Интегральные усилители — Circle Labs Audio A200

The A200 is a hybrid integrated amplifier from Circle Labs, a Krakow company set up by engineer Krzysztof Wilczyński and design specialist Krzysztof Lichoń, who spent almost ten years on development before their first product went on sale. It replaced the earlier A100 integrated, now discontinued, and sits in a short catalogue alongside the P300 preamplifier and M200 power amplifier. A valve line stage feeds a solid-state output section built around the maker's own Circle Power topology.

Key specs that matter

Rated output is 120 W RMS per channel into 8 ohm and 200 W RMS into 4 ohm. Circle Labs lists one balanced XLR input, three pairs of RCA line inputs and a pre out. Bandwidth runs from 10 Hz to 130 kHz at the -3 dB points, gain is 35 dB, and full power is reached with 0.7 V at the input, which presents 33 kOhm. The chassis is 430 mm wide, 376 mm deep and 176 mm high, with a net mass of 23 kg and 28.5 kg in its carton. Consumption is below 0.1 W in standby, around 70 W at idle and up to 400 W at maximum.

Engineering and use context

The line stage is deliberately minimal, using an ECC88-type double triode with a separate valve for each channel and stabilised supplies built with polypropylene capacitors, and production units carry new-old-stock Siemens tubes. Level is set by a Khozmo resistor ladder whose 0.1 percent tolerance resistors are switched by relays, so the signal never passes through a carbon track potentiometer. In the power section, current-controlled bipolar output transistors are driven in the Circle Power arrangement, with JFETs feeding Sanken bipolar pairs, four transistors per channel. The amplifier is dual mono, with separate toroidal transformers per channel and 200,000 uF of total filter capacitance. The 15 mm glass front carries a metal volume knob and input selector, and an LED readout shows the volume setting. Heatsink fins run along both sides, the case stands on three metal feet with rubber rings, and a metal remote handles volume, mute and display brightness. Speakers connect through a single set of WBT nextgen binding posts.

Pairing

Thanks to the extra output into lower impedance, the A200 drives demanding floorstanding loads as well as easier speakers. The XLR socket accepts a balanced DAC or streamer, the RCA inputs cover other line sources, and a phono stage is needed for vinyl since none is built in. The pre out lets a powered subwoofer or a second power amplifier be added later.

Alternatives

The Circle Labs A100 is the discontinued hybrid integrated amplifier that preceded the A200 in the range.