wehrwulfe Posted May 13, 2013 Share Posted May 13, 2013 i was given a 2007 model sv mk 1 and while the clean sounds are very good ,turning up the drive encoder on any model results in a real nasty "barkY"(i guess thats a word) .tone.. very grainy...the tone controls seem to have minimal effect even after I spin the knobs to start at "0".the tubes are orginal .and one of the power tubes has a bright blue ring around the area where the plate(?) ends . any ideas??/id like to keep it. Quote Link to comment Share on other sites More sharing options...
toneman2121 Posted May 14, 2013 Share Posted May 14, 2013 i've read good and bad. i would change the tube. get the amp biased. http://www.marshallforum.com/workbench/22928-blue-glow-vacuum-tube.html Quote Link to comment Share on other sites More sharing options...
spaceatl Posted May 15, 2013 Share Posted May 15, 2013 +1...Sounds like one of your power tubes is going...That can put the amp way out of bias. What that means is the top (+) of the sine waves will notch as they cross to the bottom (-)...The result is generally exactly as you describe...the tone gets unusually rough really quickly. Good idea to change all the tubes on this one I think...and adjust the bias proper for the tubes you get.... 1 Quote Link to comment Share on other sites More sharing options...
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