The GRAS 40PM-1 EQset™ is a new-generation 1/4-inch pressure-field miniature production line microphone upgraded from the base 40PM model, developed by Denmark GRAS with exclusive EQset equalization correction technology, dedicated to mass automated acoustic testing of consumer audio production lines.

With a total length of 34 mm, it shares identical dimensions with traditional production microphones for direct drop-in replacement of existing fixtures. Each unit is factory-calibrated with fixed sensitivity and flat frequency response: sensitivity deviation between individual microphones ≤ ±0.2 dB, and frequency response fluctuation ≤ ±0.5 dB up to 20 kHz. It eliminates the pain points of traditional microphones requiring individual TEDS correction and frequent line downtime for recalibration.

It is ideal for full mass acoustic inspection of audio components including speakers, Bluetooth headsets, TWS earbuds, miniature speakers, receivers and car audio speakers. It enables stable batch testing of full-band sound pressure, distortion and frequency response from 20 Hz to 20 kHz. Featuring outstanding stability against temperature & humidity fluctuations, it supports 24/7 continuous production operation, drastically reducing false reject and false pass rates, and improving test yield & line throughput.