Zeus Preamplifier - Mosfet

Zeus Stereo Mosfet Preamplifier & Power Supply - Concept CAD Sketch for new Prototype.

This concept CAD sketch is for my new version preamp prototype. It is designed to incorporate my 24 way reed switch attenuator and newly designed radial reed switch XLR input selector. The latter stereo pair are mounted side by side and connected by toothed timing belts, the overall assembly being accommodated in the rear section of the preamp.

24 way reed switch attenuator PCB (with operating magnet in centre).

The 24 way reed attenuator switch is built up in sections and allows for either discreet wiring to a TVC or on the reverse has surface mount resistor sites for conventional or ladder attenuators. Each section has a radial arm mounted on the central shaft which contains a magnet that operates the reed elements.

Radial reed switch XLR input selector - PCB drawing.

An 8 way reed input selector switch plus tape loop using the same switching principle as the attenuator.

All three pins on the XLR connectors are switched, with an individual option to ground or leave open circuit for Pin 1. This arrangement reduces to an absolute minimum the internal signal paths of any source that is not specifically selected.

The individual XLR reed groups are arranged to ensure that the XLR Pin 1 ground is always made before the audio path is made and is always held until after the audio path is broken.

In addition as the magnet arm is moved from channel to channel it passes over a mute reed.