McIntosh Labs MC2000 power amplifier Measurements part 2
Fig.4 McIntosh MC2000, balanced, THD+noise (%) vs frequency at (from top to bottom at 4kHz): 2.83V into simulated loudspeaker load; 4W into 2 ohms; 2W into 4 ohms; and 1W into 8 ohms.
Fig.5 McIntosh MC2000, THD+noise (%) vs frequency at (from top to bottom at 6kHz): 2W into 4 ohms, unbalanced; 1W into 8 ohms, unbalanced; 1W into 8 ohms, balanced; and 2W into 4 ohms, balanced.
Fig.6 McIntosh MC2000, 1kHz waveform at 2W into 4 ohms (top), distortion and noise waveform with fundamental notched out (bottom, not to scale).
A spectrum of the MC2000's output while it drives a 50Hz tone at 87W into 4 ohms (two-thirds rated power) is shown in fig.7. This is a fairly unimpressive result, though the highest-level component, the second harmonic at 100Hz, is still a relatively low 0.25% (-52.7dB). The amplifier is more linear at higher frequencies. Fig.8 shows the IM distortion resulting from a combined 19+20kHz signal at 83.5W into 4 ohms. Again, the maximum distortion is approximately 0.13% (-58dB) at 1kHz. At the same power into 8 ohms, the IM distortion is only marginally lower (not shown).
Fig.7 McIntosh MC2000, spectrum of 50Hz sinewave, DC-1kHz, at 87W into 4 ohms, 4 ohm tap (linear frequency scale).
Fig.8 McIntosh MC2000, HF intermodulation spectrum, DC-22kHz, 19+20kHz at 83.5W into 4 ohms, 4 ohm tap (linear frequency scale).