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RE: Amplifier Junction Boxes with Magnetic Steel Screws

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In Reply to: RE: Amplifier Junction Boxes with Magnetic Steel Screws posted by Uncle Mike on June 25, 2018 at 14:50:42

Yes, it lifted a fuzzy veil of magnetic pollution that had previously hidden smaller musical detail, caused a degree of listening fatigue, and somewhat diminished the size of the sound stage. This is a definite improvement but cannot be comparared in scale to the larger benefit of reducing exposure of the amplifier circuit board/ other internal components to magnetic interference by shielding the toroidal transformer.

For anybody interested, the LFD RCA input unit (what LFD calls 'Interconnect PCB Board - Phono Block') comes with four magnetic stainless steel screws retaining it to the chassis. So compared nylon to brass as replacement screws and found nylon screws sounded better (less bright).

Follow Ups:

Not all stainless steel is "magnetic" - Lew 10:25:48 07/05/18 (2)
True, some grades of stainless contain more iron than other grades, but as I understand it, most stainless steel screws are "Austenitic", which means they have a very low ferrous content and are therefore essentially non-magnetic. Did you actually check the screws you removed to see if they were magnetic? If they were, you might be able to find Austenitic stainless steel screws to replace them (they are more common than other types of stainless screws), in which case they might fit better than the brass.
- RE: Not all stainless steel is "magnetic" - Dryginger2 22:09:05 07/06/18 (1)
  Lew,
  
  Agreed. The Walker Audio Talisman is always close at hand in its secondary role of instantly revealing whether stainless-steel wood or machine screws are magnetic. IFI exclusively use austenitic stainless steel machine screws but many audio manufacturers for some curious reason don't. Fit? I use exactly the same size/ pitch/ length brass replacements and eliminate the flash from their heads with a black marker pen. Nylon screws lack the rigidity to curb vibration so I use them minimally near RCA terminals where brightness is a concern.
  
  FYI Using the new generation of $49 noise-canceling AC adapters from IFI with both the first-generation iUSB Power and iTube Buffer appreciably drops the noise floor to allow the music to become more open and revealing of detail. Plugging an AC iPurifier into the duplex from which the MacBook Air is powered (on a separate circuit to those used by analog and digital components while playing music) provided a third comparable 'veil-lifting' improvement. Good floor-dropping value for $200 but enclosing the sides of each speaker magnet/ amplifier toroidal transformer with MagnetShield, replacing the toroidal transfomer retaining screw with a nylon tie, and substituting brass for magnetic stainless steel speaker/ amplifier screws is infinitely more work but far more productive noise reduction for the dollar. And, of course, first installing brass screw inserts in the soft coil speaker cabinets both front and rear eliminates the sound image blurring caused by the inability of tapered wood screws under vibration to solidly retain their hold on soft composite material.
  - Is the Walker Audio Talisman (unknown to me) a magnet? - Lew 09:57:50 07/08/18 (0)
    That's all you'd need to detect ferrous stainless steel.

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