JBL 4604B

The JBL 4604B is a compact three-way professional studio monitor from JBL's "SoundPro" Control Monitor line. It is the black-finish version of the 4604. JBL aimed it at nearfield and medium-field studio use. The record on it is mostly spec-sheet material. Production years, original pricing and period reviews haven't surfaced in the available documentation.

What is documented is a straightforward, sealed-box design built for the working studio. The 4604B pairs a 200mm (8") 128H woofer with a 100mm (4") 108H midrange and a 25mm (1") 044 titanium-laminate dome tweeter, crossing over at 900Hz and 4kHz. The 128H woofer uses JBL's Symmetrical Field Geometry (SFG) magnetic structure, and the 108H midrange is sealed-back. Sensitivity is rated at 90dB SPL (1W/1m), nominal impedance is 8 ohms, and recommended amplifier power is 150W continuous program. Frequency response is given as 45Hz–27kHz (−6dB) on the JBL Professional spec sheet and 60Hz–20kHz (±3dB) on the JBL Pro sheet — two slightly different published figures for the same cabinet. Dispersion is rated at 90° × 100°.

The cabinet is high-density particle board with a vinyl-clad black finish (the "B" suffix), a fabric-covered removable grille, and binding-post input connectors. It measures 445mm × 305mm × 270mm and weighs 11.4kg (25 lbs).

No user reviews, no common problems, no service manual details have turned up in the available record. It remains a known quantity primarily through its spec sheet and its place in JBL's professional monitor lineup of the late 1980s.

Type: 3-way, sealed (closed-box) studio monitor
Drivers: 128H 8" woofer, 108H 4" midrange, 044 1" titanium-laminate dome tweeter
Crossover: 900Hz / 4kHz
Sensitivity: 90dB (1W/1m)
Impedance: 8 ohms
Power handling: 150W continuous program
Dimensions: 445 × 305 × 270mm (H×W×D)
Weight: 11.4kg (25 lbs)