Trilogy 990 Stereo Power Amplifier

The 990 is a marriage between two technologies, each element carefully arranged to play only to its strengths. It marks a true turning point in power amplifier design.

 
Combining the effortless musicality of thermionic valves with the capable power delivery of solid state, it follows every musical twist and turn with ease and subtlety. High levels and demanding loudspeakers are effortless.

The 990 power amplifier liberates music that will touch you, both supremely poised and beautifully coherent.

Technical Details:

Single ended and balanced input connectors connect to a symmetrical arrangement of triodes.  Power supplies are fully discrete shunt regulated. There are separate transformers for HT and filament supplies. This no compromise input stage supplies all the voltage gain to the solid state output stage. Freed of the demands of sourcing current, this is what valves do best.

The power supply for the power amplifier output stage is the hungriest in any system. The 990 takes the unusual step of using a choke input power supply. This enables the power reservoir to draw current from the mains supply in a much more linear fashion than a regular supply. It also generates less electrical noise, resulting in a quiet, smooth and stable platform from which the output stage can deliver.

The output stage is arranged in a bridge configuration. The arrangement is effectively two amplifiers: one pushing and one pulling current through the speaker. This removes the large currents involved in driving the loudspeaker from the system's critical ground reference; keeping the amplifier supremely composed under heavy drive.

The first watt delivered is undoubtedly the most important. It is the most visited part of an amplifier's range at normal listening levels. By using small and agile output FETs, performance at this critical level is optimised. When demand rises, higher power bipolar devices seamlessly contribute additional current to deliver impressive power when needed.

Throughout the amplifier, great care has been taken with its physical construction. The heatsink is milled from a solid billet of aluminium. It forms a spine through the centre of the case. This provides a substantial thermal mass, and allows the output devices to operate at a constant temperature, free from the severe mechanical resonances of conventional heatsinks. It also effectively screens the power supply magnetics from the sensitive audio circuitry.

The finest quality parts are fitted throughout the signal path with silver gold loaded solder. Selected foil and main reservoir capacitors are from Mundorf and precision resistors are from Welwyn. Wiring is PTFE insulated silver plated copper. Power input is by rhodium plated Oyaide IEC. Mundorf solid copper binding posts are used to eliminate the audible mechanical resonance of more common brass.

TASLink connectivity provides functions such as remote switch on, remote status monitoring through the system controller, and security bonding. QuietBus technology ensures the integral housekeeping microcontroller's high speed lines are completely inactive during normal operation. This keeps the audio circuits completely free from digital processing interference whilst protecting the amplifier at all times.