RDL STPA18 Installation Guide

STICK-ON®SERIES

Model ST-PA18
Audio Power Amplifier

ANYWHERE YOU NEED...

x 18 Watts RMS Audio Power Amplifier
x Output for 8 Ohm Speaker
x

Maximized Audio Level at Full Power Output

x

Superior Audio Quality at High Output Levels

x Line Level Balanced or Unbalanced Input
x LOOP OUT to Feed Additional Amplifiers
x

Integral Audio Compressor to Control Clipping

x High Overall Audio Operating Level
x LED to Indicate Audio Compression

You Need The ST-PA18!

The ST-PA18 is a utility power amplifier in the convenient line of STICK-ON products. The durable bottom
adhesive permits quick, permanent or removable mounting nearly anywhere, or it may be used with RDL’s
racking accessories. The ST-PA18 gives you the advantages of a quality, high efficiency audio power
amplifier with the added convenience of STICK-ONs!

APPLICATION: The ST-PA18 is the ideal choice in many applications where a high quality utility amplifier
is needed to drive an 8 : speaker.

The ST-PA18 features a balanced line level input that may be connected unbalanced. The gain control
range will accommodate standard unbalanced levels as well as professional balanced levels. The module
bridges the input signal. LOOP OUT terminals permit a balanced input to be fed to additional amplifier
modules making the ST-PA18 an ideal component in distributed audio system design. The LOOP OUT
may also be used to feed a subwoofer amplifier (see RDL ST-CX2S Subwoofer Filter). The ST-PA18
output will drive an 8 : speaker or multiple speakers connected to present an 8 : load to the amplifier and
it is capable of driving 4 : loads.

A red COMP LED is provided to indicate the threshold of the integral compressor. Audio levels that could
cause the amplified output to clip are compressed according to two dynamic time constants. Normal audio
level signals remain unaffected by the compressor thereby preserving audio dynamics and preventing the
compressor from increasing feedback potential when the amplifier is used for paging. The compressor is
designed to remain aurally transparent while maintaining clean, unclipped amplified audio for input
overloads of up to 20 dB. The ST-PA18 produces average audio levels and audio clarity normally
expected of amplifiers delivering much higher output power.

The ST-PA18 operates from an external 24 VDC 1A power supply, sold separately. A POWER LED
illuminates when the module is powered. The module provides thermal and output short-circuit protection.

Wherever an ultra-compact, high quality, high efficiency audio power amplifier is needed to provide
reliability, compactness and unsurpassed versatility, the ST-PA18 is the ideal choice. Use the ST-PA18
individually, or combine it with other RDL products as part of a complete audio/video system.

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

STICK-ON®SERIES

Model ST-PA18
Audio Power Amplifier

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.

P

W
E
R

AUDIO

WIRING

AUDIO POWER AMPLIFIER

18 WATTS RMS PLUS COMPRESSION - 8 OHMS

SIGNAL

FROM

DO NOT GROUND OUTPUT TERMINALS

LOOP OUT

OUTPUTINPUT

POWER

CONTINUATION OF

BALANCED INPUT SIGNAL

TO OTHER AMPLIFIER

INPUTS OR TO FEED
SUBWOOFER FILTER
RDL MODEL ST-CX2S

C O

GAIN

O
M

P

BALANCED

LINE-LEVEL

SOURCE

AUDIO POWER AMPLIFIER

18 WATTS RMS PLUS COMPRESSION - 8 OHMS

C O

GAIN

O
M
P

DO NOT USE

SHIELDED WIRE

ON OUTPUT

DO NOT GROUND OUTPUT TERMINALS

LOOP OUT

OUTPUTINPUT

(4 OHM MINIMUM LOAD IMPEDANCE)

8 OHM SPEAKER

POWER

P

W
E
R

DO NOT GROUND EITHER SPEAKER WIRE !

LED INTENSITY

INDICATES

AUDIO

COMPRESSION

ACTIVITY

C O
O
M
P

POWER
WIRING

AUDIO POWER AMPLIFIER

18 WATTS RMS PLUS COMPRESSION - 8 OHMS

SIGNAL

FROM

DO NOT GROUND OUTPUT TERMINALS

LOOP OUT

OUTPUTINPUT

LED ILLUMINATES

WHEN MODULE

RECEIVES

INPUT POWER

POWER

C O

GAIN

O
M
P

UNBALANCED

LINE-LEVEL

SOURCE

AUDIO POWER AMPLIFIER

18 WATTS RMS PLUS COMPRESSION - 8 OHMS

GAIN

DO NOT GROUND OUTPUT TERMINALS

LOOP OUT

THIS

TERMINAL

IS COMMON

GROUND

OUTPUTINPUT

POWER

24 VDC

POWER

SOURCE

P

W
E
R

P

W
E
R

TYPICAL PERFORMANCE

Input: Line level (+4 dBu nominal balanced; -10 dBV nominal unbalanced)
Input Impedance: 20 k: balanced bridging; 10 k: unbalanced
Gain Adjustment: Single turn
Minimum Input Levels:
Balanced: -16 dBu (to cross compressor threshold)
Unbalanced: -18 dBV (to cross compressor threshold)
Maximum Input Levels:
Balanced: +25 dBu
Unbalanced: +22 dBV
Frequency Response: 20 Hz to 20 kHz (+/- 2 dB)*
THD+N: < 1% (50 Hz to 20 kHz)*
Compressor: Threshold 3 dB below rated output, automatically adjusting attack and release times
Noise: <-75 dB (below 18 W RMS)
CMRR: > 45 dB (50 Hz to 120 Hz)

Output Power: 18 W RMS into 8 :
Output Circuit: Class D
Ambient Operating Environment:
Power Requirement: 24 to 33 Vdc @ 1000 mA, Ground-referenced
Indicators (2): Red LED: COMP LED indicates compressor activity
Green LED: POWER on

*measured at compressor threshold level equaling 12 W RMS output power

891-1155

0° C to 30° C Maximum; 20° C Recommended

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