The single-channel OPA1677, dual-channel OPA1678, and quad-channel OPA1679 (OPA167x) op amps offer higher system-level performance over legacy op amps commonly used in audio circuitry. The OPA167x amplifiers achieve a low 4.5-nV/√Hz noise density and low distortion of 0.0001% at 1 kHz, which improves audio signal fidelity. These devices also offer rail-to-rail output swing to within 800 mV with a 2-kΩ load, which increases headroom and maximizes dynamic range. To accommodate the power-supply constraints of many types of audio products, the OPA167x operate over a very-wide supply range of ±2.25 V to ±18 V (or 4.5 V to 36 V) on only 2 mA of supply current. These op amps are unity-gain stable and have excellent dynamic behavior over a wide range of load conditions, allowing the OPA167x to be used in many audio circuits.
“The board presented here is a preamplifier for contact microphones that are used for amplifying the sound of musical instruments which do not contain electrical pickups, such as guitar and violins. Most contact microphones use a piezo element to convert …