Drawmer TwoPlusTwo Dynamics DSL424 User manual

DRAWMER
DSL424
TwoPlusTwo
DYNAMICS
OPERATOR’S MANUAL
CONTENTS
Warranty
SafetyConsideration
Chapter 1 - Introduction
Introduction
Installation
AudioConnections
PowerConnection
Chapter 2 - Control Description
TheNoiseGateChannels
TheCompressor/LimiterChannels
TheQuickSetupProcedure
Chapter 3 - Operation
TheNoiseGateChannels
TheCompressor/LimiterChannels
Chapter 3 - General Information
Ifafaultdevelops
ContactingDrawmer
Specification
Block Diagram
SessionRecallSheet
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2DRAWMERDSL424OPERATOR’SMANUAL
Drawmer Electronics Ltd., warrants the Drawmer DSL424
TwoPlusTwo Dynamics 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
warrantyclaim,your soleandexclusive remedyandDrawmer’s
entireliabilityunderany theoryofliabilitywill beto,atDrawmer’s
discretion, repair or replace the product without charge, or, if
notpossible, torefundthepurchasepricetoyou.Thiswarranty
is not transferable. It applies only to the original purchaser of
theproduct.
For warranty service please call your local Drawmer dealer.
Alternatively call Drawmer Electronics Ltd. at +44 (0)1709
527574. Then ship the defective product, with transportation
andinsurance charges pre-paid, toDrawmer Electronics Ltd.,
ColemanStreet, Parkgate,Rotherham, S626EL UK.Write the
RA number in large letters in a prominent position on the
shippingbox.Enclose yourname, address,telephone number,
copy of the original sales invoice and a detailed description of
theproblem. Drawmer will not accept responsibility for lossor
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,
WHETHERORALORWRITTEN,EXPRESSED,IMPLIEDOR
STATUTORY.DRAWMER MAKESNOOTHER WARRANTY
EITHER EXPRESS OR IMPLIED, INCLUDING, WITHOUT
LIMITATION, ANY IMPLIED WARRANTIES OF
MERCHANTABILITY,FITNESSFORAPARTICULARPURPOSE,
OR NON-INFRINGEMENT. PURCHASER’S SOLE AND
EXCLUSIVEREMEDYUNDER THISWARRANTYSHALL BE
REPAIR ORREPLACEMENTASSPECIFIEDHEREIN.
IN NO EVENT WILL DRAWMER ELECTRONICS LTD. BE
LIABLEFORANYDIRECT,INDIRECT,SPECIAL,INCIDENTAL
ORCONSEQUENTIALDAMAGESRESULTINGFROMANY
DEFECT IN THE PRODUCT, INCLUDING LOST PROFITS,
DAMAGETOPROPERTY,AND,TOTHEEXTENTPERMITTED
BY LAW, DAMAGE FOR PERSONAL INJURY, EVEN IF
DRAWMERHAS BEENADVISEDOF THEPOSSIBILITY OF
SUCHDAMAGES.
Somestates and specific countries do not allow theexclusion
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
haveadditional rightsthat vary fromstate to state,and country
tocountry.
In the interests of product development, Drawmer reserve the right to modify or
improve specifications of this product at any time, without prior notice.
ONE YEAR LIMITED WARRANTY
COPYRIGHT
This manual is copyrighted 82004 by Drawmer Electronics Ltd. With all rights reserved. Under copyright
laws, no part of this publication may be reproduced, transmitted, stored in a retrieval system or translated
into any language in any form by any means, mechanical, optical, electronic, recording, or otherwise, with-
out the written permission of Drawmer Electronics Ltd.
DRAWMER
DSL424
DualChannel
VacuumTubeCompressor
SAFETY CONSIDERATIONS
CAUTION-MAINSFUSE
TO REDUCE THE RISK OF FIRE
REPLACE THE MAINS FUSE ONLYWITH
A FUSE THAT CONFORMS TO IEC127-2.
