The Z Series Range

The heart of any CD player is the DAC (Digital to Analogue Converter). The Z210 uses a high performance Cirrus Logic 24bit 192kHz fifth order delta-sigma DAC. It actually contains four separate DACs – with push-pull outputs for each of the stereo channels. Each output feeds a differential-input low-pass analogue filter using a high-speed low-distortion FET input op-amp, close-tolerance metal film resistors and precision polypropylene film/foil capacitors. This arrangement suppresses ground-related noise from the DAC and delivers the cleanest possible audio output. To ensure no degradation of this pristine audio signal there is no coupling capacitor in the signal path to the output jacks. Instead a second high-speed low-distortion FET input op-amp is used to provide a “DC servo” to maintain no DC on the line outputs.

A major factor in the sound quality of any digital product – particularly CD players – is jitter causing distortion of the audio. The Z210 minimises jitter by using a precise low-jitter master clock mounted close to the DAC. The clock is powered from its own ultra-low noise isolated power supply so that it is unaffected by any of the other circuitry in the Z210. The same clock is used to synchronise the CD mechanism so that it can send low-jitter data to the DAC. Isolation of power supply noise is important throughout the CD player. A total of 8 separate power supply regulators are used in the Z210, each optimised for its own task.

A high quality tuner must exhibit a balance of performance in a number of key areas. Over-emphasis of one parameter, e.g. high sensitivity, can result in a degradation of a tuner’s real-world performance. The Z230 has been designed with careful attention to all the key parameters of sensitivity, noise, selectivity, distortion and interference rejection. The result is a tuner which will bring the best radio broadcasts to life in your home.

The Z230 uses a high quality 4-gang FM tuner front-end. The local oscillator is tuned by a crystal-locked frequency synthesizer which ensures precise and stable tuning under all conditions. The low-distortion FM demodulator feeds the audio signal to an advanced PLL stereo decoder which features adjacent channel interference rejection. This produces clean stereo with excellent imaging – and rejects interference from adjacent channels. The FM tuner is accompanied by a high quality AM tuner.

The chosen tuner’s audio signal is fed to a discrete Class A push-pull output buffer amplifier, which provides a low output impedance and high drive capability so that the Z230 can drive any combination of interconnect cable and amplifier input.

A total of 5 separate power supply regulators are used in the Z230, each optimised for its individual task.

In order to achieve the ultimate performance at such a competitive price the Z240 has been meticulously engineered. The selected line input signal is sent directly to a high quality motorized volume control and thence directly to the input of a high gain power amplifier via just a single low-loss film capacitor. This configuration ensures the shortest possible signal path and minimum degradation of the audio signal, but it needs an excellent power amplifier.

The Z240’s power amplifier, with its DC5 (*) circuit configuration easily meets this need. From its wideband complementary push-pull input stage through to the triple emitter follower output stage every detail of the power amplifier is optimally designed for its task. The power supply and power amplifier are of equal importance. The Z240 power supply uses a massive custom-designed toroidal power transformer (weighing 2.2kg), discrete “soft recovery” ultra-fast rectifier diodes and high-value reservoir capacitors (totalling 20,000µF) enabling it to deliver, via the amplifier, whatever current the loudspeaker load demands. Finally, to make absolutely certain that the sensitive parts of the amplifier are not disturbed by noise or distortion from the power supplies, each channel of the power amplifier, apart from the high current output stages, is fed from its own high-isolation regulated power supply.

The loudspeaker connectors are substantial gold-plated solid metal 5-way binding posts, wired directly to the power amplifier outputs via top quality loudspeaker cable (QED ‘Silver Anniversary XT’).

A “Bi-Amp” output is provided for driving a suitable power amplifier to build a bi-amplified system. The Bi-Amp output can also be used to drive a powered subwoofer.

The Z240 includes a low-noise phono preamplifier using close tolerance metal film resistors and polypropylene film/foil capacitors to provide precise and stable RIAA equalisation. Its sensitivity and headroom make it suitable for a wide range of Moving Magnet and “High-Output” Moving Coil cartridges. A rear panel push switch allows the phono preamp to be switched out of circuit if desired, providing a sixth line input.

*  Double Complementary Cross-Coupled Cascoded Current feedback