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Aphex Compellor 320D Owner's Manual

Dual mono/stereo automatic level controller with analog & digital i/o
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320D
Compellor
Compellor
®
®
Owner's Manual
Dual Mono/Stereo Automatic Level Controller
with Analog & Digital I/O
Manual P/N 999-4260 • Revision 1 • 09/30/03
Copyright 2003 Aphex Systems Ltd. All rights reserved. Printed in U.S.A. Written and produced by Donn Werrbach.
S Y S T E M S
11068 Randall St., Sun Valley, CA 91352 U.S.A.

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Summary of Contents for Aphex Compellor 320D

  • Page 1 Analog & Digital I/O Manual P/N 999-4260 • Revision 1 • 09/30/03 Copyright 2003 Aphex Systems Ltd. All rights reserved. Printed in U.S.A. Written and produced by Donn Werrbach. S Y S T E M S 11068 Randall St., Sun Valley, CA 91352 U.S.A.

  • Page 2: Table Of Contents

    Fast Finder Fast Finder Contents Quick Start Introduction Installation Specifications Using Digital Audio Operating Instructions System Description Performance Test Safety Declarations Warranty & Service Appendices For protection against electric shock, do not remove the cover. No user serviceable parts inside. CAUTION: WARNING: This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to Part 15 of the FCC Rules.
  • Page 3 320D 1. Contents Compellor 2. Quick Start - Page 6 3. Introduction - Page 7 3.1 About This Manual 3.2 What Is A Compellor? 3.3 What Does It Do? 3.4 How Does It Work? 3.5 A BIt Of Compellor History 4.
  • Page 4 320D 1. Contents Compellor 7. Operation - Page18 7.1 Introduction 7.2 Recording 7.3 Mixing 7.4 Mastering 7.5 VIdeo Post Production 7.6 Sound Reinforcement 7.7 Live Concerts 7.8 Broadcast Radio Pre-processing 7.9 Broadcast STL/Phone Line Driver 7.10 Television Broadcasting and Cable Systems 7.11 Video and Audio Tape Duplication 7.12 Voice Processing 8.
  • Page 5 Page 5...

  • Page 6: Quick Start

    320D 2. Quick Start Compellor You can use this quick setup to get a signal through your Compellor right away. Then. you’ll want to go on and read through the manual to discover the wealth of information that is available to you. Quick Start 1.

  • Page 7: Introduction

    3. Introduction 3.1 About This Manual This manual reflects the new digital audio features of the Model 320D. It contains much of the material found in the older 320A/323A manual but has been updated and streamlined to make it easier to use. There is also new content specific to digital audio. 3.2 What Is A Compellor? A Compellor is the first and only product designed specifically for the transparent control of audio levels.
  • Page 8 Honolulu, introduced Werrbach to the type 1537A VCA chip which was produced and sold by Aphex. Given a free sample, a couple of weeks time, and the inspiration brought by the VCA’s fabulous performance, Werrbach produced the first Compellor prototype.
  • Page 9 In 1994, Aphex introduced the current Compellor Models 320A and 323A. The model “A” revision signifies the inclusion of an improved patented Leveler circuit called the “Frequency Discriminate Leveler” (FDL) while all other aspects of the Model 320 remain the same. With the FDL, Compellors became even more transparent and useful than ever before.

  • Page 10: Installation

    4.1 Unpacking Your Compellor was packed carefully at the factory in a container designed to protect the unit during shipment. Nevertheless, Aphex recommends making a careful inspection of the ship- ping carton and the contents for any signs of physical damage.

  • Page 11: Power Cord

    4.9 Safety Considerations Aphex has taken care to insure the safety of its products. The Compellor is constructed to comply with international electrical safety standards.

  • Page 12: Remote Connector

    320D 4. Installation Compellor Installation should be performed only by qualified individuals. It is the installer’s responsibility to insure his personal safety and the safety of others in the work area. It is never a good idea to work alone in the vicinity of high power electrical and radio frequency equipment. 4.10 Remote Connector Remote control, a feature of the Models 320A and 323A, is not available with the Model 320D.

  • Page 13: Digital

    The output impedance of 65 ohms is optimized for driving long cables and consequently a Compellor can drive just about any kind of line, balanced or unbalanced, of any length. Unique servo balanced output circuitry automatically maintains the proper gain and level into a balanced or unbalanced output line.

