Интегральные усилители — Accuphase E-800S

The E-800S from Accuphase of Japan is an integrated amplifier operating in Class A, and it is the more powerful of the brand's two current Class A integrateds. Power MOS-FETs biased in pure Class A drive the speakers, and the signal path stays balanced right through to the outputs.

Key specs that matter

Linear output reaches 50 W per channel into 8 ohm, 100 W into 4 ohm and 200 W into 2 ohm, so power doubles with every halving of load. Distortion is rated at 0.03 percent into 4 to 16 ohm and 0.05 percent into 2 ohm. Response spans 20 Hz to 20 kHz within +0/-0.5 dB at rated output and 3 Hz to 150 kHz, -3 dB, at 1 W. Input impedance is 40 kohm for the balanced inputs and 20 kohm for the unbalanced ones, and Main In jacks give direct access to the power amplifier stage. Damping factor is quoted at 1,000. There are three sets of balanced XLR inputs alongside five unbalanced RCA line inputs, and two rear expansion slots take Accuphase option boards. A dedicated headphone amplifier with discrete circuitry is built in. The case measures 465 x 239 x 502 mm and the unit weighs 35.7 kg.

Engineering and use context

The output stage places six pairs of power MOS-FETs in parallel push-pull per channel, all operating in Class A so that no device switches off during the signal cycle. Accuphase configures the power amplification stage as an instrumentation amplifier, which fits the fully balanced signal path. Volume is governed by a balanced AAVA control, an Accuphase method that varies gain through weighted current addition and keeps a conventional variable resistor out of the audio path, with a high-accuracy, high-rigidity sensor reading the knob position. A massive high-efficiency toroidal transformer and large filtering capacitors form the power supply. The speaker outputs are protected against short circuits, and switching is done by MOS-FET devices instead of relay contacts. High-carbon cast iron insulators under the chassis isolate it from vibration. The expansion slots let an owner add functions such as digital input or phono stages as optional boards, instead of buying a separate component.

Pairing

Its specified output into very low loads keeps loudspeakers with demanding impedance curves inside the amplifier's specified operation, and the balanced inputs connect directly to sources with XLR outputs. Headphone listening needs no extra amplifier thanks to the discrete front panel output.

Alternatives

The Accuphase E-700 is the smaller Class A integrated, using four-fold parallel output devices and rated at 35 W into 8 ohm.