Originally Posted by: PoleraWell i have a traynor that is apperantly auto-biasing. I know that means i dont have to match the tubes in the back but i dont know what else that means. I think i must look to lord of the strings for this one! Hark, where are u lord of the strings?!?!

[font=trebuchet ms]Auto-bias or self-bias is a circuit design that uses a resistor between circuit ground and the cathode of the power tube(s) to set up the voltage difference between the cathode and the control grid. This is also called a grounded-grid circuit.

Since the circuit compensates for individual tube characteristics, there is no need to make adjustments to set up for a new set of power tubes. Actually, tube matching is less critical too. And since all preamps use this type of circuit, you can swap those tubes out as well, without making any adjustments.

The problem may not be one of your tubes, but since they are easy to swap out, it's the first thing to try. Just be careful about it. The voltages applied to the tubes will definitely kill anyone who touches the wrong thing, even after the amp is shut off, and/or unplugged. And tubes stay hot for quite some time.

Use a clean, dry cloth to handle the tubes. This protects you from the heat, and keeps the glass clean. Be careful to align the tube with the socket when you plug it in. Preamp tubes have a gap in the circle of pins as if one pin was missing. If you don't line that gap up with the socket, you can bend or break some pins. And if you rock a power tube back and forth too far as you pull it out, you can snap off the plastic pin in the middle of the socket.[/font]