RDL ST-VP2 Data Sheet

STICK-ON® SERIES

Model ST-VP2
Automatic Ducking Module

ANYWHERE YOU NEED...

• Fully AUTOMATIC Voice-Over Mixing

• Noiseless Paging

• Adjustable Fade Depth

• Setting to Fade Music Fully Off

• Adjustable Recovery Rate

• Built-in AGC Compressor on Music Input

You Need The ST-VP2!

APPLICATION: The ST-VP2 is part of a group of products in the Stick-On series from Radio Design
Labs. The durable bottom adhesive permits quick, permanent mounting nearly anywhere, or use it with
RDL’s racking accessories. The ST-VP2 offers the ultimate in fully automatic mixing functions for voice­over and paging applications, with a big plus, you can put it right where you need it!

FUNCTIONAL DESCRIPTION: The module is a line-level device with two inputs; MUSIC and VOICE.
The MUSIC input normally feeds the output when no audio is present at the VOICE input. When a signal
appears on the VOICE input, the MUSIC source is immediately compressed to preserve the beginning
syllable of voice. As long as a VOICE signal continues, the MUSIC remains attenuated to the level set by
the DEPTH trimming potentiometer on the module. This control may be adjusted from 0 dB to –25 dB, or
turned fully OFF (music fully muted while VOICE input signal is active). At the conclusion of the voice
message the VOICE source is switched off and the MUSIC source is restored. The RATE control permits
adjustment of the music fade-up recovery. All switching and fading is accomplished electronically for
noiseless operation.

The MUSIC input provides an AGC/compressor which transparently produces a consistent audio level for
varying music sources. When adjusted normally, 6 dB of compression is applied to the MUSIC input.
Signal levels varying above or below the normal signal level are adjusted by up to 18 dB of AGC action.
The AGC/Compressor operates independently from the ducking attenuator, so consistent music levels
are maintained at all times. Excessive music levels encountered during voice-over operation are
controlled to prevent sudden level increases from masking the voice messages. The dynamic content of
soft music passages is preserved so that the ST-VP2 may be used with all music types.

Setup is made easy by two LED indicators at the front of the module. One LED is provided to show
correct operating level for each of the two inputs. Each input level is set using the multi-turn precision
trimming potentiometers while observing the respective LED indicator.

TYPICAL APPLICATION: The ST-VP2 can be wired into any line-level input of a paging amplifier. A
line-level music source may be provided from a receiver, satellite decoder, tape or CD source. A line­level voice source may be provided from a telephone paging system at line-level, or a microphone which
has been preamplified up to line-level (See RDL STM-1, STM-2, STM-2X, STM-3 Microphone
Preamplifiers). When a page is initiated, the module automatically senses the audio at the input, turns
the music down to the desired level, and automatically fades the music back up after the page is
completed. The VOICE input is completely turned off by the module until the next paging signal is
received.

The audio clarity, AGC/Compressor and smooth silent operation of the ST-VP2 makes this module
ideally suited to a wide variety of demanding audio applications. Use this module in conjunction with
other RDL modules as part of a high quality, flexible audio/video system.

RDL •• P.O. Box 1286 •• Carpinteria, CA., USA 93014 •• [phone] •• FAX [phone] •• http://www.rdlnet.com

GND

STICK-ON® SERIES

Model ST-VP2
Automatic Ducking Module

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.

AUTOMATIC DUCKING MODULE

D
E

MUSIC IN

MUSIC

L

LEVEL

A
Y

SIGNAL

FROM

BALANCED
LINE-LEVEL
EQUIPMENT

LINE LEVEL INPUT / OUTPUT

VOICE IN PWR

OUTPUT

SIGNAL

FROM

UNBALANCED

LINE-LEVEL
EQUIPMENT

24 VDC

POWER

INPUT WIRING

D
E

VOICE

P

LEVEL

T
H

THIS
TERMINAL
IS COMMON
GROUND

D

L INPUT / OUTPUT

OUTPUT

PWR VOICE

LEVEL

E
P
T
H

L INPUT / OUTPUT

OUTPUT

OUTPUT WIRING

SIGNAL SIGNAL

FEEDING

LINE-LEVEL
EQUIPMENT

FEEDING

UNBALANCEDBALANCED

LINE-LEVEL
EQUIPMENT

PWR

LEVEL

P
T
H

D
E

VOICE

EACH INPUT MAY BE BALANCED OR UNBALANCED

AUTOMATIC DUCKING MODULE

D
E

MUSIC

L

LEVEL

A

MUSIC

SOURCE

PAGING

SOURCE

(TYPICAL FROM

TELEPHONE KSU)

PAGING

MIC

TYPICAL PERFORMANCE

Inputs (2): Balanced line level (or unbalanced)
Input Impedance: 20 kΩ
Input Signal Range: -20 dBu to +18 dBu
Output: 0 dBu balanced (into 600 Ω)
Gain: Adjustable using multi turn potentiometer
THD+N: < 0.02% (20 Hz to 20 kHz, no compression)
Freq. Response: 25 Hz to 20 kHz (+/- 1 dB)
Noise: < -70 dB
Indicators (2): 1 LED indicating proper Music Level, 1 LED indicating proper Voice Level
AGC/Compressor Range: 18 dB; 6 dB compression at normal input level

Attack Time: 25 ms

Release Time: 2.5 Seconds
Voice Trigger Level: 24 dB below operating level
Music Fade Depth: Adjustable 0 dB to –25 dB, or OFF
Music Recovery Delay: Adjustable 2 Sec. to 4 Sec.
Power Requirement: 24 to 33Vdc @ 35 mA, Ground-referenced

Y

G PHNTM
A
I
N

LINE LEVEL INPUT / OUTPUT

MUSIC IN

VOICE IN PWR

OR

SWITCHABLE LOW-NOISE

MICROPHONE PREAMPLIFIER

C

INPUT

LINE

T PWR
R
L

OUTPUTS

OUTPUT

MIC

P
O
W
E
R

D
E

VOICE

P

LEVEL

T
H

TO SYSTEM

AMPLIFIER

ADJUSTMENT

1

FEED MUSIC INPUT WITH THE
LOWEST EXPECTED MUSIC LEVEL

2

ADJUST LEVEL CONTROL FOR MUSIC
INPUT UNTIL THE LED JUST FLASHES

3

FEED NORMAL PAGING LEVEL VOICE
INTO THE VOICE INPUT

4

ADJUST THE VOICE LEVEL CONTROL
UNTIL THE LED FLASHES CONSISTENTLY

5

WITH THE PAGING INPUT STILL ACTIVE
ADJUST THE DEPTH CONTROL FOR THE
DESIRED VOICE-OVER MUSIC LEVEL
(NOTE: MUSIC LEVEL MAY BE SET "OFF")

6

DISCONTINUE VOICE INPUT AND ADJUST
DELAY CONTROL FOR DESIRED
MUSIC SIGNAL RECOVERY

Radio Design Labs Technical Support Centers

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

891-1025F

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