Gary Albach
Forum Participant

Hi Don – I agree, O1As are plentiful and quite cheap. The problem used to be with 1L6s when their price went crazy to over $100 each some years ago, but prices have come down and today NOS 1L6s are being offered at about the same price as a solid-state replacement (~US$40).
I mentioned WD11 replacements earlier because these tube are fragile, and hence quite valuable in working condition (>$100). Adapters to other tubes are available for about $25 each (without the new tube), and a complete replacement can be fabricated using a 5676 tube for about $15.