|
Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
|
|
|
Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
|
In Reply to: So many isolation products??? posted by chgolatin2@yahoo.com on March 5, 2007 at 19:01:01:
There are so many different isolation products because there are a lot of different isolation problems. It helps to look critically at your setup and to try to visualize how the main vibration gets in to your equipment. This is more of a geometrical exercise, and can be difficult for some people.For example, I have a Wadia CD player supported by Lovan racks. The floor is thick plywood over beams over posts in a crawl space. The beams are about four feet apart. This makes the floor most likely to vibrate like a drum head.
Unless the rack is located directly over a post, the floor will vibrate in such a way as to induce a rocking motion into the rack. The height of the rack above the floor takes the angular motion at the floor and translates it into a lateral motion at the CD player.
CD players have laser heads that move horizontally, and servo mechanisms that attempt to keep the laser head aligned with the data track. Horizontal vibration from the external world fights with the servo. Even if the servo is successful in keeping things aligned, this conflict will result in excessive power supply noise, and that may corrupt the audio signal.
These thoughts led me to try a cheap DIY version of the Symposium Roller Blocks. I made mine out of stainless steel soup spoon bowls attached to acrylic blocks with polyurethane construction adhesive, and plain old steel ball bearings from a salvage yard. A little more expensive version uses ebony for the bases and steel-loaded epoxy to hold the bowls, and this is reported to sound better.
Putting the CD player on these roller balls made a large improvement in the clarity. One has to dress the cables so that the player has freedom to swing gently if pushed, and it becomes difficult to use the buttons on the machine, but these are small inconveniences relative to the major sonic improvement.
In doing this, I also considered the acoustic responses of all the suspension parts. The Lovan rack frames are welded steel and quite lively when tapped. I filled the legs with oil absorbent clay granules, stuffed the horizontal beams with polyester batting, and lined the beams with Dynamat X-treme on their inner faces. The shelves are also resonant objects, so I replaced them with aluminum channel beams. The roller-ball bases were cut to fit exactly into the U-channels, and the remaining surfaces were damped with another automotive body damper called Sound-Off. This stuff is less effective than Dynamat, but has an attractive diamond mat finish that complements the black finish on the Lovan frames. In my opinion, it is very difficult to make a sonically neutral shelf. Even if the board material does not support resonances, the shelf size makes it a player in how sound moves around in your room.
The newer roller-ball base design, with ebony instead of acrylic, seems to have an improved acoustic response. It provides a little vertical compliance together with damping. I have not tried it on my own system yet, so I don't know if these properties are useful in my application.
My power amps are Gilmore Raptor switching amps. They have large toroidal power transformers mounted in the centers of the bottom panels, which are supported by EAR damping rubber feet in the corners. The EAR feet are troublesome, probably because they allow too many ways for the cases to move (vertical, horizontal, rocking, twisting, etc.). The case panel flexes to allow the transformer to vibrate up and down. This reduces bass clarity.
My solution was to mount the cases directly upon Deflex rubber sheets upon thick end-grain butcher-block cutting boards. The boards have stainless steel sheets cemented to their bottoms so they can ride on my roller balls. The vertical suspension is stiff except for the damping action of the Deflex. The Deflex sheets do not support other modes of movement. The amps have good horizontal freedom to decouple them from the floor motions. I am very happy with the sonic improvments this approach made in my situation.
My rule of thumb is to tap on every candidate support item, and worry about it if I can hear an identifiable tone in the response. Most stiff materials are lively and require some sort of damping so they do not contribute to the sonics in an audio system.
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Visualize the vibration problem. - Al Sekela 21:34:04 03/06/07 (1)
- Re: Visualize the vibration problem. - indycar 04:55:05 03/08/07 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]