VocoPro Musical Instrument CLG 600 User Manual

FEATURES:  
• Two Independent Compressor/Limiter/Gates in a 1RU Roadworthy Housing  
• Unique (IKC) Circuitry Intelligently Combines 'Hard Knee' and 'Soft Knee' Compression Styles,  
Providing Excellent Inaudible and Program Music Compression  
• Fully Automatic or Manually Variable Attack/Release Times, Compression Ratios and Threshold  
Levels Allow Both the Novice and the Experienced User Full Effective Use All Processing Controls  
• Dual 12-stage Gain Reduction and 8-stage Input/Output Meters for Accurate, Reliable Metering  
• Dual-Mono or Stereo Operation for a Multitude of Live, Studio or Recording Applications  
• Built-In Adjustable Dynamic Enhancer Selectively Replaces High-End Loss Even During Severe  
Compression Produced by High-energy or Low-End Content So Processed Vocals Remain Vibrant  
• IRC (Interactive Ratio Control) Expander/Gate Automatically Adjusts Expansion Per the Program  
Material, Eliminating the Noise Floor During Quiet Sections or Music Pauses  
• 1/4" and XLR-TRS Input/Outputs Provide for Balanced and Unbalanced Integrations to External Devices  
• Auto-mode Allows for "Hands-Free" Operation of CLG-600, Allowing Users to Focus on Other Aspects of  
the Show, Recording or Broadcast  
-30  
20  
-10  
-5  
-3  
0
+3  
+5  
30  
27  
24  
21  
18  
15  
12  
9
6
4
2
1
LEVEL  
INAUDIBLE  
30  
27  
24  
21  
18  
15  
12  
9
6
4
2
1
GAIN  
INAUDIBLE GAIN  
-
LEVEL  
-30  
20  
-10  
-5  
-3  
0
+3  
+5  
+
-
+
C H  
1
C H  
2
-35  
0.5  
0
3
-10  
2.5  
2.5  
-20  
-10  
2.5  
2.5  
0.5  
0
3
-35  
-35  
-20  
-10  
-10  
0
-20  
0
MANUAL  
MONO  
OUT  
IN  
MANUAL  
OUT  
IN  
1.5  
8
-50  
0
-50  
0
-30  
+10  
-30  
+10  
1.5  
8
CLG-600  
DUAL CHANNEL COMPRESSOR  
LIMITER WITH GATE  
1
0.1  
200  
.05  
4
-20  
+20  
OFF  
6
-40  
THRESHOLD  
dB  
+20  
OFF  
+10  
-40  
+20  
OFF  
+10  
1
0.1  
200  
.05  
4
-20  
+20  
6
OFF  
RATIO  
M1  
OUPUT  
dB  
THRESHOLD  
dB  
RELEASE  
Sec  
THRESHOLD  
dB  
THRESHOLD  
dB  
RATIO  
N1  
RELEASE  
Sec  
O
U
dB  
P
U
T
msec  
AUTO  
STEREO  
MODE  
msec  
AUTO  
COMPRESSOR/LIMITER  
EXPANDER/GATE  
COMPRESSOR/LIMITER  
EXPANDER/GATE  
ENHANCER  
ENHANCER  
CLG-600  
Dual Channel Compressor/Limiter with Gate  
 
Welcome...  
And Thank you for purchasing the CLG-600 from VocoPro, your ultimate choice in Karaoke entertainment!  
With years of experience in the music entertainment business, VocoPro is a leading manufacturer of  
Karaoke equipment, and has been providing patrons of bars, churches, schools, clubs and individual  
consumers the opportunity to sound like a star with full-scale club models, in-home systems and mobile  
units. All our products offer solid performance and sound reliability, and to further strengthen our  
commitment to customer satisfaction, we have customer service and technical support professionals  
ready to assist you with your needs. We have provided some contact information for you below.  
1728 Curtiss Court  
La Verne, CA 91750  
Toll Free: 800-678-5348  
TEL: 909-593-8893  
FAX: 909-593-8890  
VocoPro Company Email Directory  
Customer Service & General Information  
Tech Support  
Remember Our Website  
packages and promos. And while you're there don't forget to check out our Club VocoPro for Karaoke  
news and events, chat rooms, club directories and even a Service directory!  
We look forward to hearing you sound like a PRO, with VocoPro, your ultimate choice in Karaoke  
entertainment.  
FORYOUR RECORDS  
Please record the model number and serial number below, for easy reference, in case of loss or theft. These numbers  
are located on the rear panel of the unit. Space is also provided for other relevant information  
Model Number  
Serial Number  
Date of Purchase  
Place of Purchase  
2
 
