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That would really suck if this preamp was damaged as I just shipped my Sonic Frontiers off it's new owner and the I'd have two silent stereo systems.
There's an open debate about the usefulness of transconductance (gm) meters. Some say since they don't apply real-world voltages on the plate of the tube their readings are worthless. I'm not sure how I feel about that. The first person I heard this from was a tube vendor who happened to have designed his own tester that did use real-world voltages on the plate. Vested interest, surely. But then I heard the same thing from other sources (Building Valve Amplifiers book, Bruce Rozenblit's new book and the Audiocycolpedia). These sources have no stock in selling tubes so I have to accept their findings. I'm guessing that you can actually get a ballpark gm figure from these testers but actual readings at running voltages may differ. Freo, as you're an avid tube lover I'd be interested to hear what you think of this criticism.Steve, since you did see/smell smoke I'd have that pre looked at right away. Sounds like a resistor may have been compromised.The caveats of older tube testers are that they usually don't accommodate tubes considered obsolete when it was manufactured. For instance, my Sencore won't test early DHTs like the 45 or 300b. Also, not a single one (with the exception of the Amplitrex when you buy the adaptor) will test the 6C33. The older ones run on tubes which means these have to be carefully calibrated and monitored as a bad tube running the tester can give a false tube reading.I've had the great pleasure of hearing Freo's 807 tube amps, albeit too briefly due to my travel companions. They sound absolutely mahvelous! Wow! A quick ebay search shows those output tubes sell for under $10 each!!!
WD-40 in the pins. Hmmm. Who recommended that?
I was wondering the same thing...WD-40 will attract grime, best to use a contact cleaner like Deoxit which has lubricating properties, but without residue.Jim
Steve, it is clear that the tubes were bad if they had brown tops. Jim
Doesn't the color (finish) of the getter depend upon the speed at which it flashes the gasses in the envelope? Yes, a getter that changed from a mirror finish to brown is a clear indication of being past its prime, but a getter can start out that way.