250 VOLT WORKING, TIME DELAY TYPE
AND BODY SIZE OF 20mm x 5mm.
THEMAINS INPUTFUSEMUST BE
RATED AT 230V=T125mAand 115V=T250mA.
CAUTION-MAINSCABLE
DO NOTATTEMPT TO CHANGE
OR TAMPER WITH THE
SUPPLIEDMAINS CABLE.
CAUTION-SERVICING
DO NOT PERFORM ANY SERVICING.
REFERALLSERVICING TOQUALIFIED
SERVICE PERSONNEL.
WARNING
TO REDUCE THE RISK OF FIRE OR
ELECTRIC SHOCK DO NOT EXPOSE
THISEQUIPMENTTO RAINORMOISTURE.

3
DRAWMERDSL424OPERATOR’SMANUAL
DRAWMER
DSL424
TWOPLUSTWO DYNAMICS
TheDSL424providestheengineerwitha1U four channel
comprehensive toolbox capable of solving the most
complex dynamic problems. Incorporated in the 1U
package are two industry standard frequency conscious
noise gates and two soft/hard knee compressors with
variablethresholdlimiting.Thechannelsmaybe frontpanel
configured as four individual stand alone processors, a
stereo linked pair of comp/limiters with a stereo linked
pairof gates.Alternatively, anycombination of processing
canbe achieved byrear panelpatching.
The DSL424 combines the gates of the DS404 with the
compressor/limitersoftheDL441toprovideaversatile1U
problemsolver invaluableinapplicationswhererack space
is limited.
Recognizing that there are many general applications
whichrequireequipmentthat issimpletooperate,Drawmer
havedesignedthenoisegatestagesoftheDSL424utilizing
‘ProgrammeAdaptive’ circuitry. This makes the DSL424
ideally suited for use over a wide range of input signals,
ranging from drums and other percussive instruments
throughto vocals, pianosand even completemixes.
Theprovisionof variable Low-Pass andHigh-Pass Filters
allows ‘without compromise’ frequency selective gating
withaKEYLISTENfacility enabling monitoring of thefilter
setting.
Each gate channel can be operated as HARD - offering
ultra-fastresponse time,stabletriggeringanda specialized
release contour which is ideally suited to percussive
materialorSOFT-aversatileExpandercapableofhandling
vocals and sub mixes.
Noise Gate
•VariableHigh/LowPassFiltersforfrequencytriggering
• Auto attack
•Variablerelease
• Switchable range with LED status
• Selectable ‘Hard’ (drums etc.) or ‘Soft’ (vocals etc.)
• 1/4 inch jack Key Inputs
• Key Listen facility
•Slave linking
CHAPTER 1
INTRODUCTION
Thecompressorsectionfeaturesahighlydeveloped,auto
attack/release system which adapts itself to the
programme material being processed and is equally
effectiveon individual soundsor complexmixes.
To maximise flexibility, each channel of the DSL424 is
switchable between traditional ratio (hard knee) and
soft-kneeoperation.Traditionally,soft-kneecompressors
arepreferable forunobtrusivelevelcontrolor forthecontrol
of finished mixes, whereas ratio type compressors are
generally considered more successful in creative
applicationsorwhere large amounts ofgain reduction are
required.Byoffering a choiceof both modes,the DSL424
is capable of outstanding results in a very wide range of
studio and live sound situations. The two channels may
be operated independently or linked for true stereo
operation.
Also included in each channel of the DSL424 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,
additionalgainreductionwillbeappliedtoreducetheoverall
signal level to within accepted limits without distortion.
Once the peak has passed, the system gain will return to
normal after a period of about one second. This facility is
extremelyvaluablebothinlivesoundapplications, fordriver
protection, and in digital recording where an absolute
maximum recording level exists. Furthermore, when
deliberatelyoverdriven,itcanbeusedcreativelyto produce
level “pumping” effects which can be useful on electric
guitar or rock vocal sounds.
