Klark Teknik DN370 User manual

Klark Teknik Group,
Klark Teknik Building,
Walter Nash Road,
Kidderminster,
Worcestershire,
DY11 7HJ
England
Tel: [phone]
Fax: [phone]
Email: [email protected]
Website: www.klarkteknik.com
OPERATORS MANUAL
DN370

These symbols are internationally accepted symbols that warn of potential hazards
with electrical products.
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 appliance.
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 manufacturers
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 is 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.
IMPORTANT SAFETY INSTRUCTIONS
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
WARNING:TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK,
DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE
AVIS:RISQUE DE CHOC ELECTRIQUE. NE PAS OUVRIR

DECLARATION OF CONFORMITY
We,
of, Klark Teknik Building, Walter Nash Road, Kidderminster, Worcestershire, DY11 7HJ.
Declare that a sample of the following product:-
to which this declaration refers, is in conformity with the following directives and/or standards:-
Klark Teknik Group (UK) Plc
Product Type Number Product Description Nominal Voltage (s) Current Freq
Company registration No. 2414018. A Subsidiary of Telex Communications Inc.
DN370 Analogue Graphic 115V AC 240mA 50/60Hz
Equaliser 230V AC 120mA
Signed:............................ Date:31 March 2004
Name: Simon Harrison
Authority: Research and Development Director, Klark Teknik Group (UK) Plc
Attention!
Where applicable, the attention of the specifier, purchaser, installer or user is drawn to special limitations
of use which must be observed when these products are taken into service to maintain compliance with
the above directives. Details of these special measures and limitations to use are available on request
and are available in product manuals.
st
Klark Teknik Group (UK) Plc, Klark Teknik Building, Walter Nash Road,
Kidderminster. Worcs. DY11 7HJ. England
Tel:[phone] Fax:[phone]
www.midasconsoles.com www.klarkteknik.com
89/336/EEC Electromagnetic Compatibility Directive
amended by 92/31/EEC & 93/68/EEC 73/23/EEC,
Low Voltage Directive, amended by 93/68/EEC
Generic Standard Using EN55103 Limits and Methods EN50081/1
Class B Conducted Emissions Pavi EN55103
Class B Radiated Emissions Pavi EN55103
Fast Transient Bursts at 2kV EN61000-4-4
Static Discharge at 4kV EN61000-4-2
Electrical Stress Test EN60204
Electrical Safety EN60065:2002

Thank You for using a Klark Teknik DN370 Graphic Equaliser. The DN370 has been developed to meet the needs of
demanding live, recording and broadcast sound engineers and meets the quality in build and performance that you
would expect from Klark Teknik.
The DN370 is a dual thirty(30) band third octave graphic equaliser with long throw forty-five millimetre (45mm)
faders, two (2) high and low pass filters per channel and two (2) notch filters per channel. The DN370 is the latest
addition to the world renowned DN300 series of Graphic Equalisers that are in use around the world today and
represents the next generation of graphic equaliser technology.
All backed up, of course, by the standard Klark Teknik three year warranty.
Please take the time to complete and return the registration card and, to obtain the best results with a minimum of
effort, also read this operators manual.
Finally, enjoy your Klark Teknik DN370!
Contents
ATTENTION
Quick Reference
System Example
Using the DN370
Functional Block Diagram
The DN370 Proportional-Q response
DN370 Applications
Technical Specification
Frequency Rage Chart
Crib Sheet
Page 2
Front Panel Page 3
Rear Panel Page 7
Page 9
Page 10
Equalising a System Page 11
The effect of equalisation Page 12
Page 13
Page 14
Page 17
Page 21
Page 22
Page 23
Rear Panel Page 4
Front Panel Page 5
Features
Thank you
DN Operators Manual -370 Page 1

