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Proteus is a completely new integrated valve amplifier built to exacting standards.
Each amplifier is totally hand built using the best quality components and materials.
The main chassis, under-tray and grill are constructed entirely in high grade laser machined polished stainless steel whilst a separate and electronically isolated aluminum sub-chassis serves to contain all the electronic components and wiring. Using solid silver "military specification" feed through insulators and silver stranded cable, the various components and associated wiring is carried on both sides of the sub-chassis to ensure minimum signal interference, maximum cooling and ease of construction and service.
The power supply will deliver 250 Watts of HT at 560 volts to the output stages whilst a regulated secondary supply provides stabilized low noise power to the pre amplifier and phono stages. A fully regulated low voltage supply provides energy to the filaments of the pre amplifier and phono stage valves to ensure stability.
The power output stages are crucially based around the output transformer. These transformers are hand made to the original Williamson* specification and was chosen for its ability to handle huge changes in signal amplitude without upsetting the integrity of the system and to provide a stable and wide frequency range within its power rating of 20 Watts RMS.
Driving each output transformer is a pair of KT88 Tetrode valves, connected in Triode class A mode and with cathode bias to provide very low distortion and a wide frequency response with total stability and clarity. These valves are driven by a simple dc coupled all Triode push-pull phase discriminator with just enough negative feedback to ensure minimum distortion with maximum stability. The amplifier is unconditionally stable driving speaker loads of between 4 and 16 ohms without alteration.
Via a Alps, 'Blue Velvet', volume control, the output stage is driven by a twin Triode dc coupled low noise, wide band pre amplifier. This tailored pre amplifier has been designed to provide a 6Db gain advantage with a high input impedance to allow for input mismatches, this helps ensure the best result from any signal source regardless of compatibility. The amplifier sources are selected by individual relays with those inputs not in use taken to earth to prevent breakthrough from other signals.
The phono stages are unique in that they use an earthed grid Triode front end feeding a Triode constant impedance loaded output, this is directly coupled to a double Triode dc coupled second stage with no direct negative feedback. The result is a very low noise phono stage that is completely free from any microphony effects. The frequency response (equalization) is easily altered by means of a small control, accessible on top of the main chassis. A high performance matching transformer is available for those who wish to use a moving coil cartridge. Please see our catalogue for additional items and specifications you might require during ordering.
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