Drawmer DL241 User Manual

DL241

DUAL AUTO COMPRESSOR

OPERATORS MANUAL

CONTENTS

SAFETY CONSIDERATIONS	page 1
INTRODUCTION	page 2
INSTALLATION	page 3
CONTROL DESCRIPTIONS	page 5
OPERATION	page 8
IF A FAULT DEVELOPS	page 10
CONTACTING DRAWMER	page 10
TECHNICAL SPECIFICATION	page 11
BLOCK DIAGRAM	page 12

i

COPYRIGHT

This manual is copyrighted © 1995 by Drawmer Electronics, Ltd. With all rights reserved. Under copyright laws, this manual may not be duplicated in whole or in part without the written consent of Drawmer.

ONE YEAR LIMITED WARRANTY

Drawmer Electronics Ltd., warrants the Drawmer DL241 audio processor to conform substantially to the specifications of this manual for a period of one year from the original date of purchase when used in accordance with the specifications detailed in this manual. In the case of a valid warranty claim, your sole and exclusive remedy and Drawmer’s entire liability under any theory of liability will be to, at Drawmer’s discretion, repair or replace the product without charge, or, if not possible, to refund the purchase price to you. This warranty is not transferable. It applies only to the original purchaser of the product.

For warranty service please call your local Drawmer dealer. Alternatively call Drawmer Electronics Ltd. at [phone]. Then ship the defective product, with transportation and insurance charges pre-paid, to Drawmer Electronics Ltd., Coleman Street, Parkgate, Rotherham, S62 6EL UK. Write the RA number in large letters in a prominent position on the shipping box. Enclose your name, address, telephone number, copy of the original sales invoice and a detailed description of the problem. Drawmer will not accept responsibility for loss or damage during transit.

This warranty is void if the product has been damaged by misuse, modification or unauthorised repair.

THIS WARRANTY IS IN LIEU OF ALL WARRANTIES, WHETHER ORAL OR WRITTEN, EXPRESSED, IMPLIED OR STATUTORY. DRAWMER MAKES NO OTHER WARRANTY EITHER EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. PURCHASER’S SOLE AND EXCLUSIVE REMEDY UNDER THIS WARRANTY SHALL BE REPAIR OR REPLACEMENT AS SPECIFIED HEREIN.

IN NO EVENT WILL DRAWMER ELECTRONICS LTD. BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM ANY DEFECT IN THE PRODUCT, INCLUDING LOST PROFITS, DAMAGE TO PROPERTY, AND, TO THE EXTENT PERMITTED BY LAW, DAMAGE FOR PERSONAL INJURY, EVEN IF DRAWMER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

Some states and specific countries do not allow the exclusion of implied warranties or limitations on how long an implied warranty may last, so the above limitations may not apply to you. This warranty gives you specific legal rights. You may have additional rights that vary from state to state, and country to country.

In the interests of product development, Drawmer reserve the right to modify or improve specifications of this product at any time, without prior notice.

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DL241 OPERATORS’ MANUAL

1

DRAWMER DL241

Dual Auto Compressor

SAFETY CONSIDERATIONS

CAUTION - MAINS FUSE

TO REDUCE THE RISK OF FIRE REPLACE THE MAINS FUSE ONLY WITH THE SAME TYPE, WHICH MUST BE A CLASS 3, 230 VOLT, TIME DELAY TYPE, RATED AT 32mA WHERE THE MAINS INPUT VOLTAGE SWITCH IS SET TO 230 VOLTS AC. AND 63mA WHERE THE MAINS INPUT VOLTAGE IS 115 VOLTS AC.

ALL FUSES MUST COMPLY WITH IEC 127-2.

THE FUSE BODY SIZE IS 20mm x 5mm.

CAUTION - MAINS CABLE

DO NOT ATTEMPT TO CHANGE OR TAMPER WITH THE SUPPLIED MAINS

CABLE.

CAUTION - SERVICING

DO NOT PERFORM ANY SERVICING. REFER ALL SERVICING TO QUALIFIED

SERVICE PERSONNEL.

WARNING

TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK DO NOT EXPOSE THIS

EQUIPMENT TO RAIN OR MOISTURE.

