Accuphase P-4600

Accuphase P-4600: A Stereo Power Amplifier

The P-4600 is a stereo power amplifier designed by the prestigious Japanese manufacturer Accuphase. As the direct successor to the P-4500, it represents the fourth generation of the P-4000 series, whose origins date back to the P-4100 launched in 2008. This new iteration brings significant improvements in performance and ease of use while preserving the very essence of Accuphase’s philosophy.

Operating in class AB, the P-4600 embodies the perfect balance between power and sound refinement. It stands out for its ability to faithfully reproduce the entire musical spectrum, from the most subtle nuances to the most dynamic passages, offering an immersive and emotionally engaging listening experience.

Impressive Power in the Service of Music

The Accuphase P-4600 is distinguished by its exceptional output capabilities:

In bridged mode, the amplifier reaches peaks of 600 W at 8 Ω and 900 W at 4 ohms. This considerable power reserve allows the P-4600 to effortlessly drive even the most demanding speakers, ensuring dynamic and uncompressed sound reproduction, regardless of the listening level.

A Sophisticated Electronic Architecture

The heart of the P-4600 lies in an output stage composed of 6 power transistors mounted in parallel push-pull for each channel. This configuration, more elaborate than that of its predecessor, helps reduce output impedance and improve speaker driving capability.

The amplifier integrates several proprietary Accuphase technologies, including:

• The instrumentation amplifier principle: This approach, used in the input section, equalizes impedance on the positive and negative sides, ensuring excellent suppression of external noise.

• Current feedback amplification circuits: They offer exceptional performance in high frequencies, preserving frequency characteristics even during gain changes.

• The MCS+ (Multiple Circuit Summing-up) circuit: By placing the voltage amplification stage in a two-parallel-circuit configuration, it theoretically reduces background noise by about 30%.

• The three-stage Darlington configuration: It minimizes the negative influence of the speakers’ counter-electromotive forces on the output stage.

Reference Sound Performance

The P-4600 stands out with its impressive technical characteristics:

• A signal-to-noise ratio of 125 dB (A-weighted), ensuring an absolutely black background.
• A high damping factor of 800, ensuring perfect speaker control.
• An extended bandwidth from 0.5 Hz to 160 kHz (-3 dB), for faithful reproduction of the entire audible spectrum and beyond.
• A total harmonic distortion rate not exceeding 0.05% (under 2 ohms) in the 20 Hz - 20 kHz range.

These specifications translate into sound reproduction of exceptional purity and transparency, characterized by a wide and deep soundstage, natural timbres, and striking dynamics.

An Elegant and Functional Design

True to Accuphase’s aesthetic, the P-4600 features a massive metal chassis topped with a thick, pale gold anodized aluminum front panel. Its impressive dimensions (465 x 190 x 427 mm) and substantial weight of 30 kg reflect its robust construction and the quality of the components used.

The sleek front is dominated by two large analog VU meters, providing precise and aesthetically pleasing output level readings. It also includes a gain selector (-12 dB to 0 dB), an output selector (A, B, and A+B), and a control knob for the VU meter display.

Connectivity and Versatility

The rear panel of the P-4600 offers comprehensive, high-quality connectivity:

• Stereo RCA and XLR inputs, allowing easy integration into any high-end hi-fi system.
• Dual sets of output terminals per channel, enabling bi-wiring or bi-amplification.
• A mode selector: stereo, dual-mono, or bridged.

This versatility allows the P-4600 to adapt to a wide variety of configurations, from the simplest to the most complex.

Technology for Reliability

Accuphase has integrated several features to ensure the longevity and reliability of the P-4600:

• A short-circuit protection circuit, using photo-couplers for perfect audio signal isolation.
• Temperature sensors installed on the heat sinks, ensuring constant monitoring of operating temperature.
• High-carbon cast iron feet, optimizing the mechanical decoupling of the amplifier.

These elements contribute to the stability and durability of the P-4600, guaranteeing years of worry-free listening.

Technical Specifications

Electronic Architecture

• Push-pull output stage with 6 parallel power transistors
• Instrumentation amplification circuit
• Current feedback amplification circuits
• Symmetrical remote sensing
• MCS+ (Multiple Circuit Sum) circuit
• High damping factor of 800
• Speaker output protection

Audio Performance

• Rated output power:
  • 150 W / channel (8 Ω)
  • 300 W / channel (4 Ω*)
  • 450 W / channel (2 Ω*)
• Bridged mode:
  • 600 W (8 Ω*)
  • 900 W (4 Ω*)
• Frequency response: 0.5 Hz – 160 kHz (0, –3 dB)
• Intermodulation distortion: less than 0.01%
• Damping factor: greater than 800 (JEITA, 8 Ω load at 50 Hz)
• Signal-to-noise ratio: 125 dB (gain: maximum), 130 dB (gain: –12 dB) A-weighted
• Input sensitivity: 1.38 V

Features

• Analog power meters with logarithmic scale
• Power meter on/off, hold selector (3 s / ∞)
• Input selector
• Gain selector
• Phase inverter for balanced inputs
• Operating mode selector
• Balanced inputs
• Compatible with bi-amplification and bridged mode

Physical Characteristics

• Maximum dimensions (W × H × D): 465 × 190 × 427 mm
• Weight: 30.0 kg
• Supplied accessories: power cord (2 m)

*Limited to musical signals