Circuit #6
Using two triodes, this circuit can offer a high voltage gain, comparable to a pentode but with less electronics and microphonics noise.
You would probably use ECC83 to make an audio cascode because of its higher intrinsic gain.
To get enough swing and symmetry on the output, you would probably set Vg around 1/3 of supply voltage.
PARAMETERS
Select T1 T2 type
V supply voltage
Ω T1 anode resistor
Ω T1 cathode bias resistor
Ω T2 bias resistor
Ω T2 bias resistor
Note: the grid resistor normally found between grid and cathode is not taken into account here, as it does not influence the operating point
SCHEMATICS