Audio T Verdict
The Sugden Masterclass ANV-50 combines the natural and expressive qualities associated with Sugden’s Class A designs with considerably greater loudspeaker-driving ability.
At its heart is a pure Class A amplifier section, coupled to an advanced final output stage with Sugden Error Correction. This allows the ANV-50 to produce 50W per channel into 8 ohms and 100W per channel into 4 ohms, making speaker sensitivity and room size less restrictive than they can be with lower-powered Class A amplifiers.
Its five line-level inputs, variable preamplifier output and compact integrated design make it straightforward to use, but there is no internal phono stage, DAC or network streamer. It is a focused analogue amplifier designed to place sound quality, power delivery and long-term engineering ahead of unnecessary features.
Sugden Masterclass ANV-50 Integrated Amplifier
The Sugden Masterclass ANV-50 is a handmade British integrated amplifier developed to celebrate Sugden Audio’s fiftieth anniversary.
Rather than simply increasing the size of the company’s established A21 circuit, Sugden created a new two-stage amplification system designed to retain its recognisable Class A character while substantially increasing available power and loudspeaker compatibility.
The design combines a pure Class A amplifier section with an advanced final output stage, Sugden Error Correction and an exceptionally fast 1MHz switching power supply.
Created for Sugden’s Fiftieth Anniversary
Sugden introduced the ANV-50 as a celebration of fifty years of British amplifier design and manufacturing.
The company released the original A21 in 1967, establishing what Sugden describes as the world’s first production pure Class A transistor amplifier.
The ANV-50 revisits this heritage through a modern circuit designed for contemporary loudspeakers, listening rooms and source components.
A Pure Class A Amplifier at Its Heart
The ANV-50 contains a pure Class A amplifier section that remains continuously active and ready to respond to the incoming music signal.
This section is coupled to Sugden’s advanced final output stage, creating a two-stage amplification system intended to preserve the open, natural and musically expressive presentation associated with the company’s traditional Class A amplifiers.
The ANV-50 should therefore not be confused with a conventional Class AB or Class D integrated amplifier, but its architecture also differs from the more traditional output-stage arrangement used in the A21 series.
Advanced Final Output Stage
The final output stage has been developed to provide the current and load stability required to control a broad range of passive loudspeakers.
This section works together with the pure Class A amplifier at the input of the two-stage circuit, allowing the ANV-50 to provide substantially greater output than Sugden’s traditional A21 integrated amplifiers.
The design is intended to retain signal authenticity while improving control into loudspeaker loads that vary with frequency.
Sugden Error Correction
The ANV-50’s final output stage incorporates a comparator and correction circuit.
This circuit compares the output of the final power section with the signal produced by the high-impedance input amplifier. Errors caused by changing loudspeaker loads or distortion within the power-output section can then be corrected.
Sugden describes this system as Sugden Error Correction. It is designed to reduce output impedance, increase load stability and help the amplifier maintain control as loudspeaker impedance changes.
Current-Feedback Circuit
The output stage also benefits from overall current feedback.
This contributes to the amplifier’s low open-loop output impedance and high damping factor, helping it control the movement of connected loudspeaker drive units.
Strong electrical control is particularly useful when reproducing bass transients or driving loudspeakers with a demanding impedance curve.
50W Per Channel Into 8 Ohms
The ANV-50 produces 50W per channel into an 8-ohm loudspeaker load, measured with both channels operating.
This provides considerably more output than the A21 and A21SE, giving the ANV-50 greater headroom in larger rooms and with less sensitive loudspeakers.
Available volume will still depend on speaker sensitivity, listening distance, room acoustics and the dynamic demands of the recording.
100W Per Channel Into 4 Ohms
Power output doubles to 100W per channel into 4 ohms, again with both channels operating.
The ability to double its published output into the lower impedance demonstrates the current delivery and stability of the power-amplifier design.
This makes the ANV-50 suitable for a much wider selection of loudspeakers than many lower-powered Class A amplifiers, although an in-store demonstration is still recommended.