2	DL241 OPERATORS’ MANUAL

INTRODUCTION

The DL241 is a dual channel compressor/limiter designed to fulfil the needs of professional studio and live sound applications. It may be used in balanced or unbalanced systems and each channel is independently switchable between +4dBu and -10dBu operating levels. In addition to the compressor/limiter, each channel also contains an independent expander and peak limiter.

In order to maximise flexibility while simplifying set up and operation, several new design concepts have been incorporated. The compressor section combines aspects of both the traditional ratio style compressor and the soft-knee approach, making it equally adept at creative work and unobtrusive level control. The control layout resembles that of a straight ratio style unit but the transition from unity gain to gain reduction at the selected ratio is progressive and occurs over a nominal 10dB input level range.

Traditionally, soft-knee compressors have been preferable for unobtrusive level control where the original sound is to be changed as little as possible, whereas ratio type compressors are generally considered more successful in creative applications or where large amounts of gain reduction are required. By combining these two elements, the DL241 is capable of outstanding results in a very wide range of studio and live sound situations.

One of the perennial problems in using compression is that maximum system gain occurs during extremely quiet passages or during pauses which results in an increase in background noise, the degree depending on the amount of compression being used. The accepted way of dealing with this problem is to include in the compressor, a separate expander section with its own threshold control so that a low level gating action may be applied to keep pauses clean. But the problem with simple expanders is that, even when properly set up, they may unwittingly process low level sounds as they have no means of identifying them from noise. On a vocal track, for example, this can lead to the starts or endings of words being accidentally removed, especially if the singer has a wide dynamic range.

The DL241 uses an entirely new Programme Adaptive expander circuit which varies its ratio depending on the dynamics of the signal being processed. Because the onset of expansion is progressive, those low level signals most at risk will be treated to a lower ratio of expansion while the residual noise during pauses will be subjected to a higher expansion ratio and will, in consequence, be attenuated more. The outcome is an expander that requires less stringent setting up and is more tolerant of wanted sounds that are only slightly above the residual noise floor.

A further feature of the DL241 is a peak limiter which allows the user to set an absolute output signal level that will not be exceeded. If the peak limiter threshold is exceeded for more than a few milliseconds, additional gain reduction will be applied to reduce the overall signal level to within accepted limits without distortion. Once the peak has passed, the system gain will return to normal over the period of about one second. This facility is extremely valuable both in live sound applications, for driver protection, and in digital recording where an absolute maximum recording level exists. Furthermore, when overdriven, it can be used creatively to produce deliberate level pumping effects.

DL241 OPERATORS’ MANUAL

3

INSTALLATION

The DL241 is designed for standard 19" rack mounting and occupies 1U of rack space. Avoid mounting the unit directly above power amplifiers or power supplies that radiate significant amounts of heat. Fibre or plastic washers may be used to prevent the front panel becoming marked by the mounting bolts.

AUDIO CONNECTIONS

Both the input and output connectors may be used either balanced or unbalanced, the wiring convention being for jacks: tip hot, ring cold and sleeve ground; and for XLR connectors: pin 2 hot, pin 3 cold and pin 1 ground. The rear panel push buttons should be out for +4dBu operation or in for -10dBu operation. For use with unbalanced systems, the unit is directly compatible with mono jacks. The mono jack actually shorts the cold terminal to ground. For the DL241 units fitted with XLR connectors, unbalanced operation is achieved by shorting pin 3 of the XLR connector to ground (pin 1) at both input and output.

Interference:	If the unit is to be used where it maybe exposed to high levels of
	disturbance such as found close to a TV or radio transmitter, we
	advise that the unit is operated in a balanced configuration. The
	screens of the signal cables should be connected to the chassis
	connection on the XLR connector as opposed to connecting to
	pin1. The DL241 conforms to the EMC standards.
Ground Loops:	If ground loop problems are encountered, never disconnect the
	mains earth, but instead, try disconnecting the signal screen on
	one end of each of the cables connecting the outputs of the DL241
	to the patchbay. If such measures are necessary, balanced
	operation is recommended.