Tannoy K3838-(15 inch) (1970)
The Tannoy K3838-(15") is a vintage 15-inch bass driver from Tannoy, the British company known for high-fidelity loudspeakers and professional monitoring gear. It was produced around 1970 and designed mainly for public address (PA) systems, studio monitors, and high-power sound reinforcement. Durability, efficiency, and clarity were what buyers wanted in that era. It is not as well documented as Tannoy's dual-concentric models, but it was a key component in several professional speaker enclosures of its time.
Design and Construction
The K3838-(15") has a 15-inch (380 mm) cone. "K38" likely refers to the cone size in millimeters, going by Tannoy's naming convention. The cone is paper with a cloth surround, which gives a balanced response with good transient characteristics. It is attached to a substantial 2.5-inch voice coil wound on a kapton former, which helps it handle high power with minimal thermal compression. The voice coil sits in a large ceramic magnet structure, giving a strong magnetic field for better efficiency and control over cone movement.
Sensitivity is 98 dB (1W/1m), which is very efficient. That let tube amplifiers and early solid-state power amps drive it well without needing a lot of power. Nominal impedance is 15 ohms. That is a somewhat unusual value by modern standards, but it was common in professional and commercial audio of the 1960s and 1970s. The 15-ohm spec likely made parallel and series wiring easier in large distributed speaker systems, such as train stations, auditoriums, and churches.
Performance Characteristics
Frequency response runs from approximately 400 Hz to 18 kHz. The K3838-(15") is not a full-range driver on its own. It was typically paired with a high-frequency compression driver in a two-way configuration. The 18 kHz upper limit suggests the unit either incorporates a titanium dome tweeter or was designed to work closely with one. Documentation and surviving speaker systems indicate it was often mated with a Tannoy HF horn driver to make a complete coaxial or two-way system.
The design favors midrange clarity and vocal intelligibility, which suited speech reinforcement. The motor structure is sturdy, and power handling is rated at 25 watts continuous and up to 50 watts peak, enough to work reliably in demanding environments. Resonance frequency is relatively high, likely around 60-70 Hz, though exact figures are scarce. That points to mid-bass duty rather than deep bass, in enclosures such as ported or horn-loaded cabinets.
Applications and Use in Systems
The K3838-(15") was frequently used in Tannoy's own professional speaker enclosures, including models for outdoor events, public address, and fixed installations. It may have been the bass section in systems similar to the Tannoy Super Twin, or other dual-driver configurations where a high-frequency unit was mounted coaxially or separately. Its 15-ohm impedance suggests it was often used in constant-voltage systems (such as 25V or 70V lines), where multiple speakers could be connected in parallel without overloading the amplifier.
In studio environments, variants of this driver appeared in nearfield and midfield monitors used by broadcasters and recording engineers, particularly in the UK and Commonwealth countries. Tannoy had a reputation for accurate sound reproduction, so even their professional drivers were engineered with fidelity in mind, along with durability.
Legacy and Collector Interest
Today the Tannoy K3838-(15") is a vintage component, sought after by audio restorers, PA system collectors, and fans of classic British sound reinforcement gear. It is not as well known as the Tannoy Dual Concentric drivers like the Red Monitor or Gold Reference series, but it has a niche appeal because of its build quality, efficiency, and historical significance in professional audio.
Original units in working condition are hard to find, since many saw heavy use in commercial installations. Refurbished units, particularly with reconed drivers or replacement surrounds, can still perform well. Some audiophiles have repurposed them in vintage-inspired speaker builds, especially where high sensitivity and vocal clarity are wanted.
Technical Specifications Summary
- Model: K3838-(15")
- Manufacturer: Tannoy (UK)
- Production Year: Circa 1970
- Type: 15-inch bass driver
- Impedance: 15Ω
- Power Handling: 25W RMS, 50W peak
- Sensitivity: 98 dB (1W/1m)
- Frequency Response: 400 Hz – 18 kHz
- Voice Coil Diameter: 2.5 inches
- Cone Material: Paper
- Surround: Cloth
- Magnet Type: Ceramic
- Diaphragm (HF): Titanium dome (when used with coaxial tweeter)
- Mounting Diameter: Approx. 13.7 inches (348 mm)
- Overall Diameter: 15 inches (380 mm)
- Depth: Approx. 7.1 inches (180 mm)
- Weight: Approx. 14.5 lbs (6.6 kg)
Conclusion
The Tannoy K3838-(15") dates from the late 20th century and was built for reliability and clarity. It served as a workhorse in countless sound systems across Europe, Asia, and beyond. Tannoy's more celebrated monitor lines overshadow it, but it continues to attract interest from vintage audio enthusiasts. It combines high efficiency, rugged construction, and smooth midrange response.
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