Optical Compressors

Optical compressors, also known as opto-compressors, are a dynamic range attenuator that have a transducer. A light source in a photosensitive cell controls the gain reduction in an Opto-compressor, as it transforms energy from one form to another. These optical compressors serve to process and audio signal. In simple terms, they work by transforming the audio signal into light and back into electricity again. When nonlinearities are present, an appealing effect is created.

Optical Compressors: How They Work

In physics, the electro-optical attenuator is quite simple. The audio signal splits into two parts. The first one passes through the gain phase, while the other works as a detector that controls the gain phase. The light sensor and the detector control the gain reduction. These units have peculiarities that cause the gain cell to react only with modern components. The way these devices work has a direct impact over the time gaps, as well as over the attack and release parameters within the compressor. Electro-optical attenuators are popular among the mixing and mastering process.

The optical compressor has a photocell which has a gradual and soothing release curve. This effect sounds quite natural and musical. The first half of the release time occurs at maximum speed in opto-compressors. In contrast, the complete range can take several seconds.

In addition, the photocell creates an effect known as memory. The release time of the cell depends on the duration and intensity of the light to which It has been exposed. This interactive release eliminates uneven fluctuations from other types of compressors.

A Perfect Example

The LA-2A Limiting Amplifier created by Teletronix was one of the first devices that used an optical attenuator. Jim Lawrence, the mastermind behind this device, had a true passion for the realm of radio and broadcasting. One time, he became frustrated with another project he was working on. Hence, a new idea came about: and thus the leveling amp was born. The original idea was to create a leveling amplifier using optical sensors that would level the incoming audio signal. In order to achieve this, he combined a luminescent panel with photo-resistors and sealed them inside a vacuum-tube-sized metal container. And voilà: this optical attenuator gives the LA-2A a soothing program dependent optical compression.