Интегральные усилители — Audio Note SORO Line PP

The SORO Line PP is the push-pull, line-only version of the SORO integrated amplifier built in Britain by Audio Note (UK), based in Hove. The SORO family is offered in push-pull and single-ended forms, with line and phono variants of each, and the single-ended models also come in Signature versions. The PP model runs its valves in pure Class A and meets the Audio Note Level 1 criteria, which the company lists as pure Class A push-pull pentode operation plus its materials and component quality standard.

Key specs that matter

Rated output is 20 W RMS per channel into 4 or 8 ohm loads, against 18 W for the single-ended SORO versions. Each line input presents 100 kOhm to the source and reaches full output at 300 mV, while left and right levels match to within plus or minus 0.3 dB. The valve complement listed for the push-pull model is two ECC82, two ECC83 and four 5881 or 6L6G output tubes. The chassis measures 140 mm high, 440 mm wide and 410 mm deep and weighs 16 kg, and maximum mains draw is 100 W from a 100-120 V or 220-240 V supply at 50 or 60 Hz.

Engineering and use context

The design uses a high gain power stage built from anode followers based on the ECC82 dual triode, feeding parallel connected 6L6G output valves. Because the power section has that much gain, the designers could fit a passive line stage with the volume control ahead of it instead of an active preamplifier circuit. Output transformers come from the maker's own design and production. The power supply is a multi element design so that each circuit stage is fed separately, and a DC supply heats the filaments of the low level valves. Four line inputs are labelled CD1, CD2, Tuner and Aux, and a tape loop with a source or tape switch serves a recorder. The front panel carries an input selector, volume and balance controls, while the power switch sits at the rear above an IEC inlet. A ground post is provided for sources with a separate earth lead. The amplifier needs about 45 seconds to initialise after switch-on, and Audio Note quotes roughly 8000 hours of life for the supplied valves, which should be replaced in matched pairs. Audio Note (UK) covers the unit for two years and the valves for three months.

Pairing

Each channel has three binding posts, a common terminal plus two separate impedance taps on the output transformer, so the owner connects the speaker to the tap that matches its rated impedance. With no phono stage on board, records need a separate phono stage, or the SORO Phono PP can be chosen instead.

Alternatives

The Audio Note Tomei is a single-ended integrated amplifier with a pair of 211 triodes and 450 mV input sensitivity in a 305 x 305 x 640 mm chassis.