Интегральные усилители — Accuphase E-650

The Accuphase E-650 is a two-channel integrated design from Accuphase Laboratory of Yokohama, Japan, announced in 2018. It was presented as the first Accuphase integrated amplifier to carry the Balanced AAVA volume control, a circuit taken from the C-3850 preamplifier.

Key specs that matter

Pure Class A operation covers output up to 30 W per channel into 8 ohm. Into lower loads the rated figures climb to 60 W into 4 ohm, 120 W into 2 ohm and, with a music signal, 150 W into 1 ohm. Damping factor is 800. Two balanced inputs sit beside the single-ended line inputs, and two option slots accept the DAC-50 digital board, the AD-50 phono board or the LINE-10 line board. Line input sensitivity is 77.7 mV, and the maker quotes 3 Hz to 150 kHz for frequency response with 0.03 % THD. The chassis measures 465 x 191 x 428 mm and weighs 25.3 kg.

Engineering and use context

Balanced AAVA uses two AAVA circuits arranged in balanced form, so the level is set without any potentiometer in the audio route and external noise picked up on the way is cancelled. In the power section Accuphase applies the instrumentation amplifier principle, giving a fully balanced signal route from input to output, together with its MCS+ topology and current feedback. Each channel drives the speaker through a triple parallel push-pull stage built with power MOSFETs. A large toroidal transformer feeds two 50,000 uF filter capacitors. Protection is handled by MOSFET semiconductor switches rather than mechanical relays in the speaker line. The preamplifier and power amplifier sections can be separated and used on their own, which lets the E-650 serve as a preamp for another power amplifier or as a power amp fed by an external preamp. The front panel carries LED bar graph power meters, balanced tone controls and a numeric display for the volume setting, and the phase of each input can be set individually. A discrete headphone amplifier is also built in.

Pairing

Because the rated output doubles with each halving of load impedance down to 2 ohm, the E-650 copes with speakers whose impedance dips low. The modest Class A ceiling favours speakers of decent efficiency for a listening space near 20 m2. Large speaker terminals take spade lugs or banana plugs, and with the DAC-50 board fitted a transport or network source can be connected digitally.

Alternatives

The Accuphase E-5000 is a Class AB integrated from the same maker, rated at 240 W per channel and weighing 33.8 kg.