RDL STSSR1 Specifications

STICK-ON® SERIES

Model ST-SSR1
Solid-State Audio Relay

ANYWHERE YOU NEED...

• To Switch Line Level Sources

• To Select Between Two Balanced Lines

• Silent Audio Switching

• Audio Switching for Audio Muting

• Fast Switching for Audio Muting

• Switching by Open Collector Logic

You Need ST-SSR1!

The ST-SSR1 is part of a group of products in the STICK-ON series from Radio Design Labs. The durable
bottom adhesive permits quick, permanent or removable mounting nearly anywhere or it may be used with
RDL’s racking accessories. The ST-SSR1 offers the ultimate in totally solid-state audio switching, with the
big PLUS, you can put it right where you need it!

APPLICATION: The ST-SSR1 has two line-level audio inputs and a single, line-level audio output. In the
absence of a control input, the NORMAL audio input feeds the module output. When the TRIG control
terminal is pulled to ground, the SELECT input is switched to the output and the NORMAL input is
switched off. When the TRIG terminal is again allowed to go HI, then the SELECT input is turned off and
the NORMAL input is switched to the output. The module contains no mechanical relays or other devices.
The audio inputs are applied to a low-noise preamplifier. The control circuits utilize solid-state switching to
apply one of the input signals to the balanced output line driver with OFF attenuation better than 80 dB at
all audio frequencies!

The ST-SSR1 has user-selectable switching rates. The module can be used in muting applications where
audio must be switched off extremely fast. This could be required to prevent feedback in automatic
microphone mixing installations. For muting, the audio source is connected to the NORMAL input, and
the ST-SSR1 is used to turn this line off. In this mode, the audio off-time switching is accomplished in
less than 100 microseconds. Although necessary in some circumstances, this fast switching transition can
sound harsh to the ear and would be undesirable where the module is being used to select inputs to a
high power amplifier or in high quality studio applications. Installation of a jumper between the SOFT
terminal and GROUND slows the switching transition by implementing a soft knee, ramping the audio to
the on or off condition. This still sounds instant to the ear, but is slowed sufficiently to remove any
unpleasant edge from the switch transition. For most applications, the module is used in the SOFT mode.

The control current required at the TRIG terminal is so minimal (< 0.5 mA) that the ST-SSR1 can be
controlled from nearly any source, from switches to logic circuits. The TRIG input feeds a comparitor,
which switches at a threshold of 2 volts, permitting open-collector switching, or switching directly from
circuits operating from a 5 volt supply! The exceptional low noise and low distortion performance of the
ST-SSR1 makes it the ideal choice for noiseless line-level audio switching in both sound system or
recording installations. Used in conjunction with other RDL RACK-UP
FLAT-PAK™ series products as part of a complete audio/video system.

®

, STICK-ON, TX™, or

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

STICK-ON® SERIES

Model ST-SSR1
Solid State Relay

SOLID STATE RELAY

LINE LEVEL AUDIO SWITCH

S

T

NORMAL

SIGNAL

FROM

BALANCED

LINE-LEVEL

SOURCE

NORMAL

INPUTS

INPUTS

SELECT

SIGNAL

FROM

BALANCED

LINE-LEVEL

SOURCE

SOLID STATE RELAY

SELECT

POWER OUTPUT

O

R

F

I

TG

FEEDING

BALANCED

LINE-LEVEL

EQUIPMENT

LINE LEVEL AUDIO SWITCH

T

S

POWER OUTPUT

R

O

F

I

TG

SIGNAL

AUDIO

WIRING

FEEDS OUTPUT WHEN

UNIT IS NOT TRIGGERED

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.

SOLID STATE RELAY

LINE LEVEL AUDIO SWITCH

T

NORMAL

SIGNAL

FROM

UNBALANCED

LINE-LEVEL

SOURCE

NORMAL

INPUTS

SELECT

UNBALANCED

LINE-LEVEL

SOURCE

INPUTS

SELECT

SIGNAL

S

POWER OUTPUT

R

O
F

I

TG

FROM

SOLID STATE RELAY

LINE LEVEL AUDIO SWITCH

T

S

POWER OUTPUT

R

O
F

I

TG

SIGNAL

FEEDING

UNBALANCED

LINE-LEVEL

EQUIPMENT

OPEN

COLLECTOR

OR

MANUAL

OPTIONAL

SOFT

SWITCHING

SUPPLY

WIRING

ACTUATION

TYPICAL PERFORMANCE

Switching Time: Fast Soft
Time required for Normal input to turn off: 10 µs 5 ms
Time required for Normal input to turn on: 15 µs 70 ms
Time required for Select input to turn off: 15 µs 10 ms
Time required for Select input to turn on: 20 µs 35 ms
Control Signal: TRIG terminal must be externally pulled to ground.
Control Current: 0.5 mA
Headroom: > 18 dB above +4 dBu

THD+N: < 0.030% (@ 1 kHz)

CMRR: > 45 dB (either input, 100 Hz)
Freq. Response: 15 Hz to 20 kHz (+/- ½ dB into bridging input)
30 Hz to 20 kHz (+/- ½ dB into 600 Ω)
Noise: < -80 dB below +4 dBu unweighted (-85 dB typical)
ON Gain: Unity (nominal, either input into bridging output)
OFF Attenuation: > 80 dB @ 1 kHz (either input)
Reference: 0 dBu = 0.775 V RMS
Power: 24 to 33 Vdc @ 40 mA, Ground-referenced

Radio Design Labs Technical Support Centers

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

891-0035K

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

24 VDC

POWER

SOURCE

RDL PS-24

TYPE

SUPPLY