Compressor/Limiter
•SwitchableHard/Softkneecompressionwithvariable
threshold, ratio and output gain
• Auto attack/release
•Variable‘zeroovershoot’transparentlimiter
•High resolution bargraphmetering ofgain reduction
andinput/output level
• Stereo linking
• Balanced +4dB XLR in/out

4DRAWMERDSL424OPERATOR’SMANUAL
The DSL424 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 and always connect
the mains earth to the unit. Fibre or plastic washers may
be used to prevent the front panel becoming marked by
the mounting bolts.
INSTALLATION
AUDIO CONNECTIONS
Theinputsand outputs are electronicallybalanced on conventionallywired XLRs (pin1 screen,pin 2 hot,pin 3 coldand
XLR shell is connected to chassis). The operating level is nominally +4dBu. Balanced use is recommended.
•Interference:
If the unit is to be used where it maybe exposed to
highlevelsof disturbance such asfound close toa TV
orradiotransmitter,weadvisethattheunitisoperated
inabalanced configuration. Thescreens of thesignal
cablesshouldbeconnectedtothechassisconnection
on the XLR connector as opposed to connecting to
pin1.The DSL424conforms tothe EMC standards.
•Ground Loops:
If ground loop problems are encountered, never dis-
connect the mains earth, but instead, try disconnect-
ingthesignal screen on oneend of eachof the cables
connectingtheoutputsof the DSL424 to the patchbay.
If such measures are necessary, balanced operation
isrecommended.
The unit will have been supplied with a power cable suitable for domestic power outlets in your country. For your own
safetyit is importantthatyou use thiscable. The unitshould always beconnectedto the mainssupplyearth using this
cable,and no other.
If for some reason the unit is to be used at a mains input operating voltage which is different to that as supplied, the
followingprocedure must becarried out :
POWER CONNECTION
Disconnect the unit from the mains.
Remove the two self-tapping screws
that hold the voltage selection switch
cover-plateontothe rear panel.
Remove the cover plate and slide the
switch fully to its opposite end.
Rotate the cover plate one half turn,
(180degrees)and refit the two screws.
Replacewith a correctlyrated fuse for
theselected operation voltage.
Re-connectto mains powersource.
Neverdisconnect the earth
fromthemainssupply
115V Setting
230V Setting
1:
2:
3:
4:
5:
6:

5
DRAWMERDSL424OPERATOR’SMANUAL
CONTROL DESCRIPTION
Bothgatechannels of the DSL424are identical andmay beused completely independentlyor linked forstereo channel
operation. In the linked mode, only the left channel’s controls are functional and serve as master, though the channel
bypass switches remain independent. When linked, the control signal is derived only from the programme material
present at the input of the master channel.
Threshold: Setsthe level belowwhich gating startsto takeplace and maybeset in therange -70dB to+20dB.
Display The famous Drawmer traffic light display shows gate status
Gate Closed Hold Time GateOpen
Release 10mS to 5S.
Additionally, some envelope hold time is built into the system which varies with the release time.
This prevents chatter when processing material with inconsistent decay characteristics and is
quite invisible to the user.
Range Determines how much gain reduction is applied when the gate is fully closed. A setting of -90dB
effectively silences the signal completely, while the -20dB setting will still allow an attenuated
version of the signal to pass through. We recommend this switch is left in the -90dB (out)
position.
For signals with a high levels of background noise, the very fact of closing down to -90dB can be
disconcertingly noticeable. In such cases the -20dB switch setting can achieve better results.
Note: This control is active on both channels, even in stereo linked operation.
Key Listen / Gate / Bypass
When this switch is set to Key Listen, the effect of the key filters on the programme material is
heardat the output. Innormal operation,the Gate positionis selected; thefilters onlyaffect theway
the DSL424 responds to the incoming programme material - they do not have any direct effect on
the output signal. The Bypass position routes the input signal to the output with no processing.
Note: It is possible to leave the switch in the Key Listen position in order to use the DSL424
simply as a filter rather than a gate.
