Aphex Systems 320A owner manual Appendix C Proper Wiring Techniques

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Appendix C

Appendix C: Proper Wiring Techniques

A true balanced line should be used wherever your equipment allows. Use “twisted pair” shielded cable. For unbalanced wiring you should use high grade, low capacitance shielded wire for best results. If you have an unbalanced output but have a balanced input, the “pseudo-balanced” con￿guration may help deal with ground loop hum. This method and others are illustrated in Table 2.

CONNECTOR WIRING STANDARDS

The 3 pin XLR, 1/4” (63.5 mm) TS mono phone and the 1/4” (63.5 mm) TRS stereo phone are the most commonly used line level connectors in pro audio. Less common is the use of the “RCA” phono jack, which is essentially a consumer type connector. The XLR and the TRS are three conductor and are used for balanced connections. The TS and the RCA are two conductor and are used for unbalanced connec - tions.

In addition to the three main contacts on an XLR

 

there is also a grounding lug contact. This lug is con

-

nected to the connector’s case (shell). In all Aphex

 

products audio ground and chassis ground are one

 

and the same. Aphex products that use XLR connec

-

tors tie Pin I to the XLR case automatically. Therefore

it is not necessary to use the XLR case-ground lug. This

also makes possible the use of XLR ground drop adapters (see Note 3).

TABLE 1: The wiring convention shown is now standardized in 17 countries including the USA. Please note that any equipment that still uses Pin 3 as positive on XLR connectors is not adhering to the standard.

THE PIN 1 DILEMMA AND HOW IT AFFECTS CABLE SHIELD CONNECTIONS

The three main contacts on an XLR (or TRS) and the accepted wiring assignments shown above are only part of the picture. The standard for terminat - ing ground is Pin 1 (Sleeve). But which ground? It could be connected to audio signal ground or chassis ground depending on the method of grounding used by the equipment manufacturer. In all Aphex prod - ucts audio ground and chassis ground are one and

the same at all I/O jacks. This is just good, common sense engineering practice (which is what you would expect from us, course). Unfortunately, many prod - ucts are designed so that the noisy currents from the shield drain into signal ground instead of chas - sis ground. This practice creates a real hum and noise problem for end-users. The appropriate overall grounding scheme of an audio system would be a lot easier to predict without this problem 1.

The standard balanced line wiring recommenda - tion from Aphex Engineering is this: In the majority of cases maximum noise rejection occurs when the shield is connected to the input ground only (espe - cially in locations with high levels of RFI). That means the sending end shield should be left disconnected.

However, if you already have cables with the shield connected at both ends, go ahead and try them out. If you are connecting a fairly simple audio system it may be ￿ne as is.

A word on optional shield connections: Connecting

the cable shield of a balanced line at both ends cre - ates unnecessary ground loops which may carry noise and hum currents that can be ampli￿ed. Connecting the shield only at the sending end (instead of the receiving end) may exaggerate common mode noises at the receiving input stage. It can actually increase RFI and noise more than having no shield at all. Because of the “Pin I Dilemma” (mentioned above) you may be forced, in some situations, to experiment with how the cable shield is connected to ground to eliminate a pesky hum or radio interference problem. It might be good to try XLR ground drop adapters (see Note 3) as a method of trying these con￿icting methods out and being able to change easily if nec - essary.

IMPEDANCE

Regardless of inaccuracies, it has become more or less standard over the years to refer to balanced lines as low impedance and unbalanced lines as high impedance. The fact is, however, that both balanced and unbalanced lines are operated at low imped - ance in modern practice owing to the fact that all output stages have become low impedance. A few exceptions might be outputs from passive mixers, instrument pickups, electric guitars and some key - board synthesizers. It is generally ideal to drive any

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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 Mains Voltage Selection And Fuse UnpackingDamage & Claims Safety Considerations Power CordMounting In a Rack Proper VentilationRemote Connector InstallationReference Level Setting Input ConnectionsSummary Specications Ratio Recording IntroductionMixing MasteringBroadcast Radio Pre-processing Video Post-ProductionLive Concerts Television Broadcasting and Cable Systems Broadcast STL/ Phone Line DriverVideo and Audio Tape Duplication Voice ProcessingHard Disk Recording Leveling Function Signal FlowProcessing Functions 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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