Klark Teknik DN540 User manual

Klark Teknik,

Klark Industrial Park,

Walter Nash Road,

Kidderminster.

Worcestershire.

DY11 7HJ.

England.

Tel: +44 1562 741515

Fax: +44 1562 745371

Email: [email protected]

Website: www.klarkteknik.com

DN540

Creative Quad Compressor

Operator Manual

DN540 Creative Quad Compressor — Operator Manual

DOC02-DN540 Issue B — February 2011

In line with the company’s policy of continual improvement, specifications and function may be

subject to change without notice. This Operator Manual was correct at the time of writing. E&OE.

IMPORTANT SAFETY INSTRUCTIONS

The lightning flash with arrowhead symbol within an equilateral triangle 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.

The exclamation point within an equilateral triangle is intended to alert the user

to the presence of important operating and maintenance (servicing) instructions

in the literature accompanying the product.

1 Read these instructions.

2 Keep these instructions.

3 Heed all warnings.

4 Follow all instructions.

5 Do not use this apparatus near water.

6 Clean only with a dry cloth.

7 Do not block any of the ventilation

openings. Install in accordance with the

manufacturer’s instructions.

8 Do not install near any heat sources such

as radiators, heat registers, stoves, or

other apparatus (including amplifiers) that

produce heat.

9 Do not defeat the safety purpose of the

polarized or grounding-type plug. A

polarized plug has two blades with one

wider than the other. A grounding type

plug has two blades and a third grounding

prong. The wide blade or the third prong

are provided for your safety. If the

provided plug does not fit into your outlet,

consult an electrician for replacement of

the obsolete outlet.

10 Protect the power cord from being walked

on or pinched particularly at plugs,

convenience receptacles and the point

where they exit from the apparatus.

11 Only use attachments/accessories

specified by the manufacturer.

12 Unplug this apparatus during lightning

storms or when unused for long periods of

time.

13 Refer all servicing to qualified personnel.

Servicing is required when the apparatus

has been damaged in any way, such as

power-supply cord or plug is damaged,

liquid has been spilled or objects have

fallen into the apparatus, the apparatus

has been exposed to rain or moisture,

does not operate normally, or has been

dropped.

14 Use the mains plug to disconnect the

apparatus from the mains.

15 Warning: To reduce the risk of fire or

electric shock, do not expose this

apparatus to rain or moisture.

16 Warning: Do not expose this

equipment to dripping or splashing

and ensure that no objects filled with

liquids, such as vases, are placed on

the equipment.

17 Warning: The mains plug of the power

supply cord shall remain readily

operable.

INSTRUCTIONS DE SÉCURITÉ IMPORTANTES

Le symbole représentant un éclair fléché dans un triangle équilatéral a pour but

d'alerter l'utilisateur de la présence d'une "tension dangereuse" non isolée à

l'intérieur du boîtier, pouvant être d'une force suffisante pour constituer un risque

d'électrocution.

Le point d'exclamation dans un triangle équilatéral a pour but d'alerter

l'utilisateur de la présence d'instructions importantes concernant le

fonctionnement et la maintenance, dans la documentation qui accompagne

l'appareil.

1 Veuillez lire ces instructions.

2 Conservez ces instructions.

3 Respectez toutes les consignes de

sécurité.

4 Suivez scrupuleusement toutes les

instructions.

5 N'utilisez pas cet appareil près d'un point

d'eau.

6 Utilisez uniquement un chiffon sec pour le

nettoyer.

7 N'obstruez aucune des ouïes de

ventilation. Installez-le en respectant les

instructions du fabricant.

8 Ne l'installez pas près de sources de

chaleur tels que radiateurs, panneaux

chauffants, étuves, ou autres appareils

produisant de la chaleur (dont les

amplificateurs).

9 Ne pas utiliser d'adaptateur pour

supprimer la prise de terre des prises à

trois fiches. Si la prise fournie ne peut pas

être branchée dans la prise électrique,

adressez-vous à un électricen qui

remplacera la prise obsolète.

10 Protégez le cordon secteur afin que l'on ne

marche pas dessus et qu'il ne soit pas

pincé, surtout au niveau des prises, ou à

l'endroit où il sort de l'appareil.

11 Utilisez exclusivement des fixations et des

accessoires recommandés par le fabricant.

