Trilogy 993 Stereo Power Amplifier

The 993 is Trilogy's hybrid stereo power amplifier, in the range since 2016 and designed to complement the 903 preamplifier. All of its voltage gain comes from a 6H6П super tube, a Russian military triode chosen for its high transconductance and low mu. The valve operates in Class A in a grounded grid configuration with zero negative feedback. Because of the output stage's topology the valve sees only a small MOSFET as its load, which lets it deliver the flow and micro detail valves are good at.

The 993 takes the unusual step of specifying a choke input power supply for the output stage. The choke is nearly as large as the power transformer. The high current spikes conventional supplies pull from the mains are avoided; the choke allows a much more linear current draw, keeping dynamic noise under drive much lower. Premium reservoir capacitors and soft recovery diodes complete it.

The first watt an amplifier delivers is where most tonal and spatial cues sit at normal listening levels, so the output stage uses a small, agile FET to serve that region. When current demand rises, higher power bipolar devices supply the additional current, up to 125 watts into 8 ohms. There is zero global negative feedback, but high bias keeps output impedance low. TASlink adds remote switch-on, status monitoring and security bonding.

• Rated power: 125 watts per channel into 8 ohms; 200 watts per channel into 4 ohms
• Recommended load impedance: 4–16 ohms
• Topology: hybrid; 6H6П grounded grid Class A voltage gain; small FET plus higher power bipolar output stage; zero global negative feedback
• Power supply: choke input for the output stage; premium reservoir capacitors, soft recovery diodes; discrete shunt regulated driver supplies
• Inputs: 1 pair RCA phono sockets; 400 kohms; 2.0 V RMS for rated output
• Frequency response: 5 Hz – 30 kHz +/- 0.5 dB
• Distortion: less than 1% A weighted at rated output
• Phase: phase correct (non inverting)
• Power consumption: under 1 W standby / 50 W idle / 700 W maximum
• Dimensions / weight: 465 x 346 x 106 mm (465 x 378 x 106 mm including connectors) / 19 kg