AMISCL2 COMPRESSOR LIMITER

Transcription

1 SERVICE INFORMATION AMISCL COMPRESSOR LIMITER CONTENTS: OPERATION MANUAL SCHEMATIC DIAGRAM Australian Monitor Clyde Street, Silverwater NSW Australia

2 AMISCL STEREO COMPRESSOR LIMITER INSTALLATION & OPERATION MANUAL

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4 INTRODUCTION AND CONTENTS The Australian Monitor Pro Series AMISCL is a RU, dual channel compressor limiter. Featuring an expander/gate, compression and limiting per channel, the AMISCL utilises a high quality VCA to give excellent performance from a budget priced dynamics processor. With added features like selectable Automatic attack and release times and EQ enhancement which automatically compensates for high end loss when heavy compression is taking place, the AMISCL has the features and the performance of a compressor/limiter many times the price. INTRODUCTION FRONT PANEL REAR PANEL SET UP & OPERATION SPECIFICATIONS AUS, EUR, USA Copyright th Oct 00 Rev A: th Oct 00 This symbol is intended to alert the user to the presence of uninsulated dangerous voltage within the product s enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons. This symbol is intended to alert the user to the presence of important operation and maintenance (servicing) instructions in the literature accompanying the appliance. Caution: To prevent electric shock do not use this (polarised) plug with an extension cord, receptacle or other outlet unless the blades can be fully inserted to prevent blade exposure. To prevent electric shock, match wide blade of plug to wide slot, fully insert. AMISCL INSTALLATION & OPERATION MANUAL PAGE

5 FRONT PANEL POWER SWITCH This switches the mains power "on" to the unit. COMPRESSOR/LIMITER SECTION Refer to inset box immediately opposite. EXPANDER/GATE THRESHOLD This control adjusts the threshold level of the expander/gate within a range from off (bypass) to 0dB. The Red LED glows when expansion occurs. ENHANCER ENHANCEMENT Dynamic enhancement allows you to replenish any high frequencies lost through the compression process, for natural sounding dynamics control. This control allows you to vary the amount of dynamic enhancement added. Enhancement is only added when compression is taking place. 0 COMPRESSOR LIMITER SECTION THRESHOLD This controls threshold at which compression will start to occur. It has a range from -0 to0 dbu. RATIO This control determines the compression ratio between the input and output level for all signals exceeding the threshold point. The ratio can be adjusted from : (unity gain) to infinity: (Limiting) ATTACK The attack control determines the speed at which the compressor will respond to signals that exceed the threshold. The attack range is from 0. to 00 milliseconds. RELEASE The Release control determines the amount of time it will take the compressor to return to unity gain after signal falls below the threshold level. This can be adjusted from 0.0 to seconds. 0 the program material. This function allows for unobtrusive musical compression of signals or mixes with widely varying dynamics. OUTPUT LEVEL This control allows for an increase or decrease of the output level by up to 0dB, thus allowing the user to compensate for any level loss due to the compression or limiting process. IN/OUT SWITCH This switch allows the compressor/limiter section to be bypassed. This makes A/B comparisons between original and processed material very simple. GAIN REDUCTION METER This segment LED meter shows the actual gain reduction per channel and has a range from 0 to 0dB. AUTO LED This shows when the Compressor Auto function is active. AUTO IN The Auto In switch disables the Attack and Release controls and controls these parameters automatically from ACTIVE LED This shows when the compressor/limiter is switched in. PAGE AMISCL INSTALLATION & OPERATION MANUAL

6 REAR PANEL CHANNEL DETAIL Refer to inset box below. 0 CHANNEL DETAIL TRS LINE OUT This.mm TRS connector is a balanced or unbalanced line level output. XLR LINE OUT This XLR connector is a balanced line level output. XLR LINE IN This XLR connector accepts a balanced line level input. TRS LINE IN This.mm TRS connector accepts a balanced or unbalanced line level input. MAINS VOLTAGE SELECTOR This switches mains voltage from 0VAC to 0VAC. Please ensure that this switch is set to the correct voltage for your part of the world. FUSE HOLDER Please note that the AC voltage selection is defined by the position of the fuse holder. If you intend to change the operating voltage, remove the fuse holder and twist 0 degrees before re inserting it. Matching the two markers monitors the selected voltage. MAINS POWER LEAD This connects to mains AC power. Please ensure that the correct voltage is set for your part of the world. (See ) 0 DETECTOR LOOP INSERT This.mm TRS jack allow for an equaliser or other processor to be inserted into the signal path. Note that the ring of the insert point is the send and the tip is the receive. AMISCL INSTALLATION & OPERATION MANUAL PAGE