Female XLR
Male XLR
Pin 1 - Screen/Ground
Pin 2 - Hot Signal
Pin 3 - Cold Signal
Pin 1 - Screen/Ground
Pin 2 - Hot Signal
Pin 3 - Cold Signal
Note: XLR Sockets are viewed from the
front face.
Phoenix Type Connector
Pin 1 - Channel IN Screen/Ground
Pin2 - Channel IN Hot Signal
Pin 3 - Channel IN Cold Signal
Pin 4 - Channel OUT Screen/Ground
Pin 5 - Channel OUT Hot Signal
Pin 6 - Channel OUT Cold Signal
Note: Pin assignments as viewed from the
socket. Phoenix connector is wired in parallel with
the corresponding XLR.
The following special limitations must be observed in order to maintain safety and electromagnetic compatibility
performance.
Power Connection
The DN370 Graphic Equaliser should only be operated with the
power supply connected to ground via the ground in the mains
connector.
Audio Connections
The DN370 should only be operated with high quality twisted-
pair audio cables. XLR connector shells should be of metal
construction so that they provide a screen when connected to
the console and should have pin one (1) connected to the cable
screen.
Electric Fields
If the DN370 is operated in an electromagnetic field that is
amplitude modulated by an audio frequency signal, the signal
to noise ratio may be degraded. Degradation of up to 60dB
may be experienced under extreme conditions (3V/m, 90%
modulation).
INSTALLATION
Position
Power
The DN370 should be mounted in a nineteen inch (19”) rack of suitable construction for it’s intended purpose. Four (4) rack
mount holes are provided through the front panel to support fully, the weight of the unit in the rack. Position of the unit will
depend upon how it is to be used however:-
- Avoid placing the unit such that the faders may be accidentally knocked or snapped off
- Avoid placing the unit such that the front mounted power switch may be accidentally knocked
Also try to avoid placing the unit directly near or on any power distribution units or power amplifiers.
The internal power supply is a switch mode type which automatically senses the incoming mains voltage and will work where the
nominal voltage is in the range 100-240 VAC. A single fused IEC mains inlet is provided on the rear panel and the correct lead for
connection in the area to which the unit was shipped is provided in the box.
Connections
After Unpacking
To ensure the correct and reliable operation or your DN370 Graphic Equaliser, only high quality balanced screened twisted pair
audio cable should be used.
After unpacking your DN370, please retain the original packing in the event that you should need to transport or ship the unit.
Please inspect the unit carefully for any signs of damage that may have occurred in transit and notify the courier immediately if
you feel that any damage has occurred.
1
2
3
12
3
123456
ATTENTION
DN Operators Manual -370 Page 2

DN370 DUAL GRAPHIC EQUALISER
+6+12
+12
-612
-
12
-
+6
-6
Front panel quick reference
Equaliser bands
may be switched
between 6dB
and 12dB .
Level metering.
High and low
pass filters per
channel.
Notch filters
per channel.
Power switch
and power
indicator.
Equaliser in/out
switch to bypass the
effect of the equaliser
Channel
A
Channel
B
45mm faders
The Klark Teknik DN370 is a dual thirty (30)
band, third octave graphic equaliser.
DN Operators Manual -370 Page 3

Rear panel quick reference
TO REDUCE RISK OF FIRE, REPLACE WITH SAME TYPE OF FUSE. THIS DEVICE COMPLIES WITH PART 15 OF THE FCC RULES. OPERATION IS SUBJECT TO THE FOLLOWING CONDITIONS:
(1) THIS DEVICE MAY NOT CAUSE HARMFUL INTERFERENCE, AND
(2) THIS DEVICE MUST ACCEPT ANY INTERFERENCE RECEIVED, INCLUDING INTERFERENCE THAT MAY CAUSE UNDESIRED OPERATION.
FOR CONTINUED PROTECTION AGAINST RISK OF
ATTENTION:
FIRE REPLACE WITH THE SAME TYPE AND VALUE FUSE INDICATED.
REMPLACER PAR UN FUSIBLE DE MÊME TYPE
COMME INDIQUÉ.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO
QUALIFIED SERVICE PERSONNEL.
DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE
TO REDUCE THE RISK OF ELECTRIC SHOCK,
WARNING:
RISQUE DE CHOC ELECTRIQUE.NEPAS OUVRIR.
MADE IN KIDDERMINSTER, ENGLAND
OUTPUT B INPUT B
AC~50-60Hz 60W
MOUNT IN RACK ONLY
PUSH
PUSH
CAUTION:
AVIS:
CUS
OUTPUT A INPUT A
100-240V
R
FUSE: 5x20mm
T0.5A L250A
SUPPLY
VOLTAGE
INPUT TX
OUTPUT TX
Fused IEC type
connector
Audio connections are
provided by two male XLR
and two female XLR sockets
for channel A and B.
Two six pin Phoenix
connectors
DN Operators Manual -370 Page 4

