Pioneer A-90D (1987)
High-end stereo pre-main amplifier with built-in D/A converter, released in 1987 as part of Pioneer's EX series
Overview
The Pioneer A-90D is a stereo pre-main amplifier with a built-in D/A converter, released in 1987 as part of Pioneer's EX series. It builds upon the design foundation of the Pioneer A-717, expanding its core architecture with advanced digital and analog integration. Designed for high-fidelity audio reproduction, it features separate digital and analog power supplies, extensive shielding, and a unique honeycomb chassis structure to reduce noise and vibration.
Specifications
| Year of Production | 1987 |
| Rated Output (20 Hz to 20 kHz) | 180W + 180W (4 Ω, 0.005%) / 150W + 150W (6 Ω, 0.003%) / 120W + 120W (8 Ω, 0.003%) |
| Dynamic Power | 400W + 400W (2 Ω) / 280W + 280W (4 Ω) / 160W + 160W (8 Ω) |
| Harmonic Distortion Factor | 0.003% (8 Ω, 20 Hz to 20 kHz) |
| Input Sensitivity / Impedance | Phono MM: 2.5mV/50k Ω / Phono MC: 0.25mV/40 Ω / CD, Tuner, Line, Tape: 150mV/50k Ω |
| Maximum Allowable Input (1 kHz, 0.008%) | Phono MM: 200mV / Phono MC: 20mV |
| Output Level / Impedance | Tape Rec, Rec Out: 150mV/0.8k Ω |
| Frequency Characteristic | Phono MM: 20 Hz to 20 kHz ± 0.2 dB / Phono MC: 20 Hz to 20 kHz ± 0.3 dB / CD, Tuner: 1 Hz to 200 kHz +0, -3 dB |
| Tone Control (Volume -40dB) | Bass: 100 Hz, ± 8 dB / Treble: 10 kHz, ± 8 dB |
| Subsonic Filter | 7 Hz |
| Digital Inputs | Two optical inputs |
| Digital Outputs | One optical output |
| Original Price | ¥220,000 |
Design
The A-90D uses a honeycomb-shaped chassis formed by drawing for the frame and transformer, with punched honeycomb patterns on the bottom plate and bonnet case. An extruded aluminum honeycomb heat sink is used, and five insulators—four resin-molded honeycomb and one cast iron—support internal components, including the heavy transformer housed in a cast iron case. Digital and analog sections are physically separated, with dedicated power supplies and shielding for digital circuits including data demodulation, PLL, and digital filter. The signal path is minimized via direct construction, and the unit features gold-plated input/output terminals, OFC grounding bus bars, copper-plated structural parts, and a newly developed large-capacity sealed capacitor resistant to electromagnetic induction. It includes a hybrid MC transformer in the phono stage, which automatically turns off when not in use, and employs a non-switching TypeIII circuit to eliminate switching distortion. Each channel has its own D/A converter, equipped with a glitch-less IC, MSB error correction, and a high-jitter-suppression PLL. The digital filter oversamples by a factor of four, uses a high-performance IC for minimal in-band ripple (±0.0001 dB), and feeds into a 5th-order Butterworth low-pass filter built with FDNR discrete circuits. A digital recording selector allows independent DAT recording, and input sources can be routed directly to the main volume via a Source Direct Switch.
Product Family
The A-90D expands on the core design of the Pioneer A-717, enlarging its basic configuration with enhanced digital integration and structural refinements.
Market
A used unit was listed for sale at 1,881.46 Canadian dollars with free shipping from Japan. One listing notes the unit as "testé fonctionnel" (tested functional).
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