Western Electric 597A (1929–?)

Name: Western Electric 597A
Brand: Western Electric

A whisper-thin aluminum ribbon, wound like a secret, lives inside a die-cast fortress—built not to impress, but to fix what the big horns got wrong.

Overview

You don’t just plug in a Western Electric 597A and forget it. This isn’t background gear. It’s a field coil compression driver with an attached horn—specifically a high-frequency correction unit, born out of frustration. Back in 1929, Western Electric engineers realized something was off: their flagship 15A, 16A, and 22A horns, while powerful, had a frequency response that started falling off sharply around 3–4kHz at 6dB per octave. That meant mids and highs lost energy fast, leading to complaints, bad press, and a reputation for dullness in real-world listening. The 597A wasn’t designed to dazzle—it was engineered to correct. It was the scalpel to the horn’s sledgehammer, a precision tweeter meant to restore clarity where the system was bleeding out.

Officially known as the Western Electric 597A Field Tweeter—also referenced as the WE-597A or the Bostwick Tweeter—this unit sits at the intersection of brute mechanical precision and delicate material science. It’s not just a tweeter; it’s a field coil driver, meaning it needs an external power supply to energize its magnetic field, just like the big WE low-frequency drivers of the era. That alone makes it a project, not a plug-and-play component. But for those willing to wire up the extra supply and design the right crossover, the payoff is reportedly transformative. When paired with a WE-555 driver, or even integrated into ALTEC or Jensen systems, owners note a distinct “WE unique luster” and a “very soft texture” in the highs—qualities that modern drivers often struggle to replicate. The sound is described as clear, transparent, and beautiful—no small praise for a component designed nearly a century ago to solve an engineering flaw.

What’s striking isn’t just the performance, but the build. The voice coil uses an edgewise-wound aluminum ribbon, made from wire so fine it’s “about the same thickness as a hair”—even finer than that used in the WE-594A. That ribbon is wound on an ultra-thin bobbin and mounted rigidly in a die-cast aluminum frame with zero play. There’s no slop, no wiggle—just absolute mechanical integrity. It’s the kind of construction that makes you question whether anything made after 1950 has any right calling itself well-built. The patents stamped on its label—1707544, 1707545, 1730425, 1734624, and 1907723—aren’t just decoration. They’re a paper trail of innovation, each representing a small battle won in the war for fidelity.

Specifications

Manufacturer	Western Electric Co., Inc.
Product type	high frequency compression driver with attached horn, field coil driver
Voice coil impedance	20.6 ohms
Field coil impedance	7.1 ohms
Field coil power supply requirement	6-7 volts at one amp
Serial number (example)	1480

Key Features

Edgewise-Wound Aluminum Ribbon Voice Coil

The heart of the 597A is its voice coil—a ribbon of aluminum so fine it defies belief. Wound edgewise (meaning the flat side of the wire faces outward, maximizing surface area in the magnetic gap), it’s made from wire thinner than that used in the WE-594A, reportedly “about the same thickness as a hair.” This isn’t just a gimmick; it reduces mass dramatically, allowing the diaphragm to respond with extraordinary speed and detail. The result is a tweeter that doesn’t just reach high frequencies—it reveals them, with a transparency that owners describe as “very clear” and “beautiful.” The trade-off? Fragility. That delicate ribbon demands respect, proper crossover protection, and stable operating conditions. You don’t abuse a 597A and expect it to survive.

Die-Cast Aluminum Frame and Rigid Mounting

Western Electric didn’t skimp on structure. The voice coil assembly is mounted in a “very sturdy die-cast aluminum frame” with no looseness—every part locked down, every vibration damped. This isn’t overbuilt; it’s precision-built. Any flex or resonance in the frame would smear the transient response, but the 597A’s construction eliminates that risk. The frame isn’t just a housing—it’s part of the acoustic design, ensuring the magnetic gap stays perfectly aligned and the diaphragm moves only as intended. It’s one reason the unit still commands awe nearly a century later: the build quality is so far beyond its time that it feels almost alien today.

Field Coil Excitation

Like the best WE drivers of its era, the 597A uses a field coil instead of a permanent magnet. That means it requires an external 6–7 volt DC power supply delivering one amp to energize the magnetic field. It’s an inconvenience by modern standards—another box, more wiring, another point of failure—but it’s also the source of its sonic magic. Field coils produce a stronger, more stable magnetic field than early permanent magnets, leading to lower distortion, better damping, and a more dynamic presentation. It’s why owners report that “WE unique luster”—a shimmer and ease in the highs that solid-state magnet systems often lack. But it’s not plug-and-play. You need to research the correct crossover frequency and ensure the power supply is clean and stable. This isn’t a tweeter for the lazy.

Integrated Horn and Patent Portfolio

The 597A isn’t just a driver—it’s a driver with an attached horn, making it a complete high-frequency compression unit. The horn shape and flare are tuned to work with the driver’s output, ensuring smooth dispersion and efficient coupling to the air. It’s not user-replaceable or modular; this is a matched system, engineered as a whole. And the five patents listed on its label—1707544, 1707545, 1730425, 1734624, and 1907723—are not just legal formalities. They cover core innovations in voice coil construction, magnetic circuit design, and horn coupling—each a piece of the puzzle that made the 597A a solution, not just another component.

Historical Context

The Western Electric 597A BOSTWICK TWEETER was developed starting in 1929 as a high-range correction unit for the 555W receiver. It wasn’t conceived as a luxury add-on or a high-end upgrade—it was a necessary fix. The 15A, 16A, and 22A horns, while powerful and widely used in theater and broadcast systems, suffered from a narrow frequency band. Energy dropped off steeply around 3–4kHz at a rate of 6dB per octave, making music sound dull and speech lack presence. Complaints piled up, reviews turned negative, and Western Electric responded not with marketing, but with engineering. The 597A was the answer: a targeted high-frequency supplement to restore balance. It wasn’t meant to stand alone—it was meant to make the whole system sound right.

Collectibility & Value

The original WE-597A is considered particularly hard to obtain, even by Western Electric standards—units that are already rare and sought after. Collectors report that currently, almost no WE-597A units are circulating on the used market. One auction listing confirms the existence of at least one unit (serial number 1480), but no sale price was disclosed, leaving current market value unknown. Given its scarcity and the complexity of field coil operation, ownership is limited to specialists and restoration experts. Before acquiring one, buyers are advised to measure both voice coil and field coil continuity and impedance to verify functionality. Restoration requires a dedicated power supply for the field coil and a properly designed crossover—research into historical literature is recommended to determine the correct crossover frequency. Common problems include loss of voice coil and field coil continuity and incorrect impedance, which should be measured before use; the unit requires a dedicated power supply for the field coil and a properly designed crossover—research into historical literature is recommended to determine the correct crossover frequency.