Loudspeaker Matching
The ANV-50 is designed to drive the majority of conventional passive loudspeakers, including many models with a nominal 4-ohm impedance.
However, impedance, electrical phase, sensitivity, room size and preferred listening volume all affect how an amplifier and loudspeaker perform together.
Contact your local Audio T store to discuss your speakers or arrange a demonstration using your preferred music.
1MHz Switching Power Supply
The ANV-50 uses a high-speed switching power supply operating at 1MHz.
Sugden developed this supply to deliver power rapidly to the continuously active Class A amplifier section, helping the circuit respond immediately to changes within the music signal.
Its operating frequency is substantially above the audible range, while the high-current design provides the reserves required by the amplifier’s final output stage.
Fast and Stable Power Delivery
The power supply is designed to provide high current while remaining fast and stable under changing musical demands.
This allows the amplifier to reproduce sudden dynamic changes without waiting for power to be drawn through a conventional mains transformer and bridge-rectifier arrangement.
The combination of the fast supply and continuously active Class A section is fundamental to the ANV-50’s design.
Fully DC-Coupled Signal Path
The ANV-50’s preamplifier and power-amplifier sections are fully DC coupled.
This means that coupling capacitors are not placed within the audio signal path between the preamplifier and power-amplifier stages.
Sugden uses this approach to avoid the potential influence of signal-path capacitors and to maintain a direct electrical connection through the amplifier circuit.
Purpose-Designed Internal Preamplifier
The ANV-50 includes an internal preamplifier developed specifically for this model.
It uses a line-drive circuit with a deliberately low component count, helping to keep the signal path direct and uncomplicated.
Sugden selects high-quality components throughout the preamplifier, with the aim of achieving an open and natural presentation without adding unnecessary circuit complexity.
Five Relay-Selected Line Inputs
Five stereo line-level inputs are provided for connecting analogue source components.
Input selection is relay operated, helping to maintain a short and controlled signal path between the selected source and the preamplifier circuit.
Compatible source components can include:
- CD and SACD players with analogue outputs
- Network streamers
- External digital-to-analogue converters
- Radio tuners
- Cassette decks and other analogue sources
- Turntables used with a separate phono stage
No Internal Phono Stage
The ANV-50 does not include an internal moving-magnet or moving-coil phono stage.
A conventional turntable must be connected through a suitable external phono stage, with the phono stage’s line-level output connected to one of the amplifier’s five inputs.
A turntable with its own switchable phono preamplifier can also be connected, provided that its output is set to line level.
Connecting a Turntable
Do not connect a conventional turntable cartridge directly to one of the ANV-50’s line-level inputs.
The cartridge signal requires additional gain and equalisation from a compatible moving-magnet or moving-coil phono stage.
Audio T can help select a phono stage that is electrically suitable for your cartridge and appropriate for the rest of your system.
No Internal DAC or Network Streaming
The ANV-50 is a focused analogue amplifier and does not contain an internal DAC, Bluetooth receiver or network streamer.
A digital source can be used by connecting its analogue output to one of the five line inputs.
A source with digital-only outputs will require a separate compatible DAC.
Variable Preamplifier Output
One variable stereo preamplifier output is provided.
Its output level follows the ANV-50’s main volume control, allowing a volume-controlled signal to be sent to a compatible external power amplifier, active loudspeaker system or another suitable component.
Connection and gain requirements should be checked before combining the ANV-50 with additional amplification.
Fixed Tape Output
A fixed-level stereo tape output is also included.
This can supply a compatible recording device or another component that requires a fixed analogue signal.
The tape output is not affected by the ANV-50’s volume control and should not be connected directly to a power amplifier or active loudspeaker unless the receiving component provides its own volume adjustment.
RC5 Remote Control Included
The ANV-50 is supplied with Sugden’s RC5 remote-control handset.
The remote provides convenient everyday operation from the listening position, while the front panel retains Sugden’s clean and uncluttered appearance.
