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BSS Audio DPR-944 User Manual

2+2 parametric compressor-gate
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DPR 944
User Manual
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Summary of Contents for BSS Audio DPR-944

  • Page 1 DPR 944 User Manual...

  • Page 2: Important Safety Information

    IT SHOULD NOT BE NECESSARY TO REMOVE ANY PROTECTIVE EARTH OR SIGNAL CABLE SHIELD CONNECTIONS TO PREVENT GROUND LOOPS. ANY SUCH DISCONNECTIONS ARE OUTSIDE THE RECOMMENDED PRACTISE OF BSS AUDIO AND WILL RENDER ANY EMC OR SAFETY CERTIFICATION VOID. For continued compliance with international EMC legislation ensure that all input and output cables are wired with the cable screen connected to Pin 1 of the XLR connectors and/or the jack plug sleeve.

  • Page 3: Table Of Contents

    Contents Contents Mechanical installation Unpacking Mains Power Connection Mains Power Introduction Audio Connections Main Inputs Main Outputs Key Insert Control Operations - Gate Gates In Key filter Filter narrow Key listen Threshold Depth 20dB Attack slow Release Stereo link 6.10 Open/Shut LEDs 6.11 Key insert connector...
  • Page 4 Contents Ratio Release fast Gain Side chain listen Frequency Width Stereo link 9.10 Below threshold meter 9.11 Gain reduction meter 10.0 General guide to compressing 10.1 The need for gain control 10.2 Compressors & limiters 10.3 The effect of compression & limiting on sound 10.4 Frequency selective compression...

  • Page 5: Mechanical Installation

    Mechanical Installation Mechanical installation A vertical rack space of 1U (1 3/4"/44.5mm high) is required, with a depth of 190mm, excluding connectors. Ventilation gaps are unnecessary. If the unit is likely to undergo extreme vibration through extensive road trucking and touring, the unit must be supported at the rear and/or sides to lessen the stress on the front mounting flange.

  • Page 6: Unpacking

    Unpacking Mains Power Connection Unpacking As part of the BSS system of quality control, we check every product carefully before packing to ensure that it reaches you in flawless condition. Before you go any further, please check the unit for any physical damage and retain the shipping carton and all relevant packing materials for use, should the unit need returning.

  • Page 7: Introduction

    UL rated type fuse for continued compliance with safety standards. Introduction The BSS Audio DPR 944 is a FOUR channel unit containing two channels of ADVANCED GATING and two channels of PARAMETRIC COMPRESSION. Both channels of the gate may be stereo linked, as can both channels of the compressor.
  • Page 8 The DPR 944 Fig 4.1 Front Panel Fig 4.2 Rear Panel...
  • Page 9 All numbers in bubbles refer to Section numbers.

  • Page 10: Audio Connections

    Audio Connections Audio Connections 5.1 Main Inputs There are 2 input sockets on the rear panel of the DPR 944, Inputs 1 and 2. Each is electronically balanced on standard 3 pin female XLRs at an impedance greater than 10k Ohms. The ‘HOT, + or in phase’ connection is to pin 2 and the ‘COLD, -, or out of phase’...

  • Page 11: Key Insert

    When using the DPR 944 to drive unbalanced inputs, best performance is usually obtained by connecting the DPR 944s ‘+’ signal to the equipment signal pin and the ‘-’ signal to the equipment shield. Fig 5.4 The DPR 944 shield should normally be connected to the equipment shield, preferably at the equipment end.

  • Page 12: Control Operations - Gate

    Control operations - Gate Control operations Control operations Control operations Control operations Control operations Control Operations - Gate 6.1 Gates In When the Gates In switch is in the out, non illuminated position, all DPR 944 functions are bypassed and the input is connected directly to the output with a high quality relay.

  • Page 13: Key Listen

    This switch adjusts the width of the internal key filter. This filter should be considered as a pair of tracking high pass and low pass filters, with the space between them controlled by this switch. With the switch out, the filter has an approximate width of 3 octaves, but when depressed the width goes down to approximately 0.5 of an octave.

