Усилители мощности моно — Line Magnetic G-212

The G-212 is a single-ended tube mono power amplifier from Line Magnetic, the Chinese manufacturer known for hand-wired tube electronics whose styling recalls classic amplifiers from the first half of the 20th century. It is built around the 212, a large directly heated power triode, and it is split into two chassis per channel - the amplifier itself and a separate power supply. It sits alongside Line Magnetic's other 212-based designs, such as the LM-212PA monoblock and the AS-128 212 integrated monoblock.

Key specs that matter

The G-212 produces 30W per chassis, single-ended and Class A, from one 212 output triode. Frequency response extends from 10Hz to 20kHz, input impedance is 100 kilohms and the output transformer has 4, 8 and 16-ohm taps. Construction is hand-wired, with the power supply housed in its own enclosure. A pair is needed for stereo.

Engineering and use context

The 212 is a large transmitting-type triode with a thoriated-tungsten filament, and it runs at a much higher plate voltage than common audio power tubes such as the 300B. That high voltage swing is what allows a single 212 to deliver, in single-ended Class A, several times the output of a single 300B stage, while keeping the simplicity of one output device per channel with no phase splitter or output pair dividing the signal. In a single-ended Class A stage, the output tube conducts continuously, and the output transformer must carry a constant DC current without saturating, which requires a large, air-gapped core. Housing the supply in its own box keeps the mains transformer, rectification and filter chokes away from the sensitive input stage and the output transformer, reducing hum induced by magnetic fields, and spreads the weight and heat across two units. Hand-wired, point-to-point construction, typical of Line Magnetic, avoids long printed-circuit traces in the signal path and allows components to be replaced individually. The multiple secondary taps let the output transformer be matched to the loudspeaker's nominal impedance so the tube works into its intended load. Because the tube operates at high voltage, adequate ventilation and care around the chassis are essential.

Pairing

The G-212 has more power than most single-ended triode amplifiers, but it is best matched to efficient loudspeakers of around 90dB or more with a benign impedance curve, such as horn or high-efficiency designs. The high input impedance suits tube preamplifiers as well as solid-state line stages.

Alternatives

Line Magnetic's own LM-212PA is another 212 monoblock, using a 310A input tube, a 300B driver and a 274B rectifier.