7 SET UP AND OPERATION the threshold, the signal is reduced in level, relative to the amount the signal exceeds this point. This gain reduction is set by the ratio control. Fig The interactive relationship between the operating level and the headroom It is possible to further improve the audio quality by constantly monitoring the programme material with the aid of a volume fader, which manually levels the material. During low passages the gain is increased, during loud passages the gain is reduced. Of course it is fairly obvious that this kind of manual control is rather restrictive; it is difficult to detect signal peaks and it is almost impossible to level them out. Manual control is simply not fast enough to be satisfactory. The need therefore arises for a fast acting automatic gain control system which will constantly monitor the signals and which will always adjust the gain to maximise the signal-to-noise ratio without incurring signal distortion. This device is called a compressor or limiter. COMPRESSOR/LIMITERS By measuring the dynamic range of musical instruments and microphones, you will find that extreme amplitudes will occur which will often lead to overload in subsequent signal processing equipment. These signal peaks can lead to heavy distortion. To avoid this kind of distortion or, for example, to avoid loudspeakers being damaged by overload, Compressors or Limiters are used. The principal function used in these devices is dependent on an automatic gain control as mentioned in the previous section, which reduces the amplitude of loud passages and therefore restricts the original dynamics to a desired range. This application is particularly useful in microphone recording, to compensate for level changes which are caused by varying microphone distances. Although compressors and limiters perform similar tasks, one essential point makes them different: A Limiter abruptly limits the signal above a certain level, while a compressor controls the signal gently over a wider range. A limiter continuously monitors the signal and intervenes as soon as an adjustable level is exceeded. This level is called the threshold. Any signal exceeding this threshold will be immediately reduced back to the adjusted threshold level. Generally, threshold levels for compressors are set below the normal operating level to allow for the upper dynamics to be musically compressed. For limiters, the threshold point is set above the normal operating level ini order to provide reliable signal limiting and thus protect subsequent equipment. EXPANDERS/NOISEGATES Audio, in general, is only as good as the source from which it was derived. The dynamic range of signals will often be restricted by noise. Synthesisers, effects devices, guitar pickups, amplifiers etc generally produce a high level of noise, hum or other ambient background hiss, which can disturb the quality of the program material. Normally these noises are inaudible if the level of the desired signal lies significantly above the level of the noise. This perception by the ear is based on the masking effect: noise will be masked and thus becomes inaudible as soon as considerably louder sound signals in the same frequency band are added. Nevertheless, the more the level that the desired signal decreases, the more the noise floor becomes a disturbing factor. Expanders or noisegates offer a solution for this problem: these devices attenuate signals when their amplitudes drop, thereby fading out the background noise. Reliant on this method, gain controlling amplifiers, like expanders, can extend the dynamic range of a signal and are therefore the opposite of a compressor. In practice, it is shown that an expansion over the entire dynamic range is not desired. With an expansion ratio of : and a processed dynamic range of 0dB, an output dynamic range of 0dB will be the result, exceeding all subsequent signal processors, as well as human hearing. Therefore, the amplitude control is restricted to signals whose levels are below a certain threshold. Signals above this threshold pass through the unit unchanged. Due to continuous attenuation of the signals below this threshold, this kind of expansion is termed downward expansion. The noisegate is the simplest form of an expander: in contrast to the expander, which continuously attenuates a signal below the threshold, the noise-gate cuts off the signal abruptly. In most applications this method is not very useful, since the on/off transition is too drastic. The onset of a simple gate function appears very obvious and unnatural. To achieve an inaudible processing of the program material, it is necessary to be able to control the signal s envelope parameters. A compressor also monitors the program material continuously and has a certain threshold level. However, in contrast to the limiter, signals exceeding the threshold are not reduced abruptly but gradually. Above PAGE AMISCL INSTALLATION & OPERATION MANUAL

8 SPECIFICATIONS AUDIO INPUT Impedance Nominal Operating Level Maximum Input Level khz DETECTOR INPUT Impedance Maximum Input Level RF-filtered, Servo-balanced input stage 0KΩ balanced -0dBu to dbu dbu balanced and unbalanced >0dB DC de-coupled, unbalanced input >0KΩ dbu GATE SECTION Threshold IRC (Interactive Ratio Control) Expander/Gate Variable (Off to 0dBu) DYNAMIC ENHANCER SECTION Dynamically Controlled Frequency Correction Process Variable (Off to ) FUNCTION SWITCHES In/Out Bypass switch Auto Programme-dependent attack and release times AUDIO OUTPUT Electronically buffered output stage Impedance <0Ω Maximum Input Level dbu Bandwidth Hz to 0kHz, 0, -db dbu 0.0% typ. 0dBu 0.% typ. IMD 0dBu 0.0% typ. Noise & Hum, unity gain >dbu Noise & Hum, fully off >dbu 0kHz >dbu khz >0dBu COMPRESSOR SECTION IKC (Interactive Knee Control) Compressor Threshold Variable (-0 to 0dBu) Ratio Variable (: to LIM.) Attack Variable (0. to 00 msec./0db) Release Variable (-0 to 0dB) INDICATORS CLOSE LED LED indicates onset of the Expander/Gate element GAIN REDUCTION meter ////0//0/0dB POWER SUPPLY Mains Voltages Power Consumption Fuse Mains Connection PHYSICAL Dimensions H x W x D Net Weight Shipping Weight 00-0/00-0 VAC 0-0Hz Watts 0mA (00-0V); 0mA (00-0V) slow-blow Standard IEC receptacle / (.mm) x (.mm) x. (mm) kg.kg As a result of these efforts, modifications may be made from time to time to existing products without prior notice. Specifications and appearance may differ from those listed or shown. AMISCL INSTALLATION & OPERATION MANUAL PAGE

