Conclusion
  Are we done with hybrids? No, not even close. Just adding one new active device to our palate exponentially increases the potential circuits we can paint. Next time, but not necessarily in the next issue, we will cover hybrid power amplifiers, both tube front-ends with solid-state output stages and solid-state front-ends with tube output stages. Also, we plan to cover one of my favorite topics: transposing topologies from dissimilar technologies.


                            // JRB
   

   An Op-Amp senses the voltage at each cathode through 1 meg resistors and adjusts the first triode's bias voltage until its cathode voltage matches the second triode's cathode. If the voltage at each cathode is the same, then the voltage across each 50 ohm resistor must be the same, which in turn means that the current flowing through each triode is the same, which finally means that the voltage across each plate resistor is the same. Now, we can confidently DC couple the second stage.

pg. 9

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