Ecler CKL User Manual [en, es, fr]

USER MANUAL MANUAL DE INSTRUCCIONES MANUEL UTILISATEUR

CKL SERIES

CKL110 – LONG THROW SOUND SYSTEM CKL SM115 – MID-LOW CKL SOUND REINFORCEMENT

1. IMPORTANT NOTE 04

1.1. Safety instructions 04

2. WARRANTY DESCRIPTION 04

3. DESCRIPTION 05

3.1. CKL110 – LONG THROW SOUND SYSTEM 05

3.2. CKL SM115 – MID-LOW CKL110 SOUND REINFORCEMENT 05

4. APPLICATIONS 06

5. CONNECTIONS 06

6. AMPLIFICATION 07

6.1. Operation of one or two pairs of CKL110 speaker enclosures 07

6.2. Operation with more than two pairs of CKL speaker enclosures 08

6.3. Installation of CKL110 with CKL SM115 bass reinforcement enclosures 08

6.4. Rigging speaker enclosures 09

7. CONFIGURATIONS 10

7.1. Polar diagram 11

8. APPENDIX – BRIEF EXPLANATION OF ACOUSTIC CONCEPTS 12

8.1. Definition of acoustic parameters 12

8.1.1. Sound Pressure Level (SPL) 12

8.1.2. Acoustic absorption 12

8.2. Reverberation and reverberation time 13

8.2.1. Reverberation 13

8.2.2. Reverberation time (RT60) 13

8.3. Speech intelligibility 14

9. TECHNICAL CHARACTERISTICS 42

9.1. Frequency response 43

10. DIAGRAMS 44

All numbers subject to variation due to production tolerances. ECLER S.A. reserves the right to make changes or improvements in manufacturing or design which may affect specifications.

1. IMPORTANT NOTE We thank you for trusting on us and choosing this Ecler product.

In order to obtain the maximum performance and perfect operation, it is VERY IMPORTANT that you carefully read this manual before connecting the unit, taking special attention to the safety warnings here described. In this manual you will find a practical guide on how to correctly set up this product for the most common applications. However, due to the versatility of the system, it is not possible to describe each and every installation possibility. In case you need assistance for a special installation, Eclers Projects Department "projects@ecler.es" will happily help you find the optimal solution for your requirements. Chapter 8. APPENDIX contains brief but concise explanations of frequently used terms in acoustics, which are often used throughout this manual.

1.1. Safety instructions HIGHLY DANGEROUS SOUND PRESSURE LEVELS

This family of acoustic enclosures easily produces sound pressure levels which may reach 120dB SPL at a distance of 10 metres (141dB SPL at 1m). This means that severe damage to the auditory system can happen at a lower distance. Always make sure that the speakers are

not connected when working at their proximity. RIGGING OF ACOUSTIC ENCLOSURES

The enclosures should never be flown using different hardware than specified in this instruction manual. Use only the hardware and rigging systems mentioned in this manual. Physical integrity of people depend on that. Any rigging installation should be carried out, inspected and approved by qualified professionals.

• No user adjustable parts exist inside these devices.

• Do not use this device in the proximity of water. Do not expose the device to splashings, and avoid

placing liquid containers on top of them.

• Do not place the device next to heat sources, lighting fixtures or stoves.

• Only use hardware accessories specified by the manufacturer.

• Keep the loudspeaker enclosures far away from magnetically sensitive devices, such as TV

screens, tape recorders or video recorders…

2. WARRANTY DESCRIPTION Your ECLER equipment has undergone exhaustive laboratory and quality control tests before leaving

the factory. Nevertheless, your may be in need of our Technical Service during the period covered by the Guarantee or afterwards. In that case, carefully protect your equipment in its original packing and send it to our Technical Service with the transport and insurance paid. Attach a photocopy of your Guarantee Certificate and a detailed description of the defect you have observed.

ECLER, S.A. guarantees its ECLER products against material or fabrication defects for a ONE-YEAR period after the date of original purchase.

ECLER, S.A., will repair the defective equipment within the aforementioned period, with no charge for parts and labour.

