Biasing question - if power tubes are matched but...

[Chrissy]

It seems that conventional wisdom dictates that "matched" power tubes will have current draw to within about 5mA of oneanother. I have a couple of sets that hover on this limit (and some GT KT66HP that measuer up around 8mA off when in my Germino. Now, if I have a bias recommendation for a certain type of tube in a particular amp that has a target range 33-36mA, then I obviously can't get both tubes within the range...

What is important to take account of? Is it the sum of the 2 tubes that counts? Or do I just make sure the hotter tube doesn't go above the recommendation (which will leave one tube biased colder than I want.

To be clear - I know what sounds best to me, I'm just curious if there are any issues to be addressed that I'm not thinking about...

Thanks in advance
Chris

[Whoopysnorp]

Those are not terribly huge figures, so I would just split the difference between the two tubes and have one be a few mA hotter and one a few mA colder. It should sound fine that way.

[VacuumVoodoo]

Also, since primary windings on the output transformer are never perfectly symmetrical you may want to try swapping the tubes to minimize hum. That is, if there is any to begin with.

[Chrissy]

Thanks for the replies...

So no issues to be expected by one tube running quite a bit hotter? Life expectancy etc.???

Chris