JBL 4301B Broadcast Monitor

1979 - 1981

The JBL 4301B Broadcast Monitor is a compact two-way monitor built for broadcast and quality control work. JBL introduced it in 1979. It was small enough for OB trucks, remote recording setups, and compact control rooms.

Overview

Type	Two-way broadcast monitor
Enclosure	Sealed acoustic suspension
Dimensions	15.5" H × 10" W × 9.5" D (394 × 254 × 241 mm)
Weight	22 lbs (10 kg)
Impedance	8 ohms
Sensitivity	90 dB (1W/1m)
Power Handling	60 watts RMS
Frequency Response	50 Hz - 20 kHz (±3dB)
Crossover Frequency	2,500 Hz

Driver Configuration

Woofer: 8" JBL 116H-3 with ferrite magnet and coated paper cone
Tweeter: JBL 035Ti 1" dome tweeter with titanium diaphragm

History & Design Philosophy

JBL built the 4301B around what broadcast people dealt with. Unlike a studio recording room with treated acoustics and plenty of space, a broadcast facility often faced tight constraints:

Space Limitations: Mobile production trucks and remote recording setups demanded compact, portable monitoring
Environmental Durability: Equipment needed to withstand constant relocation and varied environmental conditions
Consistent Accuracy: Broadcast engineers required absolute confidence in their monitoring regardless of location
Magnetic Shielding: Essential for use near video monitors and other sensitive equipment

JBL engineers went for a portable design that kept the sound quality the company's monitors were known for. The 4301B used magnetically shielded drivers, which matter a great deal in broadcast use, and kept the smooth, wide-range response audio professionals expected.

The titanium dome tweeter was a forward-looking choice for its era. Many competing monitors used conventional soft domes. JBL's titanium dome offered better transient response and more extended high-frequency detail, which helped broadcast engineers spot problems in their audio chains.

Sound Character

The 4301B is small, but it delivers a surprisingly complete sound for its size:

Surprising Bass Extension - The sealed enclosure and carefully engineered 8-inch woofer provide surprisingly deep, articulate low frequencies for the cabinet size
Detailed Highs - The titanium dome tweeter delivers crisp, extended treble that reveals subtle details without harshness
Smooth Midrange - Vocal frequencies are rendered with natural warmth and clarity, essential for broadcast dialogue monitoring
Excellent Imaging - Precise driver integration creates a focused stereo image that aids in positioning decisions
Low Fatigue - The balanced presentation allows for extended monitoring sessions without listener fatigue

The 4301B is a sealed acoustic suspension design. That suited broadcast work, where predictable bass response was essential. Ported designs could sound boomy in confined spaces. The 4301B kept a consistent low-frequency character wherever it was placed.

Broadcast Applications

The 4301B found its way into a number of professional broadcast applications:

Mobile Production: OB trucks relied on the 4301B's compact size and consistent performance
Quality Control: Used in audio QC suites for program verification and loudness monitoring
Remote Recording: Location sound engineers appreciated the portability and accuracy
Radio Broadcast: On-air studios and production rooms valued the magnetic shielding

Technical Innovations

The 4301B had several technical features that set it apart from consumer speakers of the era:

Magnetic Shielding: Complete magnetic containment allowed safe placement near CRT monitors
Professional Terminals: Robust binding posts designed for repeated connection cycles
Coated Woofer Cone: Specialized coating improved weather resistance and consistency
Compact Crossover: Sophisticated network design optimized for the two-way configuration

Collector's Notes

The 4301B has a niche of its own in the vintage JBL market:

Rarity: Shorter production run and specialized application make well-preserved examples uncommon
Build Quality: Professional-grade construction ensures durability decades after manufacture
Modern Utility: Magnetic shielding and compact size make them practical for contemporary desktop audio
Underrated Performance: Often overlooked in favor of larger JBL monitors, the 4301B offers surprising capability

Common Issues to Check:

Woofer surround condition (foam surrounds may need replacement)
Titanium tweeter diaphragm integrity
Crossover capacitor condition
Cabinet seal integrity (critical for acoustic suspension performance)
Professional binding posts for corrosion or damage

Listening Tips: The 4301B works best for nearfield monitoring. Put them on sturdy stands at ear level for the best imaging. They aren't designed for high-SPL work, but at moderate listening levels they are very accurate.

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