The P-7500 inherits technology features and concepts of the 40th anniversary commemorative model A-200 and subsequent M-6200 and takes these even further. Some of the highlights are a drastic reduction in noise and a significant further improvement of the damping factor. In the final stage, the parallel configuration of output devices ensures high current capacity and keeps the output impedance of the power amplifier extremely low. In addition, intensive research has culminated in an improved NFB loop with remote sensing, and the use of MOS-FET switches characterized by low 'on-resistance'. This further improves the ability to handle any speaker with competence, realizing constant-voltage drive even with extremely low load impedances. The guaranteed damping factor of at least 1,000 demonstrates the impressive success of this approach. By further refining the parallel drive and gain allocation of the input stage, Accuphase engineers were able to push the noise floor to previously unthinkable levels, achieving an amazing signal-to-noise ratio of 125 dB at maximum gain and 131 dB at the –12 dB gain setting.
The balanced input stage circuitry features Instrumentation amplifier topology such as used in high-precision measuring equipment. To achieve ultra low noise, the input stage gain is set to a high value, which in turn allows using a high power supply voltage so that distortion at large amplitudes is eliminated. Signal purity is further elevated by the use of ultimate-quality fully discrete components.
Accuphase's original MCS (Multiple Circuit Summing) principle uses a number of identical circuits connected in parallel to achieve superior performance characteristics. MCS+ is a further refined version of this approach, which extends the parallel operation approach to the class-A drive stage of the current/voltage converter, thereby further lowering the noise floor.
Output stage with 10-parallel push-pull power arrangement of bipolar power transistors mounted directly to large diecast aluminium heat sink, also comprising MCS+ circuitry and current feedback amplifier. Two completely identical units arranged at left and right are used.
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Continuous Average Output Power : Stereo operation - 800 watts per channel into 1 ohm, 500 watts per channel into 2 ohm, 500 watts per channel into 2 ohms, 250 watts per channel into 4 ohms, 125 watts per channel into 8 ohms. Monophonic operation (bridged connection) - 1600 watts into 2 ohms, 1000 watts into 4 ohms, 500 watts into 8 ohms.
Total Harmonic Distortion: Stereo operation - 0.05% with 2 ohm load, 0.03% 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: 1000
Input Sensitivity (with 8-ohm load, GAIN selector in MAX position): Stereo operation - 1.26 V for rated continuous average output. 0.11 V for 1 watt output. Monophonic operation - 2.52 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): 125 dB (GAIN selector at MAX), 131 dB (GAIN selector at -12 dB) At rated continuous average output
Output Level Meters: －40 dB to +3 dB (indication in dB and %) Logarithmic scale, with defeat switch, hold time switchable 3 s / ∞
Power Requirements: AC 120 V/230 V, 50/60 Hz (Voltage as indicated on rear panel)
Power Consumption: 117 watts idle. 820 watts in accordance with IEC 60065
Maximum Dimensions: Width 465 mm, Height 238 mm, Depth 515 mm
Mass: 48.6 kg net, 58.0 kg in shipping carton