Non-adjustable "Fixed" BiasNon-adjustable fixed bias amplifiers without an adjustment pot cannot be bias adjusted. These amps (for example, all Mesa Boogie models) use a fixed resistor to bias the tubes, not a bias pot, and are designed to run with tubes that have a specific current draw range and should only use tubes that fall within that certain range. Fortunately, these amps are very forgiving and will work well with a pretty wide range of tubes. For the best results, when you order be sure to specify the make and model of your amp in the Comments box on the checkout page (or simply order a Shop by Amp tube package) and we will make sure you get the best tubes for your amp. One more thing: some fixed/non-adjustable bias amps have a "bias switch" to select for a specific tube type. Often it is a switch that can select bias for EL34 tubes, or 6L6 tubes depending which is installed. These are still fixed/non-adjustable bias amps as there is no internal bias trimmer pot to fine tune. |
 Top of Page The easiest way to buy vacuum tubes. |