Sylvania 6CA7's.

A couple of weeks ago I purchased a 212HD 130. It's in very good shape overall, but did have a bad reverb tank (broken wire). Since I'd purchased a new tank for my 210, that didn't fix my problem, I used it in the 212. Mission accomplished. It's got a great reverb now.
The amp had a mixture of tubes, two being big-bottles Sylvania 6CA7's, one Japanese Amperex, and one GE slim bottle EL34. The Amperex had internal burn marks on opposite sites of the bottle, one of which looked like the glass had actually had a partial meltdown, as it was dimpled. Anybody ever seen that?
Anyway, the amp sounded a bit distorted after just getting slightly warmed up. So yesterday I pulled a couple of my 6CA7's out of my 210 and put them in the 212. It made a huge difference in clean tone and perhaps even overall power. While I also dialed in my amp using Steve K.'s suggestion for "diming" the master volume and guitar volume, zeroing the channel volume, then adjusting the channel volume to taste. Great suggestion. The amp now sounds awesome. I know that I should get the amp biased for the tubes and will be doing so soon. I'm considering doing it myself. I'll end up buying one of those bias testers from Eurotubes, or on Ebay, or maybe even the Compubias (Pricey!). Posts by MusicMan wisemen, mention using a non-conducting too for making the adjustment, but I can't seem to locate anything like that for sale. Anybody know a source for such a thing? Maybe I should just flatten the tip of a chopstick? Ideas?

What I use is an old TV adjustment tool. They used to be around everywhere. It's basically a plastic screwdriver is all. Anyway, if you're careful, the pots on the bias adjust are very low voltage and pose no real threat. It's the things around it, like those 450 volt caps and the bottoms of the sockets when live. If you want, just grind a chopstick flat and use it like a screwdriver. JUST BE CAREFUL. Our old rule is always have your left hand in your pocket while working on theat stuff while live. Of course, that's not always practical but it still good advice. If you want the tools look at ebay under TV tools and stuff like that.

I had a hard time finding the adjustment tool, although I'm sure that it would be in with some of the sets that I saw advertised. I wasn't sure of the exact size of the tip needed, etc. Ultimately, I ended up taking one of my probe tools (wooden chopstick) and filing the tip into a flat screwdriver. I did this by placing an emery board on the edge of my desk and taking the tip down flat. It worked quite well.
As far as bias tools, I opted for the Quadstage Bias Pro (By AsharpFretworks) with the removable/replaceable socket leads. It had good instructions, worked as designed, and is made in the good old U.S.A. I'm happy with my choice.

Never used one of that type because I'm cheap and old but they all seem to be OK. As long as you use SOMETHING and check your settings, you should be OK. I usually do it old school and just insert precision 1 ohm resistor in there and measure them. On fenders, I usually leave them in. Never was one to do the crossover distortion method. I keep the scope for other things like distortion and something to sit my coffee cup on. Mike.