  • Page 14: Specifications

    320D 5. Specifications Compellor 5.1A ANALOG INPUTS Connector: 3 pin XLR female Type: transformerless, servo balanced, RFI fIltered Impedance: 22K-ohms balanced, 11K-ohms unbalanced Operating Level: user selectable +4dBu or -10dBV Max input level: +27dBu(ref = +8), +25dBu(ref = +4), +10.8dBV(ref = -10) CMRR: >90dB/100Hz, >70dB, 1KHz, >50dB, 20KHz 5.1B DIGITAL INPUT...

  • Page 15: Ratio

    5.6 RATIO Compressor: 1.1:1 to 3:1 program dependent Leveler: 20:1 Limiter: >30:1 5.7 ATTACK TIMES Compressor: 5 to 50mSec program dependent Leveler, fast: 20Hz = 1.5 Sec > 1KHz Frequency Discriminate Leveler Leveler, slow: 20Hz = 5 Sec > 1KHz Frequency Discriminate Leveler Limiter: 1 uSec 5.8 RELEASE TIMES...

  • Page 16: Using Digital Audio

    320D 6. Using Digital Audio Compellor 6.1 How the Compellor Interfaces Being an analog processor at the core, the Model 320D contains a high quality 24-bit low noise codec to receive digital audio and to transmit digital audio. Once the incoming digital audio is converted by the DAC section, it passes through the Compellor as normal audio.
  • Page 17 when in Bypass, the Compellor cannot feed the analog input to the digital output. The digital output will simply go dead with no carrier. There is no practical way to avoid this. NOTE: Because the digital I/O is inherently a stereo interface (two channels on one AES/EBU connection), the Model 320D must have both bypass switches set to Bypass in order to get the digital I/O to go into bypass.

  • Page 18: Operation

    320D 7. Operation Compellor 7.1 Introduction The “Quick Start” guide in the front of this manual is the best way to begin using your Compellor. You will get a good feel for what is going on, and you will have a signal going through the processor, ready for fine tuning.

  • Page 19: Video Post Production

    has too wide a dynamic range, it can cause broadcast processors (if the processing does not include the Compellor) to work too hard and generate audible artifacts. These are all reasons to master a final mix which has a controlled dynamic range. The goal, of course, is to maintain the sound quality of the studio while you are trying to ‘tighten’...

  • Page 20: Broadcast Stl/Phone Line Driver

    320D 7. Operation Compellor numerous other devices which effectively control the level differences, but none have the transparency of the Compellor. These other devices, particularly multiband compressors and limiters, have a ‘sweet spot’ which renders the best results. Adjust the Compellor so that its output is driving the downstream processors at their sweet spot.
  • Page 21 7.13 Hard Disk Recording Transferring music to hard disk can be improved using a Model 320D. It is a known fact that CD’s are mastered at varying average levels with some strikingly lower or higher in volume level than others. When building a broadcast or webcast music library on a hard disk audio server, it would be nice to have a way to even out those levels so the on-air segues will always be smooth and fat.

  • Page 22: System Description

    320D 8. System Description Compellor 8.1 Model Evolution The model 320D Compellor is a dual channel audio processor capable of being stereo linked. It is essentially a Model 320A with a digital audio interface added. In order to make room for the necessary additional connectors on the back panel, we eliminated the analog input imped- ance selectors and the remote control jack of the Model 320A.

  • Page 23: Compressor Function

    8.5 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.

  • Page 24: Stereo Enhance

    320D 8. System Description Compellor ground noise, but below the lowest program signal expected. Typically, a setting of -30dB (at about 9 o’clock) is satisfactory for all purposes. If, for some reason, you want to prevent the Compellor from bringing up program fades below a certain point, simply set the Silence Gate threshold to the level where you want the fade to become “uncorrected”.

  • Page 25: Output Control

    8.17 Input/Output The Compellors use the Aphex active servo balanced input and output stages. We like to specify pin 2 as positive but this is purely arbitrary since the balanced input and output pins are directly in phase and there is no dedicated unbalanced output which would be specified in relation to the input phase.

  • Page 26: Gain Reduction Metering

    320D 8. System Description Compellor 8.20 Gain Reduction Metering When the Meter Select is toggled into “G.R.” the bi-color LED meter is programmed to indi- cate a bar graph from left to right but differing from the program level indications. In this case, the bar is entirely green except for a possible red dot which floats within the green bar.

