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[SOLD] JBL 4311 Alnico WX-A Walnut Early Generation Monitoring Speakers 12″ Woofer

The JBL 4311 Control Monitor (specifically the early versions and the 4311WX variant featuring the oiled walnut veneer) is an iconic, 1970s 3-way studio monitor.

Vintage enthusiasts highly prize the early iterations of this speaker because they utilize Alnico V magnetic assemblies across the drivers. These magnets provide incredible flux density and transient speed before JBL had to transition to Ferrite (muddy-looking gray magnets) due to the cobalt shortage of the late 1970s.

1. The Alnico Driver Complement

The driver layout of the original 4311 is unique because it was designed to be hung upside down near studio ceilings.Because of this, the woofer is placed at the top of the cabinet, closer to the ceiling boundary to couple the bass response.

Equipboard

 

  • Woofer (Model 2213 / 2213H early): A massive 12-inch (300mm) long-excursion bass driver. It uses a 3-inch edgewound copper ribbon voice coil and a 6.75-pound Alnico V magnet structure. The paper cone is coated with a sticky, proprietary white damping formulation (Aquaplas) to add mass and damp unwanted cone ring.

    Rhythm Gears+ 1

     

  • Midrange (Model LE5-10): A 5-inch (130mm) paper cone driver utilizing a 2.75-pound Alnico V magnet. It sits in its own isolated internal chamber so the air pressure from the woofer doesn’t distort its movement. It acts as a true rigid piston for clean vocals.

    Manuals.plus

     

  • Tweeter (Model LE25-2): A 1.4-inch (36mm) paper cone direct radiator surrounded by a distinctive ring of orange or dark dense foam to stop diffraction waves off the baffle. Powered by a 1.6-pound Alnico V magnet assembly.

    Rhythm Gears

     

2. Comprehensive Technical Specifications

Parameter Factory Specification
System Configuration 3-Way, 3-Driver Bass Reflex (Front Ported)
Cabinet Finish Oiled American Walnut (WX version) or Textured Gray
Frequency Response
Power Capacity Continuous Program
Nominal Impedance
Sensitivity (Very efficient for low-powered tube or solid-state amps)
Crossover Frequencies and
High Frequency Dispersion Horizontal and Vertical
Front Controls Independent Continuously Variable L-Pad Attenuators for “Presence” (Midrange) and “Brilliance” (Treble)
Enclosure Volume Approx.
Cabinet Construction dense particle board with lock-mitered joints
Dimensions (H x W x D)
Net Weight per speaker

3. Sonic Review & Performance Character

The Sound: “West Coast” Forwardness

The Alnico JBL 4311 is the quintessential “West Coast Sound” speaker. It does not possess a modern, ultra-flat frequency curve. Instead, it is highly musical, dynamic, and forward.

  • The Bass: Punchy, fast, and chest-thumping rather than ultra-deep. It rolls off cleanly below 45Hz, meaning it won’t shake your floor with sub-bass, but kick drums and bass guitars have an unmatched, live-in-the-room impact due to the massive 12-inch Alnico cone.

  • The Midrange: Very prominent. Rock music, brass instruments, and electric guitars sound alive and raw. Because the 12-inch woofer runs nearly wide open up to 1,500Hz without a heavy low-pass filter slope, the transition to the midrange is seamlessly fast.

  • The Top-End: Smooth but roll-off limited. The LE25 paper tweeter gives a very warm, vintage vibe but doesn’t extend into the modern stratosphere ( limit). It lacks the modern “air” of titanium or beryllium domes, but it ensures older or harsh recordings never sound painfully sibilant.

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