Musical Fidelity B1xi - Integrated Amplifier

The B1xi integrated amplifier channels Musical Fidelity’s renowned amplifier expertise into a versatile, high-performance package. Driven by the design principles of their flagship models, the B1xi delivers 100W per channel into 4 ohms through a refined Class A/B circuit, offering a rich and dynamic tube like sound.

Designed for today’s diverse listening needs, it features a comprehensive input selection: MM phono stage, coaxial and optical digital inputs, ARC, Bluetooth, and three RCA line inputs—all engineered for seamless source integration. A variable RCA pre-out supports subwoofer connection or bi-amping, while a 5V USB-C output provides convenient and clean high-quality power for an external streamer.

Encased in robust all-metal construction with solid metal controls and a solid aluminium front panel, the B1xi offers the sonic and build quality Musical Fidelity is known for, delivering a pure, uncompromised audio experience for discerning music lovers.

Pure Class A/B Excellence with True High-End Audiophile Design

Transistor amps in Class A/B are best after tubes and Class A amps. Musical Fidelity is tube like sound and power. The B1xi delivers 60 watts per channel into 8 ohms, 100 watts into 4 ohms and 140W peaks into 2 ohms. It won’t struggle to drive a wide range of speakers, even power-hungry models.

Discrete power and toroidal transformer

The fully discrete Class A/B power amp, complemented by its dedicated power supply and generously proportioned toroidal transformer, guarantees reserves for proper peak delivery and a wide dynamic range. Power hungry and difficult speakers are driven with ease. Low impedance dips are managed gracefully and the judiciously rated output devices won‘t faulter under any load.

Low noise preamp and phono stage

The preamp section features its own dedicated linear power supply—a rarity in integrated designs. This separation ensures ultra-low noise and excellent channel separation, rivaling high-end pre/power separates. Volume control is handled via a motor-driven analogue potentiometer, preserving signal purity—unlike many modern digital volume controls that compromise fidelity due to a loss in signal resolution.

Vinyl lovers will appreciate the B1xi’s exceptionally low-noise, high-gain phono stage. Carefully tuned for musicality and detail, it brings out the best in your MM cartridges without adding coloration or distortion.

Separate digital boards

Digital and analogue hardware needs to be carefully separated from each other. Even the smallest amount of RF interference is known to cause trouble for analogue amplifier stages. Therefore, the digital and ARC boards are physically separated on their own PCBs and have their own linear power supply.

Drawing from our decade long experience in designing DACs (recently with our ground-breaking Nu-Vista DAC and M8x DAC), the B1xi uses a carefully trimmed DAC design using the superb ESS9018 chip. The digital coaxial and optical inputs accept high-resolution sample rates up to 24bit and 192kHz and the HDMI ARC input allows your home theatre to be brought to life and properly invigorated by the powerful B1xi analogue amp stages.

The B1xi In Brief

Amplifier

• Fully discrete transistor based Class A/B power amp design in Musical Fidelity tradition
• Drives power hungry speakers with ease
• 60W/8 Ohm, 100W/4 Ohm & 140W/2 Ohm output power
• Power reserves for proper peak power delivery and wide dynamic range
• Pure sound quality instead of WiFi, display and App
• No WiFi, display and App on purpose: Instead, we invest in components, which decide the sound quality

Preamplifier

• Low noise design for best THD and signal integrity at low as well as high levels
• High quality motor-driven analogue potentiometer
• Pre out for bi-amping or active subwoofer connection
• MM phono stage

Digital

• Separate digital and ARC boards with own linear PSU
• Up to 24bit/192kHz Stereo PCM: 1x Coaxial, 1x optical, 1x ARC inputs
• Bluetooth 5.1 input

Power Supply

• Generously rated toroidal transformer
• Independent power supplies for preamp, poweramp and digital part
• Output devices, and power supply generously rated to provide peaks even into difficult to drive speakers
• 5V USB C power output to power many new modern external streamers

Mechanical Construction

• Uncompromising metal work in typical Musical Fidelity tradtion
• Heavy front panel milled from extruded aluminium profiles
• Clean, stunning and indestructable metal exterior protects against electromagnetical

Technical Specifications

Amplifier

• Power, both channels driven @ 1% THD: 60 Watts per channel into 8 Ohms; 100W into 4 ohms; 140W peaks into 2 ohms
• Power, both channels driven @ 0.09% THD, 20Hz to 20 kHz: 50 Watts per channel into 8 Ohms; 80W into 4 ohms
• Voltage 21 Volts RMS, 20Hz to 20 kHz; onset of clipping
• 30 Volts peak to peak
• Current 8 Amps peak to peak
• Damping factor 30
• Output devices 1 pair per channel

Line input

• THD+N < 0.02 % typical, 20Hz to 20 kHz
• Signal / noise ratio > 100dB ‘A’-weighted
• Input impedance 47k Ohms
• Frequency response +0, –3dB, 10Hz to 30 kHz

Phono input

• Sensitivity (nominal): 5mV (suitable for cartridges giving 1.5mV or more including high output MC types)
• Signal / noise ratio: >70dB ‘A’-weighted
• Input impedance: 47k Ohms
• Input capacitance: <100pF
• Gain: 42dB
• Frequency response: RIAA/IEC ±1dB, 20Hz to 20 kHz

Connections

• Line level inputs 3 pairs line level RCA connectors
• MM phono input
• Optical, coaxial, ARC digital inputs (up to 24bit/192kHz stereo PCM)
• Bluetooth 5.1 input
• 1 pair line level RCA connectors, preamp outputs for e.g. bi-amping
• Speaker outputs 1 pair 4mm banana plug/binding posts

Power requirement

• Mains voltages 115/230VAC 50/60Hz (factory pre-set)
• 100VAC 50/60Hz (alternative)
• Consumption 280 Watts maximum

Weight

• Unit only, unboxed 7.2 kg
• In shipping carton 8.9 kg

Dimensions

• Wide 430 mm
• High, including feet 90 mm
• Deep (front to back) including terminals 324 mm

Further Information

Musical Fidelity B1xi - User Manual (PDF)