12 Débranchez l'appareil en période d'orage

ou s'il doit rester inutilisé pendant

longtemps.

13 Confiez toutes les réparations et

interventions à un personnel qualifié. Une

intervention est nécessaire si l'appareil a

été endommagé d'une façon ou d'une

autre, si son cordon ou sa prise secteur

ont été endommagés, si du liquide a été

renversé ou si des objets sont tombés à

l'intérieur, ou encore si l'appareil a été

exposé à la pluie ou à l'humidité, s'il ne

fonctionne pas normalement, ou s'il est

tombé.

14 Débrancher l'appareil du réseau électrique

par la prise de secteur.

15 Avertissement : afin de réduire le

risque d'incendie ou de choc

électrique, ne pas exposer cet

appareil à la pluie ou à de l'humidité.

16 Avertissement : n'exposez pas cet

équipement aux éclaboussures et

veillez à ce qu'aucun récipient rempli

de liquide, verre ou vase, ne soit posé

dessus.

17 Avertissement : la prise secteur doit

toujours rester directement

accessible.

EC-Declaration of Conformity

Klark Teknik

DOC04-DN540ECDOC Rev. C

EC-Declaration of Conformity

The undersigned, representing the following manufacturer

Manufacturer: Address:

Midas Klark Teknik Ltd. Klark Industrial Park, Walter Nash Road,

Kidderminster. Worcestershire. DY11 7HJ.

hereby declares that the following product

Product Type Number Product Description Nominal Voltage(s) Current Freq.

DN540 Creative Quad Compressor

115V AC

230V AC

200mA

100mA

50/60Hz

is in conformity with the regulations of the following marked EC-directives and bears the

-mark accordingly

reference number title

2004/108/EC EMC Directive (EMC)

2006/95/EC Low-Voltage Directive (LVD)

The conformity of the product with EC directives for use in environments E1, E2, E3 and E4 is provided by

the compliance with the following standards:

Standards/date:

reference number title

EN 60065:2002 Audio, video and similar electronic apparatus. Safety requirements.

Applied EMC emission test standards:

w

ref. no. title

EN 55103-1:1996

Class B

EN 55103-1 Annex A: Radiated

magnetic disturbance, 50Hz-50kHz

CISPR 22: Radiated disturbance,

30-1000MHz

EN 55103-1 Annex E: Conducted

disturbance, ac & signal ports

EN 61000-3-2:2006 Mains

harmonics

EN 61000-3-3:1995 Mains voltage

flicker

Applied EMC immunity test standards:

ref. no. title

EN 61000-4-2:1995 Electrostatic

discharge

EN 55103:1996

Class B

EN 61000-4-3:1996: Radiated RF

disturbance, 80-1000MHz

EN 55103-2 Annex A: Magnetic LF

disturbance, 50Hz-10kHz

EN 61000-4-4:1995: Fast transient

bursts, ac & signal ports

EN 61000-4-5:1995: Surge, ac port

EN 61000-4-6:1996: Conducted RF

field, ac & signal ports

EN 61000-4-11:1994: Mains voltage

dips and interruptions

Place, date: Kidderminster, UK

9th February 2011

SVP, Midas Klark Teknik AVP, Product Development

Printed name: John Oakley Printed name: Alex Cooper

DN540

Operator Manual vii

Precautions

Before installing, setting up or operating this equipment please ensure that you have read

and fully understand all of this section and the “IMPORTANT SAFETY INSTRUCTIONS” at

the front of this manual.

This equipment is supplied by a mains voltage that can cause electric shock injury!

The following special limitations must be observed in order to maintain safety and electromagnetic

compatibility performance.

Safety warnings

This equipment is fitted with a mains

power socket. For safety reasons the

earth leads must not be disconnected.

Signal 0V is connected internally to the

chassis.

To completely disconnect this equipment

from the AC mains, while observing full

safety precautions (see “Power” on

page vii), switch off the mains at the

mains outlet. It is now safe to isolate the

unit by unplugging the mains lead from

its rear panel.

To avoid electrical shock do not remove

covers. Refer servicing to qualified

personnel only.

The power supplies — even the DC ones —

have a high current!

