Figure 4 shows the output circuit of the popular H-P 200CD oscillator. Although the attenuator is unbalanced, the transformer provides isolation, if the front-panel ground jumper is disconnected. The primary-to-secondary capacitance measured about 260pF. Note: all capacitance measurements here were made with a General Radio 1650-A impedance bridge at 1KHz.

     Figure 5 shows the output circuit of the Audio Precision System 2. (Note that this is different from the System 1). The normal balanced output impedance is 40 ohms, but resistors can be switched in to give a 150 or 600 ohm output impedance. Even when grounded, the output is still balanced. The capacitance from both outputs to ground measured 0.016uF