Inside the Valve Amplifier systems

The circuit used in the Quad II-forty power amplifiers is virtually identical to that used in the original Quad II. What has changed dramatically, is the standard of components used. We have scoured the globe for the very finest vacuum tubes, balanced and matched perfectly. The transformer is, in itself, a work of art. Everything is hard-wired and hand crafted with incredible precision.

The II-forty uses KT-88s, rather than the original KT66s in push-pull orientation for the output stage (for more power). The input valves are 6SH7s(military spec.) and the rectifier is a 5UG4. The II-classic is virtually identical to the original 1950s design.

The pre-amplifier supplied with the system is a completely new design. It uses a very special high-end military 6111 twin triode, which is so reliable and accurate, it has been hard-wired into the circuit.

All inputs are line-level. It uses relay signal switching to preserve signal integrity. This is one of the most neutral and transparent pre-amplifiers available today. It contains no tone controls, has no remote control. Quite simply, it adds nothing and takes nothing away from the signal.