Two gain stages. First is 100k Ra standard gain stage with 12ax7. Then, there is a 50k resistor between plate and input grid of next stage and a 50k to ground for a 50% voltage divider.
Zout of first stage is ~40k (100*63/163)
Zin of second stage
Is it 50k (Rg)?
Or is it the sum of both resistors in the voltage divider (100k)?
Or, is the Zout of stage one = 40k parallel resistance PLUS the 50k R1 of the voltage divider?
Quick Impedance Question
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tubelectron
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Re: Quick Impedance Question
Hi surfsup,
The input impedance of a tube without Rg is circa some millions of megohms, depending on the tube itself (type, condition - it would be less for a power tube) and it's grid 1 current. So usually input impedance = Rg.
A+!
The input impedance of a tube without Rg is circa some millions of megohms, depending on the tube itself (type, condition - it would be less for a power tube) and it's grid 1 current. So usually input impedance = Rg.
A+!