Listening For A Lifetime  
Selecting fine audio equipment such as the unit you've just purchased is only the start of your musical enjoyment. Now it's  
time to consider how you can maximize the fun and excitement your equipment offers. VocoPro and the Electronic  
Industries Association's Consumer Electronics Group want you to get the most out of your equipment by playing it at a  
safe level. One that lets the sound come through loud and clear without annoying blaring or distortion and, most  
importantly, without affecting your sensitive hearing.  
Sound can be deceiving. Over time your hearing 'comfort level' adapts to a higher volume of sound. So what sounds  
'normal' can actually be loud and harmful to your hearing. Guard against this by setting your equipment at a safe level  
BEFORE your hearing adapts.  
To establish a safe level:  
• Start your volume control at a low setting.  
• Slowly increase the sound until you can hear it comfortably and clearly, and without  
distortion.  
Once you have established a comfortable sound level:  
• Set the dial and leave it there.  
• Pay attention to the different levels in various recordings.  
Taking a minute to do this now will help to prevent hearing damage or loss in the future. After all, we want you listening for  
a lifetime.  
Used wisely, your new sound equipment will provide a lifetime of fun and enjoyment. Since hearing damage from loud  
noise is often undetectable until it is too late, this manufacturer and the Electronic Industries Association's Consumer  
Electronics Group recommend you avoid prolonged exposure to excessive noise. This list of sound levels is included for  
your protection.  
Some common decibel ranges:  
Level  
Example  
30  
40  
50  
60  
70  
80  
Quiet library, Soft whispers  
Living room, Refrigerator, Bedroom away from traffic  
Light traffic, Normal Conversation  
Air Conditioner at 20 ft., Sewing machine  
Vacuum cleaner, Hair dryer, Noisy Restaurant  
Average city traffic, Garbage disposals, Alarm clock at 2 ft.  
The following noises can be dangerous under constant exposure:  
Level  
Example  
90  
Subway, Motorcycle, Truck traffic, Lawn Mower  
Garbage truck, Chainsaw, Pneumatics drill  
Rock band concert in front of speakers  
Gunshot blast, Jet plane  
100  
120  
140  
180  
Rocket launching pad  
-Information courtesy of the Deafness Research Foundation  
3
 
CLG-600  
Dual Channel Compressor/Limiter with Gate  
Contents  
Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Welcome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Listening for a Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
1
2
3
4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
AC Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Mounting / Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Front Panel Description and Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Rear Panel Description and Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Connections and Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Typical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Troubleshooting Tips. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
5
6
6
6
7-9  
9
10  
10-12  
13  
14  
15  
Useful Compressor Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
CLG-600 FEATURES  
• Two Independent Compressor/Limiter/Gates in a 1RU Roadworthy Housing  
• Unique (IKC) Circuitry Intelligently Combines 'Hard Knee' and 'Soft Knee' Compression Styles,  
Providing Excellent Inaudible and Program Music Compression  
• Fully Automatic or Manually Variable Attack/Release Times, Compression Ratios and Threshold  
Levels Allow Both the Novice and the Experienced User Full Effective Use All Processing Controls  
• Dual 12-stage Gain Reduction and 8-stage Input/Output Meters for Accurate, Reliable Metering  
• Dual-Mono or Stereo Operation for a Multitude of Live, Studio or Recording Applications  
• Built-In Adjustable Dynamic Enhancer Selectively Replaces High-End Loss Even During Severe  
Compression Produced by High-energy or Low-End Content So Processed Vocals Remain Vibrant.  
• IRC (Interactive Ratio Control) Expander/Gate Automatically Adjusts Expansion Per the Program  
Material, Eliminating the Noise Floor During Quiet Sections or Music Pauses  
• 1/4" and XLR-TRS Input/Outputs Provide for Balanced and Unbalanced Integrations to External Devices  
• Auto-mode Allows for "Hands-Free" Operation of CLG-600, Allowing Users to Focus on Other Aspects of  
the Show, Recording or Broadcast  
4
 
