Simaudio Moon P-5 preamplifier & W-5 power amplifier part 2
Fig.8 Moon W-5, THD+noise vs frequency at (from top to bottom at 10kHz): 4W into 2 ohms, balanced; 4W into 2 ohms, unbalanced; 2W into 4 ohms, balanced; 2W into 4 ohms, unbalanced; 1W into 8 ohms, balanced; 2.83V into simulated loudspeaker load; and 1W into 8 ohms, unbalanced.
Fig.9 Moon W-5, 1kHz waveform at 2W into 4 ohms (top), distortion and noise waveform with fundamental notched out (bottom, not to scale).
The spectrum of the W-5's output while it reproduces a 50Hz input at 200W into a 4 ohm load is shown in fig.10. The distortion products are all extremely low—the maximum value is -72.9dB, or just under 0.025%, with now the third harmonic a little higher in level than the second.
Fig.10 Moon W-5, spectrum of 50Hz sinewave, DC-1kHz, at 200W into 4 ohms (linear frequency scale).