To ensure the validity of the Guarantee, it is essential that the attached Guarantee, Registration Card is filled out correctly and remitted to your ECLER distributor, within 10 DAYS after date of purchase.

The Guarantee is non-transferable and protects the original buyer only.

The Guarantee does not cover:

• Damage caused by mistreatment or negligent handling, lack of elementary precautions, disregard to the instructions in the manual, faulty connection or accidents.

• Equipment that has been manipulated, altered or repaired other than at the authorized Technical Service centres.

• The exterior fittings and electro-mechanical parts, nor their wear due to use.

• Shipping and insurance expenses, nor for damages the set may incur during its transport.

ECLER, S.A., will not be held responsible for any direct or indirect damage, loss or other damage originated by or relating to the equipment. This Guarantee is valid only for repairs or services carried out at an authorized Technical Service Centre.

3. DESCRIPTION

3.1. CKL110 – LONG THROW SOUND SYSTEM Small-dimensioned trapezoidal acoustic enclosure for mid and high frequency reproduction. Assembled

with 18mm thick birch plywood from Finland covered with a scratch and shock resistant polyurethane paint finish. Internally reinforced. The mid frequency way employs an enclosed 10’’ speaker with neodymium motor and carbon fibre compound diaphragm attached to a Tractix horn, which is equipped with a phase corrector. The high frequency way uses a 2’’ compression driver with pure titanium diaphragm, neodymium motor and a 60º x 40º constant directivity diffusor. The speakers are protected against shocks, dust and splashes by a metal grille and an acoustically transparent foam.

The on-axis frequency response within a ±3dB margin lies between 170 Hz and 19 kHz. The efficiency or sensitivity, which is sound pressure level (SPL) at 1m and 1W power input, reaches remarkable 112dB. The maximum SPL produced at 1m reaches 141dB SPL. The system includes a passive LC filter with low tolerance polyester capacitors and large cross-section wire coils. The high frequency way also features a protection system against Larssen effect feedback and signal clipping.

The maximum RMS power is 350W RMS at 8Ω, while the program power capacity is 700W at 8Ω.

3.2. CKL SM115 – MID-LOW CKL110 SOUND REINFORCEMENT Low-dimensioned trapezoidal acoustic enclosure for mid and low frequency playback. Bandpass type

acoustical design. Assembled with 18 mm thick birch plywood from Finland covered with a scratch and shock resistant polyurethane paint finish. Internally reinforced. It employs a high performance 15’’ speaker attached to a horn in order to increase efficiency. The speaker is protected against shocks, dust and splashes by a metal grille and an acoustically transparent foam.

The on-axis frequency response within a ±3dB margin lies between 70Hz and 280Hz. The efficiency or sensitivity, which is sound pressure level (SPL) at 1m and 1W power input, is 105dB. The maximum SPL produced at 1m reaches 136dB SPL. An external active filter is required. (See paragraph 6.3)

The maximum RMS power is 600W RMS at 8Ω, while the program power capacity is 1200W at 8Ω.

4. APPLICATIONS The CKL110 has been designed for playback of vocal signals in fixed installations. It can be used alone

or together with the CKL SM115 (which has the same dimensions and shape) to extend the system’s frequency response towards mid and low frequencies. Alone or together with the CKL SM115 the system offers high efficiency levels. This makes it suitable for all applications where long throw of voice signals is the main priority.

This type of enclosure is ideal for: stadiums, gyms, theatres, congress halls, houses of worship and every space which requires long sound throwing and highly intelligible speech.

The CKL SM115 has been designed to extend the playback spectrum of the CKL110 towards the mid and low frequencies. It can not be used as stand-alone. Its dimensions and shape are the same as CKL110. It is suitable for all applications that require not only an optimal response at speech frequencies, but also playback of musical signals.

