how do you know a bad tube?

What is cheap for a tube tester compared to a second set of tubes at today's spiraling prices or damaging a component with a bad tube?

I found a Sencore Mity Mite VII for $100 without looking to hard. But even at $200 or $300 if you have a long term commitment to tube gear then it makes sense to have one.

Entrope

yes, $100 - $300 is cheap. I'd have no issues going for something like that. My concerns, are it's use. meter/display size, and calibration needs... doing twin triodes, large power tubes, in all, it's flexibility and naturally it's accuracy.

meters/displays need be of substantioal size for me. Figuring it out is not much of a problem there after. although I appear dumb as a stump sometimes, i don't believe I really am.

Waht resource sells these things?

they won't look you in the eye.

How ironic the timing for a personal delima. Last nite I turned off my pre-amp fist and got a right side pop in my speaker. Since I hadn't turned off my amp 'it had to be as a result of something in the pre'.

Switched tubes from side to side as I had suggested. No change! Then I went to the amp and switched one of the sets of small tubes. Not only did the pop leave the right channel it left the system (for now anyway). If I had a tube tester I could probably test it and detect some imbalance that I can't hear in use. I'm not sure if that is a loss.

Back in the days I was frugal and thought my tubes would (should) last forever I had a spare tube of each type set aside for testing. Then when I changed tube sets I had lots of tubes available for testing as well as spares.

My biggest fear about owning a tester is just imagine how anal you could get about tube condition and how much time you could spend monitoring their condition. Oh, my. Got enuf on my plate worrying about things like set-up etc with out taking on that responsibility.

Have fun, it ain't really a big deal. I am as dumb as a stump, even if I don't appear to be so sometimes. :-)

Newbee,

The act of turning off a component, often results in noise, without any component necessarily being defective. That is why one should not turn off sources or the linestage/preamp first, because any such transient "pop' will be amplified by the power amp, perhaps to destructive levels.

Sometimes noise in tubes is eliminated by the very act of pulling and reseating the tube. Often noise comes from poor contact at the pins, other times, something deposited on a surface inside the tube can be shaken loose and the source of noise eliminated.

Perhaps the best reason to have a tube tester is not to find out if a tube is beginning to go bad, but rather, to determine if a new tube is safe to use at the outset. I own a tester and lent it to a friend. The tester determined that one of the rectifier tubes he was keeping as a replacement showed no voltage drop in either direction (shorted); it is frightening to think what that tube would have done had he inserted into an amp.