Graphic EQ Section
The graphic EQ section of the DN370 features long throw forty-five millimetre (45mm) faders to allow fine adjustment of each
frequency band. Each fader has a centre detent (’click stop’) to denote the 0dB (unity gain of the band) point of the scale. The
DN370 uses standard ISO third-octave standard frequency centres.
The range of the faders on each channel is switchable using that channel’s RANGE
switch between 6dB and 12dB. The current setting is indicated by the ‘6’ and
‘12’ LEDS above the range switch.
It may be desirable to hear the effect of the graphic equaliser settings (e.g. during
sound check). This can be achieved by depressing the EQ IN/OUT switch which will
bypass the EQ (and gain) settings of the DN370 allowing the user to hear the
original without adjusting any fader or control. The red and green LEDs indicate
whether the unit is bypassed or not.
Placing the fader of any band at the extreme upwards position will apply either
6dB or 12dB gain to the
frequencies in that band.
(depending upon the setting of the range switch)
Placing the fader of any band at the extreme downwards
position will apply either 6dB or 12dB attenuation (depending upon the setting of
the range switch) to the frequencies in that band.
The gain control provides continuous adjustment of the channel gain from -infinity
(off) to +6dB with a centre detent at 0dB (unity gain). When using EQ with large
amounts of cut or boost, it may be necessary to use the gain to make up or
attenuate the signal. Note, however, that the gain control is bypassed when the EQ
IN/OUT switch is in the OUT position but control over the channel LEDs is retained
by the gain control.
Although range is discussed above, a description is included here for clarity. The
range of the graphic equaliser section faders on each channel is switchable using
the RANGE switch between 6dB and 12dB. The current setting is indicated by
the ‘6’ and ‘12’ LEDS above the range switch.
The EQ IN/OUT switch will bypass all the functions of the DN370 including the Gain
control such that the output will be the same as the input. The IN/OUT switch may
be used to audition settings (for example, during sound check).
Gain and Range Settings
GAIN
RANGE
EQ IN/OUT
±±
±±
+6
-6
+12
12
-
Front panel features
Front Panel Features
Metering
The Klark Teknik DN370 is a dual thirty (30) band, third octave graphic equaliser. The range of the equaliser bands may be
switched between 6dB and 12dB (individually for each channel). In addition to the graphic equaliser itself; high and low pass
filters and two notch filters are provided per channel and an equaliser in/out switch to bypass the effect of the equaliser and filter
stages. Power to the unit is provided on the rear panel, but switched from the front. A power indicator is provided.
The DN370 provides two LEDs per channel for the purpose of level metering. The signal LED shows incoming signal to the unit
and is Pre EQ (but post gain control). The clip LED shows that the maximum output level of the unit has been achieved and the
unit has entered clipping. The clip LED is sourced Post EQ (and post gain control) such that internal clipping due to excessive EQ
(i.e. if a high input level is further boosted by the use of EQ) will also be shown. The clip and signal levels are shown below.
Signal (Green) -40dBu
Clip (Red) +22dBu
DN Operators Manual -370 Page 5

