From: John Thaden Date: Thu, 01 Oct 1998 11:53:32 -0500 Subject: amp rebiasing and "starved-plate" operation
In another thread, Don D. wrote
>On a stock RI Bassman, there is no way to >easily rebias the amp, and Fender usually biases the amps "cold" to save >on tube wear and to cut down on warranty replacement on the cheap, >imported tubes they use. This will tend to make the amp sound "thin" or >"lifeless." If you replace the rectifier and power tubes with good US >NOS tubes and rebias the amp a bit hotter, you'll find you get a big >improvement in tone.
I'm not sure I know what Don means by 'cold', but I've read that some amp designs run the output tubes with less plate voltage than spec, because they then distort at lower volumes and have a round tone. Also, that the single 12AX7's in some of the tube distortion pedals are set up this way. My question is, does 'bias' refer to the plate voltage? If so, wouldn't lower (colder?) bias give a nice tone at lower volumes?
John Thaden -Gil Franklin Band Little Rock, Arkansas, USA
