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Isolation Ward From ebony pucks to magic foil, mystical and controversial tweaks. |
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Isolation Ward From ebony pucks to magic foil, mystical and controversial tweaks. |
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In Reply to: Posey's Doubly-Sad Mathematical Model & The Mars Lunar Lander posted by Posy Rorer on July 30, 2007 at 20:38:51:
Ah, but I did take your response as humor. That's why I didn't really answer. You were sort of poking fun at me, but that indeed is no biggie in my book. I most definitely was not trying to 'weasel' out of anything as accused, I simply had really nothing productive or funny to add.The 'sad' was in no way directed at you or your comments. Despite our contrasting views as to causality, your passion is duly noted and I, for one, have no doubts that you are sincere in what you write of.
As for your tests, well, I have posted on some things which lead me to such conclusions which I have come to. I will reiterate a few.
I've a several friends who leave IC's and wires coiled in their sound rooms, a la Belt. One listener has had severe issues with RF entering his TT system, audible not only as static type noise but as a bona fide radio station. He accidentally discovered that placing a coiled up IC on top of his preamp eliminated the RFI. The wire was not hooked up to anything, BTW.
In an old ham radio text, we found a recipe for reducing RFI reception: an octopus arrangement of wires, with each leg trimmed preferably to a fraction of the offending frequencies. We've tried this and it works extremely well, once you figure out the wavelengths. However, a simple random arrangement also works fairly well also
I have used ERS, link provided below, for some time now. The specs and description of it are on the websites, but essentially it is a paper sandwich with a carbon fiber web upon which shards of nickel plated CF are sprinkled. The random lengths of the shards serve as minute antennas for RF which are then grounded to the CF mesh. It is a basis for some of the 'Stealth' technology employed by the military. It works well in areas where the 'Rainbow foil' seems to work best.
RFI has been a large stumbling block for digital/video audio since it's inception. I have been using copper foil tape since at least 1990 to shield every single semiconductor in my CD players, with significant increase in sonic quality. My experiments reached Positive Feedback's writer Doug Blackburn and he actually wrote an article about these mods, however, I had asked me to keep my name out of it at the time. A piece of foil on such chips seems to be effective although I do prefer the ERS.
I routinely advice my customers to ground their metal racks and speaker stands. In my case I have a ladder type rack which actually is an excellent simulation of a Yagi antenna. At any rate grounding the rack seems to create a lower noise floor.
In addition I place small magnets on the supports, midway between the ends. As long as the TT is not on the rack, the result is an improvement in dynamics and subtle tonal textures. Here I know that the magnets are restricting the magnetic induction created by the proximity of the power transformers to the ferrous legs of the rack.
Similarly grounding a metal top plate of a speaker stand seems to 'speed' up the sound. It may be subtle at times since the effect is obviously dependent upon the distance from the magnet structure to the top. Additional experimentation with grounding of the metal speaker driver baskets have yielded positive results. In the case of the ubiquitous stamped steel baskets the ferrous material has a much greater effect on the magnetic field generated from the speaker itself than say a cast aluminum or magnesium basket.
Of great interest is the fact that some speakers are now using composite baskets for even greater performance by a lowering of the magnetic induction. I once discussed this with a noted speaker designer who laughed and told me that he was not surprised since he could measure the magnetic field f his 12 inch woofers five feet away. In this case we were discussing the fact that using non magnetic screws to secure the drivers to the cabinet generated noticeably 'better' sound. The use of such screws is also of benefit any where magnetism is present: transformers are a good target. Replacing the steel bolt in a toroidal transformer mount with one of Nylon or even brass creates a significant 'ease' to the sound, greater midrange, and less high frequency anomalies. As for those steel bolts holding the laminations of the standard EI cores together, they are an abomination. I like to switch them out to brass screws, especially if they are output transformers.
About 25 years ago, I had purchased mu metal and was experimenting with it, building shields for transformers and such. Because mu metal sheet requires a re annealing in a pure hydrogen atmosphere after fabrication, I gravitated to foil and simply used multiple layers.
It is fascinating to see what can be accomplished by 'channeling' magnetic fields. Not in any spiritual sense, but channeling in that magnetic fields would rather enter and remain in a ferrous object rather than enter air. A simple toroidal ring placed over (or under) a motor greatly reduces the size of the field of the motor.
Used under a TT motor the effect is immediately noticeable and greatly beneficial. Centered over the spin motor of a CD also yields great audible benefit, and I have tried this on machines from a the infamous RS portable to the the latest $15K Esoteric machines, with positive results.
The use of this on a CD/DVD player is understandable as the laser head is in very close proximity to the motor. In a TT, the motor can be a foot or even further away, and yet the effect is immediately noticeable. Older VPI's and SOTA's have an external cover upon which you can place the toroid while in play. I can hear the sound changing even before I set the toroid down. Placing a magnet on the steel rack is instantly audible too, but in a negative way, because the steel 'channels' the magnetic field to distances far greater than you would think possible and it affects the field of the cartridge. This is measurable, BTW.
While EMI and RFI fields are relatively mundane and have no 'mystery' to them, the true wonder is the sensitivity of the human organism. While large variations do exist, the defining sensitivity of the human body has yet to be set. I have commented about this on several occasions. The sensitivity of some individuals can be quite amazing, and I do NOT claim such sensitivity by any means.
Stu
Edits: 08/01/07
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Follow Ups
- Re Clark's Mathematical Model & The Mars Lunar Lander - unclestu52 22:19:43 07/30/07 (3)
- RE: Re Clark's Mathematical Model & The Mars Lunar Lander - Posy Rorer 00:31:26 07/31/07 (2)
- Lest this silliness continue... - clarkjohnsen 08:08:33 07/31/07 (1)
- Let's dance - unclestu52 13:54:09 07/31/07 (0)
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