12BH7 in 12AU7 cathode follower circuit

[perkri]

Less than 3% difference is pretty darn good, not a discrepancy.

One of my many personality defects - needing things to be the same 🙂

 

[perkri]

That makes sense. So a small discrepancy in the resistor value, can have an effect of measured voltage because of the divider being created. Thank you.

 

[NIXIE62]

For example, my BK 393 multimeter has a 10Meg input impedance. If you look at the simulation above, you connect a 10 Meg resistor from grid to ground (my multimeter), and the grid voltage goes from 69V to 56V.

Multimeter + R6 are parallel to R5, shouldn't change much. It can also be measured directly on R5 to GND.

 

[jcalvarez]

R5 to GND yes, but if you measure directly the grid, then the multimeter is in series with R6 and the voltage source, which is the intersection of R5 and R4. You get a voltage divider if you measure at the grid.