Introduction  
The CLG-600 Compressor/Limiter/Gate was designed for use in the Karaoke community, but of course can also  
be used in the multitude of situations that compressors commonly handle. If this is your first experience using a  
compressor, or are completely new to the process of compression, limiting and gating, it is well advised to read  
this manual thoroughly to best acquaint yourself with them prior to any live application of the CLG-600.  
The CLG-600's range of applications can be divided into three basic categories, compressing, limiting and  
gating. When used as a protective device to prevent audio levels from overloading systems such as tape  
recorders, power amplifiers, speakers, or transmitters, it is generally referred to as 'Limiting'. It may also be used  
to even out a Karaoke performance by deliberately reducing the dynamic range (volume range) of the overall vocal  
signal, and setting the output gain to bring the compressed signal back to a normalized volume level. Doing this  
allows the operator to avoid unexpected volume peaks and secure a much louder and full sounding vocal signal at  
the same time. That is referred to as 'Compressing'. Also common, is the application of completely removing  
audible noise from low-volume sections of an audio signal, i.e. fans, air conditioning units, electric hums. This is  
referred to as 'Gating'.  
In any case, the CLG-600 offers exceptional performance and precise controls for the Karaoke and audio  
enthusiasts, and with time and experience, you will soon harness the full potential of the CLG-600, never doing  
another show or studio recording without it!  
Common Compression Terms  
Threshold - Volume level at which the compressor begins compression.  
Ratio - The relative level the volume above threshold will be brought down by.  
Attack & Release - Attack controls how fast the compressor reacts to signals passing over the threshold point.  
Release is how quickly it stops reacting once the signal passes under the threshold again.  
Output Gain - Amplifies the signal after it has been compressed to compensate for the reduction in high  
volumes.  
Hard Knee or Soft Knee - These are widely used and referred to styles of compression that can smoothen out  
threshold point processing, or abruptly apply threshold point processing. Soft Knee compression uses an  
"acceptable range" around a particular threshold point, providing a smoother transition. Hard Knee compression  
starts exactly at the threshold point, providing razor-like abrupt transitions.  
5
 
Unpacking  
As a part of our system of quality control, every Vocopro product is carefully inspected before leaving the factory  
to ensure flawless appearance. After unpacking, please inspect for any physical damage. Save the shipping carton  
and all packing materials, as they were carefully designed to reduce to minimum the possibility of transportation  
damage should the unit again require packing and shipping. With your new CLG-600, you should have received  
the following items:  
UNPACKING  
30  
27  
24  
21  
18  
15  
12  
9
6
4
2
1
LEVEL  
-30  
20  
-10  
-5  
-3  
0
+3  
+5  
INAUDIBLE  
30  
27  
24  
21  
18  
15  
12  
9
6
4
2
1
GAIN  
-30  
20  
-10  
-5  
-3  
0
+3  
+5  
INAUDIBLE GAIN  
-
LEVEL  
+
-
+
C H  
1
C H  
2
-35  
2.5  
0.5  
0
3
-20  
-10  
2.5  
-10  
2.5  
2.5  
0.5  
0
3
-35  
-35  
-20  
-10  
-10  
0
-20  
0
MANUAL  
OUT  
IN  
MONO  
MANUAL  
OUT  
IN  
1.5  
8
-50  
0
-50  
0
-30  
+10  
-30  
+10  
1.5  
8
CLG-600  
DUAL CHANNEL COMPRESSOR  
LIMITER WITH GATE  
1
0.1  
200  
.05  
4
-20  
+20  
OFF  
6
-40  
THRESHOLD  
dB  
+20  
OFF  
+10  
-40  
+20  
OFF  
+10  
1
0.1  
200  
.05  
4
-20  
+20  
6
OFF  
THRESHOLD  
dB  
RATIO  
M1  
RELEASE  
Sec  
O
U
dB  
P
U
T
THRESHOLD  
dB  
THRESHOLD  
dB  
RATIO  
N1  
RELEASE  
Sec  
O
U
dB  
P
U
T
msec  
AUTO  
STEREO  
MODE  
msec  
AUTO  
COMPRESSOR/LIMITER  
EXPANDER/GATE  
COMPRESSOR/LIMITER  
ENHANCER  
EXPANDER/GATE  
ENHANCER  
AC Main's  
Power Cable  
CLG-600  
AC Power Requirements  
A standard IEC-320 AC inlet is provided on the rear panel of the CLG-600 to accept the detachable power cord  
shipped with the unit. Units are pre-selected for 115 VAC, 60Hz and should be plugged into a standard NEMA 5-  
15 3-wire grounded AC receptacle. For use of the unit outside the US, 230VAC, 50-60Hz power supplies are  
required. The CLG-600 will perform normally from 100 to 125 VAC. An internal line fuse is used. In the event of  
fuse failure, refer to a qualified service technician for servicing. Power consumption is 9 watts.  
Mounting Installation  
TOP VIEW  
Rack Unit with Empty Space  
The CLG-600 mounts in a standard 19-inch equipment rack. The mounting screw threads vary with different rack  
manufactures and you should refer to your rack instructions for proper hardware. An oval head or flat head screw  
with a plastic countersink washer is preferred to protect the finish of the CLG-600 under the screw. The CLG-600  
is housed in a rugged steel case and can tolerate "in the field" abuse, however proper care will best suit the unit  
for long-life and performance.  
1. To mount, carefully place the CLG-600 in the desired rack space.  
2. It is recommended to allow at least 4" of space deep in order to make cable connections easily.  
3. Make sure all four holes are aligned evenly.  
4. Using an alternating "X" rotation, screw mounting bolts in to ensure even tension and alignment.  
6
 