General precautions

The following information gives basic safety

precautions that should be observed to reduce

the risk of fire, electric shock and personal

injury:

• Never operate damaged equipment and

never operate equipment with damaged

cables.

• Do not remove, obscure or deface any

warnings or cautions.

Power

Please note that the system power supplies

contain LETHAL VOLTAGES greatly in excess of

the mains voltage and that its rails can

produce extremely large currents that could

burn out equipment and wiring if shorted. All

testing and servicing must ONLY be carried out

by approved service engineers.

This apparatus should only be operated with

the power supply connected to ground via the

ground in the mains connector.

The internal power supplies are of the switch

mode type that automatically sense the

incoming mains voltage and will work where

the nominal voltage is in the range 100VAC to

240VAC.

When removing the equipment’s electric plugs

from the outlets, always hold the plug itself

and not the cable. Pulling out the plug by the

cable can damage it.

Never insert or remove an electric plug with

wet hands.

Handling the equipment

Completely isolate the equipment electrically

and disconnect all cables from the equipment

before moving it.

When lifting or moving the equipment, always

take its size and weight into consideration.

Do not insert your fingers or hand in any gaps

or openings on the equipment, for example,

vents.

Avoid inserting or dropping foreign objects,

such as paper, plastic, metal etc., into any

gaps or openings on the equipment, for

example, vents. If this happens, immediately

disconnect the equipment from the mains (see

“Safety warnings” on page vii). Then, have

the equipment inspected by the

manufacturer's qualified service personnel.

Precautions

DN540

viii Operator Manual

Installation

Before installing the equipment:

• Power plugs must be inserted in socket

outlets provided with protective earth

contacts. The electrical supply at the

socket outlets must provide appropriate

over-current protection.

• Both the mains supply and the quality of

earthing must be adequate for the

equipment.

• Before connecting up the equipment, check

that the mains power supply voltage rating

corresponds with the local mains power

supply. The rating of the mains power

supply voltage is printed on the equipment.

Location

• Ideally a cool area is preferred, away from

power distribution equipment or other

potential sources of interference.

• Do not install the equipment in places of

poor ventilation.

• Do not install this equipment in a location

subjected to excessive heat, dust or

mechanical vibration. Allow for adequate

ventilation around the equipment, making

sure that its vents are not obstructed. To

prevent excessive heating of the

equipment, avoid mounting it directly

above power amplifiers or other devices

that radiate significant amounts of heat,

such as radiators and heaters. Keep the

equipment out of direct sunlight.

• Make sure that the mains voltage and fuse

rating information of the equipment will be

visible after installation.

Audio connections

To ensure the correct and reliable operation of

the equipment, only high quality balanced,

screened, twisted pair audio cable should be

used.

XLR connector shells should be of metal

construction so that they provide a screen

when connected to a console and, where

appropriate, they should have Pin 1 connected

to the cable screen.

In the event of ground loop problems,

disconnect the signal screen at one end of the

connecting cables. Note that this can only be

done when the equipment is used within a

balanced system.

Radio frequency

interference - Class B

device

This equipment has been tested and found to

comply with the limits for a Class B digital

device, pursuant to part 15 of the FCC Rules.

These limits are designed to provide

reasonable protection against harmful

interference in a residential installation. This

equipment generates, uses, and can radiate

radio frequency energy and, if not installed

and used in accordance with the instructions,

may cause harmful interference to radio

communications. However, there is no

guarantee that interference will not occur in a

particular installation. If this equipment does

cause harmful interference to radio or

television reception, which can be determined

by turning the equipment off and on, the user

is encouraged to try to correct the interference

by one or more of the following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the

equipment and receiver.

• Connect the equipment into an outlet on a

circuit different from that to which the

receiver is connected.

• Consult the dealer or an experienced radio

TV technician for help.

Electric fields

Caution:

In accordance with Part 15 of the FCC

Rules & Regulations, “… changes or

modifications not expressly approved by

the party responsible for compliance

could void the user's authority to operate

the equipment.”

Should this product be used in an

electromagnetic field that is amplitude

modulated by an audio frequency signal (20Hz

to 20kHz), the signal to noise ratio may be

degraded. Degradation of up to 60dB at a

frequency corresponding to the modulation

signal may be experienced under extreme

conditions (3V/m, 90% modulation).

Operation

To avoid electrical shock, never operate the

equipment with the covers removed.

