One of the most sought-after vintage midrange drivers ever made, and still commanding high resale values decades later.
Overview
The 713B is a phenolic diaphragm high-frequency driver, built for professional and high-end audio systems. It is not a full speaker, a receiver or a tube. The page describes it as "one of the most sought after vintage midrange by Western Electric," and that demand hasn't faded. It is the driver to have if you're piecing together a period-correct L-9 system.
Owners build whole systems around these. Paired with horns like the 12505 or the KS12024, the 713B has a rated frequency response of 500 Hz to 15,000 Hz. That covers the midrange and lower treble. It is not a brute-force tweeter. Sensitivity and power handling numbers were lost to time or never formally published. What is known is that the driver was designed as part of a matched system, not as a standalone upgrade.
Specifications
| Manufacturer | Western Electric |
| Product type | High frequency phenolic driver |
| Frequency response | 500 - 15,000 Hz |
| DCR (Direct Current Resistance) | Conflicting values reported: 3.6Ω (Audiogon), 2.9Ω/2.8Ω (eBay) |
| Voice coil impedance (V.C.Z) | 4Ω |
Key Features
Phenolic Diaphragm Design
The 713B uses a phenolic diaphragm. Phenolic drivers are known for rigidity and low resonance, which helps maintain clarity under load. It isn't plastic or metal. It's a composite that behaves differently across the frequency band, with a balance of stiffness and damping that many vintage enthusiasts find irreplaceable. The design is simple and works well when paired with the right horn.
Optimized for Western Electric Horns
This driver wasn't meant to go into just any cabinet. It was engineered for Western Electric horns, most notably the KS12024 and KS12025. The horn loading shapes the driver's output, extending its effective range and controlling dispersion. One user reports running a 713B with a 12505 horn, so mixing and matching within the Western Electric lineup was clearly done. Modern equivalents rarely get the same balance.
Post-War Alnico Magnets
Collectors describe the 713B as one of the "post-war Alnicos," and it uses the magnet technology of its era. Alnico magnets give a smooth, dynamic response with a natural compression that many associate with "warm" or "musical" sound. Unlike ceramic magnets, they cost more and are less powerful for their size, but they respond differently to signal transients. That is a key reason these drivers are still revered. Whether the 713B was part of a broader shift or a continuation of pre-war practice isn't documented.
Historical Context
The 713B was released simultaneously with the KS12024 horn, which suggests it was developed as part of a coordinated system rather than as a standalone upgrade. It was used in vintage Western Electric loudspeaker systems, most notably the L-9 speaker system, where it was the high-frequency element. No official production timeline exists. The reference to "critical 1940" in some sources is ambiguous, but it lines up with the post-war period, when Western Electric was refining its audio components for both commercial and high-fidelity applications. The company's audio division would later be re-established in 1996.
eBay Listings
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