biasing

[rickvox]

Hi , I did the change the aux7 with at7 thing in my blackface module and that worked great. Then I checked the bias on the power tubes I have a rm20 in which the manuel says should read 15-20 milamps . the el84's were biased at 34 miliamps so I lowered them to 20 miliamps which is where the manuel says they should be at. Help me out on that did I make the amp more distorted or as the manuel says more clean at high volumes. by haveing the bias set so high for el84's what was being accomplished there. I bought the amp used so I was wondering what the previous owner had in mind. I want to thank you all for the education on tube amps I am getting here. I have used them in the past but never knew what was going on or even replaced a tube in one now I am biasing mine and learning a lot here . This is a very cool forum. Phi Henzig

 

[Mister Joshua]

Biasing high will produce more power tube saturation more easily. In short more distortion. It also will shorten the life of the tubes substantially. Some folks love the sound of a hot bias. I love not buying tubes.

Peace, Joshua

 

[Julia]

Some people back in the 1980s used to bias things so hot they'd go through sets of tubes in a single show. You never want to exceed the maximum rated power of the tube via a particular formula regarding the bias. It isn't good for the tubes, nor is it good for the amp. But it boils down to this question... How much money do you have?