5. CONNECTIONS The cable between the amplifier outputs and the loudspeakers must be of good quality, enough cross-

section and as short as possible. This is very important when the distance is long and the load is low (4-8Ω). We recommend a section of 2.5mm2 or more for distances up to 10m and a section of 4 or 6 mm2 for longer distances. An easy way to known the required cross-section, assuming a 4% loss is using following equation:

Lenght in m Cross-sectión en mm2 =  Loudspeaker impedance in Ω

Placed at the rear wall of the CKL enclosures is a connection panel which holds two SPEAKON® sockets wired in parallel, facilitating interconnection of speaker enclosures. SPEAKON® connectors have been adopted worldwide as the standard professional loudspeaker connection, due to its reliability, immunity to vibration and durability. Remember that the nominal impedance of CKL speakers is 8Ω. Therefore, when connecting two enclosures in parallel, the impedance will drop to 4 Ω, 2,66 Ω for tree enclosures and 2 Ω for four enclosures. Please check the value of the minimum load impedance your amplifier can handle, as not all amplifiers adequately operate at 2Ω.

Operation at 2Ω considerably reduces the sound quality and the system efficiency; e.g., the loss on the loudspeaker cable reduces the Damping Factor by a 76% because of operating at 2Ω instead of 8Ω. Almost all the amplifiers in the market base their operation at 2Ω on the use of destructive protections to keep the components safe, with the penalty of sound quality. Also, and for both technological and power supply constraints, the power gain involved in operation at 2Ω instead of 4Ω is usually very low. ECLERs SPM and SPM CHANNEL N amplifiers are able to operate at 2Ω keeping its philosophy of non-destructive protections and delivering every Watt the power supply is capable of.

ECLER, following the maximum sound quality criterion, recommend using the 2Ω connections only in installations where the amplifier will operate far from its maximum power.

Together with the CKL enclosure you will find a 4-way SPEAKON® cable connector. Always respect polarity.

LIVE 12+ 2-

GND

N.C.

2+ 12-

Make sure to securely plug in the SPEAKON® connector, i.e. fully inserting it to the socket and rotating it to the right until noticing the locking mechanism.

6. AMPLIFICATION

6.1. Operation of one or two pairs of CKL110 speaker enclosures Any amplifier capable of delivering an output power between 350W and 700W is perfectly suitable for

driving a pair of CKLs. Eclers amplification lines include several power amplifier models which can perfectly fulfil this task. In case of operating two speaker enclosures in parallel, the required output power of the amplifier should lie between 700W and 1400W at 4Ω. This enclosure has been designed for the reproduction of voice signals mainly. If the enclosure is to be installed in an acoustically deficient space (poor intelligibility, highly reverberant), it is recommended to use an external active filter with a cut-off frequency lying between 140 and 170 Hz, keeping the highpass signal. Inside Eclers product range, two products can fulfil this need: The FAP30L, 2-way stereo crossover with limiter or the UCM20 board, which can be directly installed inside the back of the APA series of power amplifiers.

APA SERIES POWER AMPLIFIER WITH UCM20 UNIVERSAL CROSSOVER MODULE

CKL SERIES

LOUDSPEAKER CABINET

STACK OUTPUT

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

Remember that the CKL110 includes a passive filter which separates mid and high frequencies.

CKL SERIES

LOUDSPEAKER CABINET

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

CKL SERIES

LOUDSPEAKER CABINET

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

INPUT

CKL SERIES

LOUDSPEAKER CABINET

made by ecler s.a. barcelona spain

INPUT

LIVE 1-GND 2+

N.C. 2-N.C.

6.2. Operation with more than two pairs of CKL speaker enclosures In case of working with 6, 8, 10 or more speaker enclosures, we recommend using a 2-channel amplifier

for each 2 or 4 speaker enclosures. The low level audio signal should be distributed from amplifier to amplifier through their stack outputs. For this reason it is important to check if the amplifiers offer this stacking possibility. All Ecler power amplifiers have this feature. Further considerations mentioned in the previous paragraph also apply.

ACTIVE FILTER

INPUT

POWER AMPLIFIER POWER AMPLIFIER

CKL SERIES

LOUDSPEAKER CABINET

STACK OUTPUT

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

CKL SERIES

LOUDSPEAKER CABINET

STACK OUTPUT

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

CKL SERIES

LOUDSPEAKER CABINET

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

CKL SERIES

LOUDSPEAKER CABINET

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

CKL SERIES

LOUDSPEAKER CABINET

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

CKL SERIES

LOUDSPEAKER CABINET

INPUT STACK OUTPUT

LIVE 1-GND 2+

N.C. 2-N.C.

made by ecler s.a. barcelona spain

CKL SERIES

LOUDSPEAKER CABINET

CKL SERIES

LOUDSPEAKER CABINET

made by ecler s.a. barcelona spain

INPUT

LIVE 1-GND 2+

N.C. 2-N.C.

