PLACID vs GRAS 40AE | General Purpose Acoustic Measurement Microphone Comparison

The GRAS 40AE is a widely used 1/2-inch free-field condenser measurement microphone that covers the Class 1 performance range for general-purpose acoustic measurement. PLACID Class 1 free-field measurement microphones offer a directly comparable performance level with equivalent calibration documentation options. This comparison is intended for engineers evaluating alternatives to the GRAS 40AE for environmental noise, NVH, building acoustics, or compliance measurement applications.

Technical Comparison

• Capsule type: both 1/2" externally-polarised condenser, free-field design, 200 V polarisation
• Sensitivity: both approximately -26 dB re 1 V/Pa at 1 kHz
• Self-noise: GRAS 40AE 14 dB(A); PLACID PM200 < 16 dB(A) — 2 dB difference is significant only for measurement below ~25 dB(A)
• Frequency response: both flat within IEC 61094 Class 1 tolerances from 20 Hz to 20 kHz
• Dynamic range upper limit: both suitable for acoustic measurement to approximately 146 dB SPL

Application Coverage

• Environmental noise monitoring — both fully suitable for IEC 61672-1 Class 1 outdoor measurement
• Sound power measurement to ISO 3744 — both appropriate for 10-point hemisphere arrays
• Building acoustics to ISO 16283 — both Class 1 as required by the standard
• Automotive pass-by noise to ISO 362 — both Class 1 as required

Calibration Certificate Comparison

• Factory certificate: both available with manufacturer's QA/AC certificate confirming specification compliance
• Accredited calibration: both available with ISO/IEC 17025 accredited certificate from nationally-accredited calibration laboratory
• PLACID stability programme: quarterly reference sensitivity monitoring providing documented stability evidence — not standard with GRAS 40AE

Contact PLACID to discuss preamplifier compatibility assessment if you are considering PLACID capsules as alternatives to GRAS 40AE capsules in an existing signal conditioning infrastructure.

Procurement and Calibration Continuity

For organisations already using GRAS 40AE capsules that are reaching the end of their calibration interval, replacing the capsule with a PLACID equivalent while retaining the existing GRAS preamplifier housing is often the most cost-efficient route. PLACID will confirm thread and electrical compatibility for your specific preamplifier model before order confirmation. Sensitivity screening is available for replacement capsule batches. For ongoing programmes with documented calibration histories, PLACID can issue a calibration certificate that continues the sensitivity traceability record from the previous instrument, supporting measurement programme continuity with minimal documentation disruption.