Low Distortion Mono Preamp with Compression

A precision-engineered mono microphone preamplifier board measuring 2.2 cm in length and 1.5 cm in width, designed for reliability in embedded audio applications. Powered by a single DC rail from 3V to 5V, it draws low quiescent current and maintains stable operation across voltage fluctuations typical of battery discharge curves. The SSM2167 IC forms the foundation—offering factory-trimmed gain, excellent PSRR (>80dB), and built-in RF filtering to reject common-mode noise from nearby digital traces. Compression acts transparently to reduce peak-to-average ratio—keeping output within safe ADC input limits while retaining natural vocal tone. The noise gate activates only during sustained low-energy periods, avoiding choppy artifacts near speech onset/offset thanks to carefully tuned attack and release characteristics inherent to the SSM2167’s analog design. Use cases span voice-controlled home automation hubs, handheld field recorders, classroom lecture capture tools, and industrial voice loggers—any application where consistent, noise-resilient mono audio must be captured with minimal external circuitry.