Aphex Systems 320A manual

Owner’s Manual Dual Mono/S tereo A utomatic Lev el Controller Manual P/N 999-0760 • Revision 2 • 09/30/03 Copyright 2003 Aphex Systems Ltd. All rights reserved. Printed in U.S.A. Written and produced by Donn Werrbach. Compellor ® 320A Compellor ® S Y S T E M S 11068 R andall S t., Sun V alley, CA 91 352 U.S.A.[...]

Page 2 F ast Finder F ast Finder 1 Contents 2 Quick Start 3 Introduction 4 Installation 5 Specications 6 6 Operating Instructions 7 System Description 8 9 W arranty & Service Appendices Safety Declarations CAUTION: For protection against electric shock, do not remove the cover . No user serviceable parts inside. WARNING: This equipment has b[...]

320A Compellor Page 3 2. Quick Start - Page 6 3. Introduction - Page 7 3.1 What Is A Compellor? 3.2 What Does It Do? 3.3 How Does It Work? 3.4 A BIt Of Compellor History 4. Installation - Page 10 4.1 Unpacking 4.2 Damage & Claims 4.3 Main V oltage Selection 4.4 Power Cord 4.5 Mounting In A Rack 4.6 Proper V entilation 4.7 Panel Security 4.8 T o[...]

320A Compellor Page 4 6. Operation - Page16 6.1 Introduction 6.2 Recording 6.3 Mixing 6.4 Mastering 6.5 VIdeo Post Production 6.6 Sound Reinforcement 6.7 Live Concerts 6.8 Broadcast Radio Pre-processing 6.9 Broadcast STL/Phone Line Driver 6.10 T elevision Broadcasting and Cable Systems 6.1 1 Video and Audio T ape Duplication 6.12 V oice Processing [...]

320D Compellor Page 4 Page 5[...]

320A Compellor Page 6 Y ou 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. Make sure there is signal going through the Compellor with Process both “In” and “Out”. If not, check t[...]

Page 7 3.1 What Is A Compellor? A Compellor is the first and only product designed specifically for the transparent control of audio levels. While other audio processors are designed simply to compress and limit audio signals, a Compellor is designed to intelligently manage the dynamic range of audio without causing noticeable changes to the charac[...]

320A Compellor Page 8 circuit. They thought that all audio processors should be noticeable. We had to explain that the unit was in fact working, and we asked them to listen to their mixes with and without the Compellor . After they did that, they were amazed at the results. Meanwhile, broadcast- ers were discovering the Compellor . They found it gr[...]

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 [...]

320A Compellor Page 10 4.1 Unpacking Y our 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. 4.2 Damage & Claims If damage is evident, do not discard the [...]

320D Compellor Page 10 Page 1 1 4.4 Power Cord The Compellor uses a standard IEC power cord set. The appropriate mains plug for each country is normally shipped with each unit. However , if you must install or replace the plug, use the correct wiring code as follows: 4.5 Mounting In A Rack The Compellor occupies one standard 19 in. x 1 3/4 in. rack[...]

320A Compellor Page 12 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 f[...]

Page 13 The output impedance of 65 ohms is optimized for driving long cables and consequently . h t g n e l y n a f o , d e c n a l a b n u r o d e c n a l a b , e n i l f o d n i k y n a t u o b a t s u j e v i r d n a c r o l l e p m o C a Unique servo balanced output circuitry automatically maintains the proper gain and level into a balanced or [...]

320A Compellor Page 14 5.1 INPUTS Connector: 3 pin XLR female T ype: transformerless, servo balanced, RFI fIltered Impedance: 22K-ohms balanced, 1 1K-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 5.2 OUTP[...]

Page 15 5.6 RA TIO Compressor: 1.1:1 to 3:1 program dependent Leveler: 20:1 Limiter: >30:1 5.7 A TT ACK 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 Compressor: 200 mSe[...]

