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

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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 W ARRANTIES, 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 DRAW MER 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 W ITH THE

SAME TYPE, WHICH MUST BE A CLASS 3, 230 VOLT, TIME DELAY TYPE, RATED

AT 32mA WHERE T HE MAINS INPUT VOLTAGE SW ITCH 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 T AMPER W ITH 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.

DL241 OPERATORS’ MANUAL2

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 conf iguration. 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.