Phono Preamp Reviews

Michael Fremer was impressed by the sound quality of Channel D's Lino C 3.3 phono preamplifier when he reviewed it in his June 2022 Analog Corner column. Editor Jim Austin suggested I examine its performance on the test bench.

The Lino C 3.3 ($3799, basic version1) resembles its predecessor, the Lino C 2.0, which Mikey reviewed in June 2019. The 3.3 is powered by a rechargeable battery and features a direct-coupled, wide-bandwidth, balanced, transimpedance circuit, which generates an output voltage that's proportional to the current generated by a moving coil cartridge. The fully loaded review sample ($7082) was supplied with a remote control and fitted with the optional moving magnet input, voltage-mode moving coil input, ultrahigh-precision RIAA certification, and front-panel LED indicators.

I measured all three of the Lino C 3.3's inputs with my Audio Precision SYS2722 system, using a two-channel, balanced attenuator module sent to me by Channel D's Rob Robinson for the transimpedance input. I set this module to reduce the signal level by 66dB with its source impedance set to 6 ohms, this typical of a moving coil cartridge. I operated the preamp on battery power for the testing, using the "Off the Grid" adapter so it would function with the battery charger unplugged. I left the cartridge damping button on the bottom panel set to Low and the adjacent DIP switches set to a gain of "0." (The other options are +6dB and +12dB.)

The moving magnet input has four additional gain settings. I measured gains at 1kHz of 44.1dB, 48.2dB, 50.8dB, and 52.9dB. The voltage-mode moving coil input offered 62.6dB of gain; the current-mode moving coil input 62.9dB. The bottom-panel DIP switches increased the MC gain at 1kHz to 68.9dB and 74.75dB. I left the moving coil gain at 62.9dB for the testing of this input. The balanced output impedance was a very low 48 ohms from 20Hz to 20kHz. The single-ended output impedance was even lower, at 10 ohms, again across the audioband.

All three inputs preserved absolute polarity with the polarity button set to Direct. Out of the box, the voltage-mode MC input's impedance measured 93 ohms from 20Hz to 20kHz. Setting all this input's loading choices to Off with the rear-panel DIP switches resulted in the specified input impedance of 2000 ohms. With the parallel input capacitance set to 100pF, the moving magnet input offered an impedance of 45k ohms at 20Hz and 1kHz, 39k ohms at 20kHz.

The Lino C 2.0 featured superbly accurate RIAA equalization, the best I had measured at that time. The Lino C 3.3's RIAA equalization (fig.1) was even better, the measured error less than ±0.015dB! The channel matching was also superb. The green and gray traces show the response with the switchable high-pass Rumble filter. The output rolls off below 30Hz and is down by 9dB at 11.5Hz. Channel separation (not shown) was excellent at close to 90dB in both directions.

The current-mode input's unweighted, wideband S/N ratio, measured with the input shunted with the 6 ohm resistor, was a good 62.3dB (average of both channels), ref. 1kHz at 500µV. Restricting the measurement bandwidth to 22Hz–22kHz increased the ratio to 64.5dB, while switching an A-weighting filter into circuit increased it further, to 73dB. Spectral analysis of the Lino's low-frequency noisefloor with the transimpedance input shunted by a 6 ohm resistor (fig.2) revealed that random noise components were very low in level and, as the preamp was running on battery power, there were no mains-frequency components present. The voltage-mode moving coil input's S/N ratios were very similar and with its lower gain, the moving magnet input's S/N ratios were even higher, at 71dB, wideband, unweighted; 74dB, 22Hz–22kHz, unweighted; and 80.1dB, A-weighted. The ratios were taken with the gain at the lowest setting. Each increase in gain reduced the S/N ratios by 2–3dB, but even with the highest moving magnet gain, this is still a very quiet preamp.

With its gain set to "0dB," the current-mode MC input's overload margin (ref. 1kHz at 500µV) was a very good 16dB at 20Hz and 1kHz. (I couldn't measure the margin at 20kHz because, even with the attenuator module, this meant exceeding the Audio Precision's maximum output of 15V.) The voltage-mode MC input's overload margin was even better, at 19dB at 20Hz and 1kHz, 15dB at 20kHz. The moving magnet input's overload margin was 15dB at 20Hz and 1kHz, 9.4dB at 20kHz. I calculate these margins by comparing the input level that produces a measured THD+noise of 1% with the nominal cartridge output level. All three inputs clipped, ie, reached 1% THD+N, when the balanced output voltage was 4.3V.

Like its predecessor, the Lino C 3.3 offered extraordinarily low distortion before the onset of clipping. Fig.3 shows the spectrum of the Lino's output with the current-mode MC input fed 1kHz at 2mV, 4dB below the overload level. The only distortion harmonic that can be seen above the noisefloor is the third, at just –110dB (0.0003%).

The Lino C 3.3 also had extremely low levels of intermodulation distortion (fig.4). This graph was taken with the current-mode MC input. The MM input had slightly higher levels of intermodulation products (fig.5), but these are still extremely low in level.

With its superbly accurate RIAA equalization, very low noise, and vanishingly low distortion, Channel D's Lino C 3.3 is the best-measuring phono preamplifier I have encountered. Wow!—John Atkinson