Усилители мощности стерео — Circle Labs Audio M200

The M200 is a hybrid valve and transistor power amplifier from Circle Labs, a Polish company founded in 2007 by engineer Krzysztof Wilczynski, whose range also includes the A200 integrated amplifier, the P300 preamplifier and the V1000 phono stage. The M200 is a true dual-mono design and can be switched to operate as a fully balanced monaural amplifier, so two units can be used as a pair of monoblocks. The stereo version was listed at EUR 6,780 excluding VAT.

Key specs that matter

Used as a two-channel amplifier, the M200 delivers 160 W per channel into 8 ohm and 300 W into 4 ohm. Bridged as a monoblock, output rises to 600 W into 8 ohm and 930 W into 4 ohm. The quoted frequency response runs from 2 Hz to 1 MHz at minus 3 dB. Gain is 35 dB, full power is reached with an input of 0.85 V, and input impedance is 100 kohm. The amplifier draws under 0.1 W in standby, 90 W in constant operation and up to 950 W at maximum. The case measures 430 x 355 x 178 mm, with a net weight of 20 kg and a shipping weight of 28.5 kg.

Engineering and use context

In the input section, voltage amplification is done by ECC88 double triodes, coupled through Supreme Silver/Gold/Oil capacitors. Circle Labs selects NOS Siemens triodes made in the 1960s for this voltage amplification path. The current stages use the company's own Circle Power circuit, developed for high power and high current applications, with high-current bipolar transistors from Sanken. Power supplies are split per channel, with a dedicated toroidal transformer and a separate supply path on each side. Together the transformers total 850 W. The valve section is fed from its own EI core transformer, kept apart from the output stage supplies. Filter capacitance of 200,000 uF uses capacitors adapted to work with high currents. Speaker connections are WBT nextgen series terminals.

Pairing

Circle Labs offers the M200 with its P300, a fully balanced preamplifier with a minimal signal path, two XLR outputs and a 63-step relay-switched resistor ladder for volume, and the balanced input of the monoblock mode suits a balanced preamplifier of this kind. With its high input impedance, the M200 presents an easy load to valve preamplifiers as well as solid-state ones.

Alternatives

The Circle Labs M500 is another two-channel power amplifier in the range that also relies on the Circle Power circuit and can likewise run as a monoblock.