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Luxman MB3045 biasing guide/help

Ive installed new production Gold Lion KT88 and they worked fine. These aren't particularly abusive to tubes. Voltage and current doesn't push them to the limits.
 
Blue Shadow said:
Gonna need more info on that as mine use 6550s and seem to work just fine. They have been modified to use the KT88/6550.
Click to expand...
His explanation was that the 6550 are run in triode mode in these amps, and in triode mode the screen grid sees over 500V in the MB3045, so one needs a 6550 that can handle this, and the ones that can are not so common nowadays.
 
The voltage ratings are a lot less critical in triode mode. Its more about voltage difference between plate and screen, and in triode mode there is no difference. Arguably more dangerous to run them in pentode mode since the screen is always at ~500v and the plate can be very near to zero volts at full output peaks. Blue Shadow's are in pentode mode and haven't eaten any tubes.

The set of Gold Lions I installed was in a triode-wired unit.
 
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