock kit, but I don't know if it's still available. I've had good success with cocobolo, mahogany, and tiger-eye (in no particular order).

Sometimes you also need to consider the stability of the component; if you push a button and it goes sliding toward the edge, well, that's a problem. :)
Answer to your isolation question. You cannot isolate anything. Even if you are in outer space you may encounter a direct hit..So other than the expected sarcasium about outer space and who of us maybe suffering from lack of oxygen, my answer is, it is a waste of time and will only serve to store the energy you wish to evacuate from your hi-fi. Tom
Theaudiotweak is correct. You cannot isolate vibration. You might be able to alter or even dampen a bit, but not isolate.

Therefore, your best bet is mechanically transfer the vibration using appropriate points and racking systems.

Vibration and resonance need an exit path. Without that exit path, you'll reek sonic havoc at the micro-dynamic level.

Stehno, just what are "appropriate points and racking systems," in your experience?

My experience tells me that those variables would vary for every different component available due to the fact that the resonant nodes would vary from component to component...
Plato, before I consider a response to your question, I'd like to ask; why do you wish to know?

I ask because you stated above that based on your experience nobody can provide a definitive answer to Brimac's question. Therefore, I would think that my answer to your question would be of no use to you.

One correct answer. Collage is not the one.

If my memory serves, you are supposed to put the flat side of the BDR cone on the Shelf. Can't you have your dealer open the Capitole and unscrew the BDR cones?

Alan Hsu
The answer is yes, I think. Vibration drains in the direction of the pointed end of the cone, I think. So, the way the BDR is fixed to the CDP should be correct.

And, having the pointed end touching the CDP might have more isolation benefits, but, the, in this application, it probably has more mechanical vibration influence over the CDP by changing the resonance of the CDP rather than draining or isolation.

Rollerblocks under the shelf is hard to say. There definitely is benefit from isolating the Shelf, but whether you can hear the benefit varies between systems just like anything else.