Nilfisk CLE4.0 User Manual
User's Manual
CLE4.0
QUAD COMPRESSOR/LIMITER
R
LTO
www.altoproaudio.com
Version 2.0 Dec. 2002
English
SAFETY RELATED SYMBOLS
CAUTION
RISK OFELECTRIC SHOCK
DO NOTOPEN
This symbol, wherever used, alerts you to the presence of un-insulated and dangerous voltages within the product enclosure. These are voltages that
may be sufficient to constitute the risk of electric
shock or death.
This symbol, wherever used, alerts you to important operating and maintenance instructions.
Please read.
Protective Ground Terminal
AC mains (Alternating Current)
Hazardous Live Terminal
ON: Denotes the product is turned on.
OFF: Denotes the product is turned off.
WARNING
Describes precautions that should be observed to
prevent the possibility of death or injury to the user.
the recommended fuse type as indicated in this
manual. Do not short-circuit the fuse holder. Before
replacing the fuse, make sure that the product is
OFF and disconnected from the AC outlet.
Protective Ground
Before turning the product ON, make sure that it is
connected to Ground. This is to prevent the risk of
electric shock.
Never cut internal or external Ground wires. Likewise,
never remove Ground wiring from the Protective
Ground Terminal.
Operating Conditions
Always install in accordance with the manufacturer's
instructions.
To avoid the risk of electric shock and damage, do
not subject this product to any liquid/rain or moisture.
Do not use this product when in close proximity to
water.
Do not install this product near any direct heat source.
Do not block areas of ventilation. Failure to do so
could result in fire.
Keep product away from naked flames.
CAUTION
Describes precautions that should be observed to
prevent damage to the product.
WARNING
Power Supply
Ensure that the mains source voltage (AC outlet)
matches the voltage rating of the product. Failure
to do so could result in damage to the product and
possibly the user.
Unplug the product before electrical storms occur
and when unused for long periods of time to reduce
the risk of electric shock or fire.
External Connection
Always use proper ready-made insulated mains
cabling (power cord). Failure to do so could result
in shock/death or fire. If in doubt, seek advice from
a registered electrician.
Do Not Remove Any Covers
Within the product are areas where high voltages
may present. To reduce the risk of electric shock do
not remove any covers unless the AC mains power
cord is removed.
Covers should be removed by qualified service
personnel only.
No user serviceable parts inside.
Fuse
To prevent fire and damage to the product, use only
IMPORTANT SAFETY INSTRUCTIONS
Read these instructions
Follow all instructions
Keep these instructions. Do not discard.
Heed all warnings.
Only use attachments/accessories specified by the
manufacturer.
Power Cord and Plug
Do not tamper with the power cord or plug. These are
designed for your safety.
Do not remove Ground connections!
If the plug does not fit your AC outlet seek advice from
a qualified electrician.
Protect the power cord and plug from any physical
stress to avoid risk of electric shock.
Do not place heavy objects on the power cord. This
could cause electric shock or fire.
Cleaning
When required, either blow off dust from the product
or use a dry cloth.
Do not use any solvents such as Benzol or Alcohol.
For safety, keep product clean and free from dust.
Servicing
Refer all servicing to qualified service personnel only.
Do not perform any servicing other than those instructions contained within the User's Manual.
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PREFACE
Dear Customer:
Thanks for choosing LTO CLE 4.0 Quad/Compressor/Limter and thanks for choosing one of the results of LTO
AUDIO TEAM job and researches.
For our LTO AUDIO TEAM, music and sound are more then a job...are first of all passion and let us say... our
obsession!
We have been designing professional audio products for a long time in cooperation with some of the major brands
in the world in the audio field.
The LTO line presents unparalleled analogue and digital products made by Musicians for Musicians in our R&D Centers
in Italy, Netherlands, United Kingdom and Taiwan. The core of our digital audio products is a sophisticated DSP
(Digital ound rocessor) and a large range of state of the art algorithms which have been developed by ourSP
Software Team for the last 7 years.
Because we are convinced you are the most important member of LTO AUDIO TEAM and the one confirming the quality
of our job, we like to share with you our work and our dreams, paying attention to your suggestions and your comments.
Following this idea we create our products and we will create the new ones! From our side, we guarantee you and
we will guarantee you also in future the best quality, the best fruits of our continuous researches and the best prices.
Our LTO CLE 4.0 is the result of many hours of listening and tests involving common people, area experts, musicians
and technicians.
