Sugden Masterclass SPA-4 power amplifier

Sugden Masterclass HA-4 Headphone Amplifier

The Masterclass HA-4 headphone amplifier is a pure Class A design, developed to extend the boundaries of 'near field listening' to a new level of musical performance. It has the ability to recreate all types of music in dynamic, detailed, transparent and harmonic performance, with every nuance retained. Euphonic performance which will enthuse and encourage the listener to enjoy " Simply More Music".

 The HA-4 is housed in a most attractive composite metal case of Aluminium and Steel, with Anodised and Powder Coated surfaces that exude quality. The HA-4 is equipped with: two inputs, two outputs, and a manual volume control.

Availability: In stock

It's one of the few high end headphone amplifiers to accept both XLR (balanced inputs) and RCA (single ended) inputs (selectable on the front panel). In addition to the headphones output, the HA-4 includes RCA (single ended) outputs on the back, allowing you to connect it inbetween your source and main amplifier if needed, without needing to unplug and plug every time you use it (RCA output is disconnected when a headphones jack is inserted).

This is another Sugden product of ingenuity and integrity subjectively mastered to allow its user to enjoy many years of superior musical performance.

The Electronic circuitry is a variant of Sugdens 'VCV' PreAmplifier. coupled to a Pure Class A. Zero Feedback. Mosfet output stage. The circuitry has been enhanced by a Discrete Constant Voltage Series Power supply driven by a custom built single wound and shielded 43VA torroidal transformer.

The 'VCV' circuit consists of a high input impedance voltage to current converter, variable current source and a current to voltage conversion stage. This configuration ensures absolute minimum loss of input information due to the high impedance and perfect current gain without attenuation problems. 

The final current to voltage conversion stage is based on current feedback in line with the other stages previously mentioned. The Pure Class A. Zero Feedback. Mosfet Output Stage is both very fast and unconditionally stable.

Whilst the circuit concept and application are technically superb the final balance of musical performance is obtained by the use of quality components. Gold plated circuit boards silver soldered with components which are selected for their. sonic qualities. stability in performance and often many years of Sugden testing. application and listening. The volume control, located in the centre of the front panel, has infinitely fine control for maximum user friendliness, even for the most sensitive of ears.



Input Impedance: 20K Ohms
- Gain: 6dB
- Channel Separation: >90dB
- Frequency Response (-0.3dB): 20Hz 
- Frequency Response (-0.5dB): 30Hz
- Signal to Noise: >95dB
- Output Impedance: 1 Ohm
- Dimensions (mm): 250W x 80H x 310D
- Weight: (kg): 4.5

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