Originally Posted by roguegeek
When looking for tubes online, they are showing certain rating next to them. This like "tested at 70/60, 63/66"
. What in the world does this mean and are there any other specifications I should know about before going off and buying various tube for the Lyr?
In the old days, there wasn't any consistent standard for old tube testers.
E.g. The minimum good standard could be 50% or 60% of GM life left.
Or even 80% for serious audiophiles, my own personal reference standard.
Usually 50% tubes sound like crap.
So every tester has its own scale with a "minimum good" marking.
I suggest that you ask the seller to explain what are the tube tester readings for "new" and "minimum good" tubes.
That info, coupled with the current tube readings should provide the buyer with some basic gauge of the life left in the tube.
As for your question, there are 2 halves in a tube belonging to the 6DJ8 family.
Hence there are 2 sets of readings, I'm referring to the "," comma portion.
One thing to look out for is balanced halves.
If possible, try to get tubes with similar readings on both sides.
BTW, this is a really complex issue and I have therefore only provided a brief answer.
Hope this helps !