9 AUSTRALIA AND NEW ZEALAND SYDNEY (NSW & ACT SALES) MELBOURNE (VIC & TAS SALES) BRISBANE (QLD SALES) ADELAIDE (SA & NT SALES) PERTH (WA SALES) AUCKLAND (NZ SALES) Beaconsfield Street Silverwater NSW Private Bag Silverwater NSW Phone: (0) Fax: (0) / Middleborough Road Box Hill VIC PO Box Blackburn South VIC 0 Phone: (0) 0 Fax: (0) 0 vic@audiotelex.com.au Commercial Road Fortitude Valley QLD 00 PO Box Fortitude Valley QLD 00 Phone: (0) Fax: (0) qld@audiotelex.com.au Walsh Street Thebarton SA 0 PO Box Hindmarsh SA 00 Phone: (0) Fax: (0) sa@audiotelex.com.au Fitzgerald Street West Perth WA 00 PO Box 0 North Perth WA 0 Phone: (0) Fax: (0) wa@audiotelex.com.au Unit B, Piermark Drive Albany New Zealand PO Box Albany Phone: (0) Fax: (0) audiotlx@nznet.gen.nz EUROPE/ASIA/MIDDLE EAST INTERNATIONAL SALES Beaconsfield Street Silverwater NSW Australia Private Bag Silverwater NSW Phone: Fax: international@audiotelex.com.au USA/SOUTH AMERICA SENNHEISER ELECTRONIC CORPORATION Enterprise Drive Old Lyme CT 0 USA Phone: 0 0 Fax: 0 jalexander@sennheiserusa.com

10 I D C B A AUDIO INPUT DETECTOR LOOP J0 Q0 BC R0 00K R K C 0.u/0V R 0K R R 0M IC0 C CA0 0M -V R M CHANNEL R0 00K R0 0K R0 0K R0 0K C0 P IC0: TL0CN - C 0.u C u R K VR0 VR R 00K R K Q0 BC Q0 BC R0 0K 0 IC0 D CA0 IC0: TL0CN C0 P - -V IC0 : JRC0D IC0 B CA0 R0 0K C0 u/v IC0 A CA0 R K D0 N D0N D0 N R R0 K K R V R K K -V R K R -V K IC0: JRC0D R0-0K R0 0K R 0K R0 K THRESHOLD VR0 0KB IC0: TL0CN - R R0 M 0M IC0 E CA0 C0 00u IC0 C0 0.0u R0.K IC0: JRC0D v PROCESS VR0 0KB R K R 0 R 0K -v v R C 0R 0U/V R R 00K R 0R -V V VR0 00K IC0: TL0CN R K D0 N R 0K EXPANDER\GATE - D0 N C 0.u IC0: TL0CN C0 0.u -V R K R0 0K R M IC0: TL0CN LD CLOSE R 0K R 0K C u - 0 IC0: JRC0D R K R 0K R 0K R 0K C0 P C0 - u/v v V R 00 THRESHOLD VR0 0KB R K V C 00u D0 N 0 R -V K IC0: TL0CN VR0 KB RATO - ENHANCER C u/0v LD0 IC0: JRC DX IC0: 0 C 0.0u -V IC0: C 00u/V COMPRESSOR\LIMITER TL0CN V R K0 R 0 R K COMPRESSOR\LIMITER SW0 IN/OUT COMPRESSOR\LIMITER OUTPUT LEVEL VR0 0KB R K R K C 0.0u R.K R 0K R 0R R0 K IC0: JRCDX R 00K C0 IC0: ATTACK VR0 MA R 0R C 0.0u R V COMPRESSOR\LIMITER 0M -v 00u R K R0 K C 0p IC0: C 0.0u V R K IC0: C u R.K IC0: C0 JRCDX u/v -v R 0K R 0 R K R K R 0K R0 K R K Q0 CB R K R K Q0 CB NOTE:This stadard circuit but if subject to change without notice IC0: v JRCDX R K R K C u/v -V RELEASE VR0 MA SW0 IN/OUT -V IC0: IC0: LD0 IC0: V -V LD0 IC0: 0 R 0K IC0: IC0: IC0: COMPRESSOR\LIMITER V LD0 LD0 LD0 LD0 LD0 R R V LD0 0 IC0: V V V V V V LD0 R R AUDIO OUTPUT J0 BASE C 0.u C 000u/V V V -V H0 V SW DB PT IC C 0.u C 00u/V PIN ~ ~ C0 0 SW C 0.u V -V V O 0V G 0V 0V 0V BASE G I O 0V C 000u/V IC C 0.u C 00u/V PIN F ma C PIN 0/0V 0/0Hz PIN D C B A