#1
My Marshall JCM 900 is overdue for new powertubes, and it originally came with 5881's. I know there are some variation of a 6L6, but I was wondering if it matters what type of 6L6 I replace them with; do they have to be 5881's, or will other 6L6 variations do? And must the amp be re-biased even if I replace them with 5881s? or does the bias need to be adjusted no matter what tubes are put in? and if so, can I do this myself, without buying any other equipment?

Thanks!
Quote by Dave_Mc
less headroom than the windsor head? what, does it distort before you plug it in?