Front Panel Description and Controls  
1. POWER button - This button turns the CLG-600's main power ON/OFF.  
1
CLG-600  
DUAL CHANNEL COMPRESSOR  
LIMITER WITH GATE  
-30  
20  
-10  
-5  
-3  
0
+3  
+5  
30  
27  
24  
21  
18  
15  
12  
9
6
4
2
1
LEVEL  
INAUDIBLE  
30  
27  
24  
21  
18  
15  
12  
9
6
4
2
1
GAIN  
INAUDIBLE GAIN  
-
LEVEL  
-30  
20  
-10  
-5  
-3  
0
+3  
+5  
+
-
+
C H  
1
C H  
2
-35  
0.5  
0
3
-10  
2.5  
2.5  
-20  
-10  
2.5  
2.5  
0.5  
0
3
-35  
-35  
-20  
-10  
-10  
0
-20  
0
MANUAL  
MONO  
OUT  
IN  
MANUAL  
OUT  
IN  
1.5  
8
-50  
0
-50  
0
-30  
+10  
-30  
+10  
1.5  
8
CLG-600  
DUAL CHANNEL COMPRESSOR  
LIMITER WITH GATE  
1
0.1  
200  
.05  
4
-20  
+20  
OFF  
6
-40  
THRESHOLD  
dB  
+20  
OFF  
+10  
-40  
+20  
OFF  
+10  
1
0.1  
200  
.05  
4
-20  
+20  
6
OFF  
RATIO  
M1  
OUPUT  
dB  
THRESHOLD  
dB  
RELEASE  
Sec  
THRESHOLD  
dB  
THRESHOLD  
dB  
RATIO  
N1  
RELEASE  
Sec  
O
U
dB  
P
U
T
msec  
AUTO  
STEREO  
MODE  
msec  
AUTO  
COMPRESSOR/LIMITER  
EXPANDER/GATE  
COMPRESSOR/LIMITER  
EXPANDER/GATE  
ENHANCER  
ENHANCER  
EXPANDER/GATE SECTION  
3
2.THRESHOLD control - The THRESHOLD control has a  
range of -50dB to +10 dB, allowing applications from low  
level compression to high level limiting. The THRESHOLD  
control determines the audio level above which  
gain reduction occurs.  
INAUDIBLE  
-
+
-35  
2
-35  
-10  
-50  
0
3. EXPANDER/GATE LED's - These LED's indicate  
when EXPANSION or GAIN REDUCTION is occurring  
within a signal process. The visual range is from 1 to 30dB.  
When the GREEN (-) LED comes on, that means that  
GAIN REDUCTION is beginning to occur, due to input signal  
peaks exceeding the selected threshold in dB. When the  
RED (+) LED comes on, that means that EXPANSION is  
beginning to occur, due to the input signal dropouts falling  
OFF  
+10  
THRESHOLD  
dB  
EXPANDER/GATE  
7
 
