• Power amplification stage with 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 ultra-low impedance load of 1 ohm (music signals)
• Instrumentation amplifier principle
• Current feedback topology
• Balanced Remote Sensing
• 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
  
  

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.

As in the A-75, the signal input stage is entirely configured with low-noise discrete circuit components which can handle high power supply voltages. This makes it possible to design the circuit for a high gain of 22 dB, something that cannot be achieved with OP amp ICs that have power supply voltage constraints. As a result, the S/N ratio of the P-4500 is an astonishing 121 dB.

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.