Signal Level
Signal
Clip
High Pass, Low Pass and Notch Filters
- The signal LED shows incoming signal to the unit and is Pre EQ (but post
gain control).
- The clip LED shows that the maximum output level of the unit has been
achieved and the unit has entered clipping. The clip LED is sourced Post EQ (and
post gain control) such that internal clipping due to excessive EQ (i.e. if a high
input level is further boosted by the use of EQ) will also be shown. The clip and
signal levels are shown below.
Signal (Green) -40dBu
Clip (Red) +22dBu
Each channel of the DN370 includes one (1) High Pass filter, one (1) Low Pass Filter and two (2) variable frequency Notch filters.
Each filter can be enabled by depressing the pot until it clicks (only a small amount of force is required). When active, the annular
ring around the filter control will illuminate.
To audition the effect of the filters, either the EQ IN/OUT switch (which will also bypass the graphic equaliser) or the individual
filter switch may be used.
Low Pass filter
The cut off frequency is
continuously variable from
20Hz to 500Hz
Notch Filter 1
The notch centre frequency
is continuously variable from
20Hz to 2kHz
Notch Filter 2
The Notch filter centre
frequency is continuously
variable from 200Hz to 20kHz
High Pass Filter
The Cut off frequency is
continuously variable from
2kHz to 20kHz
Front panel features
DN Operators Manual -370 Page 6

Mains Supply
Audio Connection
Mains power is supplied to the DN370 by a single fused IEC socket on the rear of
the unit. The DN370 contains an auto voltage sensing switching mode power
supply that will operate where the nominal mains voltage is in the range 100 to
240 VAC.
The audio connections to the DN370 are electronically balanced. Isolation transformers can also be fitted as factory option or
retro-fit (please consult an approved Klark Teknik service agent). The input and output connectors are shown below, please read
the audio connections section at the beginning of this manual for wiring diagrams and pin assignments.
AC~50-60Hz 60W
CUS
100-240V
R
FUSE: 5x20mm
T0.5A L250A
SUPPLY
VOLTAGE
OUTPUT B INPUT B
PUSH
INPUT TX
OUTPUT TX
Channel Input XLR
Channel Input/Output Phoenix Connector
Channel Output XLR
Indicates whether the
transformer isolation input and
output options have been factory
fitted.
Rear panel features
Rear Panel Features
The rear panel provides the audio and power connections to the DN370.
Power is provided by a single fused IEC type connector. The correct mains lead for the country to which the unit was shipped is
supplied with the unit. Always replace the mains fuse with the same type and rating.
Audio connections are provided by two (2) male XLR and two (2) female XLR sockets for channel A and B inputs and outputs
respectively; and also by two (2) six (6) pin Phoenix connectors. Both connectors provide balanced audio connections such that:
Pin 1 - Ground/Screen
Pin 2 - Hot Signal
Pin 3 - Cold Signal
DN Operators Manual -370 Page 7

DN Operators Manual -370 Page 8

EQUALISER
FOH Console
Delay Line
EQUALISER
EQUALISER
X-Over &
Amplifiers
X-Over &
Amplifiers
X-Over &
Amplifiers
X-Over &
Amplifiers
Delay FoH Delay FoH
Centre Cluster
Main FOH Main FOH
Stage Monitors
Monitor
Console
Example: System connection
DN Operators Manual -370 Page 9

