[cangle]

I was using my Schiit Lyr today and noticed some burn marks on the tubes I am using. They are the stock GE 6BZ7.
 

 
Is this normal? I read elsewhere that this could be a faulty driver tube or that it is absorbing oxygen that is inside the tube causing the top to darken.
 
What should I do?

 

[Nic Rhodes]

look normal, usual discolouration of getter with initial usage. I would carry on as usual and not worry about this. Some tubes are even 'burned in' like as new by the supplier  [a great way to get low prices on 12SX7GTs ].