Bruel-Kjaer – 83.2 dB

Overview

This listing, catalogued as Bruel & Kjaer 83.2 dB, covers a Brüel & Kjær 1/4-inch condenser measurement microphone cartridge – the precision transducer class used for acoustic testing, environmental noise measurement, audio equipment calibration and sound quality analysis. The “83.2 dB” in the catalogue reference is a measurement value rather than a Brüel & Kjær type designation. The manufacturer identifies its measurement microphones by type number, and the 1/4-inch family comprises Types 4135, 4136, 4178, 4938 and 4939, each specified by open-circuit sensitivity, frequency range, dynamic range and cartridge thermal noise. Seven Star LLC will confirm the correct type number against your field type, sensitivity and bandwidth requirement before an order is placed.

As the an experienced supply partner for Bruel & Kjaer, Seven Star LLC proudly supplies this 1/4-inch condenser microphone and its full range of compatible preamplifiers and measurement accessories to acoustic and vibration laboratories across Oman and the GCC. Every unit is sourced through Bruel & Kjaer’s trusted supply channel, giving research institutions and industrial test facilities genuine calibration traceability and full manufacturer support.

Operating Principle

The microphone uses condenser (capacitor) transduction: a thin, tensioned diaphragm forms one plate of a capacitor with a fixed backplate, and sound pressure fluctuations deflect the diaphragm, producing a proportional change in capacitance that a matched preamplifier converts into a clean, low-distortion voltage signal. Because a 1/4-inch diaphragm is small and stiff, its resonance sits far above the audible band, which is precisely why Brüel & Kjær builds this size for wide-bandwidth work: the published frequency ranges of the 1/4-inch cartridges extend to 70 kHz on the pressure-field Type 4136 and to 100 kHz on the free-field Types 4135, 4178 and 4939. The trade the designer accepts for that bandwidth is sensitivity, and therefore noise floor, since a smaller diaphragm produces less output for the same sound pressure than a 1/2-inch or 1-inch cartridge.

Brüel & Kjær quantifies that noise floor as cartridge thermal noise, published as 29.5 dB(A) for Types 4135 and 4178 and 30.5 dB(A) for Type 4136, with Type 4939 specified at 28 dB(A) inherent noise. At the opposite end of the range the same cartridges accept very high levels before distortion becomes significant: better than 164 dB SPL for Types 4135, 4178 and 4939, and better than 172 dB SPL for Type 4136, each measured at 3% distortion at 100 Hz. That span is what makes the 1/4-inch class the standard choice for work a conventional audio microphone cannot survive – jet and turbine noise, blast and impulse measurement, high-intensity acoustic qualification – as well as for ultrasonic emission from leaks, bearings and valves.

Engineering Design of the Bruel-Kjaer 83.2 dB Microphone

The Bruel-Kjaer 83.2 dB microphone is housed in a rugged stainless steel body that protects the precision diaphragm and backplate assembly from mechanical damage, moisture, and dust while preserving full acoustic transparency. The capsule threads directly onto a matched Bruel & Kjaer preamplifier, forming a complete measurement chain that connects to standard data acquisition front ends, sound level meters, or portable analyzers via the preamplifier’s output cable.

As an interchangeable cartridge, the microphone can be swapped between preamplifiers and measurement positions without re-cabling an entire test setup, supporting both stationary laboratory installations and portable field measurement configurations. Its stable long-term calibration characteristics and rugged housing make it equally suited to a fixed test bench or a technician carrying it between multiple field measurement points in a single day.

Key Features

This 1/4-inch condenser microphone brings together low-noise precision and durability for demanding acoustic work.

• Brüel & Kjær 1/4-inch cartridges carry published frequency ranges of 4 Hz to 70 kHz (Type 4136) or 4 Hz to 100 kHz (Types 4135, 4178 and 4939), covering the audible band and well into the ultrasonic.
• Cartridge thermal noise is published at 28 dB(A) for Type 4939 and between 29.5 and 30.5 dB(A) across Types 4135, 4136 and 4178, giving a low and well-characterised measurement noise floor.
• The rugged stainless steel housing protects the diaphragm assembly during transport, handling, and field deployment.
• The microphone is fully compatible with the broader family of Bruel & Kjaer preamplifiers and measurement systems.
• Its compact 1/4-inch diameter suits both stationary and portable measurement configurations.
• Stable, repeatable calibration supports long-term monitoring programs as well as one-off acoustic surveys.
• Low self-noise makes it well suited to quiet environments where background noise assessment demands high sensitivity.
• The interchangeable cartridge design simplifies reconfiguring an existing measurement chain without full re-cabling.