The DN370 is a thirty (30) band third octave graphic equaliser which utilises premium quality, low tolerance components to
achieve a high degree of accuracy and control. Graphic equalisers may be used for corrective or creative purposes depending
upon whether it is to be used live (Monitors or Front of House) or in the studio (Broadcast or Recording).
In the control room, a graphic equaliser may be used to remove problem frequencies and improve deficiencies in room acoustics.
This is commonly achieved with the use of a Real Time Analyser (RTA) such as the Klark Teknik DN60 or DN6000. The frequency
centres of the DN60/6000 and the DN370 conform to ISO standards and so corrections can be made by sight directly from the
RTA to the graphic.
It is important to mention, however, that graphic equalisers can only compensate so much for a room with severe acoustic
problems (which may require further remedial treatment work). Graphic equalisers can only help to reduce the audible effects of
standing waves and resonances and cannot overcome the loss of clarity due to rooms with long reverberation times.
The DN370 can be used to create filter effects (for example the effect of someone speaking on the telephone) using the thirty (30)
equaliser bands and the high and low pass filter; in conjunction with a compressor to create a de-esser; for tonal correction of
instruments or vocals and many other creative uses.
It is often desirable to add equalisation to a venue in order to remove any frequency deficiencies in the room before trying to
engineer using the system. Again, it is common to use an RTA and measurement microphone in order to set up the equaliser using
additive and subtractive equalisation to correct problems in the room. It is recommended to attenuate peaks in the room’s
response to the level of the surrounding frequencies rather than boost the lower bands to meet the highest. This will help to retain
headroom in the equaliser and slight dips in frequency response are less noticeable than large peaks. If an overall reduction in
volume is observed, the gain makeup can be used to return the output of the equaliser to the desired level.
Beware, however, that excessive equalisation (for example, using large amounts of boost at lower frequencies to compensate for
poorly performing bass enclosures) will use up large amounts of system headroom which could cause the system amplifiers to
clip. Causing damage to loudspeaker HF components and introducing high frequency harmonics which may sound unpleasant.
Also, large amounts of low frequency boost may cause the over-excursion of bass drivers and their subsequent mechanical and
electrical breakdown.
Also, many sound reinforcement systems are only capable of adequately producing frequencies up to around 18kHz. Providing
high levels of boost at 20kHz to extend the frequency response of the system is likely to result in reducing the life of high
frequency components in the loudspeaker while the frequency response may not be significantly improved.
There are occasions where deficiencies in room acoustics cannot be corrected by equalisation. For example, bass reduction due to
phase cancellation or the cancellation around the crossover point of a loudspeaker must be corrected before the use of
equalisation.
Monitors used on stage often need equalisation to remove any peaks in their frequency response in order to prevent feedback
from on stage microphones where those frequencies exceed the maximum gain before feedback level. Further equalisation may
be required in order to remove similar peaks from the characteristics of the microphones in use.
A monitor engineer may use an RTA in order to detect these peaks, but more often than not, monitor engineers have a developed
sense of hearing that enables them to remove these frequencies by ear. The DN370’s thirty (30) frequency bands allow a majority
of feedback to be removed from the monitors, however, for feedback that is more difficult to locate or lies between bands, two
variable frequency notch filters are provided which can be swept through the frequency range until the location of the feedback is
located.
In addition to notch filters, a high and low pass filter are provided which can be used to remove high frequency feedback and bass
rumble or over excursion of bass drivers. It may also be undesirable to have large amounts of bass in the on stage monitors. In
vocal monitors, bass does not assist projection of vocals and can make the stage sound unbearable and hence, the bass element
can be rolled off at the desired frequency. The fundamentals of Vocals are transmitted in a narrow audible range and will appear
unaffected.
Studio and Creative Use
Live Use (Front of House)
Live Use (Monitors)
Using the DN370
DN Operators Manual -370 Page 10

