• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

S11E12 TUBES

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Jaap

Jaap

Member
Joined 2003
I have tried them shortly in a breadboarded KT66/EL34 type PP amp. They sounded great. I first tried them with fixed bias but they did not like it (kept running away). I believe they need cathode bias because they were designed as pass tubes in regulated supplies.
They are like 12E1 I believe.
 
richwalters

richwalters

Member
Joined 2003
Running away. I've always assumed that g1 gets too hot to cause this, effectively re-emitting to cathode, shunting neg volts hence tube is out of control. This doesn't make sense esp the data sheets quote max 100K grid leak for fixed bias and 1M for auto and that agrees well with modern day tubes of the same power. Have to read up on this.

richy
 
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