Precautions

DN540

Operator Manual ix

Safety equipment

Never remove, for example, covers, housings

or any other safety guards. Do not operate

the equipment or any of its parts if safety

guards are ineffective or their effectiveness

has been reduced.

Optional equipment

Unless advised otherwise, optional equipment

must only be installed by service personnel

and in accordance with the appropriate

assembly and usage regulations.

Special accessories

To comply with part 15 of the FCC Rules, any

special accessories (that is, items that cannot

be readily obtained from multiple retail

outlets) supplied with this equipment must be

used with this equipment; do not use any

alternatives, as they may not fulfil the RF

requirement.

Precautions

DN540

x Operator Manual

DN540

Operator Manual xi

Contents

Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

About this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Chapter 2 What Is A Compressor? . . . . . . . . . . . . . . . . . . . . . . . . 5

Principles of compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Uses of compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Unwanted side effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Chapter 3 Getting Started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Checking the mains fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Connecting the power cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Connecting the audio cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Channel I/O pin-outs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Sidechain inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Connecting to unbalanced equipment . . . . . . . . . . . . . . . . . . . . . . 12

Powering the unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Chapter 4 Front Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Compressor section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Switch section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Chapter 5 Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Mains input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Channel connector section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Chapter 6 Compressor Control Functions . . . . . . . . . . . . . . . . . .19

Attack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Make up gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Presence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Soft knee and hard knee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Chapter 7 Using The Compressor . . . . . . . . . . . . . . . . . . . . . . . . 23

Modes of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Manual mode with soft knee (linear peak) . . . . . . . . . . . . . . . . . . . 23

Manual mode with hard knee (linear peak) . . . . . . . . . . . . . . . . . . 24

Contents

DN540

xii Operator Manual

Auto mode with hard knee (exponential RMS) . . . . . . . . . . . . . . . .24

Auto mode with soft knee (exponential RMS) . . . . . . . . . . . . . . . . .24

Limiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Simple compression (auto mode) . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Advanced compression (manual mode) . . . . . . . . . . . . . . . . . . . . . . .26

Stereo and multiple channel operation - linking . . . . . . . . . . . . . . . . .27

Sidechain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Appendix A Application Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Drums and percussive instruments . . . . . . . . . . . . . . . . . . . . . . . . . .29

Stringed acoustic instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Stringed electric instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Brass instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Vocals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Presence accentuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Appendix B Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . 31

Appendix C Balanced/Unbalanced Audio . . . . . . . . . . . . . . . . . . . 33

Appendix D Technical Specification . . . . . . . . . . . . . . . . . . . . . . . 35

Appendix E Crib Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Appendix F Service Information . . . . . . . . . . . . . . . . . . . . . . . . . 39

Routine maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Replacing the mains fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Equipment disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

DN540

Operator Manual 1

Chapter 1: Introduction

Thank you for purchasing a Klark Teknik DN540 Creative Quad Compressor. The

DN540 is a user-friendly, high-performance, four-channel (quad) analogue compressor

designed for live sound reinforcement primarily on tour, in theatres and at corporate

events, with applications in both front-of-house and monitoring situations. Other

possible areas for use include broadcasting, the recording studio and installation.

The DN540 provides a wide variety of easy-to-use controls for the precise manipulation

of compression parameters. These enable you to, for example, alter the character of an

instrument that is being processed or make sounds seemingly louder, but without

distortion. Other features include channel linking for stereo and multiple channel

operation, and a presence control for protecting vocals.

Your DN540 was conceived by Klark Teknik to offer audio professionals

high-performance audio equipment, designed to provide no-compromise sonic quality

with a feature set that offers all essential facilities and functions. It represents the very

best of British design and engineering combined with contemporary, efficient

manufacturing methods, and will give you many years of reliable service.

All this is backed up, of course, by the standard Klark Teknik three year warranty.

Please take the time to complete and return the registration card or fill in the Warranty

Registration Form online by visiting our website at www.klarkteknik.com and, to obtain

the best results with a minimum of effort, also read this operator manual.

Finally, enjoy your Klark Teknik DN540!

Overview

The DN540 consists of four linkable channels of compression that provide full control of

all essential audio-compression parameters. All this is housed in a compact 1U high

rack-mount unit.