The Noise Gate Channels
CHAPTER 2
Noise Gate 1 Noise Gate 2 Compressor 1 Compressor 2

6DRAWMERDSL424OPERATOR’SMANUAL
L.F. 25Hz - 10kHz
TheLow Frequency filterworks byseverely attenuatingfrequencies belowthe cut-offfrequency
selected.
H.F. 200Hz - 35kHz
TheHigh Frequency filter attenuatesfrequenciesabove the selected cut-offvalue. Inotherwords,
when both filters are set, it is the range between the two settings that is allowed to pass.
Ext/Int In the INT position, this switch causes the gate to respond to the dynamics of the signal being
processed.
IntheEXT position, an externalaudio signalfedto the keyinputis used tocontrol thegate,making
it possible to gate one sound using another, independent signal.
Gating Thisbutton selects betweenthe Hard and Softmodes of operation.In theHard mode, theDSL424
Hard/Soft behavesas a fast,conventional gate whilein Softmode, it performsas aprogramme adaptive
expander. Hard mode is signified by a red status LED while the Soft mode is identified by a yellow
LED. If two channels are linked, the mode is determined by the master (left) channel and the
Hard/SoftLEDs onthe slavechannel will extinguish.
Master Link When the link button is depressed, the gate 2 channel on the right is controlled by the gate 1 left
handchannel. In linked mode,the redstatus LEDbeneaththe Slave Link switchwill beilluminated,
and both the yellow and red HARD/SOFT LEDs of the slave channel will be extinguished. This
assists to show that the only controls of the slave channel that still function are the Key Listen /
Gate / Bypass switch and the Range switch.
The Noise Gate Channels cont...
Bothcompressor channels ofthe DSL424are identicalandmay be usedcompletely independentlyorlinked for stereo
operation. In the linked mode, only the left hand channel (compressor 1) controls are functional and serve as master
controls,though thechannel bypassswitches remain independent.In linked mode,the compressor/limiters andpeak
limitersof the two linkedchannelstrack together to avoidtheinevitable image shifting thatoccurs ifthetwo channels of
astereo signal aretreated independently.
Compressor
Threshold Determinesthe inputlevel abovewhich gain reductionwill be appliedand may beset in therange
-40 to +20dB. When Soft Knee compression is selected, the onset of compression is progressive
overan input range ofapproximately15dB, above which levelconventionalratio compression is
applied. For this reason, the signal level may appear to fall when the compressor is switched from
Hard to Soft Knee operation and some readjustment of the threshold setting may be required.
Knee SelectsHard or SoftKnee operation. Ingeneral,the Soft Kneemode provides theleastobtrusive
Hard/Soft gaincontrol andis oftenthe preferred settingwhen treating finishedmixes.
The Compressor/Limiter Channels

7
DRAWMERDSL424OPERATOR’SMANUAL
THE QUICK SETUP PROCEDURE
Quickly Setup the Gate
Select the Key trigger source.
Select Key Listen, and trim down to the desired
frequency for triggering the Gate using the HFand LF
Key filters.
Select the desired amount of reduction using Range.
Normally fully counter clockwise.
Set the Attack, Hold. Decay and Range controls. For
aprogrammewithlonglegatorelease,thenReleasewill
alsoneedtobelong.Eg.Piano with reverb. For material
with much low frequency content, the Attack will need
to be quite slow, unless a ‘click’ is desired.
UsingtheTrafficLightLEDdisplay,rotatetheThreshold
until some gating activity can be seen. As a rule, the
Thresholdwill need tobe about3dBbelow the average
inputleveltobothseeand hear the dynamic processing.
Ratio Setsthe final compressionratio that willbe appliedonce the thresholdlevel isexceeded. The ratio
may be continuously adjusted from 1.2:1 to infinity:1 allowing the possibility of true hard limiting.
