Усилители мощности моно — Line Magnetic AS-134

The Line Magnetic AS-134 is a single-ended stereo valve amplifier from the Ange range, whose grey chassis identify products of the Foshan branch of Line Magnetic, and it uses the 2A3 directly heated triode as its output valve. Introduced at the end of 2023 together with the 300B-based AS-135, it works both as an integrated amplifier with a real preamplifier section and as a pure power amplifier.

Key specs that matter

Rated output is 3 W RMS per channel. Input impedance is 100 kOhm or 600 ohms, sensitivity in the pure power amplifier mode is 250 mV, and the output transformer offers 4, 8 and 16 ohm taps. The frequency response spans 20 Hz to 30 kHz within 2 dB, S/N reaches 87 dB with AC filament heating, and total harmonic distortion is 1 percent. The chassis measures 480 x 255 x 470 mm and weighs 37 kg. Power consumption is listed as 0.5 A at 220 V, with the mains voltage specified at 220 V within 5 percent at 50 Hz.

Engineering and use context

Line Magnetic describes the AS-134 as a pure class A design with fully hand-wired point-to-point construction. The circuit follows the framework of the Western Electric WE12 and was modified by the Foshan design team. The preamplifier section uses a replica of the Western Electric 618 input transformer and two stages of 12AX7 amplification, and the output stage runs through matched 618 and 171 type output transformers. Rectification is handled by a 5Z4 valve, which can be replaced by a 5Y3, and the high voltage and the secondary high voltage have separate supplies. The mains cable is fitted with the PO-1 anti-vibration clamp. The Foshan studio says it had taken part in more than 40 single-ended 300B-related designs over three decades, from OEM kits to a replica of the Western Electric WE91 power amplifier, before creating the AS-134 and AS-135 in answer to requests for a low-power 2A3, 300B or 45 single-ended amplifier under the Ange name. With these two models the Ange range covers all of the basic valve types it set out to use, alongside the KT88, 211 and 212 amplifiers.

Pairing

With its very low output the AS-134 is intended for very efficient loudspeakers. At its launch event it was shown with the Line Magnetic LM-812 horn system, rated at 102 dB sensitivity, and with the AS-121 CD player and the AS-123A valve buffer from the same range. The choice of taps lets it match drivers of 4, 8 or 16 ohms, which is common among vintage horn and full-range units.

Alternatives

The Line Magnetic AS-135 uses the 300B in place of the 2A3 in the same chassis and delivers 7 W per channel.