• 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.

Output Impedance?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Must be a little dense this afternoon, but Im trying to figure the O/P impedance of my recent OTL.

At 8 ohm and 10V p-p o/p into 8 ohm.

At 4 ohm I get 9V p-p o/p without altering amp input level from sig-gen. (used WW resistors as load)

This was not done at full amp O/P, as I didnt want to over-stress my single pair of 6C33 in the O/P stage, although I have achieved 30W P-P before the onset of visible distortion into 8Ohm WW resistor......

Could some kind and more intellegent guy give me some clue as to the O/P impedance and maybe the damping factor?
 
I don't know about the intelligence part, but:

A theoretically perfect voltage source of 11.25V p-p with a 1 ohm resistor in series with it will give the same results as your amp. This is known as the Thevenin equivalent circuit. The 1 ohm part is the output impedance. Which would indicate a damping factor of 4 with a 4 ohm load, and 8 with an 8 ohm load.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.