Valve circuit by Tim de Paravicini

The QC-24P is Quad’s dedicated valve phono stage, designed by Tim de Paravicini and built around four 6111 sub-miniature twin triodes — small, rugged tubes originally developed for military and avionics use, chosen here for low microphony and consistent gain. RIAA/IEC equalisation is handled within the valve circuit, and the unit holds total harmonic distortion below 0.08% (A-weighted) with frequency response of 20 Hz–20 kHz ±0.5 dB. Hum and noise sit better than 60 dB below output in the MM position, which is the relevant figure for how black the silences between notes feel on quiet passages.

MM and MC support with three gain settings

A rear-panel toggle selects between MM and MC inputs, with input impedance of 47 kΩ for moving magnet and 10 Ω for moving coil — the very low MC loading reflects a transformer-coupled input, which is the approach de Paravicini favoured for keeping noise out of the lowest-level signals. Three sensitivity settings (high, medium, low) accommodate cartridges from 1.3 mV down to 5.2 mV for MM and 130 µV to 520 µV for MC, so the unit can be matched to anything from a hot MM to a low-output MC without forcing the volume control to extremes downstream.

Outputs, scale, and system fit

Two outputs are provided: a fixed line-level RCA pair for feeding a preamplifier, and a variable output that can drive a power amplifier directly if the phono stage is the only source in the system. Build follows Quad’s preamplifier philosophy — relay input switching and carefully specified transformers in service of Peter Walker’s “straight wire with gain” ideal. The chassis measures 90 × 220 × 300 mm with a 15 VA maximum draw, sized to sit alongside the rest of Quad’s Classic series rather than dominate a rack.