![](https://www.radialeng.com/wp-content/uploads/2019/01/SW8-USB-front-1.jpg)
PSU A/B
Dual green LEDs indicate that the SW8-USB is receiving power from each power supply. Only one connection is required to power the SW8-USB, the other is provided for redundancy to eliminate loss of power.
Mic/Line
Determines whether the front panel XLRs are mic-level or line-level outputs. When set to mic (out position), the XLR outputs are also transformer isolated to reduce noise from ground loops.
Auto
Determines whether the SW8-USB switching is controlled by the user or set to Auto-Switch mode where the SW8-USB will automatically select the B inputs should a fault be detected on the A side.
Playback Activity
Dual green LEDs illuminate to indicate that the SW8-USB is receiving MTC or tone via SPDIF - depending on the Auto-Switch Input setting on the rear panel of the SW8-USB.
Mute
Mutes the analog outputs of the SW8-USB. This will silence the XLR outputs, but signal will still pass through the DB25 and TRS outputs on the rear panel.
Standby
This switch allows the SW8-USB to hold on input A when in Auto-Switch mode, regardless of whether MTC or tone via SPDIF is being received. This feature can also be activated remotely using the optional JR-2 footswitch.
Input Select
Latching switch allows you to select the active USB inputs. This switch is deactivated when the SW8-USB is in Auto-Switch mode.
Reset
Momentary switch is used after a fault is detected, allowing the SW8-USB to switch back to the A inputs.
Alarm
Flashing red LED indicator illuminates when a fault is detected on the A playback computer, showing that the SW8-USB is now playing back from the B computer.
XLR Outputs
Analog outputs operate at mic or line level depending on the setting of the MIC/LINE switch.
Ground Lift
Lifts pin-1 on the XLR output to help eliminate hum and buzz from ground loops.
![](https://www.radialeng.com/wp-content/uploads/2019/01/SW8-USB-Back-2.jpg)
PSU A & B Inputs
Connections for locking 4-pin power supplies (included). The SW8-USB uses switching supplies to allow for easy international usage.
MIDI In/Out
Allow you to to pass MIDI signal to and from the computer on the active USB connection. When SYNC LOCK is disengaged, signal sent to the MIDI IN feeds both the primary and backup computers at once, allowing you to use an external MIDI controller to trigger playback on both computers simultaneously.
Sync Lock
When engaged, this switch passes MIDI information from USB-A to USB-B to allow for syncronized playback between both computers. Disengaging this switch allows you to use an external MIDI controller to trigger playback on both computers simultaneously.
USB A & B
Type-B USB connections to directly connect your primary and backup playback computers for up to eight channels of analog audio playback. Compatible with Mac OS only, featuring 192kHz/24bit converters.
Auto-Switch Input
Selects whether tone via SPDIF or MTC is used for the auto-switch inputs of the SW8-USB. Tone (SPDIF) should be used for the lowest latency when switching over to the B inputs.
Start/Stop
TRS connection allows you to send stop/start MMC controls to your playback computers. Can be used with standard contact closure footswitches such as the JR-1 remote footswitch.
DB25 Outputs
These outputs are always on regardless of the setting of the front panel MUTE switch, and they will follow the primary or backup computer along with the main XLR outputs.
1/4" TRS Outputs
Balanced output jacks are wired in parallel with the DB25 monitor outputs. These outputs are line level and will always be active regardless of the MUTE switch setting on the front panel.
JR-2 Footswitch Inputs
XLR and 1/4” TRS connections allow the optional JR-2 remote footswitch to control the switching and Standby functions of the SW8-USB. Standard 1/4” TS contact-closure footswitches and MIDI controllers with switching outputs can also be used to select between the primary and backup computers.
Alarm
1/4” TS connection from an internal relay can be used to turn on an external beacon when a dropout is detected. This output can also be used to link together multiple SW8-USBs for higher channel counts.