I like Rushton's answer. Simplistic works best for me when it comes to hot and cold running electrons. Eldartford's answer was far too correct! (Actually very helpful, thanks.)
We just biased our new tube amp for the first time, manually. Really, really exciting moment. There's nothing like dragging 65 pounds of iron out of the rack just so you can get to it with a multimeter. Auto-biasing must be like auto-return tonearms, keeps you from truly bonding with your stereo.
One possibly useful tidbit: if the amp has more than one output tube per channel there may be a facility for balancing the tubes against each other as well as biasing the overall DC voltage level. Unbalanced tube voltages on the same channel apparently feeds DC into the output trannies, which tends to saturate them. (Eldartford can correct that if I messed anything up.)
We just biased our new tube amp for the first time, manually. Really, really exciting moment. There's nothing like dragging 65 pounds of iron out of the rack just so you can get to it with a multimeter. Auto-biasing must be like auto-return tonearms, keeps you from truly bonding with your stereo.
One possibly useful tidbit: if the amp has more than one output tube per channel there may be a facility for balancing the tubes against each other as well as biasing the overall DC voltage level. Unbalanced tube voltages on the same channel apparently feeds DC into the output trannies, which tends to saturate them. (Eldartford can correct that if I messed anything up.)