MEASUREMENTS

For logistical reasons, I measured a different sample of the Mark Levinson No.5805 integrated amplifier (serial number 0951) than the one auditioned by Jim Austin (serial number 0906). There were some setup issues with this early sample—the firmware was version 1.36—but these were generally solved by rebooting. I measured the Mark Levinson No.5805 with my Audio Precision SYS2722 system (see the January 2008 “As We See It”¹), and before performing any testing, I ran the amplifier for an hour at one-third power into 8 ohms. (Thermally, this is the most stressful condition for a design with a class-AB output stage.) At the end of this time, the No.5805’s top panel was quite warm, at 120.5°F (49.2°), and the internal heatsinks measured 133.7°F (56.5°C). Commendably, this amplifier has enough heatsink capacity for sustained operation at high powers.

Looking first at the line-level analog inputs: With the volume control at its maximum setting of “80,” the voltage gain at 1kHz into 8 ohms measured 32.5dB from the speaker terminals for both balanced and unbalanced input signals and 8dB from both the preamplifier and headphone outputs, which is slightly but inconsequentially lower than the specified 8.5dB., were noninverting) from all the outputs. The unbalanced input impedance was 16k ohms at low and middle frequencies, dropping slightly to 13.5k ohms at 20kHz, while the balanced input impedance was 20k ohms across the audioband. The preamplifier output had a low output impedance of 52 ohms, this close to the specified 55 ohms, and the headphone output was a very low 2.8 ohms. Both values were consistent from 20Hz to 20kHz.