Toroidal transformer and reverb tank

[Leevi]

I have met this problem before and succeeded to fix it by placing tank in abnormal position.


This time it's very difficult to find a suitable and silent position for the tank because of the magnetic field
caused by a big toroidal transformer. It helps when I move the tank far enough of the cabinet.


Are there any ways to avoid the problem? I'm almost ready to change the PT to traditional one.
Metal covering doesn't help.


/Leevi

[eleventeen]

How about TWO metal coverings? And, is EMF entering the reverb tank through the cardboard bottom or do you have shielding there?


(I am only making suggestions, I have no experience working with toroids in this content. I once wound a 3.5" toroidal transformer for a power supply for the engineering department where I worked, in the 70's. The transformer had 40 qty 1-1/2 turn secondaries and could put out 12 volts 50 amps!

[kagliostro]

Some time ago I've read a thread about shielding and the better results were achieved using aluminium, better than iron and inox steel

Have you tried to shield the transformer or only the tank ?

Franco

[Willabe]

Something doesn't seem right.

Toroidal transformers are self shielding because of the way their wound, there should be a much smaller EMF radiation then with a EI transformer.

 

[Leevi]

How about TWO metal coverings? And, is EMF entering the reverb tank through the cardboard bottom or do you have shielding there?

Some time ago I've read a thread about shielding and the better results were achieved using aluminium, better than iron and inox steel
Have you tried to shield the transformer or only the tank ?

I have tried to cover both transformer and tank, no success
I use aluminium.

Toroidal transformers are self shielding because of the way their wound, there should be a much smaller EMF radiation then with a EI transformer. 

This is my understanding as well. I think the magnetic fields go in different way in case of toroidal transformer which causes that they affect easier
the coil of the tank. That's why the reverb tank is silent only in few selected positions.

/Leevi

[kagliostro]

Leevi, can you post a photo ??

Have you tried to install the toroidal at 90° respect to the top of the amp ?

Franco

[Leevi]

I have solved the problem by changing the PT.
Now it's much more silent and you can place the tank almost everywhere in the cabinet.
The root cause was definitely the toroidal transformer.


Picture after the change:


/Leevi