Shielding a toroid tranny

[Grover Gardner]

This is my first project with a toroid PT. I plan to use a metal chassis and mount the toroid on top with a cover for shielding. Fortunately, I happened upon a discussion of the issues involved and the ugly things that can happen! My question is, is the Antek cover arrangement sufficient to avoid the dreaded core loop? I assume so but I wanted to ask the experts here. Here's what Antek sends you:

https://www.antekinc.com/ca-005-steel-cover/

I'd appreciate any input to avoid a nuclear meltdown.

[David McGown]

Grover,

Yes, the top cover is fastened with black nylon insulating bushing and acorn nut, so that it does not complete the loop. It should work fine. The heavy (and more expensive) steel cover is what I use and it is extremely effective, though overkill. I have a pair of the stamped covers in hand waiting for the next project.

https://www.antekinc.com/ca-050-steel-cover/

David

[SoundMods]

Actually when it comes to toroids that are inherently shielded by virtue of their toroidal construction. Put another way -- they don't emit a magnetic field.

So -- money and effort does not have to be spent to shield what doesn't need shielding.

[Roscoe Primrose]

Theory and practice don’t always agree…. That’ll be true the next time someone builds a perfect toroidal transformer, which will also be the first time.

[Grover Gardner]

Actually when it comes to toroids that are inherently shielded by virtue of their toroidal construction. Put another way -- they don't emit a magnetic field.

So -- money and effort does not have to be spent to shield what doesn't need shielding.

A year ago I experimented with some toroids on a pair of monoblocks and had no problem, but the preamp project is a bit more sensitive and I've got it hanging 6 inches off the breadboard to avoid interference, so I think the shielding makes sense in this case. It's also a cossmetic thing, at the very least.

[SoundMods]

Actually when it comes to toroids that are inherently shielded by virtue of their toroidal construction. Put another way -- they don't emit a magnetic field.

So -- money and effort does not have to be spent to shield what doesn't need shielding.

A year ago I experimented with some toroids on a pair of monoblocks and had no problem, but the preamp project is a bit more sensitive and I've got it hanging 6 inches off the breadboard to avoid interference, so I think the shielding makes sense in this case. It's also a cosmetic thing, at the very least.

10-4

[TubeDriver]

I have wondered whether it would be worth it to fabricate a shield between my preamp PT and the board? I don't have any noise issues that I can detect (preamp is virtually as quiet as a passive) but the location of the PT seems less that ideal. A copper sheet, cut out to fit and form an internal wall between PT and board, bolted in and grounded? Worth it or just destroying the resale value of an Ayre preamp?

Last edited by TubeDriver on March 25th, 2023, 1:31 pm, edited 1 time in total.

[Roscoe Primrose]

The first rule of engineering: If it aint broke, don’t fix it……

[SoundMods]

[quote="TubeDriver"]I have wondered whether it would be worth it to fabricate a shied between my preamp PT and the board? I don't have any noise issues that I can detect (preamp is virtually as quiet as a passive) but the location of the PT seems less that ideal. A copper sheet, cut out to fit and form an internal wall between PT and board, bolted in and grounded? Worth it or just destroying the resale vale of an Ayre preamp?

Like Rosco said -- ". . . if it ain't broke - don't fix it."

So -- the way find out if its "broke" -- short out a pair of inputs to isolate the pre-amp from the outside world -- switch to those inputs and run the pre-amp up to full volume. Does it know the words or is their hum?

No hum? It ain't broke.

[TubeDriver]

Does that trump the 3rd rule of audiophilia: nothing is good enough, make it more better!

The first rule of engineering: If it aint broke, don’t fix it……