The main compressor controls consist of continuously adjustable threshold, ratio and

make up gain, and a bypass switch and a hard knee switch. Used in auto mode, these

controls are all that are required to set up simple transparent RMS compression suited

to normal (not difficult) signals.

The envelope time constant controls (attack and release) are activated by disabling

auto mode and operating the DN540 in manual mode. The DN540 can then be used for

creative compression effects using a semi-linear attack shape.

Front panel

Rear panel

Chapter 1: Introduction

DN540

2 Operator Manual

The presence control progressively reduces compression in the 5kHz region.

Attenuation depth and input level meters are provided, plus a switch that changes the

output level meter to monitor the input signals.

A external sidechain input on the rear panel is switchable via the front panel.

Applications

The DN540 provides a quality, cost effective and compact compressor unit presented in

a traditional 1U quad channel format. This makes it ideally suited to applications where

space is limited or when there is no need for eight channels.

The default compressor mode (manual) is ideal for creative compression, whereby the

manual envelope controls for attack and release can be adjusted as necessary. This

mode provides a semi-linear type of compression, which is suited to percussive

instruments (especially thickening drums) and difficult instruments, or for more

advanced effects where the added manual control gives vastly superior results, as

compared to auto mode.

The auto compressor mode (with the pushbutton AUTO on) provides a

root-mean-square (RMS) type of compression. This mode is easy to use because the

envelope time constants (attack and release) are automatically adjusted, taking into

account threshold and ratio settings relative to signal levels and transients. This makes

the DN540 ideal for the novice user or for situations where there is not enough time to

set up the envelope manually.

The presence control will be especially useful on vocals to eliminate pumping effects

caused by, for example, cymbal spill — because singers typically stand with their

microphones (mics) pointing directly at the drum riser — and to add air to the sound

without introducing noise.

The DN540 has been primarily designed for the following main application areas:

• Touring live sound In applications where analogue consoles are still required due

to their ease of use. Here the DN540 can be used for channel inserts on drums, bass

guitars and other instruments. The compressor can be used to control both the

dynamic range and to generate musical effects. The presence control reduces

pumping on vocals and also increases brightness to a desired level without

increasing the risk of squealing if mics are held too close to monitor speakers.

• Theatre live sound Theatres can make use of the compressor in the same way as

touring live sound, for vocals and orchestra, but in this case they can probably make

more use of the compressor’s more transparent linear style. The presence masking

is useful, increasing vocal brightness without bringing up the noise floor, which may

be quite poor due to the use of radio mics and mic placement limitations.

• Corporate live event As above, transparent control and effects can be used on

channel inserts.

Features

DN540

Operator Manual 3

Features

The DN540 has the following features:

• Great sounding compressor that provides good audio performance at extremely low

noise and distortion levels.

• Easy to use basic compressor, requiring minimum set up to produce excellent

results.

• Advanced envelope generator with manual controls that can be easily switched in or

out to produce transparency or creative dynamic effects, as required, for any given

source material.

• Extremely transparent compression.

• Multiple compression styles that are easily matched to the programme material

and/or generate dynamic effects.

• Unique and intuitive presence control that improves the high frequency sound

quality without increasing noise or squealing (howl-round).

• Intuitive ‘turn it up, turn it down’ control knob labelling avoids confusion during fast

adjustment. Also, good control status visibility enables you to see the status of all

pushbuttons, which are boldly presented to avoid mistakes.

• Comprehensive metering, making set up simple and intuitive.

• Totally analogue, which precludes the use of complex set up menus and means that

there is absolutely no audio delay. Thus, compressed and non-compressed signals

can be recombined without producing comb filter effects.

• Stereo and multiple channel linking. Linking has true power summing, so that it

always provides true threshold setting for stereo material. For example, for using

the compressor across a stereo group.

• Housed in a compact 1U high unit.

• Puts back dynamics and punch for creative effects.

About this manual

This is the operator manual for the DN540. It is intended to help get your DN540

installed and in operation as quickly as possible by giving you unpacking, installation,

connection and setting up instructions. To help familiarise you with the DN540 there is

a description of the front and rear panels, along with easy-to-follow user instructions.

Chapter 1: Introduction

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Chapter 2: What Is A Compressor?