Gain Duringcompression, the signalisattenuated depending onthedynamics of thesignal.As a result,
gain may need to be applied in order to produce the desired output level. The GAIN control has a
range of -20dB to +20dB. If the limiter is in operation, only increase GAIN until the limiter operates
onsignal peaks. Anyfurther GAIN willjustcause excessive limiting,thus reducing theeffectof the
compressor.
Bypass Thisswitch will disable thefunctioning ofthe Compressorsectionand the Peak Limiter. Ifoperating
in Stereo Linked mode, both linked compressor channels will be bypassed simultaneously.
Gain Reduction Meter
An eight segment LED bargraph meter continuously monitors the gain reduction applied by the
compressor/limiterover the range0 to 30dB.
Output Level Meter
Thisis a5-segment LEDbargraph level meterthat monitors thelevelof the outputsignal over the
range-10dB to +10dB.
Peak Limiter
Level Thiscontrol sets anabsolute limit tothelevel that theoutput signal willnot bepermitted to exceed.
Thislimiter is very fastacting enabling itto controlany peakswithout audibledistortion. If theoutput
signal is so high as to cause the limiter to operate for more than 20mS, the system gain is
automatically reduced to bring the signal back within range. The system gain is then returned to
normalover a periodof approximatelyone second.
The compressor Gain control should be used to ensure that the peak limiter operates only rarely
if at all if the limiter is to be used purely for peak protection.Alternatively, the unit may be
deliberatelydriven into limitingto producecreativeeffects.
•
•
•
•
•
Quickly Setup the Compressor/Limiter
SelectHard Knee ifcompressingpercussivetracksand
Soft Knee for vocals.
Ensure the Limiter control is fully clockwise.
Fromthe programme material,set the Ratio. Theratio
settingdependsonhowfirmlythesignal dynamics need
controlling; as a rule, higher ratios provide a higher
degree of control but also tend to be more audibly
apparentinoperationwhenhighlevelsof gain reduction
arerequired. Ingeneral, wesuggest less than2.5:1 for
vocals, less for full mixes, and more for dynamic single
tracks.
Usingthe VUmeterandthe CompressorGainReduction
(GR)meter,rotatetheThreshold untilsomeGR activity
can be seen. As a rule, the Threshold will need to be
about6dBto10dB below the average input levelto both
see, and hear, much change.
Adjust the Gain to give the desired amount of level on
the VU Meter.
Adjustthe Peak Limiterso thatthelimiter led onlylights
on signal extreme peaks.
•
•
•
•
•
•

8DRAWMERDSL424OPERATOR’SMANUAL
OPERATION
The Noise Gate Channels
CHAPTER 3
Theunit should beconnected in-line withthe signal tobe
processed via suitable insert points. Ensure, where
possible, that the insert send and return level on your
consoleapproximately matches the operatinglevel ofthe
DSL424.
Formonouse, each channelmay be consideredas being
completely independent and set up accordingly. For use
with stereo signals, all setting up is then done using the
noisegate 1(left) channel'scontrols.
For percussive material such as drums, fast synthesised
sounds or percussive bass guitar, the Hard mode of
operation will give the fastest response. However, with
material having a slower attack, the Hard setting may
produce transient clicks at the beginning of sounds in
which case the Soft setting may produce better results.
Initially, the Low filter should be set fully anti-clockwise
whilethe High filtershould beset fullyclockwise.This will
allowthefullaudiospectrum of the input programmeto be
monitored by the side-chain control circuitry. Set the
Range control to -90dB and the output selector switch to
Normal.
Withthereleasecontrolsetat its mid-way position, Range
set to -90dB and with suitable programme material fed
intothe DSL424, increase the Threshold levelfromitsanti-
clockwise position until the gate starts to operate. This
will be indicated by the activity of the traffic light LEDs
and you should also hear the effect on the outputs signal
in that pauses in the programme will now be silent. If the
threshold setting is too high, the gate will start to cut out
wantedpieces of programme soyou shouldadjust it toas
low a setting as possible consistent with the effective
removal of low level noise. If the ends of sounds are
obviouslybeingtruncated,thena longer release time may
help.Onthe other hand, ifunwanted noise isaudible after
thewanted sound hasended,a shorter releasetimemay
wellbe more appropriate.
