RDL Solid-State Audio Routing Switcher

RDL Solid-State Audio Routing Switcher

The ST-RX2 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 it may be used with RDL's racking accessories. The ST-RX2 offers the ultimate in totally solid state audio switching, with a big plus, you can put it right where you need it!

The ST-RX2 has a single line-level audio input and two line-level audio outputs. In the absence of a control input, the NORMAL module output is fed from the audio input. When the TRIG control terminal is connected to ground, the input audio is fed to the SELECT output and the NORMAL output is switched off. When the TRIG terminal is again disconnected from ground, then the SELECT output is turned off and the NORMAL output is fed from the input. The module contains no relays or other mechanical devices. The control circuits utilize solid-state switching to route the input signal to one of the balanced output line drivers with off attenuation better than 80 dB at all audio frequencies!

The ST-RX2 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 output is connected to the NORMAL output, and the ST-RX2 is used to turn this line off. In this mode, the audio turn-off time switching is accomplished in less than 100 µs. 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-RX2 can be controlled from nearly any source from switches to logic circuits. The TRIG input feeds a comparator, which switches at a threshold of 2 volts, permitting open-collector switching, or switching directly from circuits operating from a 5 Vdc supply. The exceptional low noise and low distortion performance of the ST-RX2 makes it the ideal choice for noiseless line-level audio switching in both sound system or recording installations. Used in conjunction with other RDL audio and control modules, the ST-RX2 can be the foundation for many high quality, innovative audio systems!

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Features

To route line-level sources

Audio switched to 1 of 2 destinations

Silent audio switching

Balanced or unbalanced routing

Switching by "Open-collector" logic