Front Panel Description and Controls (cont.)  
4. IN/OUT button - This switch enables you to quickly  
hear the CLG-600 compressor/limiter IN or OUT of the  
audio chain. When the switch is in the OUT position,  
all limiting and compression controls and functions  
are bypassed, with the exception of the gain and  
output controls, which continue to function as  
straightforward level controls.  
8. RELEASE control - The RELEASE control  
determines how fast or slow a compressed  
segment returns to its original volume. The  
available range is from .05 to 4 seconds. This  
control when used correctly creates either a  
9. AUTO/MANUAL switch - By activating the AUTO  
switch to the ON position, the attack and release  
controls are handled by the CLG-600  
5.THRESHOLD control - The THRESHOLD control  
has a range of -40dB to +20 dB, allowing applications  
from low level compression to high level limiting. The  
THRESHOLD control determines the audio level above  
which GAIN REDUCTION occurs. When the  
automatically. When it is set to the MANUAL  
position, the attack and release controls will  
adhere to settings of the controls in place. This  
allows for unobtrusive musical compression with  
widely varying dynamics to occur without  
"manning" the sound system.  
THRESHOLD LED comes on, that means that GAIN  
REDUCTION is beginning to occur, due to input signal  
peaks exceeding the selected threshold in dB.  
11  
12  
10  
8
7
6
4
5
-30  
20  
-10  
-5  
-3  
0
+3  
+5  
30  
27  
24  
21  
18  
15  
12  
9
6
4
2
1
LEVEL  
GAIN  
C H 1  
0.5  
0
2.5  
-10  
2.5  
-20  
0
MANUAL  
OUT  
IN  
8
1.5  
-30  
+10  
4
1
0.1  
200  
.05  
-20  
+20  
OFF  
-40  
THRESHOLD  
dB  
+20  
RATIO  
M1  
O U P U T  
dB  
RELEASE  
Sec  
msec  
AUTO  
COMPRESSOR/LIMITER  
9
6. RATIO control - This control determines the RATIO  
of change in output level to changes in input level  
for all signals above threshold. The numbers printed  
around the RATIO control are calibrated in dB and  
indicate the increase in input (above threshold)  
required to produce a 1db increase in output. This  
can be expressed conveniently as a ratio. If the  
output remains constant no matter how high the  
input level, we have an infinite input/output ratio.  
10. OUTPUT LEVEL control - OUTPUT Level control  
is provided to fully cut or restore up to -/+ 20 dB  
of system gain. For unity gain, set the control to 0.  
NOTE: When the unit is in the BYPASS mode the  
output control still functions.  
11. GAIN REDUCTION meter - This 8-stage LED  
meter indicates the actual GAIN REDUCTION  
processing level and displays this in range  
of 0-30 dB.  
NOTE: It should be remembered that the RATIO  
control has no effect on signals which are below  
threshold. There is a common but incorrect  
notion that limiting always implies the use of an  
infinite ratio. Although there are times when an  
infinite ratio is desirable, there will be situations  
where infinite, or "hard", limiting action is neither  
appropriate nor necessary.  
12. LEVEL EXPANSION meter - This 8-stage meter  
indicates the actual LEVEL EXPANSION level and  
displays this in a range of -30dB to +6dB.  
7. ATTACK control - ATTACK controls how fast the  
compressor reacts to signals passing over the  
threshold point. The available range is from 0.1 to  
200 ms. This control when used correctly creates  
either a smooth or abrupt signal process.  
8
 
Front Panel Description and Controls (cont.)  
Enhancer Section  
13. PROCESS control - This control sets the  
available amount of ENHANCEMENT between  
OFF and 6. DYNAMIC ENHANCEMENT allows  
you to replenish any high frequencies that may  
have become lost during the compression  
process. ENHANCEMENT should only be  
added when compression is taking place.  
13  
3
6
OFF  
ENHANCER  
Rear Panel Description and Controls  
17  
14  
OPERATING  
LEVEL  
INPUTS  
OUTPUTS  
OUTPUTS  
OPERATING  
LEVEL  
INPUTS  
AC INPUT  
+
-
TIP/PIN2  
RING/PIN3  
SLEEVE/PINT  
+
-
TIP/PIN2  
RING/PIN3  
SLEEVE/PINT  
+
-
TIP/PIN2  
RING/PIN3  
SLEEVE/PINT  
+
-
TIP/PIN2  
RING/PIN3  
SLEEVE/PINT  
+4dBU  
+4dBU  
+
+
+
+
-10dBU  
-10dBU  
VOLTAGE  
SELECTOR  
FUSE  
16  
18  
19  
15  
14. AC POWER terminal - This terminal is where the  
17. AUDIO INPUT jacks - Each channel has an  
AUDIO INPUT section. Each AUDIO INPUT section  
has an XLR and a ¼" INPUT jack for audio source  
connections.  
MAINS POWER CABLE is connected.  
NOTE: Before your power on the unit, make sure  
you have the correct voltage setting in place.  
NOTE: The XLR and ¼" input jacks on the same  
channel cannot be used simultaneously.  
15. FUSE housing - This is where the CLG-600's fuse  
resides. If for any reason the fuse blows, it is  
recommended to seek assistance from a  
technician prior to re-installing another fuse, due to  
the fact that further damage could occur to the  
CLG-600.  
18. AUDIO OUTPUT jacks - Each channel has an  
AUDIO OUTPUT section. Each AUDIO OUTPUT  
section has an XLR and a ¼" INPUT jack for audio  
device connections.  
NOTE: If replacing the fuse, ONLY replace with the  
same type and rating.  
NOTE: The XLR and ¼" input jacks on the same  
channel cannot be used simultaneously.  
16. VOLTAGE selector - This selector is used to toggle  
between 115V and 230V power settings.  
Select 115V for a North American based power  
setting and 230V for a European based power  
setting.  
19. OPERATING LEVEL control - Professional-level  
audio equipment just about always employs a  
+4dBU operating setting, while consumer level  
audio equipment tends to employ the -10dBU  
setting. This control is used to maintain  
compatibility with both "classifications"  
of sound equipment.  
NOTE: Before your power on the unit, make sure  
you have the correct voltage setting in place.  
9
 