The results of this effort is that you can acquired an extremely efficient and universal dynamics processor. It Contains
several new circuits design which make the unit an ultimate dynamic processor: intelligent program recognition and
super low distortion VCA (Voltage Controlled Amplifier).
Nothing else to add, but that we would like to thank all the people that made the LTO CLE 4.0 a reality available to our
customers, and thank our designers and all the LTO staff, people who make possible the realization of products containing
our idea of music and sound and are ready to support you, our customers, in the best way, conscious that you are our best
richness.
Thank you very much.
LTO AUDIO TEAM
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TABLE OF CONTENTS
1. INTRODUCTION......................................................................................................................................4
2. THE CONCEPT BEHIND........................................................................................................................4
2.1 Some technical stuff
2.2 Voltage Controlled Amplifier (VCA)
2.3 Inputs
3. CONTROL ELEMENTS .........................................................................................................................6
4. .................................................................................................................................7READY TO ROLL?
4.1 Compressor Section
4.2 Peak Limiter Section
5. INSTALLATION AND CONNECTION.....................................................................................................9
......
5.1 Mains Connection
5.2 Audio Connection
5.3 Rack Mounting
6. TECHNICAL SPECIFICATIONS .................................................................................................................................11
7. WARRANTY .............................................................................................................................................................12
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1. INTRODUCTION
You are now the Owner of an CLE 4.0 Quad Compressor/Limiter. The CLE 4.0 is a very powerful dynamicLTO processor.
We have included in it several innovative circuit designs that make the CLE 4.0 a very versatile processor: smart and
fast recognition of the program and very low distortion Voltage Control Amplifier (VCA)
Feature List:
Smart Knee Control Compressor (SKC)
Soft knee or hard knee? This is the question! SKC combines both: In the "soft knee" mode you control the program
material so that the compression will be the most musical and inaudible. On the other end, the hard knee function is
used for better precision, limiting signal peaks with precision and will allow you to add creativity to the dynamic processing.
This function also allows you to protect other equipment in the signal loop against distortion.
The AUTO Function
Your CLE 4.0 includes and AUTO function switch on the front panel. Thanks to the AUTO function attack and release times
of the program materials are automatically analysed. Then the dynamic range of the program is heavily compressed in a very
musical way so that there will not be any audible breathing or pumping effect.
Smart Gain Control peak limiter (SGC)
This function includes two important functions: Clipper and program limiter. The peak limiter will be activated above
a certain threshold that is adjusted by the User and will radically restrict signal peaks. But what about if the
threshold of the Limiter is surpassed only for a few milliseconds? SGC will turn on automatically and reduce the
output signal so that you will not hear any distortion. Smart, isn't it? The SGC proves to be very efficient in loudspeaker
protection and to reduce undesired peaks in digital situations.
2. THE CONCEPT BEHIND
2.1 Some technical stuff
Good old analog technology: It will allow us to manufacture audio equipment with a very high dynamic range:
up to 125 dB. But the dynamic range of digital equipment is more or less 25 dB less. A further reduction in
dynamic range occurs with the use of tape recorders and/or vinyl records.
2.1.1 It is not just Music
Yes, a piece of electronic will produce some noise. When the current flows through a conductor this will generate
a certain movement of the electrons and therefore: noise. And throughout the whole spectrum of audio. Imagine
what happens when this inherent noise will be amplified. Yes, today one can use "low-noise" components but
still such components will present a certain level of residual noise. For example with tape recorders it will not
be possible to get an S/N (signal to noise) ratio better than 70dB. This level would not be accepted today by the
increased sensitivity of the Listeners. It is possible to improve the performance of a tape recorder: Absolutely no!
2.1.2 Introducing Audio Dynamics
The human ear can detect the noise generating by falling leaves as well as the roar generated by the taking off space
shuttle. Unfortunately no analog, nor digital device can reproduce such wide spectrum. Please look at Chart. 1 and
you will see the difference if dynamic capacity of various devices when compare to the human ear. More problems
occur when handling high level signals and low level signals. When you reach the high level limit you may incur in
distortion because of the dynamic range of the instrument therefore a certain "reserve" must be maintained to avoid
distortion. This reserve is known as "headroom" and it is usually set at 10-20 dB. Would not be easier just to reduce
the operating level? Yes it would but you would put low level music signals at the same level of the basic noise floor
so the overall quality of the signal would be highly deteriorated. Please look at Chart. 2 and note the Usable dynamic
range (including headroom) versus high level distortion generated by peaks, and Noise floor level.
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