Product Overview
The G.R.A.S. 1⁄2-inch Pressure Microphone Type 40AP is a precision condenser microphone designed for general-purpose acoustic measurements. It is suitable for use in couplers, boundaries, and enclosures, offering a large dynamic range and wide frequency response.

Specifications

• Frequency Response: 3.15 Hz to 10 kHz (± 2.0 dB), 12.5 Hz to 7.5 kHz (± 1.0 dB)
• Nominal Sensitivity: 50 mV/Pa
• Polarization Voltage: 200 V
• Upper Limit (3% Distortion): 148 dB re. 20 µPa
• Microphone Thermal Noise: 16 dBA re. 20 µPa
• Capacitance: 20 pF
• Temperature Range: -40 °C to +150 °C
• Dimensions: Length with grid: 16.2 mm, Diameter with grid: 13.2 mm
• Weight: 7 gm

Design and Compatibility
The microphone is externally polarized and measures sound pressure at the diaphragm location. It features a flat pressure-frequency response and requires corrections for reflections and diffractions in open sound fields. It is compatible with G.R.A.S. preamplifiers and other similar makes.

Compliance and Durability
All G.R.A.S. microphones comply with IEC 1094 standards for measurement microphones. They are made from non-corrosive, stainless materials to withstand rough handling and corrosive environments. Each microphone is guaranteed for 5 years and comes with an individual calibration chart.

Applications
Typical applications include precision acoustic measurements, coupler measurements, and flush (boundary) measurements.

Figures and Corrections
Figures included in the document illustrate the typical frequency response and free-field corrections for various angles of incidence, highlighting the need for adjustments in certain measurement conditions.