Since it started from P-300 in 1973, during the past half
century, the history of Accuphase Power Amplifiers is
continually evolving with a wide range of variations as
Monophonic, Class-A and Class-AB.
P-4500 is the succession model of P-4200 launched in 2013.
This new model is a direct descendant of the first P-300, notonly acting as a strong introduction but realizing the great
electrical performance and sound quality coming close to theflagship A-250.
P-4500 features best-in-class low noise and high damping
factor performance, and with the enhanced power output
stage, it enables to perfectly drive the modern high-end loudspeakers.
Thanks to the enough margin of separate system, new P4500 clearly expresses the dynamics and excitements ofmusic sources, and it also offers the best performance in all
kinds of environments.

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Unit dimensions are same but the mass is 300g heavier
than former model P-4200.
Users are able to switch output to speaker pairs A and B
depending on their preferences.
New painting processes are applied on the top plate andheat sink. It helps to enrich the texture.

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High-sensitivity needle power meter creates an elegant
ambience with the swing at lower levels less than -60dB.

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Accuphase traditional symmetry layout keeps the power
supply section centered with power amp blocks on bothsides.
Newly designed massive toroidal transformer realizes thehigher efficiency, less heat generation during high output,
and better reliability than P-4200.
Custom-made large filtering capacitors increase thecapacity from 47000uF to 50000uF, Accuphase choose
the best ones after hundreds of trials and tunings.

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The continuous average output power(rated outputpower) is 90W into 8Ω load.
However, its actual maximum output power is bigger,saying 145W into 8Ω and 560W into 1Ω load.
**Rated output power is same as P-4200.

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The performance highlights of P-4500 are “Ultra lownoise” and “Super high Damping Factor”.
The P-4500 features the latest instrumentation amplifier
topology. It consists of a complete balanced input
amplifier block and a power amplifier block.
The balanced input amplifier block is related to the noise
performance and the power amplifier block is related tothe Damping Factor.

6The former model P-4200 has the excellent noiseperformance.
However, P-4500 achieves even 48% lower output noisevoltage than P-4200.
P-4500 guarantees,SN ratio: 121dB @Maximum-gain

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The output noise is also reduced by the fully discreteconfiguration amplifier which no ICs are installed on thesignal paths.
This makes it possible to allocate a high gain of 22dB tobalanced input amplifier section and conversely keep thegain of the power amplifier section to a low 6dB.
As a result, the noise influences at both the signal input
stage and power amplification stage are minimized, andthis realizes an astonishing noise reduction.

8P-4500 has the guaranteed 700 of Damping Factor.
It is 40% higher than the former model P-4200.
The actual value is in excess of 800.
**Damping Factor:
A index of speaker driving ability.
Higher Damping Factor amplifier has higher speakerdriving ability.
D.F. = 8Ω / Output-impedance9

4 Bi-polar transistors pair are installed in a parallel pushpull configuration though P-4200 was 3 parallel push-pull,
this contributes to reduced output impedance and higher
Damping Factor.
Also, while generating high output power, the electricalload per pair is dispersed and this enables the amplifier
to provide the stable power to loud speakers.

10Remote Sensing is the technique to lower the output
impedance of amplifier by the negative feedback withsignal sensing from nearby the speaker terminals.
Balanced Remote Sensing is the technique to make theoutput impedance even lower by both the signal sensing
and the GND sensing, that is the negative feedback ofGND level.
Not only Damping Factor, but also Total Harmonic
Distortion and Intermodulation Distortion are all improvedby the Balanced Remote Sensing.

11Mechanical relays are the common components forspeaker protection but the super high Damping Factor isachieved by the lower impedance component.
As the contact resistance of mechanical relay is higher
than people think, Accuphase has chosen the MOS-FETswitch instead of conventional mechanical relays forspeaker protection.
*On-resistance of MOS-FET used for P-4500: 2.0mOHM(MOS-FET for P-4200 : 2.1mOHM)
Thanks to the MOS-FET switch, the Damping Factor,
reliability and sound quality are all improved.
The large speaker terminals are directly mounted on
PCB, this enables to draw the shortest signal paths. P4500 is the amplifier which aims thorough low impedance
drive.

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