As a side note, watch out for eBay sellers who offer "NIB" (new-in-box) or "NOS" tubes in "original" boxes. Some of theose boxes are reprinted stock white tube boxes. You can usually tell when you see white edges outside the original labelling. Another tell is identical coding on the inside flaps of the box, indicating there were printed from an image of a single box.
For Tube Folks...
Hi All,
I am rather new to tube gear and recently purchased a 'NOS' GE 6550 Power Tube.
A. It was advertised as: "New old stock in original or OEM box. A nice USA tube that will outperform any current production 6550 made. An excellent lot, matched to within 5 percent and then aged in a hi-fi shop demo unit. Very low hours, burn-in time only, and the performance has been verified by us..."
B. The seller also sells used GE6550 tubes that are advertised as: "Light use, tested good with good match, and white box..."
The large black spot on the glass where it GE is etched makes wonder how many hours of usage this tube has seen...
My question - Within reasonable certainty, is this tube is NOS or is it USED?
Thanks in advance for any clarity.