Accuphase P-360
The Accuphase P-360 is a stereo power amplifier from Accuphase Laboratory. It's rated at 200W per channel into 8Ω, 300W into 4Ω, and 400W into 2Ω, and it will drive 1Ω loads. Accuphase's own sales literature leans hard on that low-impedance capability. It notes that a nominal 8Ω speaker can dip to around 2Ω at certain frequencies, and says the amp is built to handle it. Bridged, it becomes a monophonic amplifier rated at 600W into 8Ω.
The output stage uses seven parallel push-pull transistor pairs per channel. The manual claims they can deliver 210A for 1ms, which Accuphase frames as equivalent to 44kW into 1Ω. Power comes from a 1kVA toroidal transformer and two 40,000µF filter capacitors. The driver stage is a class-A cascode push-pull circuit paired with a MOS-FET cascode push-pull stage. The literature calls this the ideal configuration for this kind of amplifier, because it avoids the switching distortion inherent in conventional NPN/PNP output switching. The front end is a balanced differential FET input stage in pure complementary push-pull. It's direct-coupled throughout, with a DC servo circuit to block DC offset instead of coupling capacitors. Balanced inputs are XLR at 40kΩ. Unbalanced RCA jacks are 20kΩ. The P-360 has three input systems total - one balanced pair and two unbalanced pairs. One of the unbalanced pairs sits on the front panel behind the hinged sub-panel, for hooking up peripheral gear.
Two details set the P-360 apart from a lot of power amps of its era. First, it has a dedicated headphone amplifier. It's an independent FET servo-controlled circuit with its own volume control, isolated from the main amplifier so headphone listening doesn't compromise the speaker path. Second, the input level controls are 1dB-step double-ganged attenuators per channel, one for the positive and one for the negative signal path. They use mirror-finished resistors with collectors fixed directly to the external terminals. Accuphase's literature makes a point of the reduced metal joints (five down to three) and the absence of grease between collector and resistor, both framed as sound-quality measures. The peak power meters read from −50dB to +3dB on a logarithmic scale, showing direct output power into 8Ω, and can be switched off along with their illumination. Two pairs of speakers can be connected and driven separately or together, and bi-wired speakers are supported. The chassis is brushed champagne gold aluminum with natural persimmon wood side panels. All function switches except the power button hide behind the hinged front sub-panel.
On the period press, the only magazine appearance located for the P-360 is a classified listing in Audio (June 1995, p.101). That's a "for sale" column, not a bench test or review. No full review from Audio, High Fidelity, Stereo Review, or the other major US and UK audio monthlies appears to have survived in the usual archives. The Archive would welcome a scan of a period review or the original owner's manual.
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