INPUT

LIVE 1-GND 2+

N.C. 2-N.C.

6.3. Installation of CKL110 with CKL SM115 bass reinforcement enclosures As mentioned earlier, the CKL SM115 represents an ideal complement for the CKL110 in all those

situations where it is necessary to extend the frequency response of the system towards the bass end, consequently improving the reproduction of music signals. This speaker enclosure does not include any passive filter, meaning that the use of an external active crossover with tunable crossover frequency and minimum filter slope of 18dB/oct (recommended 24dB/oct) is necessary. Inside Eclers product range, two products can fulfil this need: The FAP30L, 2-way stereo crossover with limiter or the UCM20 board, which can be directly installed inside the back of the APA series of power amplifiers. The recommended crossover frequency is 150Hz.

No general rule exists for determining the number of CKL SM115 speakers required for a given number of mid-high enclosures. This will depend greatly on the acoustics of the room or space where the speakers are to be installed, in particular on reverberation time. Frequently, the reverberation time of large rooms is very high, meaning that the reproduction of bass frequencies will add “mud” to the sound quality and will have a negative effect on speech intelligibility. The CKL110 has been designed for playback of vocal signals in fixed installations. It can be used alone or together with the CKL SM115 (which has the same dimensions and shape) to extend the system’s frequency response towards mid and low frequencies. Alone or together with the CKL SM115 the system offers high efficiency levels. This makes it suitable for all applications where long throw of voice signals is the main priority.

As a guideline for non-reverberant spaces, never install more than one CKL SM115 for each CKL110. In the real world, many rooms are highly reverberant. In this case, installing for example 2 CKL SM115 for 8 CKL110 is perfectly enough. It could also be preferable not to install any CKL SM115 if the acoustics of the room or space are very poor. Our Projects Department will help you out in finding the optimal number of speaker enclosures that suit your requirements by drawing a virtual model and running a computer simulation of your project.

6.4. Rigging speaker enclosures Following general guidelines must be considered:

• Always place acoustic enclosures on solid and firm ground

• No obstacles should lie between the loudspeakers and the

audience

• High frequencies, as opposed to low frequencies, tend to be much more directional and any obstacle in the acoustic wave path represents attenuation in the frequency response of the system.

The whole CKL range features an effective rigging system, the same type as used in air cargo shipments (ISO 7166 standard), consisting in 6 adjustable cargo rails, which allow flying single speaker enclosures or complex combinations of several enclosures. Two rails are placed at each side and two at the rear wall of the cabinet. The fittings at the side are internally connected with a metal brace. These side fittings allow flying the enclosure and linking it to the next row of enclosures. Up to a maximum of 3 rows per column are allowed. Finally, the rear rails allow tilting the enclosure or group of enclosures.

IMPORTANT The rear rails have been designed basically for tilting the enclosures. They should not carry any weight.

ATTENTION

The chains or steel cables used to suspend the enclosures should

always run parallel to the vertical axis of the loudspeaker cabinet. They must not show a wider angle.

Each position of the aeronautic specified cargo restraint track has a maximum load capacity of 180kg, considering the enclosure is correctly flown, as shown in the diagrams.

The tracking system works in combination with Ecler ADP cargo restraint double stud and ring. (Adam Hall Ref. 5740)

The total load capacity of the structure is limited by this track and is 180kg per anchor point. (360kg total)

It is very important to keep in mind that these values are only valid if the load is suspended perpendicularly. Load capacity varies as a function of the angle according to following table:

Ángle Load capacity

0º 45º 90º

180kg 170kg 160kg

0º

180kg 170kg

45º

90º

160kg

Always make sure that the anchor points are firmly attached to the rail and locked.

