The quest for the optimal power amplifier has just taken another giant leap forward. The P-4500 features an instrumentation amplifier configuration realized with discrete semiconductors in the signal path, triple Darlington 4-parallel complementary push-pull architecture, and many other technical advantages. The result is an impressive S/N ratio of 121 dB, rated output of 500 watts into 1 ohm (music signals), and a damping factor of 700. A newly developed output protection circuit can also detect any short-circuiting of the speaker terminals, for complete peace of mind. This power amplifier is the ultimate tool for immersive music enjoyment on the highest level.

Warranty:

1-year manufacturer’s warranty

Features:

  • Power amplification stage with a 4-parallel complementary push-pull configuration
  • Linear output characteristics (90 W / 8 ohms, 180 W / 4 ohms, 360 W / 2 ohms)
  • 500 W output into an ultra-low impedance load of 1 ohm (music signals)
  • Instrumentation amplifier principle
  • Current feedback topology
  • Balanced Remote Sensing
  • The high damping factor of 700
  • Speaker output protection with short-circuit detection
  • Highly responsive, large peak power meters
  • Support for bi-amping and bridged mode

STEREO POWER AMPLIFIER WITH OUTSTANDING PERFORMANCE
Since it started from P-300 in 1973, during the past half-century, the history of Accuphase Power Amplifiers has been continually evolving with a wide range of variations such as Monophonic, Class-A, and Class-AB. The P-4500 is the successor model of the P-4200, launched in 2013. This new model is a direct descendant of the first P-300, not only acting as a strong introduction but also realizing the great electrical performance and sound quality, coming close to the flagship A-250. The P-4500 features best-in-class low noise and high damping factor performance, and with the enhanced power output stage, it enables perfect driving of the modern high-end loudspeakers.

Instrumentation amplifier topology further improves noise performance
The P-4500 employs an instrumentation amplifier configuration that is highly effective in keeping external noise from affecting the signal transmission lines. The configuration comprises a signal input unit that receives the signal from the preamplifier and a power amplification unit that sends power to the speakers. The input stage is designed for high gain (22 dB) and the power amplification stage for low gain (6 dB). Consequently, the internal signal has a large amplitude, which makes it much less prone to interference, thereby further improving the noise performance.

Power amplification section with linear output characteristics
The power amplification stage of the P-4500 features bipolar power transistors mounted directly to large heat sinks for highly efficient thermal dissipation. The devices are configured as a triple Darlington 4-parallel complementary push-pull circuit that is capable of doubling the rated output when the impedance is halved. In other words, it achieves a fully linear power progression of 90 watts into 8 ohms, 180 watts into 4 ohms, and 360 watts into 2 ohms. It can even supply loads as low as 1 ohm with 500 watts of power (music signals). The impressive damping factor of 700 means that the amplifier has ample leeway to drive any kind of loudspeaker.

Technical Specifications:

Continuous Average Output Power Stereo operation – 500 watts per channel into 1 ohm, 360 watts per channel into 2 ohms, 180 watts per channel into 4 ohms, 90 watts per channel into 8 ohms. Monophonic operation (bridged connection) – 1000 watts into 2 ohms, 720 watts into 4 ohms, 360 watts into 8 ohms.
Total Harmonic Distortion Stereo operation – 0.05% with 2 2-ohm load, 0.02% with 4 to 16-ohm load. Monophonic operation (bridged connection) – 0.05% with 4 to 16 ohm load
Intermodulation Distortion 0.01%
Frequency Response At rated output: 20 – 20,000 Hz +0, -0.2 dB. At 1 watt output: 0.5 – 160,000 Hz +0, -3.0 dB
Gain 28.0 dB (with GAIN selector at MAX) (Stereo and monophonic operation)
Gain Selection MAX, -3 dB, -6 dB, -12 dB
Output Load impedance Stereo operation – 2 to 16 ohms. Monophonic operation: 4 to 16 ohms
Damping Factor 700
Input Sensitivity Stereo operation – 1.07 V for rated continuous average output. 0.11 V for 1 watt output. Monophonic operation – 2.14 V for rated continuous average output. 0.11 V for 1 watt output
Input Impedance Balanced – 40 kilohms. Line – 20 kilohms
Signal-to-Noise Ratio (A-weighted, input shorted) 121 dB (GAIN selector at MAX), 126 dB (GAIN selector at -12 dB) At rated continuous average output
Output Level Meters －∞ dB to +3 dB (indication in dB and %) Logarithmic scale, with defeat switch, hold time switchable 3s/ ∞
Power Requirements AC 120 V/230 V, 50/60 Hz (Voltage as indicated on rear panel)
Power Consumption 62 watts idle. 485 watts in accordance with IEC 60065
Maximum Dimensions Width 465 mm, Height 190 mm, Depth 427 mm
Mass 29.2 kg net, 35.0 kg in shipping carton