Musical Fidelity Nu-Vista PAS - Overview

The Musical Fidelity Nu-Vista PAS is based on our excellent circuit from the Musical Fidelity Nu-Vista 800; we decided to fully invest in the "fully balanced" concept for the Nu-Vista line.

The Nu-Vista PAS features the proven and tested Nu-Vista stage, with 6S51N nuvistors in a discrete Class A amplifier buffer.

Technical Details

This is followed by a balanced configuration circuit and a high-power, low-distortion output amplification stage. The power stage has 5 pairs of thermally compensated high-power output devices for reliable and stable operation.

Based on the Titan 1000W stage, it has separate capacitors for the main supply and one for each output device, significantly reducing output impedance and improving dynamics. Inductors were added to further enhance supply ripple and peak current reduction. The bias is set for over 5W of initial Class A operation; after that, the stage enters Class B operation at a point where the now much smaller discontinuity is easier to handle than the “standard” crossover distortion.

Musical Fidelity Nu-Vista PAS Power Supply

The Nu-Vista PAS comes with its own dedicated external power supply.

To achieve better noise performance, we removed the AC power supply from the main module and placed it in a separate matching case. In this case, we utilized the extra space to configure integrated AC and output filters. This significantly reduces electrical artifacts reaching the sensitive audio circuits. The power supply features ON/Standby LEDs and is controlled by the front panel of the main unit. If complete mains isolation is required, the power supply also has a rear mechanical switch for full shutdown.

Heroic Build

The mechanical construction of the Nu-Vista PAS is unyieldingly rigid and solid, following the typical Musical Fidelity tradition. The front panel and side panels are machined from extruded aluminum profiles and are extremely robust.

The separate Musical Fidelity Nu-Vista PAS PSU houses all transformers, which, by nature, generate mechanical vibrations and radiate harmful electromagnetic fields. Here, they are as far away as possible from the amplifier's critical circuits. This contributes significantly to an excellent signal-to-noise ratio. Essentially, we achieve immunity from environmental vibration effects. The same can be said about electromagnetic immunity. The massive aluminum case acts as a Faraday cage. It protects the internal components from external electromagnetic fields and, similarly, protects the rest of your hi-fi equipment from electromagnetic fields generated by the Nu-Vista PAS.

The Legendary Musical Fidelity Nu-Vista Stage

Never before in hi-fi history have Nuvistor tubes been combined with cutting-edge fully balanced and discrete technology, as well as sophisticated modern design techniques. The technical performance of the Nu-Vista PAS & Nu-Vista PAS PSU is impressive. They measure like a dream but, more importantly, sound incredible. Silky smoothness with huge transients and a sense of effortlessness that is both relaxing and engaging. A special highlight is how they project images between the speakers, making you almost able to touch them.

The new Musical Fidelity Nu-Vista PAS and its PSU have been an ongoing labor of love for Musical Fidelity. We are passionate about what we do and passionate about Nuvistor tubes, as we have always been. We hope you derive as much pleasure from listening to the Nu-Vista PAS as we had creating it.

Nuvistor Tubes

Nuvistor tubes were invented in the 1950s to address many of the shortcomings of conventional tubes. Unlike them, Nuvistor tubes offer high reliability, low microphony, low noise, batch consistency, compact size, relatively low power consumption, and excellent technical performance.

A famous application was in the Ampex MR-70, an expensive studio tape recorder whose entire electronics section was based on Nuvistors. Another limited application of this very small tube was in studio microphones of the time, such as the AKG/Norelco C12a, which used the 7586 as a good example.

Later, it was also found in the famous Neumann U 47 studio microphone. This microphone was highly valued by artists worldwide and was used by many prominent recording artists, such as Frank Sinatra, The Beatles, among others. Notably, you can currently see a U47 microphone, with its mount, cables, and power supply on eBay for $10,999 “Buy-it-now.”

Unfortunately, just as the uses for Nuvistor tubes were being explored, the transistor was invented, and it was ‘game over’ for Nuvistors. The matter remained so until about fifteen years ago, when Musical Fidelity created the first of its innovative Nu-Vista series. These legendary, limited-edition products sold out within months. Today, fifteen years later, they command very high prices on the second-hand market due to their beautiful sound, build quality, and longevity.

Nu-Vista PAS - Specifications

Amplifier

• High output power, over 300W into 8 ohms, 500W into 4 ohms, 1000W peaks into 2 ohms
• Output voltage: 49 Volts RMS
• Output current: 130 Amps peak-to-peak
• Damping factor: 200
• Output devices: 5 pairs per channel
• Gain: 16x (23.5 dB)
• THD+N: < 0.003% typical, 20Hz to 20 kHz
• Signal-to-noise ratio: >108dB ‘A’-weighted
• Channel separation: >96dB
• Input impedance: 100 k Ohms
• Input sensitivity for full output: 3 Volts RMS
• Frequency response: + 0, –1dB, 5Hz to 50 kHz

Inputs and Outputs

• 4 fully independent inputs: 2x RCA & 2x XLR
• 2 loop outputs: 1x RCA & 1x XLR
• Speaker outputs: 2 pairs of 4mm banana-type connectors
• Trigger input and output: 3.5mm mono connector
• Trigger level: ±5V to ±12V

General Information

• PAS weight: 27kg net (35kg gross)
• PAS PSU weight: 40kg net (50kg gross)
• PAS dimensions (WxHxD): 483 x 187.5 x 475 (494 with connectors)
• PAS PSU dimensions (WxHxD): 483 x 187.5 x 475 (478 with connectors)
• Mains voltages: 115/230VAC 50/60Hz (factory pre-set); 100VAC 50/60Hz (alternative)
• Consumption: <0.5W in standby mode; 130W on and idle; 1060W maximum

References and Links

• Musical Fidelity Amplifiers
• Nu-Vista Products
• Musical Fidelity Nu-Vista PAS
• Hi-Fi Choice Review
• Soundstage! Australia Analysis