PINK NOISE




















CALIBRATED MEASUREMENT
MICROPHONE
REAL TIME ANALYSER
EQUALISER
As discussed before, the benefits of equalisation are fundamentally:-
In some circumstances, it may not be possible to achieve a natural sounding system that is completely intelligible due to poor
acoustics or high levels of background noise. In these cases, a compromise must be struck by the engineer depending upon the
use to which the system will be put. It may be arguable that in the case of a vocalist, intelligibility must be sought at all costs. In
the case of dance music reproduction, however, it may be felt that the material should be reproduced naturally with no real
concern for intelligibility of the individual lyrics.
Before starting to equalise the system, it is worth checking that it is performing correctly. Listening to the system without any
equalisation may reveal underlying distortion or artefacts of the room (e.g. lengthy reverberation) that may need to be rectified
before trying to equalise the room. It may also be worth using a sine tone sweep so that problems at certain frequencies that may
not be immediately noticeable with pink noise can be detected and corrected before equalisation. Check, especially, the
crossover points of the system which may reveal problems with the system. Note that poor coverage cannot be rectified through
the use of equalisation.
The measurement microphone should ideally have a flat response or be calibrated to the analyser and placed in a sensible
position where it will not be affected by nearby objects that may interfere with the local acoustics.
Using the Real Time Analyser and a pink noise source, adjust the level of the frequency bands on the graphic inversely to that
shown on the RTA display so that the peaks in frequency response are reduced to the level of the other bands and similarly, the
deficient bands are increased. You will need to perform the test at a reasonable level approaching normal usage volume so that
the equalisation can take into account the response of the loudspeakers at normal operating level (vs. low level). It may also be
desirable to take measurements at points throughout the area. It may not be possible to get perfect equalisation throughout an
entire area but it may be preferable to obtain a good equalisation of the whole area rather than a perfect equalisation at a single
point and poor performance at all other points. A compromise may need to be made in an effort to equalise the sound for the
whole area rather than just the centre FOH position.
When equalising the room, bear in mind the effect upon the electronics and mechanics of the system caused by the equalisation
process. If excessive equalisation is required at certain bands, consider the effect upon amplifier headroom and loudspeaker
driver excursion that will result. It may not be possible to produce the response required with the limitations of the system.
Excessive equalisation should act as a warning that there may be an underlying problem that may need to be rectified first (e.g.
phase cancellation, blown drivers, etc...).
During the performance, the FOH or monitor engineer may want to have a microphone or solo signal feed for the RTA so that
feedback may be easily detected and rectified.
, the equaliser is not a ‘cure all’ device and will not solve the problems of a poor sound system, installation or venue
acoustics, but when used carefully, can bring out significant improvements in the quality of reproduction of a system.
To improve the intelligibility and natural sound of the sound system.
To increase the gain available in the system before feedback.
Remember
note: when using an RTA, ensure that
it has averaging capability so that fluctuations
are smoothed out giving a good representation
of the sonic performance of the system.
Equalising a system
labc
DN Operators Manual -370 Page 11

Effects of Equalisation on Voice Reproduction
Effect of Equalisation on Music Reproduction
1/3 Octave Effect on voice
Centre Frequency
40, 50, 63, 80, 100, 125 Sense of power in some outstanding bass singers
160, 200, 250 Voice fundamentals
315, 400, 500 Important for voice quality
630, 800, 1k Important for voice naturalness. Too much boost in the 315 to 1k
range produced a telephone-like quality
1k25 to 4k Vocal fricatives. Accentuation and clarity of voice
Important to speech intelligibility. Too much boost between 2kHz
and 4kHz can mask certain speech sounds (e.g. ‘m’, ‘b’, ‘v’ can
become indistinguishable). Too much boost anywhere between
1kHz and 4kHz can produce listener fatigue. Vocals can be
highlighted by slightly boosting vocals at 3kHz whilst simultaneously
slightly cutting instruments at that frequency.
5, 6k3, 8k Accentuation & clarity of voice
10, 12k5, 16k Too much boost causes sibilance (’sss’).
1/3 Octave Effect on Music
Centre Frequency
31, 40, 50, 63 Fundamentals of bass drum, tuba, bass and organ. These give music
a sense of power but excessive use can leave the sound ‘muddy’.
Mains Hum (50-60Hz).
80, 100, 125 Too much boost produces ‘boom’. (Fundamentals of tympani & toms)
Higher harmonics of mains hum (100-120Hz)
160, 200, 250 Drum and lower bass. Too much boost produces ‘boom’.
3rd Harmonics of Mains Hum.
315, 400, 500 Fundamentals of strings and percussion.
630, 800, 1k Fundamentals and harmonics of strings, keyboards and percussion.
Boosting 600-1kHz range can make instruments sound horn-like.
1k25 to 4k Drums, guitar, accentuation of vocals, strings and brass.
Excessive boost around 1-2kHz can make instruments sound ‘tinny’.
Excessive boost around 1-4kHz can produce ‘listening fatigue’.
5k, 6k3, 8k Accentuation of percussion, cymbals and snare drum.
Reduction at 5kHz makes overall sound more distant and
transparent.
Reduction of tape hiss and system noise. 1k25 to 8k governs
overall clarity and definition.
10k, 12k5, 16k Cymbals and overall brightness. Too much boost causes sibilance.
Reduction of tape hiss and system noise.
Effect of equalisatiion
DN Operators Manual -370 Page 12

