Aphex Systems 320A owner manual Signal Flow, Processing Functions, Leveling Function

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320A

7. System Description

Compellor

 

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7.1 Signal Flow

The Compellor contains an input stage, an intermediate VCA stage, and an output stage. The input audio signal undergoes all processing in the VCA stage and is subsequently sent out through the output stage. A side chain system produces the control signals which change the VCA gain according to the signal processing requirements.

7.2 Processing Functions

A Compellor provides automatic gain control and excess peak control through the three prin- cipal functions of leveling, compression, and peak limiting. In addition, a dynamic verification gate (DVG), silence gate, and dynamic release computer (DRC) are incorporated as propri- etary support functions. A very subtle stereo enhancement technique is also included as a user selectable feature.

7.3 Leveling Function

The leveler is a slow acting automatic gain controller. This means that it responds to the aver- age power level of the audio signal much as the ear hears the loudness, or relative volume level. It constantly but slowly adjusts the VCA gain, attempting to keep the average volume level of the output signal constant. The compression ratio of the leveler is about 20:1 which means that if the input signal changes by 20dB, the leveler could keep the change of output level down to only 1dB. The actual range of leveling depends on how much gain reduction the user chooses.

The leveler has two operating speeds which can be selected by a front panel switch: “fast” and “slow”. The slow speed will not affect musical dynamics but will act fast enough to follow the general density trends of a program mix. The fast speed is better for plain voice work as it can follow the faster and more unpredictable voice changes of announcers and singers as they weave around the mic or use expression. The frequency discriminate leveling in the series “A” Compellors has so improved the leveling function that fast leveling is now feasible for use with musical programs to materially increase the loudness density of a mix without causing objectionable bass pullback and bass pumping.

The leveler is influenced by both the silence gate and dynamic verification gate whereby the gain control generated by the leveler can be frozen by either of the two gates. This means that either gate can make the leveler stop changing the VCA gain and hold the most recent leveling value.

The frequency discriminate leveler, as opposed to the previous leveler, responds more slowly to low frequencies than to higher frequencies. This represents a significant improvement whereby the ear can perceive much less effect of the bass signals controlling the Compellor gain. The prior leveler responds to all frequencies at the same rate.

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Contents 320A Safety Declarations Fast Finderi320A Contents Page Quick Start Quick StartWhat Is a Compellor? What Does It Do?How Does It Work? Bit Of Compellor HistoryIntroduction Page Mains Voltage Selection And Fuse UnpackingDamage & Claims Power Cord Safety ConsiderationsMounting In a Rack Proper VentilationInstallation Remote ConnectorReference Level Setting Input ConnectionsSummary Specications Ratio Introduction RecordingMixing MasteringBroadcast Radio Pre-processing Video Post-ProductionLive Concerts Broadcast STL/ Phone Line Driver Television Broadcasting and Cable SystemsVideo and Audio Tape Duplication Voice ProcessingHard Disk Recording Leveling Function Signal FlowProcessing Functions Compressor Function DRCDVG Silence GateStereo Enhance Stereo LinkingMeter Selections LimiterProcess Switch Output ControlInput/Output Operating LevelsGain Reduction Metering Limited Warranty To Obtain ServiceAppendices Appendix B 320A Appendix C Proper Wiring Techniques Appendix CAppendix D Appendix D Part 1 Balanced OUT to BalancedImpedance Balanced Outputs Part 5 Y Insert Cables Appendix E Appendix E Compellor to the RescueWhere The Problem Comes From Appendix FConfusion PPM StandardAppendix F VU StandardWhere The Compellor Fits Death of a Perfectly Good VU MeterBirth of dBFS DAT TragedyIdeal Audio Package Analog/Digital Level DiscrepancyWhat, 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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