Stereo Loudspeaker Connections
One pair of stereo multi-way binding posts is provided for connecting passive loudspeakers.
The terminals accept compatible terminated or unterminated speaker cables. Correct positive and negative polarity should be maintained at both ends of each cable.
The ANV-50 does not provide separate Speaker A and Speaker B outputs.
Low No-Signal Power Consumption
When the ANV-50 is not receiving an input signal, Sugden publishes power consumption of only 20W.
This is unusually low for an amplifier containing a continuously active Class A section and reflects the efficiency of its two-stage architecture and switching power supply.
Actual power consumption will increase when the amplifier is reproducing music and supplying power to the loudspeakers.
Controlled Operating Temperature
The amplifier’s heatsinks are mounted internally with limited contact against the external casework.
Sugden states that the ANV-50 therefore becomes only slightly warm to the touch during normal use, rather than producing the high external case temperature associated with some traditional high-powered Class A amplifiers.
Adequate ventilation should still be provided and the amplifier should not be covered or installed in a tightly enclosed cabinet.
Wide Loudspeaker Compatibility
The combination of 50W output into 8 ohms, 100W into 4 ohms and the error-corrected final output stage allows the ANV-50 to work with a broad selection of loudspeakers.
Its additional power makes room size and loudspeaker sensitivity less restrictive than with the lower-powered A21 models.
A demonstration remains valuable because electrical compatibility alone does not guarantee the preferred tonal balance or musical presentation.
Handmade in West Yorkshire
Sugden continues to manufacture its products at its factory in Heckmondwike, West Yorkshire.
Each amplifier is handmade by a skilled member of Sugden’s small production team, with the company retaining control of processes including engineering, screen printing, assembly and final testing.
This traditional approach allows Sugden to focus on construction quality, consistency and long-term serviceability rather than high-volume production.
Full-Width Masterclass Casework
The ANV-50 measures 430mm wide, 143mm high and 370mm deep.
Its full-width casework provides the internal space required for the power supply, amplifier stages and internal heatsinking.
Sugden publishes a gross packed weight of 11kg.
Placement and Ventilation
Place the ANV-50 on a stable and level Hi-Fi rack or equipment shelf.
Allow sufficient space around the amplifier for airflow and for its rear-panel cables to connect without sharp bends or strain.
Avoid positioning it directly above another heat-producing component or beneath equipment that could obstruct ventilation.
Key Features
- Handmade British integrated amplifier
- Part of the Sugden Masterclass series
- Originally developed to celebrate Sugden’s fiftieth anniversary
- Pure Class A amplifier at the heart of the circuit
- Advanced final output stage
- Two-stage amplification architecture
- Sugden Error Correction circuit
- Comparator and correction system
- Overall current feedback
- Low open-loop output impedance
- High damping factor
- Fully DC-coupled preamplifier and power-amplifier stages
- No coupling capacitors between the preamplifier and power amplifier
- Purpose-designed internal line-drive preamplifier
- Low component-count signal path
- 1MHz switching power supply
- High-current power delivery
- 50W per channel into 8 ohms
- 100W per channel into 4 ohms
- Both power ratings measured with both channels operating
- Five stereo line-level inputs
- Relay-operated input selection
- 110mV line-input sensitivity for full output
- Variable stereo preamplifier output
- Fixed stereo tape output
- One pair of stereo multi-way loudspeaker terminals
- RC5 remote-control handset included
- 20W published no-signal power consumption
- 12Hz to 45kHz frequency response, ±1dB
- 8Hz to 86kHz published bandwidth
- Greater than 85dB signal-to-noise ratio
Frequently Asked Questions
Is the Sugden ANV-50 a pure Class A amplifier?
Sugden describes the ANV-50 as having a pure Class A amplifier at its heart, coupled to an advanced final output stage. Its architecture differs from the traditional Class A output-stage arrangement used in the A21 series.
How much power does the ANV-50 produce?
It produces 50W per channel into 8 ohms and 100W per channel into 4 ohms, measured with both channels operating.
