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What's the best way to shield my outboard power supply, mu metal, copper?

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vikvilkhu

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My preamp uses a large power supply and at this point I have to place it about a foot away from my turntable. I know the tt deals with even smaller signals than the preamp and is susceptible to EMI/RFI interference. So with that in mind is there something I can do to the innards of the power supply (to the transformer I guess or perhaps the actual casing)to shield it?
Or more accurately can I do something to the power supply to protect my tt? I was thinking some sort of copper sheet/coating on the undrside of the power supply case or mumetal or iron something or another. I'm a real newbie here so any help would be appreciated!
-Vik

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Re: What's the best way to shield my outboard power supply, mu metal, copper? - radsvcs 19:19:17 01/02/03 (0)
Hello
mu-metal is for video shielding mainly with weaker magnetic fields like the earths magnetic field, copper is for r/f shielding and iron is used for magnetic shielding. I work on MRI's in hospitals and shielding is of the utmost importance. There is a newer magnetic shielding material but very expensive. Distance is the cheapest and then add a switch somewhere as suggested is cheapest and easiest
Re: What's the best way to shield my outboard power supply, mu metal, copper? - monk1 12:40:56 12/30/02 (0)
I would try physical separation first. The next best approach would be to enclose the power supply with highly permeable material like steel or mu-metal. Your main concern should be to contain the 60 Hz magnetic field from the PS transformer in order to minimize mutual coupling with the phone input circuitry.
It depends on how many dbs you want the noise down - Norm 11:08:47 12/30/02 (0)
John Camille once suggested that a half inch thick steel box around everything was needed to get the noise down 60dbs. You cannot do much better than greater separation with the noise decreasing at the square of the distance. I do not know what, "...I have to place it (the ps) about a foot away from my turntable." means, but I would get it at least 6 feet away.
It depends on how many dbs you want the noise down - Norm 06:17:44 12/30/02 (4)
John Camille once suggested that a half inch thick steel box around everything was needed to get the noise down 60dbs. You cannot do much better than greater separation with the noise decreasing at the square of the distance. I do not know what, "...I have to place it (the ps) about a foot away from my turntable." means, but I would get it at least 6 feet away.
- Re: It depends on how many dbs you want the noise down - vikvilkhu 11:08:15 12/30/02 (3)
  Thanks Norm, The ps is in a steel box already (Blue Circle Galatea preamp) but I guess I'll have to think about repositioning... Do you know id a layer of copper or iron on the underside of the case would help any?
  -Vik
  - Re: It depends on how many dbs you want the noise down - Norm 11:12:05 12/30/02 (2)
    I think the problem is magnetic fields that induce currents and only substantial amounts of metal can help. Again, I don't know why you cannot move the ps, but that is the most effective solution.
    - Re: It depends on how many dbs you want the noise down - vikvilkhu 12:04:02 12/30/02 (1)
      I'm just lazy. The power supply has a switch on the back to turn on the pre. I want to be able to switch the system on without bendign over everytime. I know, I'm lazy...
      -Vik
      - I know, I once used an ARC switched outlet so I could turn everything on at once. nt - Norm 17:05:41 12/30/02 (0)
        
        In Reply to: Re: It depends on how many dbs you want the noise down posted by vikvilkhu on December 30, 2002 at 12:04:02:
        
        a

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