Transformer Cans

[MarshallPlexi]

Does potting a power transformer do anything to help reduce noise that a flux band cannot do? I'm considering using a potted PT on a project and am curious if I will notice any real improvement in noise. The chassis is 12" wide so I'm concerned about the magnetic field of the PT getting into the audio circuits.

Also would putting the output transformer in a can help or could that hurt the tone of the OT?

I'm new to the idea of canning a transformer so forgive me if some of these questions are basic.

Thanks!

[booj]

placement of the tranny is crucial. cans are nice. you can paint them with psycedelic flowers.

[tedmich]

canning (potting) can improve shielding if done correctly although it hurts heat dissipation and can decrease power handling (I think Enzo or Steve quoted ~10%).

I potted several toroidal transformers with epoxy, use the slow set to avoid very high temperatures, the glue is expensive too. I used spun stainless steel containers from Target which polish up well.


You can't do anything once potted! Best to build it and try a can iff its noisy, if the can makes it great, consider potting it.

[Gaz]

cans are nice. you can paint them with psycedelic flowers.

good answer.

[Steve Conner]

A copper or aluminium can will do the same as a flux band would, if you close up the bottom. If you don't close up the bottom it won't do a whole lot.

A steel can will give some extra magnetic shielding.

If you use a flux band and then put it in a steel can, then the two kinds of shielding complement each other, and you get slightly better shielding than either would give on its own.

Non-magnetic stainless probably won't shield at all: it's not conductive enough to act as a flux band, and it can't act as a magnetic shield because it's not magnetic.

Toroidal transformers naturally leak less flux than the ordinary E-I type, and usually don't need any extra shielding at all.