  • Page 14: Depth 20Db

    Control operations - Gate In normal use the threshold control is generally set so that wanted signal peaks are just able to trigger the gate, this gives the maximum protection from false triggering by undesired signals. 6.6 Depth 20dB With the gate ‘open’, the program can pass through DPR 944 unhindered. When ‘shut’, the level of the program passed is selected to be either approximately -80dB with the depth switch out, effectively no signal at all, or -20dB with the switch depressed.

  • Page 15: Release

    6.8 Release This is a dual mode control, introducing hold as well as release. The hold time is determined internally to be about 20% of the selected release time. Hold A short hold time is required to avoid the DPR 944 from starting another attack sequence if the key signal momentarily falls below the threshold level.

  • Page 16: Open/Shut Leds

    Control operations - Gate 6.10 Open/Shut LEDs If the gate is not passing program, the shut light is illuminated. If it is passing program, the open light is illuminated. These lights fade from one to another during the attack and release times, their relative intensity giving a visual indication of the dynamic response of the gating action.

  • Page 17: Genereal Guide To Gating

    General guide to gating General guide to gating 7.1 What are gates Put simply, a noise gate is a device that blocks or switches off a signal, if that signal falls below a certain preset level. This works because the ear is much for? more sensitive to noise in the absence of other signals.

  • Page 18: Basic Operation

    General guide to gating prevent this. They are set up to open only when their particular drum is hit. Unfortunately it is sometimes not easy to set a gate up to only trigger on the desired signal, quite often the wanted and unwanted signals are close to each other in level.
  • Page 19 • Now gradually rotate the threshold control anti-clockwise. At some position you will hear your signal appear - the gate has now ‘opened’. Notice also that the green open light has come on. Spend a few minutes adjusting the threshold control and watching the display. •...

  • Page 20: Application Examples - Gates

    Application examples - Gates Application examples - Gates Each of the following application examples is accompanied by a front panel control diagram. Controls that are not highlighted should be set to the value shown - refer to the text where no initial setting is shown. Those controls which are highlighted can be set to any value, and are not critical to the given example.
  • Page 21 Select some music with a heavy beat, set the key filter and filter narrow controls so that the beat notes are prominent. When you are happy with the filter controls, release the key listen switch. Now adjust the threshold control, you should now hear the beats in the program.

  • Page 22: Control Operations - Parametric Compressor

    Control operations - Compressor Control Operations - Parametric compressor 9.1 Comps in When the Comps In switch is in the out, non illuminated position, all DPR 944 compressor functions are bypassed, and the input is connected directly to the output with a high quality relay. This is the same condition that occurs when the power is off, and ensures that signal is passed through the unit in the case of a power or fuse failure.

  • Page 23: Ratio

    The ‘progressive knee’ is an important characteristic of the DPR 944 (and all other BSS Audio compressors) and is why a ‘soft knee’ or other similarly labelled control is not required. Progressive knee is also one of the main reasons for the transparency and musicality of the unit at low compression ratios.

  • Page 24: Release Fast

    Control operations - Compressor Fig 9.2 Effect of 'Progressive knee' compression 9.4 Release fast With the release fast switch in the out position, the DPR 944 operates in an auto mode. This feature of the DPR 944 is provided to overcome some of the conflicting setting requirements associated with conventional attack and release controls.

  • Page 25: Gain

    9.5 Gain As compression is a gain reducing process, the output signal level will often be less than the input. The gain control is provided to restore the output signal to the desired operating point, and provides a range of +/-20dB relative to the input signal.

  • Page 26: Width

    Control operations - Compressor The centre frequency of the band of interest is selected with the frequency control. Depressing the side chain listen switch makes the operation of this control audible, aiding its setting on exactly the signals of interest. 9.8 Width This control is used in conjunction with the frequency control to set the width of the parametric filter.

  • Page 27: Below Threshold Meter

    If the DPR 944 is being used with the width control in any position other than out, both the width and frequency controls on each compressor must be in the same positions for correct operation. 9.10 Below threshold meter The five LEDs of the below threshold meter give an indication of where the input signal is in relation to the start of compression.

  • Page 28: General Guide To Compressing

    General guide to compressing 10.0 General guide to compressing 10.1 The need for The human ear excels in its ability to detect an extremely wide range of sound levels. These can range from the quietest whisper to the roar of a jet gain control aircraft.

