Isis Valve

The Isis Valve is a CD player in which the analogue stage is built around valves. A Wolfson WM8741 digital-to-analogue converter drives a differential amplifier using two 5814A (ECC82/12AU7) triodes. A passive second-order Butterworth LC filter follows, and two ECC88 (6DJ8/6922) triodes buffer the signal into a balancing transformer. Typical total harmonic distortion is 0.06%, mostly even order.

The digital section is shared with the solid-state Isis. It has a fully digital servo, a custom phase lock loop, extra error correction and a graded, matched transport mechanism. The player analyses each disc as it initialises, so it can often read discs with marks or scratches. The digital and analogue sections each have their own 50 VA mains transformer for galvanic isolation, and the supplies use Rega K-Power smoothing capacitors.

A USB input lets a laptop or PC play through the internal DAC. It is isolated from the main circuitry. The output is an isolated balanced one with a transformer. The case is custom designed and the player comes with a CNC reference remote control.