Ahhh...tubes. I remember when you could take your (TV) tubes to a drug store and plug 'em into a tube 'reader'. The kiosk would tell you if the tube was good or not and had a load of replacement tubes if needed. I watched my father repair our TV many times.

But then...I remember corner drugstores too. ;)

A relative started building amps as a hobby, became a name boutique amp builder in Texas and has now moved on to a major manufacturer. When he started, his tubes came from eastern Europe/the old Soviet bloc. I always found that interesting...