# Ouput voltage of a triode stage on quiescent state should be zero?

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#### Salamander1973

Hi:

I´m new to this forum and I´m taking my first baby steps into this. I´m interested in guitar preamps and I´m learning all the theory first. One of the things that keep me thinking is the expected value of the output voltage of a triode stage in the quiescent state. I'm picturing a simple stage with a cathode with a resistor and capacitor in parallel to get the bias, and on the load side a capacitor to eliminate the DC component and a resistor to get the the voltage in the output. Should the output voltage be zero in this case or is it ok for it to have a little voltage (like 0.0x volts)?. Can anyone point me in the right direction to understand this? Thanks in advance.

Regards

#### Arnulf

I don't understand what "resistor to get the the voltage in the output" is supposed to be but regarding your main question: quiescent voltage (left side of coupling capacitor) can never be 0V in a class A stage. Output voltage (on the right side of the coupling capacitor) will however always be 0V, assuming DC conditions on the left side.

#### Salamander1973

I don't understand what "resistor to get the the voltage in the output" is supposed to be but regarding your main question: quiescent voltage (left side of coupling capacitor) can never be 0V in a class A stage. Output voltage (on the right side of the coupling capacitor) will however always be 0V, assuming DC conditions on the left side.

Thanks for your answer. With resistor on the output I meant this (I hope mi ascii art is good enough ):

Vp---| |-----+-- Vo
|
R
|
v

Vp = plate voltage
Vo = output votage
R = resistor (R is supposed to be under the "+")

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#### DF96

The output will not be exactly zero, but it will have small amounts of noise and hum. Good design reduces these to the point where they are not a problem, but they cannot be eliminated.

#### Arnulf

Vo will be 0V in this case, assuming DC conditions at the Vp point )= quiescent state) and that the point below the pull-down R is grounded (your symbol implies connection to negative supply rail rather than ground).

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