What do I bias KT 77 tubes at?

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You can bias them like regular EL34's, but they will be running a little cool.

I ran some kt77's for a while and I think my research turned up 35-40mV so that's what I set them at and they seemed to be fine.

This was in an RM50 btw

You may already have or already know, the EL34/KT77s need a 400mA fuse where a 6L6 type tube used a 250mA fuse. Jaded faith told me a 500mA will do no harm if they are easier to find than a 400mA.
 
Why would a different fuse be needed for a different tube? The maximum current is determined by the HT and Plateload, not the tube.

As for bias: bias them you output tubes as ow as possible without sounding awfull. This will prolong their life multiple times and keep your amp, and the rest of your rack, cool runing, prolonging the live of al your gear.
 
hmic10 said:
Are they the same as el34"s
Well, not quite. The EL34 has an absolute max of 27W, which means that a minute drift or biased prior to warming up properly may blow them.

The KT77 has an absolute max of 32W and typically they are more rugged than comparable true pentodes, particularly those made today.

I would personally go as hot as 85% of 25W, which equals 70% of 30W. The KT77 mellows out pretty well at this point and exhibits various shades of semi-clean overtones, perhaps similar to the KT66.
 
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