Sugden HA 4 Headphone Amplifier

Sugden Masterclass HA-4 Pure Class ‘A’ Headphone Amplifier

The Sugden Audio Masterclass HA-4 is the ultimate high-quality dedicated headphone amplifier.

This special class ‘A’ amplifier is designed to push the boundaries of “near field listening” to a level of musical performance that is truly stunning.

The HA-4 has the ability to reproduce all types of music dynamically, in detail, transparently, and harmoniously, while maintaining every subtle detail. An euphonic performance that excites the listener and encourages them to enjoy music even more.

Designed and manufactured at the factory in West Yorkshire, England, where dedication to musical performance, aesthetic design, pride in presentation, and absolute customer satisfaction are paramount.

The HA-4 is housed in an attractive chassis made of composite aluminum and steel, with anodized and powder-coated surfaces radiating quality. The HA-4 features two inputs, two outputs, and manual volume control. It has its own built-in power supply and a Euro plug power connection.

Inputs

The HA-4 is one of the few high-quality headphone amplifiers that accepts two inputs: XLR (balanced mode) and unbalanced Phono RCA (single-ended), both inputs are stereo pairs. The selection of one of the inputs is done through a logical relay circuit operated by a push-button switch on the front panel.

The two outputs are: a 6.35 mm headphone jack on the front and a stereo pair of RCA phono plugs at the rear. The stereo jack connection is of the switch type, where the rear output is disconnected when the headphone jack is plugged in.

The volume control, located in the center of the front panel, provides infinitely fine control for maximum ease of use, even for the most sensitive ears.

Circuit

The electronic circuit is a variant of the Sugden ‘VCV’ preamplifier, coupled with a Pure Class ‘A’, zero feedback, mosfet output amplifier. The circuit is enhanced with a discrete constant voltage power supply powered by a custom-made and shielded 43VA toroidal transformer.

The ‘VCV’ circuit consists of a voltage-to-current converter with high input resistance, a variable current source, and a current-to-voltage conversion phase. This configuration ensures an absolute minimum loss of input information due to high impedance, perfect current gain without attenuation issues, and a matching sound structure regardless of the output.

The final current-to-voltage conversion phase is based on current feedback in line with the aforementioned stages. The Pure Class ‘A’, zero feedback, mosfet output amplifier is both very fast and unconditionally stable.

Although the circuit concept and application are technically superior, the ultimate musical performance balance is achieved through the use of quality components. Gold-plated printed circuit boards are silver-soldered with components selected for their sound qualities, stability in performance, and often many years of Sugden testing, application, and listening.

This is another example of a Sugden product of ingenuity and integrity, subjectively mastered to provide the user with many years of superior musical performance enjoyment.

• Technical specifications:

Inputs – One balanced pair XLR and one stereo pair phono connectors, gold-plated.

Outputs – One 6.35 mm headphone jack and one stereo pair phono connectors.

Input impedance – 20 kilohms.

Gain – 16 dB.

Channel separation – >90 dB.

Frequency response – 20 Hz – 0.3 dB to 30 kHz – 0.5 dB.

Signal-to-noise ratio – >95 dB.

Output impedance – 1 ohm.

Dimensions – 250 mm (W) x 80 mm (H) x 310 mm (D).

Weight – 4.5 kg.

Available in Titan/Graph/Stealth.

*Contact us for current stock and/or delivery information.