Do you have a tube tester?


2008-08-17 3:41 pm
I was wondering if many of you recommend getting a tube tester?
I have an Audible Illusions preamp: six 6Dj8's
Moscode 600 amp three 6DJ8's, two 6FQ7's, two 6LU8's
Tubelab simple se 12at7, 5ar4 various new output tubes.
I've turned them on, turned them up and lightly tapped the tubes, no microphonics. But is that the whole story.
Will a tube tester tell me that my tubes are fine, but not much time left.
I need such a variety of tubes, that I don't want to change just a few,(what if I have used up tubes, and I changed the wrong ones and don't hear any benefit).
Kind of surprising that in all of Chicagoland, I cant find a hifi store, or musical instrument store that tests tubes.
I've seen on websites about testers that you really have to continually monitor, adjust, and keep up a tester or the readings are off.
Whats a poor boy to do?
I've got one, a Triplett, and a schematic, but fixing amps is easier than fixing it. Even with new electrolytic capacitors, it reads dead short on everything. It was in the trash in 1983 for a reason. It would be nice see how mismatched my push-pull tubes were.
Things to watch for I've got some 49 year old 12AX7's I'm using; the PAS2 sounds great with new capacitors. However, with a new on-spec dropping resistor on the 4 gang B+ capacitor, they won't read the proper voltage, about 75 volts low. Don't you think the 12AX7's may be leaky?
On amps, I measure the voltage in and coming out into an 8 ohm 225 watt resistor. If it is low, the output tubes need replacing. Triplett & simpson analog meters were fine for this, DVM's only work on 60 HZ (at least my Craftsman). I have a $40 scope, now.
So far low power has never been the 7199. Good thing, since they don't make them anymore.