• 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.

6P45S/EL509 input capacitance in triode mode

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
According to 6P45S datas the input capacitance Cg-k ( BXOДHaЯ) is 55 pF.
Amplification factor in triode mode is only some 2.3 to 2.7.
Therefore the Miller capacitance is very low.
I would assume the total input capacintance is (well) below 100 pF.
As a reference the input capacitance of 12AX7 is essentially bigger, some 160 pF.

Edit: I also looked at the Svetlana EL509 datas and there the Cg-k is only 25 pF.
Therefore I assume that the input capacitance value ( 55 pF) given at 6P45S datas obviously include the Miller capacitance, but at the pentode mode.
Anyhow the input capacitance of triode connected EL509/6P45S seems so low that any special requirements for the driver stage do not exist.
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.