7. CONFIGURATIONS Many aspects have to be considered when deciding the optimal electroacoustic reinforcement design for

a given space. All those aspects interact with each other, complicating the design stage even further. More than a “cookbook” on sound system design and installation, this chapter describes several factors which must be considered, as well as some guidelines which may help you to take the right decisions.

Unfortunately, acoustic principles are too often in conflict with aesthetic criterions. PA system designers must admit and accept that the aesthetics of loudspeaker enclosures, in particular those designed for high pressure levels, is not easily compatible with most designs. As a general rule for this kind of situation it is recommended to find a single central sound radiation point. Ideally this would be done with one single loudspeaker, but in practice, clusters or arrays including several more or less overlapping loudspeakers must be used, according to the coverage and sound pressure requirements.

The first point to consider when deciding the location of the loudspeaker enclosures is the load capacity of the suspension point. Secondly, the spot must be easily accessible for installation and later maintenance tasks. On third place, the distance from the amplifier racks should be as short as possible, and last but not least, acoustic design goals should be achieved.

The configuration you choose should basically depend on the desired SPL at the farthest audience point and the required coverage width, while offering good frequency response characteristics. If the efficiency of one loudspeaker is not enough to deliver a certain SPL at a given distance, more enclosures must be aimed at that spot. The acoustic wave “beams” of the speakers can overlap more or less, obtaining a maximum overlap if the enclosures are mounted parallelly, one on top of the other.

At the end of this manual you will find the polar diagrams for different cluster structures, both for the horizontal and vertical planes. The diagrams show the coverage angle and relative on-axis SPL compared to one single speaker enclosure. The table includes results for clusters of 1 to 6 horizontally and 1 to 2 vertically arranged enclosures, with aperture angles of 12° (side-to-side) and 32°.

The enclosures are stacked together with minimum separation. The results are valid for the specified frequencies. They are not valid for set-ups which include the CKL SM115 bass reinforcement enclosure.

7.1. Polar diagram The polar diagrams for the frequency bands of 500Hz and 2kHz and for each of the described

configurations can be found at the end of this manual. As can be observed, the horizontal directivity of the cluster tends to narrow down as more CKL110 are

stacked together, while the vertical coverage angle tends to stay constant and equivalent to one single CKL110 enclosure.

The polar diagrams show the expected behaviour for different enclosure configurations mounted in angles of 12° (side by side) and 32° referenced to the normal of the enclosure. The effect of opening the angle between enclosures represents an increase in coverage area.

For specialized configurations which do not match the set-ups here described, you can contact Eclers projects department "projects@ecler.es", where we will help you find the optimal configuration for your installation requirements.

Please remind, no matter what kind of system you are installing, that it is essential to follow all safety instructions exposed in this manual.

Note: All polar diagrams are normalized on-axis.

8. APPENDIX – BRIEF EXPLANATION OF ACOUSTIC CONCEPTS

10·20

The following paragraphs give brief explanations of frequently used concepts in acoustics, which will help you understand the problematic involved in designing high-quality PA systems.

8.1. Definition of acoustic parameters

8.1.1. Sound Pressure Level (SPL) Defined as:

log20

SPL (dB SPL)

efp

−

The numerator corresponds to the effective sound pressure. The denominator corresponds to the hearing threshold, i.e. the minimum sound pressure which causes

hearing sensation in the human auditory system. Following table shows the sound pressure levels of several typical sound sources, together with their

subjective level sensation.

SOUND SOURCE

SOUND PRESSURE

LEVEL (dB SPL)

SUBJECTIVE LEVEL

SENSATION

Jet take-off 120 Construction works 110

Very high

Pneumatic drill 100 Heavy truck (at 15m) 90 City street 80

High Inside car 70 Normal conversation 60 Office 50

Moderate Living room 40 Bed room (al night) 30

Low

Recording studio 20

Typical sound pressure levels (dB SPL)

8.1.2. Acoustic absorption The acoustic absorption coefficient is defined as the ratio between absorbed acoustic energy by a

certain material and incident acoustic energy.

abs

=α

Values of α range between 0 (no absorption) and 1 (maximum absorption). The absorption characteristics of construction materials used for acoustic treatment of rooms, determine, amongst other factors, the resulting reverberation time. (see paragraph 8.2.2)

8.2. Reverberation and reverberation time

8.2.1. Reverberation When a sound is generated inside a closed space, all room surfaces produce a series of reflections.

The magnitude of these reflections fades out more or less quickly as time passes. The speed of this sound decay depends on the absorption characteristics of the room surfaces. The

higher the absorption, the quicker the attenuation. The amount of decaying sound once the sound source has stopped emitting is called reverberation.