Therearecircumstanceswhentheprogrammematerial is
corruptednotonlybyunwanted randomnoise,butbysome
othersound.Forexample,inamulti-mikeddrumkitsetup,
some hi-hat will inevitably leak into the snare mic, some
snare drum into the kick drum mic and so on. Equally,
whenrecording on location, you mayexperienceproblems
duetowind or traffic noiseor close-byconversation. Ifthe
unwanted noise is different in pitch to the wanted sound,
it is often possible, by using the Key Listen facility, to use
the filters to 'tune' into the wanted sound while excluding
as much of the unwanted sound as possible. Used
carefully, thesefilters cansignificantly increasethe gate's
immunity to false triggering.
LINKED OPERATION
It is important to note that when linked, the control signal
is derived entirely from the noise gate 1 channel. This
means that stereo signals where one channel differs
significantly from another may fare better if the channels
are not linked.
Onthe other hand,this modeof linkingisvery powerful in
synchronizing the start and finish of sounds, a typical
applicationbeing to tightenupbackingvocals.If onesinger
tendsto finish noteson time whilethe otherhangs on too
long, the correct version can be used as the master to
ensure that both finish at the same time. Similarly, one
soundcan be used to gate anotherwithouthavingtoresort
to patching in an external key signal. An example might
be to gate a low frequency tone from a bass drum signal
and then add this gated tone to the drum sound to add
depth.
DIFFICULT MATERIAL
Aswith any other gate,noise canonly beremoved during
pausesin the wantedmaterial. Ifthe noisecontamination
is serious enough to be evident even during moderately
loud programme material, then simple gating will do little
tohelp. Indeed, the veryfact thatthe gateproducesnear-
perfectsilenceduring pauses can make thenoise content
ofthe programme material seemeven worse.In marginal
cases, setting the range control to -20dB rather than -
90dBwill adequately reducethe noise duringpausesbut
notsufficientlytocauseanunacceptablydramaticchange
in noise level as the gate opens and closes.
More sophisticated processors such as the Drawmer
DF330 are better able to cope with excessive noise as
they adaptively filter the programme so as to mask the
noise during low level passages or where there is little
high frequency content present to mask it. However, the
keyfilters in the DSL424may alsobe usedto goodeffect,
particularly in situations where the wanted signal does
not occupy the full audio spectrum.

9
DRAWMERDSL424OPERATOR’SMANUAL
Taking the example of the electric guitar, this produces
little below 100Hz or above 3kHz so setting one channel
of the DSL424 to Key Listen mode will enable you to use
thefilters toexclude muchof the amplifierhum at thelow
endandhiss at thetop end whilehaving littleeffect onthe
sound of the guitar. Surprisingly, the same is true of the
acoustic guitar; (even a bright-sounding steel-strung
model),and the filterscan be usedto reducethe effect of
string squeak or the player's breathing.
Otherapplicationsofthefiltersectionincludeshaping DI'd
electricguitar sounds toremoveunpleasantovertonesand
to simultaneously clean and warm up digital synthesizer
sounds. While we should always endeavour to get the
highest quality of programme material at source, every
engineer is occasionally confronted with inferior material
fromsourcesbeyondhis control. Conventional equalisers
seldom have a sharp enough response to duplicate the
function of the Key filters which invariably results in the
wanted material being filtered as well as the unwanted
noise. Once a signal has been filtered in this way, it may
also be processed by the second channel of the DSL424
toapply conventional gating.
Theunit should beconnected in-line withthe signal tobe
processedvia suitableinsert points.For mono use,each
channel may be considered as being completely
independent and set up accordingly. For use with stereo
signals such as complete mixes or submixes, the
channelsshould be switchedtoStereo Link modeandall
settingupdone using the compressor 1 (leftcompressor)
channelcontrols.
