925 Integrated amplifier 135W

At the heart of the 925 you will find many of Trilogy’s award winning technologies. The balanced input stage uses the 6H6П super tube to provide pure triode Class A, zero feedback voltage gain of exceptional linearity. The output stage has our unique zero feedback MOSFET and bipolar topology in a bridge configuration for 135w of power with impressive control.

The amplifier is fully symmetrical inside and out. Unlike many other amplifiers claiming to be balanced, the signal positive and signal negative are never tied to ground in the 925. A powerful and fully customisable input management system also interfaces with the outside world and other Trilogy products via TASlink.

As with all Trilogy designs a short, pure signal path is central to the 925's design philosophy. The internal architecture is fully balanced, from the relay input switching and volume control, right through to the valve input stage and bridge power amplifier. The signal is never converted internally to single ended to maintain maximum signal integrity.

Three fully balanced and three single ended rear panel inputs are switched via instrumentation grade ruthenium plated relays within millimetres of the rear panel connectors. A separately selectable auxiliary loop is provided. In addition, a 3.5mm jack on the front panel allows portable sources to be connected quickly and easily. A carefully selected audio grade digitally controlled potentiometer provides volume control and balance in 1.0dB steps.

Each channel has two directly coupled dual triode 6H6П valves that form the input stage. This Russian military tube has outstanding performance, achieving both high transconductance and very high linearity for peerless audio performance. They provide all the voltage gain for the amplifier in a single stage. A carefully optimised servo ensures the valves operate perfectly symmetrically.

Our hallmark discreet HT shunt regulators provide the valves with pure regulated DC. The valves drive only the input to the output stage and need to source little current. As they operate best as pure voltage devices, the 925 can deliver all the vibrancy and detail that valves can offer, without compromising operating life or reliability.

The 925’s unconventional output stage uses a small FET with the addition of a high current bipolar device. The fast, agile FET only operates within the critical first watt region. An amplifier will typically spend most of its time in this power band at normal listening levels. The bipolar transistors then seamlessly contribute high current when music conditions demand.  This topology helps to preserve the vital micro detail that brings music alive, whilst simultaneously being able to source high currents for moving the loudspeaker instantaneously when needed.

The output stages are arranged in a bridge configuration. Each channel has two power amplifiers that simultaneously pull and push power to the loudspeaker. The principal benefit is that large currents are kept out of the system ground, keeping the amplifier stable and composed during large scale musical events. The output devices are configured to operate in a high bias state, giving a generous envelope of Class A operation. The relatively high dissipation, in conjunction with the high thermal inertia of the heatsink, keeps the devices in their optimum operating condition and improves sound quality.

Conventional extruded heatsinks display strong resonant signatures and have been rejected in favour of custom, machined solid billets of aluminum. Each weighs in excess of 5kg. Their high mass and irregular form provide outstanding mechanical and thermal stability for the output devices. This bringing substantial sonic benefits as semiconductors are surprisingly sensitive to vibration and temperature changes.

Feeding the 925 is a substantial faraday screened power supply transformer with separate windings and rectifiers for either channel. Custom Trilogy reservoir capacitors smooth each channel of the output stage DC and valve HT supplies. The valve heaters and logic supplies each have their own power transformers to keep internal electrical noise to an absolute minimum.

The power transformers are mounted on a thick machined plate of K-material. This high metal, low resin content composite has excellent mechanical properties and superior self damping to metal. It provides additional damping and stiffening of the non magnetic chassis too. K-material is also used for the feet, providing the optimum interface between the 925 and the equipment support.

The amplifier has a sophisticated monitoring system to maintain safe operation at all times. Temperatures and critical voltages report to a dedicated microcontroller. An intensive R&D project produced specially formulated algorithms to monitor output current against time and frequency with great accuracy. This enables reliable discrimination between DC faults or demanding musical conditions, providing excellent protection but avoiding unwanted shutdowns.

The perfectly weighted control knob and two machined stainless steel push buttons access the control menu hierarchy. All high level functions such as volume, balance and input select are intuitively accessible.

Remote control is via infra red handset, the machined from solid PRC is a perfect compliment. The dot matrix LED panel display is designed to be fully legible across a room. Brightness can be configured to track the ambient light level or is manually adjustable.

Each input can be left as factory preset or given a custom label of your choice which is displayed each time the input is selected. A gain trim can also be assigned to each input to equalise volume levels between sources.

Balance control is available in 1dB steps. Default start up volume and balance settings can be saved via the menu system.

Phase inversion can be easily accessed from the remote handset for comparison whilst listening or set as a default within the menu.

A real time clock provides multi event, seven day system switch on, switch off with external communication via our proprietry communication interface: TAS link. This allows you to fully warm up your system before coming home to listen. A sleep function provides power down after a selected period of your choice.

Other Trilogy products can be "Named" via TAS link for status monitoring and remote control. Any intelligent features will then be available for use or monitoring via the 925.

A wide range of user programmable defaults are possible, including setting the home page display and PIN protected control menu locking.