STICK-ON® SERIES
Model STM-3
High Gain Mic Preamplifier
ANYWHERE YOU NEED...
• High Gain Microphone Preamp
• Adjustable Output Levels
• High or Low Impedance Mic Inputs
• To Convert Line Inputs to Mic Inputs
• Two Balanced or Unbalanced Outputs
• Separate Phantom Supply Input
• RF Filtered Inputs and Outputs
• Low-Distortion Performance
You Need The STM-3!
The STM-3 is part of the group of STICK-ON products from Radio Design Labs. The STM-3 is a quality
microphone preamplifier designed for use in commercial sound, broadcast, and recording applications.
The STM-3 is very flexible with gain adjustment from 0 to 75 dB, two balanced or unbalanced outputs, and
available phantom supply input! Its compact size makes it ideally suited to locations where a larger or
heavier preamplifier cannot be used. The high gain of the STM-3 makes it useful with normal mics in
facilities using a +8 dB standard. It is also suited for use with ceiling mics or speakers designed to pick up
general activity in a room requiring more than usual gain. Some features of the STM-3 are:
• Balanced microphone input accepts impedances from 150 to 600 Ω
• Input circuitry permits connection of unbalanced microphones, or 4 or 8 Ω speakers in intercom or
monitoring applications
• Variable gain (up to 75 dB) and ample headroom allow operation with any mic
• Phantom supply input terminals allow connection of external power when STM-3 is used with phantom
powered microphones
• Supply input is single-ended and operates from 24 Vdc to 33 Vdc (12 Vdc at reduced headroom)
• Two separate outputs are provided for balanced operation
• No lugs required for reliable connections
• Convenience of STICK-ON package yields quick, efficient installation
• Use STM-3 in conjunction with other RDL STICK-ONs to make complete audio systems
Anywhere you need a high-gain Mic to Line preamplifier, STM-3 is the reliable and cost-effective solution!
RDL •• P.O. Box 1286 •• Carpinteria, CA., USA 93014 •• (805) 684-5415 •• FAX (805) 684-9316 •• http://www.rdlnet.com
STICK-ON® SERIES
Model STM-3
High Gain Mic Preamplifier
ALTERNATE INPUTS
INPUT PHNTM
SPEAKER
SIGNAL
FROM
USED AS
MIC
UNBALANCED
MIC-LEVEL
SOURCE
EACH OUTPUT MAY BE BALANCED OR UNBALANCED
PHNTMINPUT
AUDIO
WIRING
25 TURN
GAIN
ADJUST
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.
PROFESSIONAL ADJUSTABLE
INPUT PHNTM
G
A
I
N
SIGNAL
FROM
BALANCED
MIC-LEVEL
SOURCE
MICROPHONE PREAMPLIFIER
UNBALANCED
LINE-LEVEL
EQUIPMENT
OUTPUTS
A B P
SIGNAL
FEEDING
BALANCED
LINE-LEVEL
EQUIPMENT
FEEDING
PWR
SIGNAL
O
W
E
R
PBA
O
W
E
R
POWER
WIRING
OR
OPTIONAL JUMPER
TO PROVIDE PHANTOM
VOLTAGE TO CONDENSER
MIC WHICH CAN USE UP
TO 32 VOLTS PHANTOM
G
A
I
N
PROFESSIONAL ADJUSTABLE
MICROPHONE PREAMPLIFIER
G
A
I
N
BATTERY
PHNTMINPUT
-+
OR EXTERNAL
PHANTOM
SUPPLY
(UP TO 48V)
OUTPUTS
PWR
24 VDC
POWER
SOURCE
NOTE THE STM-3 WILL OPERATE (WITH REDUCED HEADROOM) ON
SUPPLY VOLTAGES FROM 9 VDC TO 23 VDC.
PROFESSIONAL ADJUSTABLE
MICROPHONE PREAMPLIFIER
PHNTMINPUT
TERMINAL
IS COMMON
GROUND
THIS
OUTPUTS
24 VDC
POWER
SOURCE
PWR
PBA
O
W
E
R
TYPICAL PERFORMANCE
Input Impedance: 150 to 600 Ω balanced; 5 kΩ unbalanced
Output Impedance: 150 Ω balanced to drive balanced or unbalanced lines of 150 Ω or higher
Output Levels: +4 dBu balanced
Frequency Response: 50 Hz to 25 kHz (+/- 1 dB)
Gain: Adjustable 0 to 75 dB
THD+N: < 0.050%
CMRR: > 60 dB (50 Hz to 30 kHz)
Headroom: > 20 dB (24 Vdc supply); 14 dB (12 Vdc supply)
Power Requirement: 24 to 33 Vdc @ 25 mA, Ground-referenced
(9 to 23 Vdc with reduced headroom)
891-0016H
Radio Design Labs Technical Support Centers
U.S.A. (800) 933-1780, (928) 778-3554; Fax: (928) 778-3506
Europe [NH Amsterdam] (++31) 20-6238 983; Fax: (++31) 20-6225-287