Connections and Cables  
Balanced vs. Unbalanced Audio Connections  
Balanced signal connections are preferred in pro audio applications because of their improved immunity to  
induced hum and noise. A properly shielded and wired balanced input stage on any audio product will reject most  
unwanted noise (RFI, EMI) picked up by the cable, as well as minimize ground loop problems. Therefore it is  
always advantageous to use balanced connections when running signal more than ten or fifteen feet, although  
particularly noisy environments may require that even short patch cables be balanced.  
Unbalanced connections are used mostly for short distance, high level signals (0dBu nominal). Most external EMI  
noise pick-up will be masked under the noise floor of the signal, assuming there is little or no gain following the  
unbalanced signal. If a gain stage does follow a signal, or if externally sourced noise persists, use balanced  
connectors.  
Inputs and Outputs  
Your CLG-600 Compressor/Limiter is provided with two different connector types. 1/4" TRS (tip-ring-sleeve) phone  
jacks, and three pin XLR connectors will allow interfacing to most professional audio products. TRS balanced  
connections use the tip as (+) and the ring as (-) signal, with sleeve used for ground. XLR connectors use pin 2  
(+) and pin 3 (-) with pin 1 ground. When possible, we recommend balanced connections between all components  
in your system. If inputs are used unbalanced, the signal should be on the (+) connection and the (-) connection  
must be tied to ground, or signal loss will result. While a mono phone plug used as an unbalanced connection will  
automatically ground the (-) ring of the jack, XLR's will not automatically do this, so attention must be given to  
proper wiring.  
Typical Applications  
The CLG-600 as A Protection Device  
The CLG-600 provides quick and accurate gain control for the prevention of sound system overload due to  
unexpected peaks/transients. Sound system distortion is usually the result of amplifiers running out of power, in  
which case nice round waveforms turn into harsh sounding squared-off waveforms. Looking at it from the  
perspective of the speaker diaphragm, this means that, whereas in normal operation the diaphragm is required to  
accelerate, slow down, smoothly change direction, and accelerate again, distorted operation requires an instant  
acceleration, instant stop, a change of direction, and instant acceleration again.  
Since speaker diaphragms are subject to the laws of physics, they won't take this kind of punishment for long. The  
diaphragm may shatter, or its voice coil may overheat. In addition to the damaged caused by sustained overload,  
the speaker may also be damaged by occasional, one-shot high level overload, for example, the sound of a  
microphone falling face-first onto a hardwood floor. Even if this type of transient doesn't destroy a speaker  
outright, it may damage the speaker surround in such a way as to cause mechanical abrasion and future failure.  
In this situation, Limiting would be used as a protective measure.  
Alternatives for Sound System Installations  
To install the CLG-600 in a system using a passive crossover, insert it between your mixers output and the power  
amplifier input. It may be inserted between the mixer output and the crossover input, in which case it will act on  
the entire audio frequency spectrum. Alternately, if the limiter is inserted between an output of the electric  
crossover and the input of a power amp, it will only affect a specific band of frequencies.  
Compression for Feedback Control  
A common practice in sound system setting-up is equalizing the room to remove feedback. This is generally  
accomplished by turning up system gain to purposely induce feedback, searching for the center frequency of the  
feedback, and then equalizing at that frequency to remove the feedback. Once this frequency has been cut,  
system gain is again increased to induce another feedback point, and the whole procedure is repeated until the  
engineer is satisfied that the significant problem frequencies have been corrected. The major problem with this  
approach is that the feedback can easily get out control, and the engineer ends up dashing back and forth  
between the mixer volume controls and the equalizer controls, while everyone in the room plugs their ears and  
prays it will end soon. The CLG-600 can turn this procedure into a fast, painless job, eliminating loud feedback  
levels and the possibility of speaker or ear damage.  
10  
 
