RDL STCL2-RST-01 Data Sheet

STICK-ON® SERIES

Model ST-CL2
Compressor/Limiter

ANYWHERE YOU NEED...

 Positive Audio Level Protection
 Smooth Inaudible Gain Reduction
 Tight Audio Peak Control
 Very Low Noise Compressor
 Multi Stage Incremental Gain Reduction
 Fully Automatic Operation
 Superb Performance with Minimal Setup

You Need The ST-CL2!

The ST-CL2 Compressor/Limiter is part of the group of STICK-ON products from Radio Design Labs. The durable adhesives
provided with the ST-CL2 permit permanent or removable mounting. Numerous available mounting accessories, brackets and
rack-mount chassis are optionally available to facilitate any system design. The ST-CL2 is a unique, high-performance electronic
module offering a sophisticated level of compression and limiting for line-level audio sources.

APPLICATION: The ST-CL2 is a high performance compressor/limiter designed to maintain a constant average output level and
effective peak control over a wide range of input levels. The input and output are line level and each may be wired balanced or
unbalanced. Trimmers provide adjustment for all usual professional and consumer audio input and output levels. Internal
detectors feed three timing circuits. The threshold level and slope of each timing circuit are incremented to respond sequentially
to signals of varying amplitude and energy levels.

The ST-CL2 features incremental gain reduction. This unique RDL circuitry continuously samples the audio at different rates and
levels. Each stage of gain reduction preconditions the audio for the next gain reduction detector. Tailoring the audio for each
subsequent increment of gain reduction, together with interactive release-time circuitry, produces nearly inaudible operation.
Although the peak control is very fast, a separate clamping circuit will attack and thoroughly limit signals of an extreme amplitude
with rise-times faster than the attack time of the peak limiting detector. This circuit is not activated by any normal program
material, but is included as a positive protection against potential extreme overload signals.

The ST-CL2 is very simple to install and set up for operation. Only two adjustments are needed: Input and Output. The lack of
complicated adjustments does not take away from the versatility of the module. The ST-CL2 features a soft-knee compression
threshold and compression ratio which automatically adjust to the program material, thereby eliminating the need for numerous
installer settings. Two LED indicators cover the incremental ranges of compression, making setting of the input level quick and
easy. The input gain determines the threshold and compression levels, with all internal levels optimized for the lowest noise
performance. ST-CL2s may be strapped together for stereo operation by connecting the coupling terminals between the two
modules.

The ST-CL2 features RDL SupplyFlex. The power supply input may be fed from a floating (not ground-referenced) 24 Vdc power
source, from a bipolar power supply (+/-12 Vdc or +/-15 Vdc), or from a ground-referenced 24 Vdc power supply. A jumper on the
terminal block is used to select the ground-referenced power configuration.

Applications: There is almost no limit to the possible places the ST-CL2 can be effectively used! Anywhere line-level inputs need
to be protected against level increases or overloads, placing the ST-CL2 in-line solves the problem. If automatic gain control and
compression/limiting are both needed, the ST-CL2 can be used with the ST-GCA3 to form an effective processing package.
Some examples of possible applications are:

 Audio feeds into paging systems
 Recording machine audio inputs
 Feeds into radio transmission devices which could overmodulate
 Line level feeds into a telephone line which must not be overloaded
 Crucial points in any system which could be inadvertently overloaded with input audio
 Power amplifier inputs fed by any audio source that may have loud bursts resulting in overload or distortion

With its unique combination of sophisticated incremental compression, exceptional audio performance, convenient installation
and low cost, the ST-CL2 is the optimum product wherever a compressor/limiter is needed! Use the ST-CL2 with other RDL
RACK-UP®, STICK-ON, TX™, or FLAT-PAK™ series products as part of a complete audio/video system.

RDL  659 N. 6th St.  Prescott, AZ., USA 86301  [phone]  FAX [phone]  www.rdlnet.com

STICK-ON® SERIES

891-1135

Model ST-CL2
Compressor/Limiter

AUDIO WIRING

ALTERNATE
WIRING

SIGNAL

FROM

UNBALANCED

LINE-LEVEL

SOURCE

HEAVY COMPRESSION / LIMITING

NORMAL COMPRESSION

Relative Intensity

L.E.D. Indicators

+3
+2

+1

0

OUTPUT LEVEL

dB

NORMAL COMPRESSION
HEAVY COMPRESSION

O

I

U

N

T

SIGNAL

FEEDING

UNBALANCED

LINE-LEVEL

EQUIPMENT

DIM BRIGHT

LI

OUTPUTINPUT COUPLE

COMPRESSION

LEVEL

LEDs

25 TURN

INPUT

BALANCED

LINE-LEVEL

LEVEL

ADJUST

CONNECT COUPLE TERMINALS AS SHOWN

WHEN TWO ST-CL2 MODULES ARE USED FOR STEREO

1 1 (NO COMPRESSION)

0 +2 +4 +6 +8 +10

INPUT LEVEL

SIGNAL

FROM

SOURCE

25 TURN
OUTPUT

SIGNAL

FEEDING

BALANCED

LINE-LEVEL

EQUIPMENT

LEVEL

ADJUST

STEREO

WIRING

NOTE: BOTH MODULES

MUST OPERATE FROM THE

SAME POWER SUPPLY

BRIGHTDIM

COMPRESSION

CURVE
CHART

+12 +14 +16

Installation/Operation

EN55103-1 E1-E5; EN55103-2 E1-E4

Typical Performance reflects product at publication time
exclusive of EMC data, if any, supplied with product.
Specifications are subject to change without notice.

GND-REFERENCED

GROUND

24 VDC

POWER

SOURCE

24 VDC

POWER

SOURCE

12

OR

15

VDC

12

OR

15

VDC

G
N
D

BIPOLAR SUPPLY

FLOATING

BIPOLAR

POWER
WIRING

OR

OR

NEGATIVE

TYPICAL PERFORMANCE

Input: 10 k Balanced (may be connected unbalanced)
Input Signal Range: -10 to +4 dBu, adjustable (for 6 dB gain reduction); +22 dBu maximum
Output: 150  Balanced (may be connected unbalanced)
Output Signal Range: OFF to +8 dBu, adjustable
Frequency Response: 10 Hz to 20 kHz +/- 0.2 dB over full compression range
Noise below +4 dBu output: < -78 dB (unweighted; +4 dBu input; +4 dBu output)
Total Harmonic Distortion: < 0.05% 1 kHz below compression threshold; < 0.1% 1 kHz at 3 dB gain reduction; < 0.15% 1 kHz at 6 dB gain reduction
CMRR: > 60dB (50 to 100 Hz)
Attack Time: Averaging Compressor: 500 ms (+4 dBu input); Fast Compression: <10 ms (+20 dBu input); Peak Limiting: Instantaneous
Release Time: Automatically adjusting up to 500 ms
Compression Ratio: Automatically adjusting 1.5:1 to 10: 1
Peak Limiter: INF: 1
Interconnection: Stereo COUPLE interconnection provided
Indicators (2): Yellow LED for NORMAL Compression, Red LED for HEAVY Compression
Power Requirement: 24 to 33 Vdc @ 50 mA, SupplyFlex

Radio Design Labs Technical Support Centers

U.S.A. [phone], [phone]; Fax: [phone]

Europe [NH Amsterdam] (++31) 20-6238 983; Fax: (++31) 20-6225-287