This technique allows amplifiers to trade gain for reduced distortion levels ( and also gave other benefits such as reduced output impedance ).
42.
A power amplifier may have a rated impedance of 8 ohms, but the actual output impedance will vary depending on circuit conditions.
43.
Tube amplifiers have sufficiently higher output impedances that they normally included multi-tap output transformers to better match to the driver impedance.
44.
Valve outputs require an output transformer to match the very high output impedance and voltage of the output valves to this lower impedance.
45.
The roll-off is due to higher device impedance and reduced feedback margins . ( More feedback results in lower output impedance .)
46.
Most tube amplifiers with their higher output impedance are less ideal voltage amplifiers than the solid state voltage amplifiers with their smaller output impedance.
47.
Most tube amplifiers with their higher output impedance are less ideal voltage amplifiers than the solid state voltage amplifiers with their smaller output impedance.
48.
The pickup is connected to a transformer with a three-position switch to select output impedance of 50, 250 or 500 ohms.
49.
A perfect logic gate would have infinite input impedance and zero output impedance, allowing a gate output to drive any number of gate inputs.
50.
Because " R " " C " is often large, the output impedance of this circuit can be prohibitively high.
