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When using 4 x cathode biased EL84's, is it possible to fit a half power switch to disconnect one pair of cathodes, in the same way as Mesa do with a quad of 6L6gc's to get their 60/100 watt switching, or will that not work with cathode biasing?
Thanks in advance.
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To be all proper ... you should then change your speaker cabinet to the next lower impedance tap to have the proper reflected impedance ...
With four EL84's you want 4k reflected impedance with two you want 8k ... so plugging your 8 ohm speaker into the 4 ohm tap gives an 8k reflected impedance etc.
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http://ceriatone.com/images/layoutPic/m ... iatone.jpg
That's a good switching system for half power in a 4 EL84 cathode biased amp.
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But if your thinking of it dropping to half the vloume of what you are hearing, It really doesn't do that.
Really a bit misleading. You will not hear much of a difference in volume between 4 tubes and 2.
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You can do it with fixed bias but not with cathode bias.
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