pulling power tubes ----> 50% power

  • Thread starter Thread starter gusfinley
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gusfinley

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Yeah, So, I got this 40W Marshall JCM2000 DSL401 with four EL84 in the power stage. I also ave a 25W celestion greenback, and I have learned that if I pull two of the power tubes I get only 20W and so the speaker should handle it.

THe questions - I just purchased two mesa/boogie tubes to use for recording. How do you bias just two power tubes in a four power tube amp?

Also - it is a matter of controversy what exaclty pulling power tubes does to your ouput taps on the output transformer. Some say it doubles the indicated value, and so I woiuld need to run my 16ohm speaker at 8 ohms.

Anybody have any experience wiht this sort of thing on Marshall amps?

Thanks for your help guys
 
Play with all four output tubes. Better to blow a $75 speaker than your output transformer. I mean, it can be, and is, done, but you want to make sure that you make any and all necessary adjustments. Besides, I'm sure a 25w Celestion can handle 40w. My friend runs his 5150 II, which is 120w, into a 100w Marshall cab all the time, and the 5150 is ridiculously high-gain. So unless overall volume is your chief concern, I would just play with everything as is.
 
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