Trilogy 975 Phono Stage

The 975 is Trilogy's reference phono stage, a two box design with an external power supply. The main unit is housed in a machined billet weighing more than 5 kg, providing physical as well as electrical isolation for each circuit element. Each channel has an independently housed and isolated gain stage.

The topology is fully discrete and single ended, reaching high bandwidth and low distortion through active current sources and cascode gain blocks. Precision matched input transistor pairs keep noise very low. The common series regulator, usually chosen for simplicity, has been rejected in favour of discrete shunt regulators biased heavily into Class A for headroom; a shunt regulator can sink as well as source current, an advantage under the dynamic conditions music creates.

DC for the regulators comes from the remote power supply, whose enclosure can be positioned to keep magnetic fields away from the active circuitry. Its custom mains transformer is a low current density design with a copper Faraday screen, feeding reservoir capacitors through a bespoke inductor to form a true choke input supply. Gain for moving magnet or moving coil and cartridge loading are set by configuration switches underneath.

• Type: two box MM/MC phono stage with external power supply
• Topology: fully discrete single ended; active current sources and cascode gain blocks; precision matched input transistor pairs; discrete shunt regulators biased into Class A
• Power supply: external; low current density mains transformer with copper Faraday screen; bespoke inductor forming a true choke input supply
• Gain: user adjustable
• Input impedance: 47 kohms, user adjustable
• Input capacitance: user adjustable
• Adjustment: configuration switches underneath
• Inputs / outputs: 1 pair RCA in; 1 pair RCA out; output impedance 150 ohms
• Frequency response (to RIAA curve): 20 Hz – 20 kHz +/- 0.25 dB
• Phase: phase correct (non inverting)
• Power consumption: 15 W
• Dimensions / weight: main unit 270 x 312 x 56 mm / 6.8 kg; PSU 270 x 312 x 74 mm / 5.7 kg