Aphex Systems 320A owner manual Ideal Audio Package, Analog/Digital Level Discrepancy

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Appendix F

Most simply stated, the Compellor will accept an audio input, digital or analog, level it out and add some compression making it more consistent in average level. The resulting aver- age output level will target around 0VU. That means –20dBFS in the digital audio world and +4dBu (or –10dBV depending in the level reference settings) in the analog world. The digital output will have peaks that may rise up to 0dBFS but will probably not consistently rise above –8dBFS. That is because audio’s typical crest factor is 10 to 14 dB.

If the Compellor’s limiter is switched in, it will stop peaks at the –6dBFS level for digital audio, or 14dB above the 0VU reference for analog signals.

If the digital audio input was previously held consistent on a dBFS meter, as if a peak limiter had been used, it may not look as peak-consistent at the Compellor output. That is because the Compellor acts to correct the average levels at the expense of letting the peaks fly where they may. This should not deter you because you’re actually getting what you wanted. If you want to also see solidly consistent peaks after the Compellor’s processing, then you can add an Aphex Dominator multiband peak limiter. It will flawlessly bring the peaks to consistent levels without affecting the average level first established by the Compellor. The Compellor- Dominator pair is the best audio packaging system there is for effectiveness and sonic trans- parency.

Handling Codecs & Digital STL’s (Studio-Transmitter Links)

The Ideal Audio Package

Digital audio that is processed by a Compellor is packaged ideally. It has a consistent level residing around –20dBFS and safe peaks for any digital medium, including bit reduction codecs.

 

 

Coder

AES/EBU INPUT

 

 

ANALOG INPUT

ADC

DSP

 

TX

Microwave STL

RX

ISDN LINK

Decoder

AES/EBU OUTPUT

DSP

DAC

 

ANALOG OUTPUT

 

Figure F-2, Typical Codec Applications

Analog/Digital Level Discrepancy

Many digital STL’s and codecs have both analog and digital audio inputs. You should be aware that there can be a level error when switching between them. That is because, while the Compellor operates at the SMPTE standard level of –20dBFS average, the STL or codec’s analog input reference may be different. For example, an STL’s analog input reference may be stated as +4dBu. If the STL coder operates with SMPTE standards, it will convert that level to –20dBFS digital like the Compellor. In that case, switching between the Compellor’s analog output and digital output will result in the same digital audio level through the coder. However, some coders have been calibrated higher than the SMPTE standard. A +4dBu analog input may translate to higher than –20dBFS, perhaps as high as –12dBFS digital. This is presum- ably for the purpose of maintaining a better SNR through the codec but at the expense of all important digital headroom. When switching between the Compellor’s analog and digital

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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 Unpacking Damage & ClaimsMains Voltage Selection And Fuse Proper Ventilation Power CordSafety Considerations Mounting In a RackInput Connections InstallationRemote Connector Reference Level SettingSummary Specications Ratio Mastering IntroductionRecording MixingVideo Post-Production Live ConcertsBroadcast Radio Pre-processing Voice Processing Broadcast STL/ Phone Line DriverTelevision Broadcasting and Cable Systems Video and Audio Tape DuplicationHard Disk Recording Signal Flow Processing FunctionsLeveling 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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