Pioneer A-09 (1992)
A high-end stereo pre-main amplifier built with pure class A operation and a minimalist, high-precision design philosophy.
Overview
The Pioneer A-09 is a stereo pre-main amplifier released in 1992 by Pioneer. It follows the company's Exclusive C7 philosophy, which centers on signal purity and structural isolation. It was built for audiophiles who want direct signal paths and clean amplification. To cut interference, it leaves out tone controls, balance and loudness circuits. It runs in pure class A with a non-feedback final stage, and it puts sonic accuracy ahead of convenience.
Specifications
| Rated Output (Both channel drive, 8 Ω) | 35W + 35W (20 Hz-20 kHz, 0.05%) |
| Rated Output (Both channel drive, 4 Ω) | 70W + 70W |
| Damping factor (8 Ω) | 150 (20 Hz to 20 kHz) |
| Input Sensitivity / Impedance Phono MM | 2.5mV/50k Ω |
| Input Sensitivity / Impedance CD, Tuner, Line, Tape | 150mV/50k Ω |
| Input Sensitivity / Impedance Balance | 150mV/600 Ω |
| Phono maximum allowable input MM | 150 mV (1 kHz, 0.05%) |
| Output Level / Impedance Tape Rec | 150mV/1k Ω |
| Frequency characteristic Phono MM | 20 Hz to 20 kHz ± 0.2 dB |
| Frequency characteristic CD, Tuner, Line, Tape | 1 Hz to 150 kHz +0, -3 dB |
| S/N (IHF, A-network Short circuit) Phono MM | 87dB |
| S/N (IHF, A-network Short circuit) CD, Tuner, Line, Tape | 109 dB |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Power consumption (Electrical Appliance and Material Control Law) | 220W |
| External dimensions | Width 440 x Height 198 x Depth 480 mm |
| Weight | 28.8kg |
Design
The A-09 uses a symmetrical twin monaural structure with a pre-power isolated design, which keeps crosstalk and interference to a minimum. The preamp circuit sits in a non-magnetic aluminum box, mounted on vibration-damping rubber, so it floats and stays shielded. Signal paths are short thanks to advanced direct construction, with the input relays and volume control placed just after the front panel terminals. The final stage runs in pure class A with no feedback, and an exclusive super linear circuit extends to the output. The chassis is newly developed, integrally molded from special resin to reduce resonance. A new aluminum heat sink design improves thermal performance. The volume control is a hand-made attenuator with carbon resistors and precision contacts, the same design as the Exclusive C7 series. All terminals are gold-plated, including the large vise-type speaker outputs, and there is one balanced input. The power supply has separate rectifiers for the pre and power sections, low-noise stack-type capacitors and a low-flux transformer. The power cord is a thick OFC type, and the knobs are machined aluminum.
Context
Pioneer engineers spent six years developing the concept behind the A-09. They wanted to express their audio philosophy inside the limits of a pre-main amplifier. The result was a flagship model that used the full scope of the company's Exclusive C7 technology.
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