The natural sounds of everyday life, which can be caused by anything from, say, the

falling of a leaf to the roar of a jet engine, vary extremely widely in sound level. This

variance is known as the “dynamic range” and is the difference — expressed in

decibels (dB) — between the loudest and quietest sounds in a piece of audio, such as

music or speech, or that can be reproduced by a piece of audio equipment without

distortion.

The human ear has an automatic gain control that enables it to accommodate all of the

sounds ranging from the threshold of hearing to near the threshold of pain, a dynamic

range of approximately 120dB. However, a dynamic range of this magnitude, even if it

were possible in audio equipment, is not required in practice for comfortable listening.

A sound pressure level (SPL) of 96dB would, in a domestic environment, almost

certainly annoy the neighbours. While, at the other end of the dynamic scale, a typical

ambient noise level of at least 40dB SPL makes it impossible to use very quiet levels in

recorded or broadcast sound media. So, it is almost always necessary to compress the

dynamic range of natural sounds to fit them into a window (usually about 30dB to

40dB) suitable both for the equipment and for comfortable listening.

The compressor is a valuable tool for the control of the dynamic range.

Principles of compression

One of the principal uses of compression is the control of level in vocals. Many singers

train for years to achieve the degree of breath control necessary for an even tone and

expressive performance. Whereas, other vocalists rely on an instinctive voice

production technique, which may need technological assistance to maintain a consistent

level that sits correctly in the programme.

Figure 1: Compression - signal level graphs

Unprocessed signal

Time

Threshold level

Signal level

3:1 Compression above threshold

With make up gain added

Time

Threshold level

Signal level

Time

Signal level

Threshold level

Chapter 2: What Is A Compressor?

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The level of a vocal may vary widely. As shown in the typical example in Figure 1

“Compression - signal level graphs”, the unprocessed signal has a large dynamic range

between the highest and lowest levels. Applying compression reduces the highest

levels, thus reducing the dynamic range, while leaving the signal below threshold

relatively unaltered. Because the peak level of the signal is now lower, make up gain is

added to restore the original peak level. The result is a much more controlled and

usable sound.

Uses of compression

Compressors were originally devised to reduce the dynamic range of audio signals. To

do this they use a gain cell that makes adjustments to signal levels automatically,

dependent on the level and dynamic of the signal itself, and depending on the character

and control settings of the particular compressor unit.

Over the years many different brands of compressor have been produced using many

different types of gain cell technology, each with a distinctive sound. Users have found

applications that suit many of these, taking the use of compressors far beyond simple

dynamic range reduction and sometimes even generating the complete reverse —

dynamic enhancement. Typical applications include:

• Protecting systems from amplitude overload.

• Improving the power of signals when an artiste’s performance is inconsistent.

• Maintaining a stable signal level to help an instrument sit better within a mix.

• Changing the percussive timbre of an instrument to produce more punch.

• Compressing a mix so that it maintains a stable signal level, typically trying to make

it sound louder.

• Changing the percussive timbre of a mix to make it sound more whole and add

punch.

• Frequency-conscious compression to remove unwanted sibilance or popping.

Unwanted side effects

Very often the process of compression produces unwanted side effects, especially if the

chosen compressor does not match the application it is being put to very well. These

can include:

• Breathing — when high frequency environmental or processing noise levels jump

up and down, sounding similar to someone breathing in the background.

• Pumping — when level modulation can be heard on an instrument, making it sound

unnatural.

• Amplitude flutter — a faster oscillating modulation that makes sounds gritty.

• Source inter-modulation — when one sound source within a mix causes amplitude

changes to another, for example, the natural decay of cymbals can be modulated by

the crack of a snare drum in a drum mix.

• Transient enhancement — unwanted accentuation clicks at the start of a sound.

• Dull sound — when all the natural attack and brilliance is stripped away from the

sound source.

Unwanted side effects

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Providing controls for threshold, attack, release and ratio, and providing responsive

metering can go along way towards helping with suitable parameter set up for any

signal source, such that most of the negative effects above can be reduced or

eliminated. However, this is a complex and critical task that often involves a degree of

compromise between the desired compression effects and the unwanted side effects,

which can be time consuming.

Chapter 2: What Is A Compressor?

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Klark Teknik DN540 User manual

Klark Teknik DN540 User manual

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