Life span of tubes?

Life span depends upon amp design/application. Originally tubes were designed with a 10000 hour life span. if the tubes are used 'nicely' then they should last. I know that the old quicksilver 8417 monoblocks would eat tubes ~ a set every 10~18 months, but a Music reference RM-9 can keep the same tubes in place for 10 years. THis I also know to be true as I just replaced the tubes on my RM-9, and have had the amp since 1990.
The mac should be on the longer tube life end of the scale.
Happy listening

how much does tubes costs when replacing ?
i can think that there are lower and higher cost tubes but..how much in general?

thanks:)

Depends on the brand (I'm assuming you mean KT88s here). The Svetlanas probably are in the $30-40 range, I think, from what I've seen on the 'Gon classifieds. Not sure about the Teslas and Chinese tubes, but probably similar, maybe a little less for the Golden Dragons. NOS Gold Lions/Gold Monarchs from Europe (not the Chinese ones from late in their history) are out of sight ($250-350 each, depending on their vintage and condition); if you can get used ones that test good, they are less expensive and can be a good buy.

Rcprince is right of course. Haven't seen any NOS Gold Lions or Monarchs for quite a while. Occasionly you can find one or two used at Billington's in the UK and they cost lots of Sterling. To get a feel for prices of other tubes, I suggest you check Ebay regularly to get a feel how the market is.

Detlof, that's because I'm hoarding over 50 of them! Told you I had a lifetime supply......