JBL 5234A (1974)

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

Overview

The JBL 5234A is a dual-channel electronic crossover introduced in 1974 for professional sound reinforcement and studio monitoring. It was designed to work with the JBL studio monitors 4343, 4350, 4345, 4355, 4430, and 4435. The inputs are transformerless differential amplifiers, and they take balanced or unbalanced line-level sources. Each channel has separate buffer amplifiers for the low and high-frequency outputs. The internal high-pass filters are programmable. Internal switching can combine both channels' low-frequency outputs into a mono 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

Plug-in Standard Crossover Frequency Modules set the filter type, slope, and frequency on the JBL 5234A. The slope is 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. They need Mylar capacitors (less than 5% error) and 1/4-watt resistors (less than 5% error). The unit has conversion protection for compression drivers. It ships with two cards that turn each channel into a unity-gain audio distribution amplifier with two identical outputs.

Context

The 5234A belongs to JBL's 5200 series of professional audio equipment and succeeds the 5234. It was developed for high-precision studio monitoring and live sound reinforcement.

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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