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SAFETY RELATED SYMBOLS

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

This symbol, wherever used, alerts you to the pre-
sence of un-insulated and dangerous voltages with-
in the product enclosure. These are voltages that
may be sufficient to constitute the risk of electric
shock or death.

Protective Ground Terminal

AC mains (Alternating Current)

Hazardous Live Terminal

ON:

Denotes the product is turned on.

This symbol, wherever used, alerts you to impo-
rtant operating and maintenance instructions.
Please read.

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.

CAUTION

Describes precautions that should be observed to
prevent damage to the product.

Protective Ground

Operating Conditions

IMPORTANT SAFETY INSTRUCTIONS

Cleaning

Servicing

Power Cord and Plug

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.

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.

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.

Read these instructions

Follow all instructions

Keep these instructions. Do not discard.

Heed all warnings.

Only use attachments/accessories specified by the
manufacturer.

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.

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.

Refer all servicing to qualified service personnel only.

Do not perform any servicing other than those instruc-
tions contained within the User's Manual.

Fuse

To prevent fire and damage to the product, use only

No user serviceable parts inside.

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.

WARNING

Disposing of this product should not be
placed in municipal waste and should be
Separate collection.

Summary of Contents for ACL4

Page 1: ...QUAD COMPRESSOR LIMITER ACL4 User s Manual LTO R www altoproaudio com Version 1 1 September 2005 English ...

Page 2: ...uct away from naked flames Read these instructions Follow all instructions Keep these instructions Do not discard Heed all warnings Only use attachments accessories specified by the manufacturer 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 po...

Page 3: ...dreams with you 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 ACL4 is the result of many hours of listening and tests involving common people area experts...

Page 4: ...IND 4 2 2 Voltage Controlled Amplifier VCA 2 3 Inputs 3 CONTROL ELEMENTS 6 4 7 READY TO ROLL 4 1 Compressor Section 4 2 Peak Limiter Section 6 TECHNICAL SPECIFICATIONS 11 7 WARRANTY 12 3 5 INSTALLATION AND CONNECTION 9 5 1 Mains Connection 5 2 Audio Connection 5 3 Rack Mounting ...

Page 5: ... 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 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 th...

Page 6: ...ters more or less do the same job but Limiters brutally limit the audio signal above a set threshold while Compressors handle signal in a much more civilised way and over a wide range of levels If an audio signal exceed the threshold set by the User the limiter will kill any audio signal above that threshold Period Also Compressors perform their function when the audio signal exceed a certain thre...

Page 7: ...oose 10dBV or 4dBu Consequently the Meter will be the Input or Output Level with a range from 24dB to 18dB 8 Meter for Gain Reduction The gain reduction will be shown by this Meter with a range of 1 to 30dB Pic 1 R LTO POWER OFF ON ACL4 QUAD COMPRESSOR LIMITER 30 25 20 15 10 6 3 GAIN REDUCTION dB 1 INPUT OUTPUT LEVEL dB 24 18 12 6 0 6 12 18 LIM dBu 10 30 20 10 40 THRESHOLD 10 1 2 N 1 RATIO 2 5 0 2...

Page 8: ...READY TO ROLL 4 1 Compressor Section Sophisticated Voltage Controlled Amplifiers VCA are responsible of the control of dynamics in the ACL4 The operating range of our VCA is more than 60dB This mean that the input level or the output level can be increased or decreased in a range of 60dB Signals below the set threshold will not be reduced so the dynamic control will be activated as soon as the sig...

Page 9: ...ould use a Ratio of 4 1 or lower With the SKC circuit Smart Knee Control you can avoid aggressive compression generated by using high ratios How we achieve this Introducing a soft knee curve in the range of up to 10dB above the threshold level Hard Knee compression is then used beyond this range Output Hard Knee Threshold Gain 0 dB Ratio 2 1 Ratio 4 1 Limiter 1 SKA Curve Input Chart 3 SKA characte...

Page 10: ...ut signal The area in between the two is the amount of gain reduction The unit will activate the limiter when the signal exceeds the threshold for more than 20 microseconds Then 1 second after that the signal is below threshold again reduction goes back to 0dB and in this case input and output signals are again identical Chart 5 SGC characteristic of the limiter section 5 INSTALLATION AND CONNECTI...

Page 11: ...ssor Limiter on high temperature devices such as power amplifiers etc to avoid overheating Pic 4 Pic 5 For XLR connector XLR Type Unbalanced XLR Type alanced B Pin3 Pin2 Pin1 Linked to Pin1 manually Pin1 Pin2 Pin3 Tip Ring Sleeve Tip Ring Sleeve Tip Sleeve Tip Sleeve Tip Sleeve Cent e r Cent e r Centre Screen Screen Screen 1 2 3 Tip Ring Sleeve 1 2 3 1 2 3 TIP SLEEVE TIP SLEEVE TIP RING SLEEVE TIP...

Page 12: ...tches input and output for the level meter Linking CH1 master and Ch2 CH3 master and CH4 stereo operation 6 TECHNICAL SPECIFICATIONS 4dBu 10dBV 55dB 1KHz COMPRESSOR SECTION PEAK LIMITER SECTION FUNCTION SWITCHES INDICATORS POWER SUPPLY DIMENSIONS WEIGHT Type Impedance Maximum input level Type Impedance Maximum output level Bandwidth THD N IMD Noise Crosstalk Type Threshold Ratio Output Type Thresh...

Page 13: ...d of LTO 1 year from the purchase date if you have completed the Warranty Registration Card in time 3 2 The warranty service is only available to the original consumer who purchased this product directly from the retail dealer and it can not be transferred 3 3 During the warranty service may repair or replace this product at its own option at no charge to you for LTO parts or for labor in accordan...

Page 14: ...13737 email alto altoproaudio com Fax 886 4 22346757 c All rights reserved to ALTO All features and content might be changed without prior notice Any photocopy translation or reproduction of part of this manual without written permission is forbidden Copyright 2005 SEIKAKU GROUP SEIKAKU TECHNICAL GROUP LIMITED ...

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