HEAD's UP: 15w 1x12 tube amp $127 today (Feb 27th) Mar 3, 2018 11:01:33 GMT -6
Post by drbill on Mar 3, 2018 11:01:33 GMT -6
OK, glad you're up and running. A couple things you should know - first, if it's a little amp with a single output tube it's self biasing. At least I've never heard of one that wasn't. (Push-pull amps can be either way.) Second, a good "seat of the pants" to determine how much life is left in a used tube is to look at the "getter", which is the silver-black deposit on the glass envelope. It might be a spot on the side or it might be a coating in the top or something similar. The purpose of the getter is to absorb stray ions floating around in the tube which will compromise performance. (Hence the term "getter" - it's there to "get" that stuff and render it inert.) If a tube is approaching the end of its life the getter will start turning white instead of a healthy silver-black. The greyer or whiter the getter is, the more worn out the tube. Of course there are a number of other things that can adversely affect the life of a tube (shorts, dead filaments, loose elements that make it microphonic - which are obvious - lotsa stuff) but as long as a tube stays on the "main sequence" of tube life, the getter is a good indication of how worn out it might be getting (Lousy pun intended.)
And the kid should have asked before immediately trying to sell you on the most expensive "solution"....
Thanks for the info John. Appreciated.
The kid was actually quite helpful. He offered to order a single for me, and suggested several alternatives. But all he had on hand was a package of two together that he couldn't break open. This is a tiny mom/pop music store. I'm actually surprised they had any tubes. LOL
All good now though. Will check the tubes life next time I have the amp opened up.