  • Page 27: Warranty & Service

    Any and all warranties are limited to the duration of the warranty stated above. EXCLUSION OF CERTAIN DAMAGES Aphex Systems’ liability for any defective unit is limited to the repair or replacement of said unit, at our option, and shall not include damages of any other kind, whether incidental, consequential, or otherwise.

  • Page 28: Appendices

    320D 10. Appendices Compellor Appendix A: Balanced and Unbalanced lines are the same. They both need two conductors. Lines and Operating Levels What makes a system unbalanced is when one of the wires is formed into a tube that wraps around Interfacing all types of equipment with balanced and the other conductor, without touching it, such that unbalanced lines and can sometimes be trouble-...
  • Page 29 320D Appendix B Compellor is cancelled out by the differential amplifier. Figure tems can sometimes never be made hum free, and 1 illustrates how the hum is induced into both wires just changing one piece of equipment in a studio can equally and therefore is cancelled out.
  • Page 30 Level Interface Units need to make sure you don’t overload the one ac cir- Aphex manufactures the Model 124A Level Interface cuit your strip is plugged into. If the load is too great box which is designed to electronically convert two...
  • Page 31 “pseudo-balanced” configuration may The standard balanced line wiring recommenda- help deal with ground loop hum. This method and tion from Aphex Engineering is this: In the majority others are illustrated in Table 2. of cases maximum noise rejection occurs when the...
  • Page 32 320D Appendix D Compellor TABLE 1 - BALANCED & UNBALANCED CONNECTOR WIRING STANDARDS 3-Pin XLR 1/4” TRS Phone Standard Wiring Convention (Balanced) Pin-1 Sleeve Ground/Shield (Earth, Screen) Pin-2 Positive (Signal, High, Hot) Pin-3 Ring Negative (Signal Reference, Return, Low, Common) 1/4”...
  • Page 33 Appendix D output circuit. We strongly recommend that you refer to your various equipment manuals to find out what XLR to XLR is used in each case before hooking up to unbalanced lines. When connecting a balanced output to a balanced input, however, you don’t need to know what kind of balanced output you are dealing with.
  • Page 34 320D Compellor PART 2: BALANCED OUT to UNBALANCED IN Voltage Balanced Outputs (Used on the 207) It was mentioned that there are several types of balanced output stages in use today. The following diagrams show you how to properly unbalance each SIMPLIFIED SCHEMATIC type of output.
  • Page 35 Appendix D PART 3: UNBALANCED to UNBALANCED Standard Cable (Guitar Cord) Mono (TS) Phone Plug Mono (TS) Phone Plug PART 4: UNBALANCED OUT to BALANCED IN Standard Method Enhanced Method (Pseudo Balanced) Advantage: Reduced Hum and Noise Pickup Mono (TS) Phone Plug Stereo (TRS) Phone Plug Mono (TS) Phone Plug Stereo (TRS) Phone Plug...
  • Page 36 320D Appendix E Compellor Appendix E: About Reference Levels ANALOG SYSTEMS Systems declaring the average reference level are very different than systems declaring the peak reference level. In the United States, most analog systems still use the VU meter and we declare the +4dBu (for example) reference level to be the average program level.
  • Page 37 If, after the average levels have been corrected by a Compellor, it is felt the PPM or dBFS indications should be made more consistent, you can use an Aphex Dominator “Precision Multiband Peak Limiter” after the Compellor. The Dominator will not act on the average levels but will transparently control the peaks and bring the program closer to having consis- tent peak levels without disturbing the average levels.
  • Page 38 320D Appendix F Compellor Appendix F Digital–vs–Analog; Peak–vs–RMS How To Deal With The Confusion By Donn Werrbach • 10/03/03 The Confusion The matter of audio level measurements and specifications can be very confusing at times. That is because some specs relate to peak measurements and some to average or RMS measurements.
  • Page 39 Appendix F room above the maximum PPM indication. By controlling the audio levels to maintain good PPM readings, there can be no possibility of the electronics clipping the audio. The disad- vantage is that to maintain a good average volume level, it takes very clever people riding the gain who can accurately guess at the crest factor of all the sounds.
  • Page 40 320D 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.
  • Page 41 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.
  • Page 42 320D Compellor outputs into the codec, the level will then shift and be louder with the analog input. That may give the effect of a fuller on-air sound when the coder is driven by analog because the on-air audio processor at the decoder side is driven with higher input level. What, Me Worry? This level mismatch need not be a problem, especially if you intend to use only the digital out- put.
  • Page 43 Page 43...

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