Transformer Orientation Testing

[WntrMute2]

I'd like to test the orientation of my transformers and chokes for interaction between each other. The recommendation from the transformer manufactures and others were to energize the power transformer and use a pair of headphones to determine the orientation that minimizes noise. I understand the concept but I have some practical questions.
Do I need a headphone amplifier? I also need some headphones as well.
Could I use my oscilloscope instead?
How do you evaluate the position of the chokes? Interaction with the power transformer on one side or the output transformer on the other?

Thanks for any guidance!
Dave

 

[Hyperion]

The recommendation from the transformer manufactures and others were to energize the power transformer and use a pair of headphones to determine the orientation that minimizes noise. I understand the concept but I have some practical questions.

I think they are assuming you have a built, working amplifier and can move or rotate the transformers in the given space while it is powered on to verify least hum/noise interaction - using headphones to monitor the output.

Could I use my oscilloscope instead?

Yes you could subject to the condition above. (i.e. working amplifier).

How do you evaluate the position of the chokes? Interaction with the power transformer on one side or the output transformer on the other?

The generally accepted rule is to keep them as far apart as possible and to orient the laminations at right angles to each other - obviously more difficult if the transformers are toroidal - but this would be rare for valve/tube amps. They can be close together, but you would need to place properly designed electromagnetic screens (usually ferrous metal) between them to prevent interaction.

 

[Stephen300]

Whenever I build a tube guitar amp one of the first things I do is something called the headphone trick. All you have to do is power up the Power Tranny and hookup a pair of headphones (no amp) to the outputs of the Output Tranny. You then move the OT around the PT to see where you get no hum thru the headphones.

 

[Scott75s1974]

Whenever I build a tube guitar amp one of the first things I do is something called the headphone trick. All you have to do is power up the Power Tranny and hookup a pair of headphones (no amp) to the outputs of the Output Tranny. You then move the OT around the PT to see where you get no hum thru the headphones.

I'm missing something here. How does this not cook the headphones?

 

[Stephen300]

The phones aren't being driven by a power amp. Do a quick search for Inductive coupling.

 

[Scott75s1974]

Sorry, my bad. I misread. That approach makes a lot of sense.