The Bruel & Kjaer 4165 is a 1/2″ diameter externally polarized condenser microphone cartridge engineered for general and low-level sound measurements. The cartridge delivers sensitivity equivalent to a 1″ cartridge while maintaining a smaller physical footprint, eliminating undesirable sound field disturbance in confined measurement spaces. Its quartz-covered diaphragm and back-vented design enable operation with the UA0308 dehumidifier in high-humidity environments.
## Technical Specifications
• **Type:** Condenser Microphone Cartridge
• **Nominal Diameter:** 1/2″
• **Diaphragm:** Quartz-covered
• **Venting:** Back-vented (compatible with Dehumidifier UA0308)
• **Polarization:** Externally polarized, 200 V DC
• **Sensitivity:** Equivalent to 1″ cartridge; calibration chart supplied with each unit
• **Dynamic Range:** Capable of -17 dB to 180 dB SPL (dependent on matched preamplifier)
• **Mechanical Dimensions:**
– Diameter with grid: 13.2 mm (0.51 in)
– Diameter without grid: 12.7 mm (0.49 in)
– Height with grid: 16.3 mm (0.63 in)
– Height without grid: 15.2 mm (0.59 in)
– Preamplifier mounting thread: 11.7 mm – 60 UNS
## Key Features
• Quartz diaphragm construction provides stability across wide operating temperature ranges
• Back-vented design permits humidity control via external dehumidifier
• High resistance to humidity and temperature extremes
• Compact 1/2″ form factor with 1″ equivalent sensitivity
## Typical Applications
• General sound measurements in confined spaces
• Low-level acoustical measurements
• Standardized noise measurement protocols
• Audible and extended frequency spectrum analysis
## Compatibility & Integration
The 4165 cartridge operates exclusively with 1/2″ Bruel & Kjaer microphone preamplifiers: Types 2639, 2645, 2660, 2669B, 2669L, and 2619. Preamplifiers provide high input impedance (10 GΩ to 50 GΩ) and supply required 200 V DC polarization voltage.