  • Page 29: Compressors & Limiters

    Fig 10.2 Operating level and headroom noise performance without incurring distortion. This device is called a compressor or limiter, two such devices are provided in the DPR 944. 10.2 Compressors & Compressors and limiters have closely related effects, and in general a limiter will reduce gain very strongly once a certain level has been reached, whereas limiters a compressor will act gently, but over a much wider range of volume levels.

  • Page 30: The Effect Of Compression & Limiting On Sound

    General guide to compressing 10.3 The effect of Consider an input signal which is applied to two units, one having its threshold point set 10dB higher than the other. Since the compressor only compression & affects signals that exceed the threshold level, the signal with the lower limiting on sound threshold applied will be more affected than the other.

  • Page 31: Frequency Selective Compression

    increased. The net effect, therefore, is for both ends of the dynamic spectrum to be pushed (or squeezed) towards each other. This squeezing effect of compression is important to remember, and provides a major difference between compression and limiting. I.e. Limiters do not make-up the gain reduction.

  • Page 32: Application Examples - Compressors

    Application examples - Compressors 11.0 Application examples - Compressors Each of the following application examples is accompanied by a front panel control diagram. Controls that are not highlighted should be set to the value shown - refer to the text where no initial setting is shown. Those controls which are highlighted can be set to any value, and are not critical to the given example.

  • Page 33: De-Essing, De-Popping & Reducing Proximity Effect

    11.3 De-essing, De- popping & reducing proximity effect A common problem encountered when amplifying the human voice is the large amount of high frequency energy, heard as the sibilant ‘sss’ sound. These high frequency or sibilant sounds can reach levels considerably greater than the normal voice level, and can result in distortion.
  • Page 34 Application examples - Compressors Fig 11.2 Difference between Bell and shelf de-essing A related problem called ‘popping’, caused by wind from the ‘p’ sound entering a microphone, is responsible for generating large amounts of explosive bass signal. To treat this, configure the DPR 944 as for de-essing, but set the frequency control to select low frequencies.

  • Page 35: Guitar Treatment

    11.4 Guitar treatment A general problem encountered with acoustic guitars is the difference in mid range signal level produced when the guitar is strummed relative to the amount when it is picked. The DPR 944 can be configured to reduce this problem. Start by setting the frequency control to 1kHz, width to 3 Oct, and the ratio control to 3 o’clock.

  • Page 36: Dynamic Bass And Treble Enhancement

    For starters, try using a large amount of compression at infinite ratio while sweeping the frequency control from one end of the band to the other. Try this with different width settings, and don’t forget to let us at BSS Audio know about any unusual applications you may find ..

  • Page 37: Warranty Information

    12.0 Warranty Information When sold to an end user by BSS Audio or a BSS Audio Authorised Reseller, this unit is warranted by the seller to the purchaser against defects in workmanship and the materials used in its manufacture for a period of one year from the date of sale.

  • Page 38: Specifications

    Specifications 13.0 Specifications Gate General Input impedance 10k Ohm balanced or unbalanced Input CMRR >40dB 30Hz-20kHz Main output level >+20dBu into 600 Ohms or greater Main output impedance <50 Ohms balanced or unbalanced Key output level >+20dBu into 1k Ohms or greater Key output impedance 100 Ohms unbalanced Key input impedance 10k Ohm unbalanced Frequency response +/-0.25dB 20Hz-20kHz...
  • Page 39 Index Index Application examples Effect of compression on sound compression gating Attack slow Filter narrow Audio Frequency connections Frequency selective compression 31 inputs Front Panel key insert Fusing outputs Gain Bass and treble enhancement Gain reduction meter Beginners guide Gate Control compressing Gates In gating...

  • Page 40: Index

    Index Key listen Voltage selection Below threshold meter Warranty Info. Gain reduction meter Width open/shut Wiring convention cabling Mains connection Open LED Outputs Peak limiting Proximity effect reducing Rack dimensions Ratio Rear Panel Release Release fast Shut LED Side chain filter use as EQ Side chain listen Specifications...

  • Page 41: User Notes

    User Notes...
  • Page 42 User Notes...

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