User's Manual ACL2 COMPRESSOR /LIMITER /GATE R LTO www.altoproaudio.com Version 1.
Fuse SAFETY RELATED SYMBOLS CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN 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. Protective Ground Before turning the product ON, make sure that it is connected to Ground. This is to prevent the risk of electric shock.
PREFACE Dear Customer: Thanks for choosing LTO ACL2 Compressor/Limter/Gate and thanks for choosing one of the results of TEAM job and researches. For our LTO AUDIO LTO AUDIO TEAM, music and sound are more than 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.
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. CONTROLS..............................................................................................................
1. INTRODUCTION You are now the owner of an LTO ACL2 Compressor/Limiter/Gate. The ACL2 is a very powerful dynamic processor. We have included in it several innovative circuit designs that make the ACL2 a very versatile processor: smart and fast recognition of the program, adjustable Expander/Gate and very low distortion Voltage Control Amplifier (VCA). Feature List: The AUTO Function Your ACL2 includes AUTO function switch on the front panel.
certain "reserve" must be maintained to avoid distortion. This reserve is known as "headroom" and it is usually set at 10-20dB. Would it 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. Chart.
But if you sing into your microphone more gently in a soft passage, the level of the signal generated by your voice will get much closer to the floor noise level and such floor noise will become disturbing. In order to kill this problem expander and noise-gate are used. An expander is the opposite of a compressor: attenuating the signal when the amplitude drops they can limit the floor noise.
3.2 Compressor Section 10 4 7 6 5 8 9 3 Pic.3: Controls of the Compressor/Limiter section 3. IN/OUT Switch Engage this switch to activate the corresponding channel. It can be used to make an A/B comparison in between processed and unprocessed signal. 4. THRESHOLD Control This control adjusts the threshold level for the Compressor section in the range of -40dBu to +20dBu. Signals above this level cause compression. 5.
11. PROCESS control This control renews any high frequencies lost through the compression process for natural sounding dynamics control, which can be varied from OFF to 6. Please note that the enhancer control is only used when compression is taking place. 3.
4. READY TO ROLL? 4.1 Expander/Gate Section Chart.3: Function of an expander As we told you previously in this manual the downward expander will reduce automatically the level of the audio signal when such signal is below a set threshold. So the expander is the opposite of the compressor/limiter. We also explained to you how the ratio curve of the expander is flat while a noise gate it is more brutal processor: It simply cuts off the entire signal below a certain set threshold.
4.2.2 Ratio control This control sets the change of input level to output level but only for the signals that exceed the threshold. The scale of the ratio control on the front panel (calibrated in dB) indicates how much input level is required to increase the output level by 1dB. If you have a ratio equal to 1:1 you will get the same level of input and output signal: So, no level change.
4.2.8 Gain Reduction Meter This consists of 12 LED on the front of the ACL2. Through this Led meter you can visualise the amount of gain reduction at any given time. GAIN REDUCTION dBu (Hard Knee) 0 1:1 -5 2:1 -10 4:1 10:1 -10 -5 0 +5 Input/dBu +10 Chart.6: The effect of a compressor can be expressed as the amount of gain reduction that is taking place for any given input 4.
a. Wiring Configuration Both types of connectors available on ACL2 can be wired in balanced and unbalanced modes. Please see following drawing for details: For 1/4" Phone jack + + - Tip Ring + Tip Tip Ring Sleeve Sleeve TS Type Unbalanced Sleeve TRS Type Balanced TRS Type Unbalanced For XLR connector Pin2 (+) Pin2 (+) Pin3 (-) Pin3 (-) (Linked to Pin1 manually, ) Pin1 ( ) Pin1 ( ) XLR Type Unbalanced XLR Type Balanced b. In Line Connection Please see following drawing for details.
c. Insert Points Connection In case you are using the main inserts of your mixing console and you have a single jack for SEND and RETURN, you can use an insert Y cable . Please see following drawing.
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7. BLOCK DIAGRAM PROCESS AUDIO INPUT DYNAMIC ENHANCER DIFFAMP L SERVOBALANCED INPUT STACE AUDIO OUTPUT IN/OUT OUTPUT DRIVER VCA SIDE CHAIN OUTPUT THRESHOLD CLOSE AUDIO DETECTOR AUDIO DETECTOR THRESHOLD AUTO GATE CIRCUITRY AUTO COMPRESSOR CIRCUITRY RATIO ATTACK AUTO RELEASE Chart.
8. WARRANTY 1. WARRANTY REGISTRATION CARD To obtain Warranty Service, the buyer should first fill out and return the enclosed Warranty Registration Card within 10 days of the Purchase Date. All the information presented in this Warranty Registration Card gives the manufacturer a better understanding of the sales status, so as to purport a more effective and efficient after-sales warranty service.
SEIKAKU TECHNICAL GROUP LIMITED No. 1, Lane 17, Sec. 2, Han Shi West Road, Taichung 40151, Taiwan http://www.altoproaudio.com Tel: 886-4-22313737 email: alto@altoproaudio.com Fax: 886-4-22346757 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 c 2005 SEIKAKU GROUP NF01958-1.
