2. amps-preamps
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Tube handling/designations

I recently purchased a BAT VK-30.It came with 6922 Teslas installed as well as the original Sovteks.I would like to try some different tubes to see how they affect the sound.My first question is do you need to wear gloves so as not to get oil off your hands on the tubes like halide lights?My next question is are 6922's the only tube that will work or are there others?I ask this because in some ads for tubes I see a slash followed by EE????.Also,what does NOS mean and why are they supposed to be better?
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joman
167 posts
 
I would recommend the Siemen CCA's in your VK 30. They are among the best in the 6 volt 9 pin family. I have not had a good experience using the 6dj8's in the BAT preamps. Other peoples experience may vary.
larryi
4,191 posts
 
Tubes will not burst the way a halide bulb will burst from skin oil depositing on the tube. With halide bulbs, the oils are subjected to extreme heat which causes the oil to break down and carbonize. The black deposit that results will then absorb much more of the light being put out by the bulb than the rest of the glass on the bulb. The difference in temperature between the other part of the glass and the part with the black spot causes stress in the glass which can lead to failure. These bulbs are under extreme stress from the high pressure gas in them.

Tubes do not operate under similar conditions -- heat is lower, no significant light output to be absorbed by a spot on the glass, a vacuum instead of high pressure, etc.

Still, I don't see why caution would hurt, particularly with hotter tubes, like a 211 or 845.
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atmasphere
12,088 posts
 
Heat is the enemy of tubes- they ought to be kept clean of dust and fingerprints for the longest life. 6DJ8s and 6922s are capable of running a fair amount of current and so can get quite hot.
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