HIGH PASS LOW PASS NOTCH 1 NOTCH 2 GRAPHIC
FREQUENCY FREQUENCY FREQUENCY FREQUENCY
PUSH
BYPASS
PUSH
BYPASS
PUSH
BYPASS
PUSH
BYPASS
BYPASS
-40dBu +22dBu
TRANSFORMER
OPTION
TRANSFORMER
OPTION
REMOVE
LINK FOR
TX OPTION
REMOVE
LINK FOR
TX OPTION
DN370 (SINGLE CHANNEL) FUNCTIONAL BLOCK DIAGRAM
PUSH
Functional block diagram
DN Operators Manual -370 Page 13

The most important design decision for the DN370 was determining the equaliser response. Proportional-Q equalisation, as
used on previous Klark Teknik analogue graphic equalisers, offers some key advantages over the more numerous Symmetrical-Q
equalisers on the market, namely at low amounts of cut or boost the width of the filter is relatively broad and becomes narrower
as the amount of boost or cut is increased, giving a more 'focused' response. This differs from a Symmetrical-Q response which
boosts or cuts an increasingly wide band of frequencies, and is an important consideration in applications such as cutting
particular problem frequencies, as more of the frequency spectrum is scooped out when using Symmetrical-Q equalisation;
proportional-Q equalisers are much better at cutting just the problem frequency band. Symmetrical-Q equalisers are frequently,
but inaccurately, termed Constant-Q as the Q is measured 3 dB up from the point of maximum attenuation when in cut, rather
than the correct definition of 3dB down from the point of maximum gain (0 dB when cutting), which results in a notch filter
response.
In all types of graphic equalisers, one of the key issues is how the summing of adjacent EQ bands alters the frequency response.
Lower-Q filters will blend together more smoothly, but higher-Q filters provide more selective control of problems - at the
expense of more frequency response ripple. A weakness of the Symmetrical-Q approach is that for small amounts of boost and
cut (a very typical situation), the EQ bands have to be comparatively broad to blend smoothly to avoid excessive ripple in the
frequency response, however as the Q of the EQ bands remains constant, larger amounts of boost or cut will affect an
increasingly wide range of frequencies, limiting the precision and usefulness of the equaliser.
and show the responses of a leading Symmetrical-Q equaliser in both its 'wide' and 'narrow' modes of
operation for 2dB of boost and cut, which is typical of the small adjustments made in corrective EQ applications. The 'wide'
response gives a very smooth combined response for the three bands shown, however the 'narrow' response shows significant
ripple in the combined response which will lead to audible artefacts such as phase distortion.
Figure 1 Symmetrical-Q equaliser “wide” mode ±2dB boost and cut
Figure 2 Symmetrical-Q equaliser “narrow” mode ±2dB boost and cut
Figure 1 Figure 2
The DN370 proportional-Q response
-15
+15
-10
-5
+0
+5
+10
d
B
u
300 4k400 500 600 700 800 900 1k 2k 3k
Hz
-15
+15
-10
-5
+0
+5
+10
d
B
u
300 4k400 500 600 700 800 900 1k 2k 3k
Hz
DN Operators Manual -370 Page 14