BSS Audio DPR 422 User manual

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DPR 422
User Manual

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This equipment has been tested and found to comply with the following European and
international Standards for Electromagnetic Compatibility and Electrical Safety:
Radiated Emissions (EU): EN55013 (1990) Associated Equipment
RF Immunity (EU): EN50082/1 (1992) RF Immunity, Fast Transients ESD
Mains Disturbance (EU): EN61000/3/2 (1995)
Electrical Safety (EU): EN60065 (1993)
Radiated Emissions (USA): FCC part 15 Class B
Electrical Safety (USA): UL813/ETL (1996) Commercial Audio Equipment
Electrical Safety (CAN): UL813/ETLc (1996) Commercial Audio Equipment
IMPORTANT SAFETY INFORMATION
DO NOT REMOVE COVERS. NO USER SERVICEABLE PARTS INSIDE, REFER SERVICING TO QUALIFIED
SERVICE PERSONNEL. THIS EQUIPMENT MUST BE EARTHED.
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. The input XLR Pin 1
and the side-chain input jack socket sleeve are connected to the chassis via a low value capacitor, providing
high immunity from ground loops whilst ensuring good EMC performance.
V 1.0 JMK 1 April 1997
Please read
We have written this manual with the aim of helping installers, sound engineers and musicians alike to get the
most out of the DPR-422. We recommend that you read this manual, particularly the section on installation,
before attempting to operate the unit.
The manual is split into two main sections. The first deals with quick reference information, regarding the
functions and operation of the unit, while the second covers a more general background to use and application
of the DPR-422.
We welcome any comments or questions regarding the DPR-422 or other BSS products, and you may contact us
at the address or World Wide Web site given in the warranty section.

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Contents
Contents
1.0 Mechanical installation 5
2.0 Mains Power Connection 6
2.1 Mains Power 6
3.0 Introduction 7
4.0 Unpacking 7
5.0 Audio Connections 10
5.1 Main Inputs 10
5.2 Main Outputs 10
5.3 Side Chain Inputs 11
5.4 Side Chain Outputs 12
6.0 Control Operations 13
6.1 Operating Level 13
6.2 Threshold 13
6.3 Ratio 14
6.4 Attack 15
6.5 Release 15
6.6 AUTO 16
6.7 Stereo Link 16
6.8 Gain 17
6.9 Channel In 17
6.10 De-ess 18
6.11 Frequency 18
6.12 De-ess HF 18
6.13 Side Chain Listen 19
7.0 Meter displays 20
7.1 Input Meter 20
7.2 Below Threshold Meter 20
7.3 Gain Reduction Meter 21
7.4 Output Meter 21

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Contents
8.0 General Applications 22
8.1 The need for Gain control 22
8.2 Compressors and Limiters 23
8.3 The effect of Compression and
Limiting on sound 24
8.4 De-essing 25
8.5 Broadband De-essing 25
8.6 HF De-essing 25
9.0 Operation and applications 26
9.1 Compression 26
9.2 De-essing 26
9.3 HF De-essing 27
9.4 HF De-essing with full Dynamic
control 27
9.5 Peak Limiting 28
9.6 Side chain insert 28
10.0 Troubleshooting 29
11.0 Warranty Information 30
12.0 Specifications 31
13.0 Glossary 32
Index 34
User Notes 36
Spare Parts Information

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Mechanical Installation
1.0 Mechanical installation
A vertical rack space of 1U (1¾" / 44.5 mm high) is required, with a depth of
190mm. Ventilation gaps are unnecessary (See Figure 1.1).
If the unit is likely to undergo extreme vibration through extensive road
trucking and touring, it is advisable to support the unit at the rear and/or sides
to lessen the stress on the front mounting flange. The necessary support can
generally be bought ready-built as a rack tray, or the DPR-422 can be mounted
between other units. Damage caused by insufficient support is not covered in
the warranty. To prevent damage to the paintwork on the front panel, always
use protective plastic cups or washers underneath the rack mounting bolts.
As with any low-level signal processing electronics, it is best to avoid mounting
the unit next to a strong source of magnetic radiation or heat, such as a high
power amplifier.
Fig 1.1 Unit dimensions.
Fig 1.2 Rack
dimensions.