Does the ANV-50 double its output into 4 ohms?
Yes. Sugden publishes 50W per channel into 8 ohms and 100W per channel into 4 ohms.
What is Sugden Error Correction?
It is a comparator and correction circuit that identifies errors within the final power-output stage and corrects them against the output of the high-impedance input amplifier.
What does the error-correction circuit achieve?
It is designed to improve load stability, reduce output impedance and maintain the authenticity of the amplified signal as the loudspeaker load changes.
What type of power supply does the ANV-50 use?
It uses a high-current switching power supply operating at 1MHz.
Why does the power supply operate at 1MHz?
Sugden developed the high-speed supply to deliver power rapidly to the continuously active Class A amplifier section.
Is the ANV-50 fully DC coupled?
Yes. Sugden states that the internal preamplifier and power-amplifier sections are fully DC coupled.
Are there capacitors in the signal path?
Sugden states that there are no coupling capacitors within the signal path between the fully DC-coupled preamplifier and power-amplifier sections.
How many inputs does the ANV-50 have?
It provides five stereo line-level inputs selected using relays.
Does the ANV-50 include a phono stage?
No. A compatible external moving-magnet or moving-coil phono stage is required to connect a conventional turntable.
Can I connect a turntable?
Yes. Connect the turntable to a compatible external phono stage and connect the phono stage’s line-level output to one of the ANV-50’s inputs.
Does the ANV-50 have digital inputs?
No. Digital sources can be connected through their analogue outputs or through a separate DAC.
Does it include network streaming or Bluetooth?
No. A separate network streamer or Bluetooth source with a compatible analogue output is required.
Can I connect a CD player or streamer?
Yes. Connect the component’s analogue output to any of the five line-level inputs.
Does the ANV-50 include a remote control?
Yes. Sugden supplies its RC5 remote-control handset with the amplifier.
Does the ANV-50 have a preamplifier output?
Yes. It provides one variable stereo preamplifier output controlled by the main volume setting.
Does it have a tape output?
Yes. One fixed-level stereo tape output is provided.
Can two pairs of speakers be connected?
The ANV-50 provides one pair of stereo loudspeaker terminals and does not include separate Speaker A and Speaker B outputs.
Will the ANV-50 drive 4-ohm loudspeakers?
Sugden publishes an output of 100W per channel into 4 ohms, making it suitable for many conventional 4-ohm speakers. A demonstration is recommended for particularly demanding designs.
Does the ANV-50 run hot?
Sugden states that its internally mounted heatsinks and amplifier architecture allow the outer case to become only slightly warm during normal use. Adequate ventilation is still required.
How much power does it use without an input signal?
Sugden publishes no-signal power consumption of 20W.
What is the ANV-50’s frequency response?
Sugden publishes a frequency response of 12Hz to 45kHz within ±1dB.
What is its published bandwidth?
The published bandwidth extends from 8Hz to 86kHz.
What is the signal-to-noise ratio?
Sugden publishes a signal-to-noise ratio greater than 85dB.
Where is the ANV-50 manufactured?
It is handmade at Sugden’s factory in Heckmondwike, West Yorkshire.
How large is the Sugden ANV-50?
It measures 430mm wide, 143mm high and 370mm deep.
How much does the ANV-50 weigh?
Sugden publishes a gross packed weight of 11kg.
Related Products and Audio T Guides
Why Buy From Audio T?
- Independent advice from experienced Hi-Fi specialists
- Careful amplifier and loudspeaker matching
- In-store demonstrations at participating branches
- Advice on choosing a compatible external phono stage
- Help connecting streamers, DACs and analogue sources
- System positioning and ventilation guidance
- Cable and equipment-support recommendations
- Home demonstrations and product loans where available
- Click and Reserve from participating stores
- Nationwide UK delivery on eligible products
- Ongoing after-sales support
Contact your local Audio T store to arrange a demonstration or discuss matching the Sugden Masterclass ANV-50 to your loudspeakers, source components and listening room.