Accuphase B-6 (1978)

Name: Accuphase B-6
Brand: Accuphase

Power bridge network designed exclusively for use with specific Accuphase amplifiers, featuring DC-coupled NF loop and capacitor-free input/output.

Overview

The Accuphase B-6 is a power bridge network manufactured by Accuphase Laboratory, Inc. (originally Kensonic Laboratory, Inc.) and released in 1978 with an original price of ¥25,000. It was developed exclusively for use with the Accuphase M-60, P-300S, and P-300 power amplifiers and cannot be used with other Accuphase products. The unit employs an operational amplifier IC with high-frequency performance and low noise in its buffer and phase inversion circuits, contributing to minimal sound coloration.

Specifications

Gain	0dB
Maximum Output	5.0V
Harmonic Distortion	0.01% (20Hz–20kHz, 5.0V output)
Frequency Response	20Hz–20kHz +0 -0.2dB; DC–600kHz +0 -1.0dB
Input Impedance	100kΩ
Output Impedance	100Ω
S/N Ratio	110dB (IHF-A, 20Hz–20kHz, 2.0V output)
Power Supply	AC100V, 50Hz/60Hz
Power Consumption	4W
Dimensions	184mm (W) × 77mm (H) × 197mm (D)
Weight	2.0kg

Design

The B-6 uses an operational amplifier IC with excellent high-frequency characteristics and signal-to-noise performance in its buffer and phase inversion stages. Its negative feedback (NF) loop is DC-coupled, and no capacitors are present at the input or output, eliminating potential coloration. No phase correction is required across a wide bandwidth, helping maintain signal integrity and suppress sound quality degradation.

Context

The B-6 was designed solely for integration with the Accuphase M-60, P-300S, and P-300 amplifiers. It is not compatible with other models in the Accuphase lineup, indicating a tightly coupled system approach in the company's early product strategy.

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