Aphex Systems 320A owner manual Death of a Perfectly Good VU Meter, Birth of dBFS, DAT Tragedy

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320A

Compellor

Digital Audio’s Contributions to the Problem

Death of a Perfectly Good VU Meter

As superior as the VU monitor is for general audio work, it seems the fate of the VU paradigm is going to be a sad but quiet death from abandonment. Digital audio technocrats are dictating technology from their laboratories far away from where people create and produce art. They don’t really know much about VU, which means they don’t really understand the demands of the art or the end user’s needs.

Birth of dBFS

In the analog world, there can always be found a little more headroom. Magnetic tape has a very soft and spongy nonlinear area above the maximum operating level. It compresses peaks without hacking off the tops. Most other electronics have some headroom to spare. It is seldom catastrophic, from a sonic perspective, when a few peaks hit analog clipping. In the digital world, the same is not true.

Digital audio has a very hard peak ceiling that literally shaves off any and all excessive peaks. That causes severe audible distortion and needs to be avoided. True also is that, when the best digital audio had only 16 bits, it was readily discovered that the best sound came from recording at the maximum level to capture all the digital quantization possible and stay out of the low level grunge.

To assist with that cause, digital audio equipment makers disavowed the VU meter in favor of a new kind of peak responding meter. After a few early experiments, the digital audio meters have emerged with instant peak response (no peak integration like the PPM) with 0dB at the very top of the scale. The new scale is called dBFS (dB referred to full scale). This allows you to accurately see how your audio waves fit below the digital ceiling so you can avoid digital clipping.

DAT Tragedy

That may seem all well and good considering the fact that 16-bit audio has such limitations. But, now with 24-bit digital audio prevalent with its much greater useful dynamic range, the VU meter has not been reintroduced and probably won’t be unless a stroke of luck knocks some sense into somebody along the line. That is because of DAT machines.

Digital audio users get precious little technical training. What little there is comes from the equipment’s user manuals. DAT machines were the first popular digital recording media. Through the DAT manuals, users were taught to record the average levels at -18dB. OK, fine, if that means you are to record the average levels at –18dBFS. That leaves 18dB for swells of volume level and the host of variable peaks that may rise above by up to 14dB. The DAT manuals forgot to tell you that, however, and it was wrongly interpreted to mean the recording of average peaks should be at –18dBFS. That has unfortunately stuck as a general digital audio practice that needs to be corrected. The Compellor Model 320D can truly help.

Where The Compellor Fits In

The Compellor is an automatic level controlling device. In a VU world, its results are readily visible. Varying input levels become better matched and consistent output levels. The meters show it. In a PPM or dBFS world, it takes some understanding to see how the Compellor can be used effectively.

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Contents 320A Safety Declarations Fast Finderi320A Contents Page Quick Start Quick StartHow Does It Work? What Is a Compellor?What Does It Do? Bit Of Compellor HistoryIntroduction Page Mains Voltage Selection And Fuse UnpackingDamage & Claims Mounting In a Rack Power CordSafety Considerations Proper VentilationReference Level Setting InstallationRemote Connector Input ConnectionsSummary Specications Ratio Mixing IntroductionRecording MasteringBroadcast Radio Pre-processing Video Post-ProductionLive Concerts Video and Audio Tape Duplication Broadcast STL/ Phone Line DriverTelevision Broadcasting and Cable Systems Voice ProcessingHard Disk Recording Leveling Function Signal FlowProcessing Functions DVG Compressor FunctionDRC Silence GateMeter Selections Stereo EnhanceStereo Linking LimiterInput/Output Process SwitchOutput Control 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 RescueConfusion Where The Problem Comes FromAppendix F PPM StandardAppendix F VU StandardBirth of dBFS Where The Compellor FitsDeath of a Perfectly Good VU Meter 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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