Typical Applications (cont.)  
Compression for Feedback Control Procedure:  
1. Set up the CLG-600 unit's controls as follows:  
a. Output level control to -20dB.  
b. Input Gain control to 0dB.  
c. Threshold control to -30dB.  
d. Ratio control to infinity (  
e. Attack time to 5mS.  
f. Release time to 1 sec.  
)
2. Adjust equalizer controls to a flat setting, and if the equalizer has an overall volume control,  
boost it by 10 to 15 dB.  
3. Open up several microphone input channels to a normal operating level, with typical EQ settings, and turn the  
console master fader up to a louder than normal setting. At this point, the system should be well into feedback,  
but the room volume will be constant due to the action of the limiter.You can listen to the feedback at any level  
you like by simply varying the CLG-600's output level control, although below a certain monitoring level, the  
feedback will stop.  
4. Try to determine the feedback frequency, and then equalize it by adjusting the center frequency, bandwidth, and  
boost/cut controls of your parametric equalizer. (Note: a graphic equalizer can also be used, although with less  
accuracy.) After eliminating the problem frequency, try to further define it by sharpening up the bandwidth, re-  
attacking the frequency control, and making the cut shallower, if possible.  
5. As soon as the first feedback frequency has been removed, bring up system gain until another feedback point  
is induced. Repeat the equalization procedure until it becomes impossible to distinguish individual, predominant  
feedback frequencies.  
6. Return all mixer, EQ overall gain, and compressor/limiter gain controls to normal settings.  
Recording  
The limiter can be used to prevent tape saturation in analog recording. Also, with modern trends toward  
inexpensive digital recording, it remains necessary to protect against input overload. With digital recording, the  
information stored on tape, hard disk, optical disk, etc., is either a 1 or 0, so actual signal level on the tape is not  
the concern it is with analog recordings, in fact it is not even a user controllable parameter. What is of concern  
however, is the signal level applied to the A-D (analog to digital) converters. If clipping occurs at the converter  
input stage, the resulting distortion is most unpleasant, and will be recorded digitally as if they were part of the  
original audio signal, forever mixed with the audio. To prevent converter distortion while preserving the extended  
dynamic range of digital recording, look up the max input level of your recorder/converter and set up the limiter as  
follows:  
1. Set Gain to 0.  
2. Set Threshold to 2-3 dB below max converter input.  
3. Set Ratio to 10.  
4. Set Attack to 2 mS.  
5. Set Release to .2 Sec.  
6. Set Output level to 0.  
If you are exceeding threshold frequently, your input signal is probably too high and should be turned down. Of  
course, every situation is different, so experimentation before final recording is always a good idea, but this is a  
good starting point. To obtain a gentler limiting action at the expense of some dynamic range, decrease the  
threshold to -15 and the ratio to 3-5. This is also a good starting point for analog recording.  
11  
 
Typical Applications (cont.)  
Broadcasting  
Compression has long been used as a tool to make an audio signal appear louder. A good example is in  
broadcasting, where competing stations with identical transmitters and power attempt to sound louder than each  
other. Since they are all restricted with respect to maximum audio level (modulation), their best tactic is to  
squeeze the dynamic range of their programs to just a few dB. The audio output level of the station virtually never  
changes, and the listener perceives this continuous high-level sound as being louder than the same material in an  
uncompressed form. Although both compressed and uncompressed programs reach the same peak levels, the  
compressed signal stays near peak level more of the time, and thus sounds louder. This technique makes the  
broadcast more intelligible over the road noise in your car, and increases the geographical area over which the  
broadcast is audible to the listener. A similar, if less pronounced, effect can be used in sound reinforcement and  
recording applications.  
SPECIAL EFFECTS  
Altering the Texture of Musical Instruments  
It would be impossible to mention here all the ways that compression is used to create new sounds with familiar  
instruments. Some typical uses are:  
1. Creating a "fatter" kick drum or snare sound.  
2. "Thickening" acoustic guitars.  
3. Adding punch and sustain to electric bass or guitar.  
In general, use a gentle compression ratio, say 4:1, with a 10 mS attack time, 0.1 sec. release time, and a  
low enough threshold to cause 6 to 10dB of gain reduction. Try using this effect to help bring out a lead  
vocal or instrumental solo in a cluttered mix. The compressor is also a great corrective tool when working with  
singers whose own dynamic control is less than perfect. A little compression helps to keep their quieter lines  
from becoming buried in the mix. Experimentation is highly recommended.  
Voice-Over Compression ("Ducking")  
The CLG-600 units can be used to automatically reduce music to a background level when an announcer is  
speaking. In this scheme, only the music signal is actually gain-reduced by the limiter. However, the detector is  
connected to respond to an announcer's voice instead of the music's peaks. Voice-Over compression assumes  
you are already using some sort of mixer to combine the music and mic signals. Use the direct out (send) of the  
mic channel to feed the detector input on the CLG-600 unit. Note: Be sure to use a mono plug for the CLG-600  
Note: Be sure to use a mono plug for the CLG-600 detector input. Then use the threshold  
and ratio controls to determine when and by how much the announcer's voice affects the  
music level.  
Gain Riding  
One solution to the noise vs. distortion trade-off is to keep your hand on the level control and manually adjust gain  
to suit the program. Indeed, there are times when this approach is entirely satisfactory. However, in most types of  
music there are instantaneous, short duration volume peaks, or transients, which would be difficult to anticipate  
and impossible to respond to with manual gain riding, you simply could not bring the level down fast enough. In  
many situations, this can present real problems. For example, in recording, an extra burst of enthusiasm from a  
lead singer might overload the capabilities of your recording tape, causing ragged distortion and necessitating  
another take. In sound reinforcement, a sudden burst of energy through the system can blow fuses or even  
damage loudspeakers. In addition to the problem of response time with manual gain riding, it also requires your  
constant attention, which takes you away from more important jobs. The need for a fast-acting, reliable, automatic  
gain control is answered by limiters and compressors.  
12  
 