Setting up is simplified by the auto attack and release
systemwhichcontinuallyoptimisestheattackandrelease
timesto suit the dynamics of thematerialbeingprocessed.
Theratiosettingdependsonhowfirmlythesignal dynamics
need controlling; as a rule, higher ratios provide a higher
degreeof controlbutalsotendto be moreaudiblyapparent
in operation when high levels of gain reduction are
required. In general, a higher compression ratio may be
used when in Soft Knee mode without compromising the
subjectivesound quality.
HavingselectedHardorSoft Kneeandseta suitableRatio,
setting up is simply a matter of adjusting the Threshold
controluntil the desiredamount of gain reductionoccurs.
This is judged partly by ear and partly by observing the
gainreductionmeter.Normallyamaximumgain reduction
of between 8dB and 12dB will be adequate. If more gain
reduction appears necessary, it is worth considering
applying a conservative degree of compression during
recordingand then furthercompression whilemixing.
Compressing during a mix does increase the subjective
levelof tape andother background noises duringpauses
and quiet passages as maximum gain is applied when
the signal level is minimum. For this reason, it is unwise
to use more compression than is strictly necessary.
However, using the DSL424 the signal can be patched
throughthe gate, either beforeor afterthe compressor, to
removeanyunrequiredsounds.
Finally,the Gain control may be set to providetherequired
outputlevel using thelevelmeterasaguide.Avoid running
at very high output levels as this reduces the available
amountof signal headroom andcould leadto distortionin
extreme cases. Once the gain is correct, the Peak limiter
Level control should be adjusted so that the limiter LED
only lights briefly on extreme signal peaks.Alternatively,
thePeaklimiter Level mayfirst be setto thedesired value
andthen the compressorGain controladjusted toensure
minimum limiter activity.
The Peak limiter has no bypass control, but turning the
Level control fully clockwise will effectively prevent the
limiterfromoperating.
Compressorsareoften accused of dulling the sound being
processed,but the autocircuitry in theDSL424 hasbeen
designed to allow transient sounds to pass through
cleanly, thus maintaining the clarity and transparency of
the original source. Soft Knee operation is usually
preferablewhenunobtrusivegain control is required.
The Compressor / Limiter Channels

10 DRAWMERDSL424OPERATOR’SMANUAL
IF A FAULT DEVELOPS
For warranty service please call Drawmer Electronics Ltd. or
their nearest authorised service facility, giving full details of
the difficulty.
A list of all main dealers can be found on the Drawmer
webpages.
On receipt of this information, service or shipping instructions
will be forwarded to you.
No equipment should be returned under the warranty without
prior consent from Drawmer or their authorised representative.
For service claims under the warranty agreement a service
Returns Authorisation (RA) number will be issued.
Write this 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.
Authorised returns should be prepaid and must be insured.
All Drawmer products are packaged in specially designed
containersfor protection.If the unit is tobe returned,the original
container must be used. If this container is not available, then
the equipment should be packaged in substantial shock-proof
material, capable of withstanding the handling for the transit.
CONTACTING DRAWMER
Drawmer Electronics Ltd., will be pleased to answer all
application questions to enhance your usage of this
equipment. Please address correspondence to:
Drawmer (Technical Help line)
Coleman Street
Parkgate
Rotherham
S62 6EL
UK
Alternatively contact us by E-mail on :
[e-mail]
Further information on all Drawmer dealers, Authorised service
departments and other contact information can be obtained
from our web pages on:
http://www.drawmer.com
GENERAL INFORMATION
CHAPTER 4
It is the responsibility of the installer to ensure that the continuous power rating of the speakers is not exceeded, as Drawmer
Electronics Ltd will not accept any responsibitlity for speaker damage caused by incorrect settings.

