On the front panel of the switchbox, plug the headphones into the headphone (mini-jack) output and connect the output BNC connector to the voltmeter. On the back panel of the switchbox connect the out...On the front panel of the switchbox, plug the headphones into the headphone (mini-jack) output and connect the output BNC connector to the voltmeter. On the back panel of the switchbox connect the output of the reference generator to input one of the switchbox with a BNC to BNC cable (the right side of the rear panel when viewed from the front). While comparing the reference to the second tone, adjust the amplitude (voltage) of the second tone so that the two tones sound as loud as each other.
