i have a fender hot rod deluxe amp, and i want to replace the preamp tubes. i have the mesa boogie tubes. do i just unplug the old ones and put in the new ones? or is there a special way of going about it like rebiasing? If so, could you explain the briefly explain process to me or perhaps, a helpful link?


just unplug and put em back in, but beware... they get so damn hot so wait for a while after you've played your amp.
Biasing should be done when you switch tubes. It involves high voltages and a steady hand AFAIK, so get it done by a tech. Do it wrong could result in a fubarred amp, or worse, injury/death.

But switching tubes is easy, pull out the old ones, stick in the new ones. Use a cloth or gloves to hold the tubes so you don't get skin oils on your tubes.

BTW, if you're interested, biasing is basically setting the negative voltage to the tubes. Certain tubes have different wattage dissipation ratings, even the same tube brand and models can vary significantly. Changing the bias changes the lifespan of the tubes as well as headroom. If you run your tubes cold, you'll get more life out of them, but your tone will suffer. Run them too hot and they'll burn out. It's up to the player to find the sweet spot.
Last edited by SolidxSnake at Aug 30, 2006,
one thing NEVER mess with tubes unless the amp is unplugged. a tube that breaks can become about 1000 volts straight through your body if the amp is on. the thing that burns tubes up is not letting them warm up before you play. if you just flip standby and the on switch up, it puts stress on the tubes.
brilliant! really helpful website, dattt. i'll try to keep the amp of when i replace them lol
If youre just replacing the smaller preamp tubes no biasing is required they are self biasing. Power tubes require biasing.