TW Raven Acustic AC Owners
As a long time user ,since 1983, of Quad electrostats and Magnepan speakers with a Linn LP12 front end right up to 2001. I never had to deal with sound pressure levels , foot falls yes. Back then ,the Linn was one of the best tables you could buy on the planet. A wall mount shelf was a must with suspended floors. Back in the day resonant devices were in their infancy, remember Mod Squad tip toe's? I used them under my speakers and table to good effect. By the mid 1980s I had added a home made sand box platform to the wall shelf,a idea thats been around for a long time. This improved the music on the neutral side of things, easily heard through the Quads. Vocals were even more life like to my delight. A myriad of active variables are at play with in a system and room. Taming resonates is just one of many that should be addressed which can have huge sonic pay offs. Whether its a home made box with sand in it or a $20,000 plus turntable platform. Experiment ,what ever works for you and your budget. |
http://forums.avguide.com/viewtopic.php?t=3588 Please see the link above for diagrams and further explanations about AIR-BORNE and STRUCTURE-BORNE sound propagation. Unfortunately, some posters without architectural, structural or acoustic qualifications presume to post fallacies. If the brackets and bolts are sufficiently sized to accommodate the loads imposed, there will be no ' material fatigue' over time just as there is none in properly designed floor or roof fixing brackets and bolts. Insulation placed in stud wall construction will NOT prevent sound from traveling between rooms. At best, it will REDUCE the sound but at only certain frequencies. Those below 200 Hz will effectively pass straight through the insulation. It is the de-coupling of the wall-mounted shelves that (as shown in my explanations) is the salient benefit. A properly executed wall-mounted shelf will NEVER ' do more harm than good' . The only harm I can see is ill-informed uneducated pontifications posing as scientific fact. |
Halcro, I do happen to have architectural, structural and acoustic qualifications because of my profession. I wasn't commenting on your specific case, but on cantilevering shelves in general. Cantilevering shelves made out of wood or mdf will tend to bow over time under such heavy load, hence my use of the term "material fatigue". An engineer can calculate the load of the equipment and design the structure to successfully support that equipment. If material fatigue didn't occur in structures, then there will be no need to inspect buildings and bridges for wear and/or structural failures. Screws attaching a vibrating structure will tend the get loose over time as well, which is why it is recommended to check them from time to time. I don't know the construction details of your shelf structure, so I can't comment on your specific case. If you used an engineer or an architect for the job, I'm sure it is well-executed. I agree that a well-executed wall-mounted shelf will work properly, but a not-so-well-executed one will do more harm than good. Regards, iSanchez |