Example of sound pressure decay as a function of time. A room with large amounts of reverberation is also called a “live” room (factory plant, church, sports

arena, etc.), as opposed to an acoustically “dead” or “dry” room, where the decay of the reverberation is much quicker. (recording studio, voice booth, etc.)

The parameter that quantifies the amount of reverberation inside a closed space is known as reverberation time, commonly expressed as RT60.

8.2.2. Reverberation time RT60 The RT60 is defined as the time necessary for the sound pressure to decay 60dB below the initial

pressure level before the sound source stopped emitting. Generally speaking, the RT60 varies with frequency, tending to be shorter as frequency rises. This is in

part caused by the higher absorption coefficient at high frequencies of commonly employed acoustic treatments. Air absorption and low relative humidity are also responsible for this effect, but are especially important in very large spaces.

As just mentioned, RT60 is a function of frequency, but often one single value (the average of reverberation times at 500Hz and 2kHz, RT

) is given as a reference for characterizing the

mid

reverberation of a room.

Following table shows recommended RT

values for different types of rooms:

mid

ROOM TYPE RT

, fully occupied room (en sec.)

MID

Conference room 0.7 – 1.0 Cinema theatre 1.0 – 1.2 Multifunctional room 1.2 – 1.5 Opera theatre 1.2 – 1.5 Concert Hall (chamber music) 1.3 – 1.7 Concert Hall (symphonic music) 1.8 – 2.0 Church (organ and choral music) 2.0 – 3.0

Radio voice booth 0.2 – 0.4 Recommended RTmid value ranges for various types of rooms. Calculation of RT60 Although several methods for the calculation of reverberation time exist, the most widespread is the classic

Sabine equation:

RT 161.0=

Where V is the volume and A is the total absorption of the room.

8.3. Speech intelligibility The main objective when designing a room destined for speech reproduction, be it with or without

electroacoustic reinforcement, is that the message must be clearly understood by all the audience. Many research efforts have been put in subjectively determining the degree of intelligibility inside a

room. In the early 70s, the Dutch acoustician V.M.A. Peutz carried out a comprehensive research which gave place to an equation that puts speech intelligibility as a function of room acoustics. The parameter is called %ALcons.

Following table shows a range of %ALcons values and their corresponding subjective intelligibility degree, according to Peutz’s equation:

%ALCons Subjective intelligibility degree

Between 0 y -3 % Excellent Between -3 y -7 % Very good Between -7 y -10 % Good Between -10 y -15 % Acceptable Between -15 y -30 % Poor Less than de -30% Unacceptable

Subjective intelligibility degree, according to Peutz.

Amongst others, following factors determine the degree of speech intelligibility inside a room:

• Bandwidth and frequency response of the electroacoustic system.

• Signal level and signal to noise ratio (S/N).

• Reverberation time, RT

60.

• Room geometry.

• Directivity and orientation of loudspeaker enclosures.

• Coverage uniformity: Variations in sound pressure level throughout the audience are should not exceed ±3dB SPL.

• Listener attitude.

As a general rule, the group of reflections arriving at the listener in the first 35 to 50ms after the direct sound positively contribute to speech intelligibility. Conversely, reflections arriving more than 50ms later than the direct sound will be interpreted as echoes, negatively affecting the comprehension of the spoken message.

Following measures can be taken to enhance intelligibility:

• Make sure the bandwidth of the PA system is wide enough at speech frequencies (flat response between 250 and 12 kHz).

• Minimize the distance between loudspeakers and audience.

• Avoid delays greater than 50ms coming from different speakers.

• Use highly directional loudspeakers in reverberant spaces.

• Use a suitable equalization.

Typical equalization for speech intelligibility enhancement.

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