Can the tube handle the amp?
Sometimes an amp will have a plate voltage that is higher, or much higher, than the tube’s maximum rated plate voltage. For instance, the max plate voltage of a tube could be 300DCV, while the amp puts 500DCV on the plates. This is not particularly good for the tube, but some of the more robust and conservatively rated tubes could handle it. Most techs agree that you should observe the maximum plate voltage, or Va for short (pronounced “V sub A”), but if you do run tubes outside of their max Va rating, be sure to bias the tube so that it still falls within an acceptable plate dissipation—which is explained thoroughly in the section after the biasing instructions. The tubes we’re interested in also have a max screen voltage, max screen dissipation, and max and min heater voltage. While we can usually exceed the maximum rated plate voltage, and then adjust the bias so that the plate dissipation is good, the screens are often overlooked! If the screens can only take 270DCV, and you have t
