Yamaha @PET RP-U100 personal receiver Measurements part 4
Fig.10 Yamaha RP-U100, channel separation vs frequency, analog input (10dB/vertical div., R-L dashed).
Plotting the RP-U100's small-signal distortion percentage against frequency gave a result dominated by the highish levels of noise present in the output, and so is not shown. Fig.11 reveals that what distortion is present is mainly second-harmonic in nature, and is dominated by noise. (Thirty-two readings were averaged to drop the noise below the level of the actual distortion residual in this graph.) This distortion profile is confirmed by fig.12, which shows the spectra of the Yamaha's output while it reproduced a 50Hz tone at 24W into 8 ohms, while being driven from its analog inputs. This is quite respectable behavior, as is its performance on the punishing high-level, high-frequency intermodulation test (fig.13).
Fig.11 Yamaha RP-U100, 1kHz waveform at 2W into 4 ohms (top), distortion and noise waveform with fundamental notched out (bottom, not to scale).
Fig.12 Yamaha RP-U100, spectrum of 50Hz sinewave, DC-1kHz, at 24W into 8 ohms (linear frequency scale).
Fig.13 Yamaha RP-U100, HF intermodulation spectrum, DC-24kHz, 19+20kHz at 128W into 4 ohms (linear frequency scale).