320A Compellor Page 16 6.1 Introduction The “Quick Start” guide in the front of this manual is the best way to begin using your Compellor . Y ou will get a good feel for what is going on, and you will have a signal going through the processor , ready for fine tuning. We strongly recommend reading section 8 describing the Compellor ’ s feature[...]

Page 17 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 ‘t[...]

320A Compellor Page 18 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[...]

Page 19 6.13 Hard Disk Recording T ransferring 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 [...]

320A Compellor Page 20 - 7.1 Signal Flow The Compellor contains an input stage, an intermediate VCA stage, and an output stage. The input audio signal undergoes all processing in the VCA stage and is subsequently sent out through the output stage. A side chain system produces the control signals which change the VCA gain according to the signal pro[...]

Page 21 7.4 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. The compressor has a variable [...]

320A Compellor Page 22 ground noise, but below the lowest program signal expected. T ypically , 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[...]

Page 23 7.14 Output Control This control allows you to normalize the output level to 0VU after the processing is set up. It will usually get set around 12 o’clock, but there is a plus or minus 10dB range available which is useful if you need to match a slightly odd level. 7.15 Process Switch This operates a bypass relay which completely bypasses [...]

320A Compellor Page 24 7.19 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 . The entire [...]

320A Compellor Page 25 8. W arranty & Service 8.1 Limited W arranty PERIOD One year from date of purchase SCOPE All defects in workmanship and materials. The following are not covered: a. V oltage conversions b. Units on which the serial number has been defaced, modified, or removed c. Damage or deterioration: 1. Resulting from installation and[...]

320A Compellor Page 26 9. Appendices 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 use[...]

320A Compellor Page 27 is cancelled out by the dierential amplier . Figure 1 illustrates how the hum is induced into both wires equally and therefore is cancelled out. Since the balanced line has wires that are twisted together , each wire tends to pick up the same amount of induction from external sources. Induction will create no signica[...]

320A Compellor Page 28 There are basically three ways to attack the prob - lem of a ground loop. First is to eliminate it from its source, and the second is to re-route it through another path. The third is to balance out your unbal - anced audio interfaces. Identify the Sources A good way to identify grounding problems is to use a multimeter to ch[...]

Page 29 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 [...]

320A Compellor Page 30 audio line from a low impedance and receive into a high impedance. Generally , a minimum 1: 10 ratio is possible. This is called “bridging”. This has become modern practice and all balanced inputs are normally running 10K ohms or higher impedance. Because of these developments, it is no longer as critical to consider impe[...]

Page 31 output circuit. We strongly recommend that you refer to your various equipment manuals to nd out what 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. Simply treat it generically . P ART [...]

320A Compellor Page 32 P ART 2: BALANCED OUT to UNBALANCED IN 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 type of output. If you follow these instructions, you should have no problems. SIMPLIFIED SCHEMATIC T ransformer Balanced Outputs Mono Pho[...]

Page 33 Stereo Plug Male XLR Female XLR Don’t Connect Pin 3 Ground Shield This End Only Ground Shield This End Only T o 207 Insert Jack T o Equipment Input From Equipment Output Tip Ring Sleeve P ART 3: UNBALANCED to UNBALANCED Mono (TS) Phone Plug Mono (TS) Phone Plug P ART 4: UNBALANCED OUT to BALANCED IN Mono (TS) Phone Plug Stereo (TRS) Phone[...]

320A Compellor Page 34 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. Peak progr[...]

Page 35 In a world where all audio levels would be monitored by VU meters, this SMPTE standard would make things simple. Since VU meters measure something close to the average level, we could simply equate 0VU to -20dBFS with a calibration tone. W e could mix and track on the VU meters, knowing there is 20dB of headroom in the digital domain for pe[...]

320A Compellor Page 36 Appendix F Digital–vs–Analog; Peak–vs–RMS How T o 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. There is no one[...]

Page 37 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 sound[...]

320A Compellor Page 38 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 [...]

Page 39 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 set[...]

320A Compellor Page 40 outputs into the codec, the level will then shift and be louder with the analog input. That may give the ef fect 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, espec[...]

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