Aphex Systems 320A owner manual Compressor Function, Drc, Dvg, Silence Gate

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7.4 Compressor Function

The compressor cooperates with the leveler to supply more consistent program level control than possible with the leveler alone. While the leveler is relatively slow responding, the com- pressor works much faster to control both the transients and other quick changes in the sound level. The compressor has a variable compression ratio depending upon depth of compres- sion. In other words, the ratio gets higher as more compression is used. Even at the highest ratio it is not excessively stiff, achieving a maximum of only about 3:1.

The attack and release times of the compressor are program dependent as a function of the audio waveform’s complexity. Thus, most of the sonic artifacts of compression are minimized or eliminated. It can be generalized that transient sounds will cause faster attack and release as well as greater compression than continuous and slow changing sounds. Like the leveler, the compressor is also influenced by the DVG and silence gate. Either gate can force the compressor to freeze and hold its gain control at a steady value.

7.5 DRC

The dynamic release computer, or “DRC” is directly imbedded in the compressor to control the release time. This circuit detects the audio waveform and directly affects the compres- sion detector. The result is a compressor which responds differently to “fat” and “dense” sounds than for “thin” and “peaky” sounds. This is how the Compellor can better match the changing elements in a program. For example, the DRC helps the Compellor match up a live announcer’s voice level and density with the relatively heavier density of a recorded cut-in or segue without resorting to excessive compression effects.

7.6 DVG

The “dynamic verification gate” continuously detects the Compellor’s processed VCA output signal and computes the historical average of peak values. It also “verifies” when the present peaks exceed or equal the historical average and outputs a “stop and go” control for both the leveler and compressor functions. Whenever the present peak amplitude is below the histori- cal average, the leveler and compressor gain controls are frozen by “gating” their respective level detectors into a “stop and hold” mode. Otherwise the level detectors are gated into the

“track and go” mode. Thus, the word “gate” does not indicate the audio signal itself is being gated in any way, although our use of the term “Silence Gate” has confused some uninformed users.

7.7 Silence Gate

This is not an audio gate. It does not affect the main audio path. The Silence Gate acts to gate the gain control functions, thereby causing the gain to either “freeze” or continue being controlled. The net effect is to prevent the background noise from swelling up when the pro- gram stops for a period of time. You could interpret the Silence Gate as an augmentation to the DVG function.

The DVG, described above, needs a continuing source of audio to maintain its operation. If the audio should stop for any reason, the DVG first freezes the VCA gain then simply relinquishes all control after about 1.5 seconds of silence. This would allow the Compellor to begin recovering gain and thus bring up the background noise level. To prevent this, the Silence Gate is used. Whenever the input audio signal drops below the user selected silence threshold for one second or longer, the silence gate circuit freezes the VCA gain in lieu of the DVG circuit. You should set the Silence Gate threshold to a level above the typical back-

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Contents 320A Fast Finderi Safety Declarations320A Contents Page Quick Start Quick StartWhat Does It Do? What Is a Compellor?How Does It Work? Bit Of Compellor HistoryIntroduction Page Unpacking Damage & ClaimsMains Voltage Selection And Fuse Safety Considerations Power CordMounting In a Rack Proper VentilationRemote Connector InstallationReference Level Setting Input ConnectionsSummary Specications Ratio Recording IntroductionMixing MasteringVideo Post-Production Live ConcertsBroadcast Radio Pre-processing Television Broadcasting and Cable Systems Broadcast STL/ Phone Line DriverVideo and Audio Tape Duplication Voice ProcessingHard Disk Recording Signal Flow Processing FunctionsLeveling Function DRC Compressor FunctionDVG Silence GateStereo Linking Stereo EnhanceMeter Selections LimiterOutput Control Process SwitchInput/Output Operating LevelsGain 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 EAppendix F Where The Problem Comes FromConfusion PPM StandardVU Standard Appendix FDeath of a Perfectly Good VU Meter Where The Compellor FitsBirth of dBFS DAT TragedyAnalog/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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