Linn Classik CD receiver Measurements: Amplifier Section part 2
Fig.12 Linn Classik, 1kHz waveform at 73W into 4 ohms (top), distortion and noise waveform with fundamental notched out (bottom, not to scale).
Fig.13 Linn Classik, 1kHz waveform at 56.5W into 8 ohms (top), distortion and noise waveform with fundamental notched out (bottom, not to scale).
Fig.14 shows the spectrum of the Linn's output while operating at around 2/3 the clipping power into 4 ohms. Again, the second harmonic is the highest in level, though the third through eighth harmonics can be seen between -90dB and -100dB. Note the spectral lines at 120Hz and 240Hz, which again suggest a power supply that is being asked to work hard. Driven just below the clipping point with a mix of 19kHz and 20kHz tones, the Classik's output spectrum (not shown) showed a 1kHz difference tone at a lowish -75dB, as well as second-order products at 18kHz and 21kHz at the same level.
Fig.14 Linn Classik, spectrum of 50Hz sinewave, DC-1kHz, at 57W into 4 ohms (linear frequency scale).
Conservatively specified at 75Wpc into 4 ohms (15.75dBW), the Linn proved capable of delivering more continuous power, even with both channels driven (fig.15). Into 4 ohms, 84W were available at the usual 1% THD+N clip point (16.25dBW), with 50W measured into 8 ohms (17dBW). Only into 2 ohms under continuous drive did the Classik stumble, with just 23W available (7.6dBW).
Fig.15 Linn Classik, distortion (%) vs continuous output power into (from bottom to top at 2kHz): 8 ohms, 4 ohms, and 2 ohms (both channels driven).
With a low-duty-cycle 1kHz toneburst, which more closely resembles a real music signal, the Linn Classik belied its tiny size by pumping out 80.4W into 8 ohms (fig.16, black trace), 131.8W into 4 ohms (red), 164.2W into 2 ohms (blue), and falling back into 1 ohm with only 47.1W available (green). The 2 ohm delivery is equivalent to an RMS output current of 9.05A, which is very respectable.
Fig.16 Linn Classik, distortion (%) vs 1kHz burst output power into 8 ohms (black trace), 4 ohms (red), 2 ohms (blue), and 1 ohm (green).
The Linn Classik is by far the most powerful "clock radio" I have ever encountered!—John Atkinson