Усилители мощности стерео — CH Precision A1.5

The Swiss maker CH Precision builds the A1.5 as a stereo amplifier, and it is the smallest power amplifier in the company range. The maker describes it as a compact interpretation of the M1.1, using the same fully discrete, complementary circuitry and the same ExactBias real-time bias control, with a linear supply whose transformer current and reservoir capacitance match the larger model.

Key specs that matter

For stereo or bi-amp duty CH Precision quotes 2 x 150 W RMS into 8 ohm, 2 x 275 W into 4 ohm and 2 x 450 W into 2 ohm, measured at under 0.1 percent THD+N with a 1 kHz tone. Run as a monaural amplifier it reaches 450 W into 2 ohm and 700 W into 1 ohm, while bridged mode gives 550 W into 8 ohm, 800 W into 4 ohm and 1,200 W into 2 ohm. Bandwidth extends from DC to 450 kHz at minus 3 dB. THD+N stays under 0.1 percent with 100 percent local feedback and under 0.01 percent with 100 percent global feedback, and signal-to-noise exceeds 115 dB, or 118 dB when bridged. Gain is +24 dB, rising to +30 dB in bridged mode.

Engineering and use context

Biased in Class AB, the output stage is fed by proprietary power supply capacitors. ExactBias reads junction temperature from a sensor built on the same silicon substrate as each output device, and a galvanically isolated control circuit corrects bias for both slow thermal drift and signal-driven swings. Global feedback can be set in six steps - 0, 10, 20, 40, 70 and 100 percent - and in monobloc or bi-amp use each channel can be adjusted on its own. The topology is software-controlled and modular, so one or two input boards can be fitted, and a single stereo unit can later be joined by a second to form a pair of monaural amplifiers. Each channel accepts a balanced XLR, a single-ended RCA and a single-ended BNC input, at 94k ohm balanced and 47k ohm or 300 ohm single-ended, with nominal levels of 2.5 V balanced and 1.25 V single-ended. A 800 x 480 AMOLED screen and five buttons handle control, alongside an Android app, and firmware updates arrive by USB stick or over the internet. The chassis measures 440 x 440 x 198 mm and weighs 47 kg, drawing under 0.5 W on standby, 150 W at idle and up to 1,800 W, through a single IEC C20 inlet selectable for 100, 115 or 230 V.

Pairing

Speaker cables attach to one set of spade and banana terminals per channel, and silver, anthracite and champagne finishes are offered.

Alternatives

The CH Precision M1.1 is the larger stereo power amplifier, rated at 2 x 200 W into 8 ohm from a 71 kg chassis.