JBL 5234A (1974)

Name: JBL 5234A
Brand: JBL

Dual-channel active crossover network designed for professional studio and sound reinforcement systems.

Overview

The JBL 5234A is a dual-channel electronic crossover introduced in 1974 for use in professional sound reinforcement and studio monitoring applications. It was specifically designed to work with JBL studio monitors including the 4343, 4350, 4345, 4355, 4430, and 4435 models. The unit features transformerless differential amplifier inputs for balanced or unbalanced line-level sources and provides separate buffer amplifiers for low and high-frequency outputs on each channel. It includes internal high-pass filters that are programmable and offers internal switching to combine both channels’ low-frequency outputs into a monaural signal for subwoofer use.

Specifications

Type	Active, 2-way electronic crossover
Gain	0 dB in the pass band
Crossover point	-3dB +/- 10%
Damping property	12dB/oct or 18dB/oct (determined by plug-in module)
Total harmonic distortion factor	0.01% THD, 20 Hz to 20 kHz @ +18 dBv into a load greater than 10 kΩ
Frequency characteristic	20 Hz to 20 kHz ± 0.5 dB (high-pass functions disengaged)
Signal-to-noise ratio	Greater than 90 dB, 20 kHz equivalent bandwidth
Channel separation	Greater than 70 dB, 20 Hz to 20 kHz
Rated output	6.2 V rms (+18 dBv) measured with 20 Hz to 20 kHz equivalent bandwidth filter
Input impedance	Greater than 50 kΩ
Load impedance	600 Ω or greater
Output impedance	50 ohms, unbalanced
Input	Screw type terminal 6.3 mm horn jack, 3-circuit balanced input
Output	Screw type terminal 6.3 mm Horn Jack, 2 Circuit Unbalanced Output
Power	100 - 120 or 200 - 240 V AC, 50 or 60 Hz
Power consumption	6W
External dimensions	Width 483mm x Height 44mm x Depth 194mm (1 EIA standard rack size)
Weight	1.8 kg (4 lb) net weight
Operating Temperature	5° C (41° F) to 55° C (132° F)

Design

The JBL 5234A uses plug-in Standard Crossover Frequency Modules to set filter type, slope, and frequency—either 12 dB/oct or 18 dB/oct depending on the module installed. Each channel has a continuously variable high-level control and internally switchable low-frequency equalization and subsonic filtering. Blank modules are available for custom crossover points, requiring installation of Mylar capacitors (less than 5% error) and 1/4-watt resistors (less than 5% error). The unit includes conversion protection for compression drivers and ships with two cards that convert each channel into a unity-gain audio distribution amplifier with two identical outputs.

Context

The 5234A is part of JBL's 5200 series of professional audio equipment and is the successor to the 5234. It was developed to meet the demands of high-precision studio monitoring and live sound reinforcement environments.

Market

The JBL 5234A had an original price of ¥140,000 around 1983. As of the research date, units are listed for $399 in excellent condition and fully functional.

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