Aphex Systems 320A owner manual Appendices

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320A

9. Appendices

Compellor

Appendix A: Balanced and Unbalanced Lines and Operating Levels

Interfacing all types of equipment with balanced and unbalanced lines and can sometimes be trouble - some. First you have to somehow connect balanced to unbalanced and then you have to deal with dif - ferent levels. This tutorial will teach you about the principles of balanced and unbalanced lines, wiring standards, and how to e￿ectively interface them.

Standards

Professional audio equipment usually comes equipped with inputs and outputs that are balanced using 3-pin XLR connectors and sometimes 1/4 inch phone jacks as well. This equipment most often is designed to operate at +4dBu, a professional indus - try standard. That translates to a magnitude of 1.23 volts RMS (Root-Mean-Squared).

Consumer gear has unbalanced I/O as standard, usu - ally on RCA jacks. The normal operating signal level follows the IHF (Institute of High Fidelity) standard of -10dBV, or 0.316 volts (316mV) RMS. Converting to dBu dimensions, this works out to be the same as -7.79dBu. There is therefore a di￿erence of 11.79dB between pro and consumer operating levels.

Grounding

There is the notion that some king of earthly “ground” exists out there that sinks all the noise and acts as some kind of a shield. You see wires connected to ground rods and water pipes that are supposed to get a good ground. This is not a correct interpreta - tion of grounding from an audio standpoint. Proper grounding of equipment and wiring is important and you will gain a better understanding of that as you read along.

Balanced -vs- Unbalanced

Every audio signal is connected through a circuit. The circuit must contain two conductors to create a com - plete return path. In other words, a signal voltage is conducted to a piece of equipment by injecting a cur - rent into a wire. That current has ￿ow though to the destination through the wire and return back to the source through another wire. Since audio is an alter - nating voltage, swinging through negative and posi - tive polarity, the current through the two conductors changes direction each alternate half cycle. Which wire is the source and which is the return alternates accordingly. In this regard, balanced and unbalanced

lines are the same. They both need two conductors.

What makes a system unbalanced is when one of the wires is formed into a tube that wraps around the other conductor, without touching it, such that the outer conductor can be said to “shield” the inner conductor. This describes all of the coaxial cable used for video, cable-TV and radio as well as most of the high ￿delity audio cables.

Balancing

If both conductors are identical insulated wires that are twisted together, then they form a balanced line. This describes telephone lines, microphone cables, and most professional audio cables. Typical balanced cables include an additional shield wrap around the twisted pair, but this is not strictly required for bal - anced lines to work properly.

Figure 1 Balanced Line Model

Figure 2 Unbalanced Line Model

Many people, because they have more experience with unbalanced wiring, think that balanced is confusing. Believe it or not, balanced lines are really easier to understand than unbalanced. There is no grounding issue with balanced, and the way it works is perfectly natural and simple. Balancing naturally rejects hum and noise and eliminates all sorts of complications in interfacing.

Balanced transmission works something like this. Your balanced input stage looks at the two wires and detects only the potential (voltage) di￿erence between them. Anything that is the same on the two wires (for all practical purposes as seen measuring from ground) is called a common mode signal and

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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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