Variable-slope-compressor-expander

Description: Compression and expansion ratios other than 2:1 can be achieved by the circuit shown. Rotation of the dual potentiometer causes the circuit connection to change from a basic compressor to a basic expander. At the center of rotation, the circuit is 1:1, exhibiting neither compression nor expansion. The input-output transfer characteristic is thus continuously variable from 2:1 compression to 1:2 expansion. If a fixed compression or expansion ratio is desired, proper selection of fixed resistors can be used instead of the potentiometer. The optional threshold resistor will cause the compression or expansion ratio to deviate towards 1:1 at low levels. A wide variety of input-output characteristics can be created with this circuit.

The described circuit is a versatile audio processing tool that allows for dynamic alteration of signal characteristics through compression and expansion. The dual potentiometer serves as a critical component, enabling real-time adjustments to the circuit's behavior. When the potentiometer is rotated, it modifies the circuit configuration, transitioning it from a compressor mode—where the input signal is reduced in dynamic range—to an expander mode, which increases the dynamic range of the signal.

In the center position of the potentiometer, the circuit achieves a 1:1 ratio, effectively neutralizing any compression or expansion effects. This central setting provides a baseline for audio signals, ensuring that unaltered signals can pass through the system without modification. The ability to continuously vary the input-output transfer characteristic from a 2:1 compression ratio to a 1:2 expansion ratio allows for a wide range of audio processing applications, catering to different sound design needs.

For applications requiring fixed ratios, the circuit can be adapted by substituting the dual potentiometer with fixed resistors. This adjustment enables precise control over the compression or expansion levels, ensuring consistent performance tailored to specific requirements. The inclusion of an optional threshold resistor further enhances the circuit's functionality. By introducing this component, the circuit can be configured to maintain a compression or expansion ratio closer to 1:1 at lower signal levels, preventing unwanted distortion or artifacts during quiet passages.

Overall, this circuit design offers a flexible solution for audio engineers and musicians, providing the capability to create diverse input-output characteristics that can enhance the quality and dynamics of audio signals in various applications, from live performances to studio recordings.Compression and expansion ratios other than 2: 1 can be achieved by the circuit shown. Rotation of the dual potentiometer causes the circuit hook-up to change from a basic compressor to a basic expander. In the center of rotation, the circuit is 1:1, has neither compression nor expansion. The (input) output transfer characteristic is thus continuously variable from 2:1 compression to 1 :2 expansion.

If a fixed compression or expansion ratio is desired, proper selection of fixed resistors can be used instead of the potentiometer. The optional threshold resistor will make the compression or expansion ratio deviate towards 1:1 at low levels. A wide variety of (input) output characteristics can be created with this circuit.