Nelson Pass B1 preamp build

[Bigman80]

[Bigman80]

So, I've put the lid on and hum has appeared. It's the same on every input so there's a problem somewhere.

Any ideas?

[Bigman80]

It does.

Does the hum go away when the lid is removed?

[YNWaN]

How odd. Is the case and lid made from aluminium or steel?

[Bigman80]

How odd. Is the case and lid made from aluminium or steel?

It looks like its steel as a magnet sticks

[walpurgis]

Have you got the case earthed?

[Bigman80]

Yes mate.

Have you got the case earthed?

[walpurgis]

Is the case earth commoned with the in/out socket negs? They may need separating if so.

[Bigman80]

Is the case earth commoned with the in/out socket negs? They may need separating if so.

They are not commoned mate. They are earthed to the chassis in a separate location.

Would this matter as the hum goes when the lid goes?

[walpurgis]

What I'm suggesting is that it may (or may not ) be best if the signal negs are not earth to the case.