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Just put a new quad of EH-EL343s in a TSL 100 and with the bias controls balanced and at the lowest mv setting I get about 90mv about (49mv on bias probe per tube) at 462v on the plates. Controls won't go any lower. Before I go digging, does anybody know off hand what resistor/s I can adjust to lower the range of the bias pots? Thanks.
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Looks like a 10k (R77 on the schematic) resistor feeds the bias pots, so you could drop that a bit, your tubes might be drawing a bit much... Could you get it in range with the old tubes? -
Thanks man. That's what I was looking for. Couldn't find the TSL bias board schematic to see how R77 fed the bias controls but I just found the DSL one and they are the same. Like you suggested, adjusting R77 should do the trick.Originally posted by trevorus View Post
The stock GT-E34Ls that were in the amp when it was brought to me were toast so I don't know where the bias was at before. Maybe it was too hot as well? Don't have any other tubes on hand to try. This is a fresh set and I just put some in a DSL 100 with no issues. If I could just get the current down a tad more. As it is in excess of 22watts static dissipation is not gonna fly... for long.Comment
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Yeah, if it sounds good, it is good, until it melts down, or the magic smoke comes out! Good luck with it. I had to do something similar on a Weber Plexi kit for my friend that the bias wouldn't sit within proper dissipation, and I had to adjust the bias feed a bit.Comment
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Popped another 10k in parrallel with R77, grabbed another quartet just to compare and now I have plenty of range to work with no matter what tubes I put in there. The heavy metal beast is risen!Comment
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For what it is worth, here is a link to the schematic. http://schematicheaven.com/marshalla...sl100_100w.pdfComment
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