Усилители мощности стерео — Esoteric S-02

The S-02 is a stereo power amplifier from Esoteric, the high-end brand of Japan's TEAC Corporation, hand-assembled in Tokyo. It sits below the Grandioso M1 monoblocks and uses technology trickled down from that flagship line, with a design focus on current delivery and very low output impedance for large woofers.

Key specs that matter

Rated output is 145 W per channel into 8 ohms and 290 W into 4 ohms, with maximum output of 580 W per channel into 2 ohms, a doubling at each halving of load. Frequency response is 5 Hz to 100 kHz (+0/-3 dB into 8 ohms). Signal-to-noise is 115 dB (IHF-A), THD is 0.003% and the damping factor is 1000. Input impedance is 44 kohm balanced and 22 kohm unbalanced, and voltage gain is 28.5 dB. Maximum consumption is 440 W. The chassis measures 445 x 221.5 x 489.6 mm and weighs 28 kg.

Engineering and use context

The main power transformer is a custom EI-type unit with a large 940 VA core, separate windings for left and right channels and a 5 mm steel base plate. Each channel draws on three parallel 4700 uF capacitors, and power wiring uses crimped cables bolted together to reduce impedance. The voltage amplification stage has its own dedicated supply with a separate toroidal transformer, so current swings in the output stage do not affect it. The output stage uses bipolar LAPT transistors twice the size of common power devices, rated for 17 A continuous and 34 A peak, in a three-stage Darlington arrangement with five parallel push-pull pairs per channel. Esoteric's LIDSC circuit, Low Impedance Drive Stage Coupling, borrowed from the Grandioso M1, keeps the drive stage stable. To reduce output impedance, nine bus bars per channel replace conventional wiring and the output coil is omitted. A simplified circuit with lower gain in the early stages allows reduced negative feedback.

Pairing

The high damping factor and stability into low loads suit large, low-sensitivity floorstanders and designs with low impedance minima. The balanced input accepts any preamplifier, including Esoteric's own C-03Xs and Grandioso C1X. The heavy, deep chassis calls for a sturdy shelf with space behind for cables. Electrostatic and ribbon hybrids with falling impedance at high frequencies also remain within its operating range. A source or preamplifier delivering 2 V reaches full output with margin to spare.

Alternatives

Esoteric's S-05 is the smaller Class A stereo power amplifier in the same range.