Industrial Applications

Across Oman’s industrial and research sectors, this microphone supports environmental noise monitoring around processing plants, audio and PA system calibration in commercial and hospitality developments, and tonal quality analysis in manufacturing quality-control laboratories. Its low self-noise floor makes it a strong fit for community and environmental noise compliance surveys around district cooling plants and commercial complexes in Muscat, where measurement accuracy at typical ambient sound levels is critical to defensible compliance reporting.

With engineering support in Muscat, Seven Star LLC supplies this microphone and its accessories to acoustic consultancies, environmental compliance teams, and industrial quality-control departments throughout Oman, Muscat, and the Sohar and Salalah economic zones, supporting both new test-bench builds and the replacement of aging measurement microphones on existing systems.

Choosing the Right 1/4-inch Type

Selecting a measurement microphone begins with field type, not with price. A free-field cartridge such as Type 4135, Type 4178 or Type 4939 is corrected to read the sound pressure that would have existed had the microphone not been placed in the field, and is the right choice for open measurements where the source direction is known – machinery surveys, vehicle pass-by, environmental noise at a boundary. A pressure-field cartridge such as Type 4136 or Type 4938 reads the actual pressure at the diaphragm and belongs in couplers, small cavities, flush-mounted wall installations and impedance tubes. Using one where the other is required introduces a systematic error that no amount of careful calibration will remove.

The second decision is level. Type 4136 trades sensitivity for headroom, reaching beyond 172 dB SPL at 3% distortion where the free-field types reach beyond 164 dB SPL, which matters in blast, launch, gunfire and high-intensity acoustic test work. Type 4939 additionally carries a wide operating temperature range of −40 to +150 °C, a laser-welded stainless steel diaphragm and protection grid, and a documented ability to withstand the 1 m drop test of IEC 60068-2-32 – qualities that matter far more in a Gulf field measurement programme than in a climate-controlled laboratory.

Preamplifiers, Calibration and Traceability

A cartridge is only half a measurement chain. Brüel & Kjær 1/4-inch cartridges of this class require 200 V external polarization, which means a classical preamplifier and a supply capable of providing it, rather than a CCLD or constant-current front end intended for prepolarized microphones. Seven Star LLC confirms the polarization requirement against the customer’s existing analyzer or data acquisition front end at quotation stage, because a cartridge and front end mismatched on polarization will produce no usable signal at all.

Traceability is the other half of a defensible result. Brüel & Kjær sensitivity calibration for the 1/4-inch cartridges is performed with Pistonphone Type 4228 together with the 1/4-inch adaptor DP 0775 at 250 Hz, and the cartridges conform to IEC 61094. For environmental compliance reporting in Oman, where a measurement may be challenged by a regulator, a contractor or a neighbouring operator, a chain built on IEC 61094 conforming cartridges with current calibration certificates is what makes the number defensible. Backed by genuine manufacturer documentation, Seven Star LLC supplies cartridges, matched preamplifiers, pistonphones and calibration adaptors as a specified set rather than as loose parts.

Technical Specifications

The table below summarizes the published Brüel & Kjær specifications for the 1/4-inch condenser microphone cartridge family covered by this listing. Figures are quoted per type, and the applicable type number is confirmed at the point of order.

Request a Quote for Bruel-Kjaer – 83.2 dB

Seven Star LLC invites acoustic engineers, environmental compliance teams, and industrial quality-control departments across Oman and the GCC to submit a formal RFQ for the Bruel-Kjaer 83.2 dB condenser microphone. We supply on request with lead time confirmed at quotation, provide full technical datasheets on request, and our instrumentation division can help match this microphone to a compatible preamplifier for your specific measurement chain. Working closely with plant engineers in the region, Seven Star LLC supplies calibration-traceable instruments on request, with manufacturer documentation and technical support for model selection.

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