MEASUREMENTS
Because of the darTZeel NHB-468’s bulk and weight, and also because the amplifiers needed to be picked up for photography as soon as Michael Fremer had finished his auditioning, I drove my Audio Precision SYS2722 system—see the January 2008 “As We See It”1—its host computer, my digital and analog oscilloscopes, cables, and all the rest of my test gear to his New Jersey home to perform the measurements.
Prior to trekking to Mikey’s, I had received several emails from designer Hervé Delétraz about the new circuit topology he had incorporated in the NHB-468, which he calls CP2C (Constant Power to Current). Hervé explained to me that CP2C, which is patent pending, “is mimicking a current source with the output impedance of a voltage source,” which if you think about it involves mutually contradictory concepts. A current-source amplifier has a very high output impedance, meaning that the frequency response