Troubleshooting Tips  
Things to remember  
Unshielded cables, improperly wired connectors, and cables with broken strands of wire are very common  
problems. Use quality cables with quality, correctly wired connectors.  
When using heavy compression, background noise is noticeable during quiet sections of the program as defined  
in the section on compression, quiet program material is effectively made louder while loud peaks are made  
quieter. When the program source is thus raised in volume, its noise floor is also raised in volume by a  
proportionate amount. This is not a defect in the Compressor/Limiter, but an unavoidable side effect of the gain  
altering process. If the noise becomes a problem, the solutions are to either decrease noise at the program  
source, or use less compression.  
No Output  
Check AC power. Is the power switch on? Check input and output connections - are they reversed? Are you sure  
you have an input signal?  
Controls Have No Effect  
Is the limiter In/Out switch In? Perhaps the ratio control is set too low to produce an audible effect or the input  
level is below threshold. Is the threshold LED lighting up? If not, lower the threshold setting or increase the gain.  
Do not expect to hear any effect when the input level is below threshold, since the unit is simply a linear amplifier  
at those levels.  
Excessive Hum or Noise  
Hum is often caused by a "ground loop" between components. Try using the suggested balanced input and output  
hookups if the other pieces of equipment used in conjunction with the CLG-600 unit have balanced inputs and  
outputs. Noise can also be caused by insufficient drive levels. Make sure you are sending a nominal 0 dBV line  
level signal to the unit.  
13  
 
Useful Compressor Settings  
General Use  
Compression ratio: 2:1  
Threshold: -10 dB  
Attack: 1ms  
Release: 300 ms (should give a good amount of punch)  
Big Radio Voice  
Gate: Off  
Threshold: -20db  
Ratio: 6:1  
Attack: Fast  
Release: Slow  
Output: +10db  
Drums  
Gate: -30db  
Threshold: -15db  
Ratio: 4:1  
Attack: Fast  
Release: Medium  
Output: +10db  
Input from Microphone to Computer  
Gate: Off  
Threshold: -15db  
Ratio: 3:1  
Attack: Fast  
Release: Medium Slow  
Output: +6db  
14  
 
Specifications  
AUDIO INPUT  
Type RF filtered, servo-balanced input stage  
Impedance 60 k Ohms, balanced  
Nominal Operating Level -10 dBu to +4 dBu  
Max. Input Level +21 dBu balanced and unbalanced  
CNR @ 1 kHz >40 dB  
DETECTOR INPUT  
Type DC de-coupled, unbalanced input  
Impedance <20k Ohms  
Max. Input Level +20 dBu  
AUDIO OUTPUT  
Type Electronically buffered output stage<40 Ohms  
Impedance <40 Ohms  
Max. Output Level +20 dBu  
Bandwidth 5Hz to 50 kHz, +0, -1 dB  
THD @ +4 dBu 0.05% typ  
THD @ -10 dBu 0.1% typ  
IMD (SMPTE) @ +10 dBu 0.01% typ  
Noise & Hum, Unity Gain >-93 dBu  
Noise & Hum, Fully Off>-97 dBu >-97 dBu  
Crosswalk @ 20 kHz>-85 dBu >-85 dBu  
CMR @ 1kHz> 60 dB >-60 dBu  
COMPRESSOR SECTION  
Type IKC (Interactive Knee Compressor)  
Threshold Variable (-40 to +20 dBu)  
Ratio Variable (1:1 to LM)  
Attack Variable (0.1 to 200 msec/20dB)  
Release Variable (0.05 to 4 sec./20dB)  
Output Variable (-20 to +2- dB)  
GATE SECTION  
Type IRC (Interactive Knee Control)  
Threshold Variable (Off to +10 dB)  
DYNAMIC ENHANCER SECTION  
Type Dynamically controlled frequency correction  
Process Variable (Off to 6)  
FUNCTION SWITCHES  
In/Out Bypass switch  
Auto Program-dependent attack and release times  
INDICATORS  
CLOSE LED indicates onset of the expander gate  
8-Element Gain Reduction Meter 1/4/6/10/15/20/30/dB  
POWER SUPPLY  
Mean Voltages 115V-120V/230V/240V VAC 30-60 Hz  
Power Consumption 9 watts  
Fuse 320mA (115V)160mA (230V) slow-blow  
PHYSICAL  
Dimensions 1.74" (H) x 19" (W) x 8.5" (D)  
Net Weight 6.6 lbs.  
Shipping Weight 9.5 lbs.  
For improvement purposes, modifications may be made from time to  
time without prior notice. Specifications may differ from those above  
15  
 

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