11
DRAWMERDSL424OPERATOR’SMANUAL
NOISE GATE CHANNELS
INPUT
Input Impedance 20k Ohms (Balanced)
Key Input Impedance 20k Ohms (Unbalanced)
Max Input level +21dBu
Max Key Input Level +21dBu
OUTPUT
Output Impedance 50 Ohms (Balanced)
Output Level +21dBu
Bandwidth <10Hz to 22kHz -1dB
Floor Level -90dB, (or -20dB)
Noise
Distortion
DSL424 TWOPLUSTWO DYNAMICS
DATA SPECIFICATION
Power Requirements 115Volt or 230Volt at 50-60Hz, 15VA
FuseType CONFORMS TO IEC127-2.
FuseRating 230V=T250mA, 115V=T125mA.
Case Size 482mm (w) x 44mm (h) x 190mm (d)
Weight (incl packaging) 3.7 Kgs
Wideband 22Hz-22kHz CCIR IEC A Q-Pk CCIR
AV -91dB -97dB -97dB -100dB -86dB
RMS -89dB -96dB -99dB
COMPRESSOR / LIMITER CHANNELS
INPUT
Input Impedance 20k Ohms (Balanced)
Max Input level +21dBuB (+17dB ref. +4dBu)
OUTPUT
Output Impedance 50 Ohms (Balanced)
Output Level +20dBu
Bandwidth <12Hz to 35kHz -1dB
Crosstalk @10kHz Better than -80dB
@20kHz Better than -75dB
Output Balance Better than 40dB 20Hz to 10kHz
Noise at Unity Gain ref. +4dBu
Distortion
Wideband 22Hz-22kHz CCIR IEC A Q-Pk CCIR
AV -90dB -98dB -99dB -100dB -88dB
RMS -89dB -96dB -97dB -98dB
100Hz 1kHz 10kHz
Gate Open with +4dB Input <0.04% <0.04% <0.04%
100Hz 1kHz 10kHz
Unity Gain, +4dB Input <0.02% <0.015% <0.035%

12 DRAWMERDSL424OPERATOR’SMANUAL
BLOCKDIAGRAM
DSL424 ver 01 B 29/06/04

13
DRAWMERDSL424OPERATOR’SMANUAL
© COPYRIGHT DRAWMER ELECTRONICS LTD 2004
DRAWMER ELECTRONICS LTD ~ Coleman Street
Rotherham ~ S. Yorkshire ~ UK
Session No. Tape Location Artist Date
Session Recall
DSL424
HARD HARD
HARDHARD
SOFT SOFT
SOFTSOFT
BYPASS BYPASS ON
OFF
KNEE KNEE
RANGERANGE
30 3010 1020 205 515 150 010 105 56 610 104 42 21 1dB dB
GAIN REDUCTION GAIN REDUCTIONOUTPUT LEVEL OUTPUT LEVEL
TwoPlusTwo
DYNAMICS
DSL424
DRAWMER
EXTEXT BYPASSBYPASS
GATEGATE
KEY
LISTEN
KEY
LISTEN INTINT
HzHz HzHz dBdB
200200 2525
500500 50
50
1010
2020 10mS10mS
00
.
1S
.
1S
1K1K 100100 250250 150150 2K2K
500500 5K5K 1K1K 10K10K
3K53K5
2K2K
35K35K
Master
Master
7070 5S5S
4S4S
2S2S 1S1S
6060
1010 2020 3030 4040 5050
90dB90dB 20dB20dB LINK
LINK
GATINGGATING
L.F. L.F.L.F. FILTER FILTERFILTER H.F. H.F.H.F. THRESH THRESHTHRESH RELEASE RELEASERELEASE
KEY SOURCE KEY SOURCEOUTPUT OUTPUT
THRESH THRESHRATIO RATIOGAIN GAINLEVEL LEVEL
COMPRESSOR 1 PEAK COMPRESSOR 2 PEAK
dB dBdB dBdB dB:1 :1
30 30
10 10
40 40
20 20
40 40
16 16
15 15
5 5
20 20
20 20
5 5
10 10
10 10
3 3
0 0
0 0
0 0
2 2
10 10
10 10
10 10
1.5 1.5
20 20
20 20
1.2 1.2