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previous: km another thing strange about this am... -- 1/23/2004 2:25 AM View Thread

Re: Marshall tones

1/23/2004 6:52 AM
M. Taylor
Re: Marshall tones
I'm not absolutely sure about the voltage but by doing some very rough estimation with PSpice I get right on 150V (assuming 330uf/820R and .68uF/2k7 on the cathodes). The voltage chart I found for a Mk2 50W with 6550's and approx 400V on the plates suggests it's as low as 100, but the schem may be different for that one.  
As I'm sure you can tell I'm not a Marshall expert by any means, but I don't think any of them came stock with 27k bias feed resistors. Seems very low to me, and since I've only experimented in reducing them to 68k I can't really say for sure if this is causing your tone troubles but I'd certainly suggest you play with these. I've found they cause a pretty noticible change.  

Dai Hirokawa If you're talking about the R in se... -- 1/23/2004 3:09 PM