S-02

The Esoteric S-02 is a stereo power amplifier developed from the technology and design approach used in the Grandioso M1 monoblock and S1 stereo power amplifiers. Its high output capability is intended to preserve the scale, dynamics and spatial information contained in original master recordings, as part of Esoteric’s Master Sound Works concept.

The S-02 is rated at 145W per channel into 8 ohms, while its power supply allows it to deliver 580W into 2 ohms. Loudspeaker impedance can vary with frequency, and deep bass places repeated demands on an amplifier through both continuous output and short bursts of peak power. The S-02’s power supply capacity is designed to meet these changing loads and maintain linear reproduction of dynamics at all volume levels.

A large-capacity custom power transformer is mounted securely on a rigid 5mm-thick steel base plate, with material selection receiving particular attention. Each channel uses three parallel 4,7001-F capacitors to shorten charge and discharge times. Heavy-duty power supply cables with crimp terminals are tightly bolted together to reduce impedance.

The output stage is designed for low output impedance, using a total of nine bus bars for each channel and no output coil. A simplified circuit design and wider operating range contribute to a damping factor of 1,000, providing controlled drive for large-diameter woofers and accurate reproduction extending to low frequencies.

The audio input passes through discrete balanced input buffer amplifiers before reaching the amplification stage through a balanced, low-impedance signal path. This configuration supports low-noise amplification and the reproduction of subtle gradations between musical crescendos and silence, while preserving spatial information such as the acoustic character of a concert hall and the presence of an audience.

The S-02 uses large bipolar LAPT transistors, each twice the size of more commonly used power transistors. They provide a continuous current capacity of 17 amps and an instantaneous peak capacity of 34 amps, together with high-frequency characteristics suited to the reproduction of subtle tonal detail.

Its power amplifier module uses bipolar LAPT transistors in a 3-stage Darlington circuit with 5 parallel push-pull sections. The amplifier circuit was simplified to reduce the number of components and parallel elements while retaining the high-frequency characteristics of the output devices.

The voltage amplification stage is independently powered to prevent fluctuations in the drive, or current amplification, stage from affecting the signal. It receives a low-level signal from the input stage and uses a dedicated power supply with its own toroidal power transformer. This arrangement provides a stable power source for the voltage amplification stage and supports the resolution of fine instrumental detail during full orchestral crescendos.

By simplifying the amplifier circuitry and reducing the gain of the preceding stage, the S-02 uses reduced negative feedback, or NFB. The amplifier is fitted with XLR and RCA input connectors, along with loudspeaker terminals made by WBT of Germany. Other components include low-impedance electrolytic capacitors and transistors with high-frequency characteristics.