Усилители мощности стерео — Esoteric Grandioso S1X

Esoteric of Japan builds the Grandioso S1X as a two-channel power amp that runs in Class A while still offering high power into low impedances. Esoteric describes it as the top model among its Class A stereo amplifiers, and a mode selector lets it work as a normal stereo amp, as a bi-amp unit for speakers with separate high and low frequency inputs, or as one half of a mono-block pair. The US list price is USD 37,000.

Key specs that matter

Output is 50 W per channel into 8 ohm and 100 W into 4 ohm, and Esoteric quotes a maximum of 2,400 W into 1 ohm. The amplifier suits loudspeakers rated from 4 to 16 ohm. Frequency response spans 5 Hz to 100 kHz at minus 3 dB into 8 ohm. The signal to noise figure is 109 dB IHF-A via XLR, and harmonic distortion is 0.006 percent at 1 kHz with 50 W into 8 ohm. Gain is 28.5 dB through XLR and 34.5 dB through RCA. Consumption reaches 310 W, and 270 W with no signal. The chassis is 491 x 221 x 536 mm including protrusions and weighs 48 kg.

Engineering and use context

The drive stage uses large bipolar transistors in a simple five-parallel push-pull layout biased in Class A. Three transformers are fitted - oversized bare-mount toroidal units for the main drive, a separate transformer for the pre-drive stages and an R-core transformer for control circuits. Rectification is dual mono, and each channel draws on six 10,000 uF custom capacitors wired in parallel. Seven busbars in the drive stage are cut from 1.0 mm high-purity OFC. Esoteric replaces mechanical relays with FET switches wherever the audio path is switched, including the input selector, and the output stage uses MOS FET switches without contacts. Connections at the back cover balanced XLR, single-ended RCA and ES-Link Analog, one stereo pair of each. Versions exist for 120 V at 60 Hz and 220 to 240 V at 50 Hz.

Pairing

Because the Class A region covers the full 8 ohm rating and current delivery rises steeply as impedance falls, the S1X can drive demanding low-impedance speakers as well as efficient designs. The ES-Link Analog input suits Esoteric preamplifiers that carry the same link. Owners can start with one unit and add a second S1X later, either bridging both into mono blocks or giving each speaker its own amplifier in bi-amp mode with the high and low sections fed separately.

Alternatives

The Esoteric S-05 is a far smaller Class A stereo power amplifier rated at 30 W per channel.