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Mains Power Connection
2.0 Mains Power Connection
2.1 Mains Power WARNING! THIS APPLIANCE MUST BE EARTHED.
The DPR-422 must always be connected to a 3-wire earthed AC outlet. The
rack framework must also be connected to the same grounding circuit. The
unit must NOT be operated unless the power cables' EARTH (ground) wire is
properly terminated - this is important for personal safety as well as for proper
control over the system grounding.
The wires in the mains lead are colour coded in accordance with the following
code.
Green and Yellow......Earth
Blue......Neutral
Brown......Live
Those units supplied to the North American market will have an integral
moulded 3 pin connector which is provided to satisfy required local standards.
IMPORTANT: The DPR-422 is designed to use 50/60Hz AC power in one of
the two voltage ranges, selectable with the mains voltage selector switch on
the rear of the unit. It is vital that the position of this switch is checked BEFORE
initial power up to ensure that it matches the local mains supply. Acceptable
input AC supply voltages range from:
115V switch position - 90V to 132V
230V switch position - 190V to 265V
The application of voltages outside these ranges may cause permanent damage
or erratic operation of the unit, and will invalidate the warranty.
IMPORTANT: The mains fuse carrier on the rear of the unit must be fitted with
the correct type and rating of fuse, depending on the position of the mains
voltage selector switch:
115V switch position - T315mA fuse
230V switch position - T200mA fuse
In the unlikely event of the mains fuse failing without good reason,
DISCONNECT THE UNIT FROM THE MAINS SUPPLY, and always replace
with the appropriately rated fuse (as specified above) for continued protection
against damage and fire.
Note: For USA and Canadian users, the replacement fuse must be of an
identical UL rated type fuse for continued compliance with safety standards.

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3.0 Introduction
The BSS DPR-422 compressor, de-esser has been designed in response to the
demand for a versatile, cost effective two channel unit which maintains the
proprietary, audibly transparent, subtractive VCA technology as used in the
well established BSS DPR-402 unit. The provision of a separate, balanced
insert input and output per channel minimises the possibility of interference
that other units with unbalanced connections may suffer from.
To aid the integration of the DPR-422 into the widest range of systems, a rear
panel switch allows the operating level of unit to be set to either +4dBu, to suit
professional or -10dBV to suit semi-professional equipment.
The compressor section allows full control over all the normal parameters, and
offers AUTO time constants for general purpose use. The side chain insertion
point allows for the patching of external filters to provide dynamic tonal
modification for special treatments or special effects. Metering and monitoring
is comprehensive and easily interpreted. The full compressor operating range is
displayed on a two part meter, indicating both signals below threshold and
actual gain reduction. The arrangement of these two meters provides a highly
intuitive view of the modification being applied to the input signal.
Two modes of de-essing are available on the DPR-422. A dedicated broadband
de-esser allows wide band sibilance control simultaneously, and
independently from the main compressor. Operation is indicated on two
separate LED indicators, and therefore does not compromise the metering for
the main compressor. For highly critical de-essing applications, the compressor
section can be switched to operate on selected high frequencies only with full
control over the ratio, attack and release.
The output signal is continuously monitored on the output level meter but
depressing the INPUT METER switch allows measurement of the input signal to
aid level matching. Provision is also provided for listening to the de-esser filters
and any external side-chain equipment to aid accurate setting.
Introduction
Unpacking
4.0 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.
In the event that damage has occurred, please notify your dealer immediately,
so that a written claim to cover the damages can be initiated. Check out
section 10.0; warranty section, for more info on the warranty, and also to
record your dealer details.

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The DPR-422
Fig 4.2 Rear Panel
Fig 4.1 Front Panel

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All numbers in bubbles refer to Section numbers.

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5.0 Audio Connections
5.1 Main Inputs There are 2 input sockets on the rear panel of the 422, 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’ connection is to pin 3. Pin 1 is internally
connected to the chassis earth via a low value capacitor. This ensures freedom
from ground loops whilst allowing good EMC performance. The screen of the
input cable should be connected to pin 1 to ensure that EMC regulations are
being met, and the cable shield ground should also be connected to the
equipment which is providing the input signal.
When feeding the DPR-422 from unbalanced sources, connect the signal
conductor to pin 2 and the cable screen to pins 1 and 3. Transformer isolated
inputs are available as a dealer fitted option.
Audio Connections
5.2 Main Outputs The output signals are electronically balanced and fully floating on 3 pin male
XLRs. Full headroom is available into any load of 600 Ohms or greater. The
signal ‘HOT, +, or in phase’ signal is to pin 2, the ‘COLD, -, or out of phase’
signal is to pin 3, with pin 1 being connected directly to the chassis.
Fig 5.1
Fig 5.2
Fig 5.3