Усилители мощности стерео — Esoteric S-05

The S-05 is a Class A stereo power amplifier from Esoteric that went on sale in October 2022. It borrows its engineering from the Grandioso M1X monoblock and follows the same idea of minimal circuitry, but in a single stereo chassis sized to sit beside the N-05XD network DAC and preamplifier, so the two boxes form a complete source and amplifier system before speakers are added. It comes in silver and, as the S-05 B, in black.

Key specs that matter

Rated output is 30 W per channel into 8 ohm in Class A and 60 W per channel into 4 ohm, and two units bridged in BTL mode give 120 W into 8 ohm each. Compatible loads run from 4 to 16 ohm in stereo and from 8 to 16 ohm when bridged. Inputs are one pair each of ES-Link Analog, XLR and RCA. Response extends from 5 Hz to 100 kHz within -3 dB into 8 ohm, signal-to-noise is 102 dB IHF-A from the XLR input, total harmonic distortion is 0.007% at 1 kHz and 30 W, and gain is 28.5 dB. Power consumption is 245 W, falling only to 210 W with no signal because of the Class A bias. The case measures 445 x 191 x 444 mm and weighs 30.7 kg.

Engineering and use context

Each channel uses high-capacity bipolar transistors in a three-parallel push-pull output stage. A 940 VA EI-core transformer is mounted bare without a case, and the rectification is dual mono, with four 10,000 uF Grandioso-grade capacitors per channel working in parallel. Critical wiring from the primary side to the drive stage is bolted with heavy-gauge cable. The circuit keeps a single-pole phase compensation network and a coil-less output stage to hold negative feedback low, while a repositioned temperature compensation circuit speeds up the settling of idling current after switch-on. Boards use 105 um copper foil, eight bus bars in the drive stage are 1.0 mm OFC, and MOSFET switches replace mechanical relays at the speaker terminals. A new balanced input amplifier serves each input, and FET switches select the source. The top panel is semi-floating, the heat sink fins have a wave profile to spread resonance, and the unit sits on Esoteric isolation feet.

Pairing

With the N-05XD, the ES-Link Analog connection sends roughly 100 times more current than a voltage link and is unaffected by interconnect impedance, and a DC trigger switches both units together. A second S-05 can run in BTL mode for low-sensitivity speakers or in bi-amp mode, where each chassis drives the high and low sections of one speaker.

Alternatives

The Esoteric S-05XE is the updated Class A stereo model with the same per-channel rating, a 1,000 VA toroidal transformer and a 104 dB signal-to-noise figure.