Microphone or Electric Guitar Pre-Amplifier with Noise Gate and Compression

In personal electronics and computer audio system, the SSM2167 is a complete and flexible solution for conditioning microphone inputs. It is also very good for improving vocal clarity in communications and public address systems. Although it is not mentioned to be applied for electric guitar in the datasheet, the frequency response of this signal processor shows that it can be used for sustain and noise gating effect for electric guitars.

To maintain a set compression characteristic, a low noise voltage controlled amplifier (VCA) provides a gain that is dramatically adjusted by control loop. A single resistor set the compression ratio and can be varied from 1:1 to over 10:1 relative to the fixed rotation point. To prevent overload and to eliminate popping, signals above the rotation point are limited. Amplification of background or hum is prevented by a downward expander (noise gate). This results in optimized signal levels prior to digitization, thereby eliminating the need for additional attenuation or gain in the digital domain. The compression ratio, the flexibility of setting, and the time constant of the level detector, coupled with two values of rotation point, make the SSM2167 easy to integrate in a wide variety of microphone conditioning applications.

The device is guaranteed for operation over the extended industrial temperature range of -40′ C to 85′ C and this device is available in a 10-lead MSOP package. [Circuit’s schematic diagram source: analog.com]