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Unfortunately, that is one of the realities of vacuum tube production and honestly it has been since the beginning. What is amp bias?
You also kind of know what to expect from a set of tubes before you pop it into your amp. Many people actually refer to them as "self-biasing" for this reason. For this reason many companies buy tubes in bulk and will test, match and grade tubes. Ive just purchased from andertons a New Victory Sherrif 44 head and they have a Bias adjustment fitted on he back that can be done outside of the amp with a mutimeter and an adjustment screw.
What I did was I checked the old tubes to get a rough idea of where the bias was originally set for each power tube. The Gear Page.
Steve Colley says: Featured Products. Tube Amp Bias is an electronic process that ensures the power amp tubes in your valve amp run at their optimimum capacity so that you can get the best possible guitar tone out of them. Show Ignored Content. For this reason, it may be advantageous to look for tubes that are graded or matched based on different characteristics. Cathode biasing is very commonly found in lower powered amplifiers and even more so in amps that use EL84's.
Brilliant piece of writing Jed I run 3 messa amps a road king Head a 25watt rectoverb and a MKV head have changed valves in them over the last few years without any problems and like you say the new valves are matched pairs.
It ensures the tubes are fed the correct voltage according the valves resistance rating.
What will I learn? This should only be done by a trained amp tech.
Example of incorrect tube spec: May 3, 2012 6. Did you enjoy reading this article? Leave a comment below and share your thoughts! When it comes to tube amps the idea is basically the same, however, instead of fuel and air we are dealing with electrical current. We proposed some changes to the Emporiums.
Home Forums Recent Posts. Do you already have an account? May 2, 2012 1.
Being that it is difficult to optimize the amp for the set of tubes like with the other two methods, it is more important to optimize the tube to the amp in terms of operating characteristics. Martin Being a great designer has allowed a great facility here.