Musical Fidelity Nu-Vista 800.2 Integrated Amplifier

The Musical Fidelity Nu-Vista 800.2 Integrated Amplifier is a major upgrade over the original and well-respected 800. It has a new modern look along with a new display and revised power supply. Unusually, this amplifier is a hybrid device. It uses four Nuvistor sub-miniature valves.

These have superior noise performance. Moreover, the Class A/B design is supplemented by a locally decoupled output stage that boosts performance. The output power is 330 Watts per channel into 8 ohms. Four analogue inputs are provided along with two balanced XLR inputs.

Additionally, there are outputs for two sets of speakers. The sound is smooth with enormous transients and a relaxing and involving presentation.

A locally decoupled output stage for improved transient response

The output stage of the Musical Fidelity Nu-Vista 800.2 Integrated Amplifier features locally placed decoupling capacitors. The capacitors are mounted close to the output transistors and provide a kind of supercharging effect.

The PCB has a similar appearance to A “V10” engine. The capacitors provide a much shorter lower impedance path for the supply current. The result is a faster transient response and improved smoothing.

The new look

The Musical Fidelity Nu-Vista 800.2 Integrated Amplifier has a new look and several upgrades. The front plate is new as is the display that can double up as a power meter The power supply and on/off control circuits have also been upgraded.

There is also added remote capability. Lastly, the power transformer has been redesigned to have a lower flux. This makes it less sensitive to any DC noise. The heavy casing acts as a Faraday cage that blocks any external interference.

Good connectivity

The front panel is kept simple, with just the volume and source knobs along with the display. However, there are plenty of inputs. Two sets of speaker outputs are provided. Inputs include four RCA inputs as well as two balanced XLR inputs.

There is also a line out and pre-out that can be connected to a subwoofer. A separate phono preamp stage would be needed for turntables. Nowadays most systems would have a streamer for the front end.

What is Class A/B?

Class A amplifiers normally have one output device such as a valve. The device operates over the entire audio cycle so there is no crossover distortion. However, they are very inefficient and need massive power supplies.

Class B uses two or more output devices to provide the output. The Musical Fidelity Nu-Vista 800.2 Integrated Amplifier uses ten output transistors per channel. These are used in pairs to get the required power output. The disadvantage of class B is the possibility of crossover distortion.

This is caused by the switching of the output transistors between each half cycle of the audio signal. However careful biasing can reduce this to very low levels. Class A/B is a combination of Class A and Class B. At lower power levels, where distortion would be the most noticeable, class A is used. At higher powers, Class B is gradually switched in.