Aphex Systems 320A owner manual What Is a Compellor?, What Does It Do?, How Does It Work?

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3. Introduction

3.1 What Is A Compellor?

A Compellor is the first and only product designed specifically for the transparent control of audio levels. While other audio processors are designed simply to compress and limit audio signals, a Compellor is designed to intelligently manage the dynamic range of audio without causing noticeable changes to the character and feeling of the sound. Contained within the Compellor are three gain controllers: a frequency discriminate leveler, a compressor, and a limiter, all working interactively. In addition, a dynamic verification gate, silence gate, and dynamic release computer intelligently guide the operation of the gain controllers to assure the least noticeable processing effects will be generated.

The name “Compellor” is a combination of “Compressor-Leveler-Limiter”.

3.2 What Does It Do?

Simply stated, a Compellor automatically evens out the varying levels in an audio system without making itself noticed. It may seem odd to have a processor you wouldn’t notice work- ing, but imagine being able to keep a wandering vocal track just right in the mix as if the talent were using perfect voice techniques. Imagine a TV show that always sounded just the right level even though scene changes were wide ranging. Now imagine these things without any background swells, pinched voices, or holes punched by a transient hitting the limiter. If you can, then you realize just a few things the Compellor can accomplish.

Without a Compellor, it is usual to insert a compressor or limiter in the line to control varying levels. That always results in degraded sound due to the processing by-products. Lost punch, overly fat backgrounds, inversion (when a loud sound gets lower than average), suck-down by transients, and noise swell ups are typical problems encountered with usual processing. The Compellor was designed specifically to avoid all of these problems and more.

3.3 How Does It Work?

Standard compressors and limiters process the sound on arbitrary principles of level detec- tion, something like an audio VU or peak meter. Our hearing is a much more complex pro- cess and we can readily hear the “attenuate and recover” effects caused by these simpler devices.

In contrast, a Compellor automatically detects and corrects the sound level according to how we hear, and therefore seems natural and relatively undetectable. The unique and patented circuitry in a Compellor resulted from years of experiments in audio processing and creates the only level controller on the market designed specifically to be as “transparent” to the ear as possible. Additional information about the processing circuits in a Compellor will be found in the various sections of this manual.

3.4 A Bit Of Compellor History

At first, there was a controversy about whether a Compellor actually did anything. Engineers would call up and complain they couldn’t hear the difference between “in” and “out” of the

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Contents 320A Fast Finderi Safety Declarations320A Contents Page Quick Start Quick StartBit Of Compellor History What Is a Compellor?What Does It Do? How Does It Work?Introduction Page Damage & Claims UnpackingMains Voltage Selection And Fuse Proper Ventilation Power CordSafety Considerations Mounting In a RackInput Connections InstallationRemote Connector Reference Level SettingSummary Specications Ratio Mastering IntroductionRecording MixingLive Concerts Video Post-ProductionBroadcast Radio Pre-processing Voice Processing Broadcast STL/ Phone Line DriverTelevision Broadcasting and Cable Systems Video and Audio Tape DuplicationHard Disk Recording Processing Functions Signal FlowLeveling Function Silence Gate Compressor FunctionDRC DVGLimiter Stereo EnhanceStereo Linking Meter SelectionsOperating Levels Process SwitchOutput Control Input/OutputGain Reduction Metering To Obtain Service Limited WarrantyAppendices Appendix B 320A Appendix C Appendix C Proper Wiring TechniquesAppendix D Part 1 Balanced OUT to Balanced Appendix DImpedance Balanced Outputs Part 5 Y Insert Cables Appendix E Compellor to the Rescue Appendix EPPM Standard Where The Problem Comes FromAppendix F ConfusionVU Standard Appendix FDAT Tragedy Where The Compellor FitsDeath of a Perfectly Good VU Meter Birth of dBFSAnalog/Digital Level Discrepancy Ideal Audio PackageWhat, Me Worry?

320A specifications

The Aphex Systems 320A is a dynamic processor designed to enhance the quality of audio recordings in professional settings. Known for its exceptional performance and versatility, the 320A offers a unique combination of compression, limiting, and expansion functionalities. This unit is an essential tool for sound engineers and producers looking to achieve polished sound.

One of the standout features of the 320A is its dual channel processing capability. This allows users to apply dynamic processing to two separate audio signals simultaneously, making it ideal for stereo or dual mono setups. The 320A offers a range of controls, including threshold, ratio, attack, release, and gain, allowing precise adjustments to be made according to the needs of any project.

The 320A utilizes Aphex's proprietary Intelligent Clipping technology, which helps to prevent distortion at high signal levels. This feature is particularly beneficial when working with dynamic sources like vocals and percussive instruments. Intelligent Clipping ensures that the audio remains smooth and clear, even when processed aggressively.

In terms of connectivity, the Aphex 320A is equipped with balanced XLR and TRS inputs and outputs, ensuring compatibility with various audio sources and devices. The unit supports both line-level and mic-level signals, providing flexibility for different recording scenarios. Additionally, its low noise operation ensures that the final output retains pristine audio quality.

Another significant characteristic of the 320A is its user-friendly interface. The front panel features easy-to-read meters and clearly defined controls, making it straightforward for users to monitor the audio levels and adjust settings in real-time.

The 320A also includes a sidechain capability, allowing users to trigger compression or expansion from an external source. This feature is useful for achieving effects like ducking or creating rhythmic dynamics in a mix.

In summary, the Aphex Systems 320A is a feature-packed dynamic processor that serves as an invaluable tool for audio professionals. With its dual channel processing, Intelligent Clipping technology, flexible connectivity options, and user-friendly design, the 320A stands out in the realm of audio processing equipment, delivering high-quality performance for a variety of recording and mixing applications.
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