Radial SW8

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Radial SW8 8-Channel Line Level Auto Switcher Radial SW8 8-Channel Line Level Auto Switcher Details

The Radial SW8 auto-switcher provides redundant backup by automatically switching between two 8-channel backing-track playback sources such as a pair of digital recorders, computers or network systems.

Designed primarily for live concerts and stage shows where backing tracks are used for orchestration, backing chorals and sound effects, the SW8 can detect a machine malfunction and automatically switch to a second backup machine to ensure a seamless performance. One merely records a steady state signal on a track and feeds it to the SW8. Should the signal drop, the SW8 will automatically switch to the B system and 'sound' an alarm. Switching can also be performed manually via the front panel A~B switch, a rear access latching switch or by using the optional Radial JR2 footswitch. For larger systems, multiple SW8s may be linked together to create 16, 24 or 32 track systems.

Using the SW8 is easy! Connect your two sync"?d playback systems and record a steady drone on track-1. If the tone disappears, the SW8"?s front panel red LED will illuminate to let you know trouble is at hand. If you like, have the SW8 trigger an alarm, trip a contact closure or have it automatically switch to your second machine. For larger systems, the SW8 may be expanded by linking machines together using a simple ¼"� instrument cable.

Housed in a heavy duty 14-gauge steel 19" enclosure, the Radial SW8 is equipped with choice of 25-pin D-sub or ¼" TRS connector inputs with both XLR and D-Sub outputs. The front panel XLRs produce a balanced DI mic level to feed a snake system and are transformer isolated to eliminate hum and buzz caused by ground loops. The rear panel D-Sub provides direct balanced line level connectivity and the transformer isolated outputs may be internally re-patched to send the mic level signal to the 25 pin D-sub output if needed. To further suppress switching noise, a series of internal filters help eliminate DC offset from offending source devices. A global mute switch may be engaged that turns off the XLR outs, enabling you to audition and cue tracks on the fly. This is augmented by a standby switch that holds the SW8 on the source-A inputs in between songs.

The Radial SW8 eliminates embarrassing system malfunctions by providing an easy to implement system that will ensure your show will go on!

Backing tracks have become a staple in live performances, like Queen's 'Bohemian Rhapsody'. Reliability and backup of playback is now a big issue.

SW8 Development

Today, it is common for bands to support their live performances with backing tracks as a means to give their audience the type of production that they expect when they see a live show. For instance, when Queen performed Bohemian Rhapsody, backing tracks were used to provide the vocal chorus. In some cases, full orchestration will be recorded and played back using as many as 16, 24 or even 32 tracks.

This is generally done using one or more stand alone digital recorders or by employing computers and some form of digital to analog converters. Unfortunately, even though these machines are dependable in the safety of the studio or office environment, traveling night after night in a truck across the continent on bumpy roads inevitably takes its toll and these machines invariably fail due to the abuse. When disaster occurs, a backup recorder is required.

During the SW8's development, we consulted with a wide number of system technicians that work with performers such as Pink Floyd, Madonna, U2 and so on. These guys know all of the ins and outs of road travel and helped us establish a common feature set. The features were further discussed and reviewed in order to bring the second generation SW8 to market.

Setting up backing tracks

Before we get into the SW8, it is worth discussing 'why' multiple channels of backing tracks are used in the first place as opposed to simply playing back a stereo mix. The reason for this is simple: Depending on the room acoustics, being able to adjust the relative mix between percussion and violins is critical. For instance in a highly reverberant room like an arena, you may want to apply less reverb to the strings. So by retaining as many of the individual stems as possible you are able 'mix' the show for the best audio results. Typical 8 channel setups include stereo left/right rhythm guitars, percussion, orchestra and backing vocals. This is often increased to 16 channels by linking two SW8s together.

Radial SW8 8-Channel Line Level Auto Switcher Features
  • Auto-switch between two 8 channel systems, automatically
  • Expandable 'link' with remote control contact closure
  • Balanced or unbalanced mic and line level operation
  • Transformer isolated XLR mic-level (DI) outputs on each channel
  • Full manual override with foot control

The Radial SW8 Feature Set

When it comes to product development, we are often accused of putting too much into our products. Fair enough. But in our view, we feel it is better to be safe than sorry. We invest a lot of time up front working out the feature set so that every possible situation we can think of is worked through.

With the SW8, Radial really wanted to pack as much as they could into a single rack unit. For instance; they could have just installed high density D-Sub connectors. Instead, they chose to add ¼" jacks to give the system tech greater flexibility when interfacing the SW8 with computer based playback systems that employ ¼" connectors. Furthermore, Radial's design engineers added transformer isolated XLR outputs on the front panel to allow the SW8 to connect to the snake just like a direct box. This way, the SW8 could 'live' on stage by connecting the DI outs to the audio snake or be positioned at the front of house (FOH) mix position using straight through balanced connections. The built-in DI boxes also enable the SW8 to be used as a multi-channel keyboard DI if need be.

  • Auto-Switching - The coolest feature on the Radial SW8 is the auto-switching circuit. This is essentially a gated switch that monitors a steady-state signal. To make it work, all you do is record a drone signal onto either track-1 or track-8 on the master recorder and send it to the SW8's auto-switch input circuit. A front panel threshold dial sets the gate switching level. If the drone stops playing, the SW8 automatically switches all 8 inputs from set A to set B and your backup machine springs to life. If you are using all 8 channels on your playback system and do not have a spare track to record the drone, you can also use SMPTE time code as an audio track by sending it to the auto-switch gated input and engaging a SMPTE filter. This special band-pass filter was developed specifically to conserve precious audio tracks and reduce your rack size. The new SW8 is now equipped with a standby function that holds the SW8 on input-A to enable the playback tech to pause the system in between songs. A global mute has also been added that turns off the XLR outputs, enabling the tech to audition and cue a track via the D-Sub out.
  • Manual switching - For those that prefer a greater degree of hands-on control, the SW8 can be set to manual mode using the front panel A-B selector to switch A and B inputs. Switching may also be performed remotely using the optional Radial JR-2 remote or via a contact closure. If you have more than one SW8 linked together, the slave units will of course all switch to set B receiving their command from the master deck. A top panel selector switch lets you link both first and second generation SW8s together. And for system-critical applications, you can also connect an alarm or beacon to provide audio or visual notification.
  • Retaining signal purity - To ensure absolute signal integrity, there are no buffers or signal amplifiers in between the inputs and outputs. Instead, sealed - gold contact - military grade relays do the work. These are exceptionally quick, dependable and deliver consistent switching without noise. To manage less than ideal sources that may introduce problems, a series of noise blocking capacitors have been added to shunt and filter DC offset noise to ground.

Today, the Radial SW8 has become an international success! It can be found on stages around the globe including Lady Gaga, Madonna, U2, Radiohead, The Eagles, Donny Osmond, Mariah Carey, U2, Lenny Kravitz, Duran Duran, American Idol and Cirque Du Soleil.

Radial SW8 8-Channel Line Level Auto Switcher Applications
  • Live backing track redundant switching
  • Eight transformer isolated DI channels
  • Interface all high-Z audio (iPods, video devices)

Real World Scenarios - Some examples...

The following are three common scenarios used today in live production. For obvious reasons, we have removed the names of the bands and technicians who provided this info as many artists like to keep their production secrets, well... secret! Each scenario might have a click track going on a separate out, usually only to the drummer, very rarely if ever, to the front of house. Sometimes alternate click tracks are sent, via the monitor desk, to individual band members that need to start at the top of a given song.

  • 'Fly-in' Scenario' - This is setup is most commonly employed in the club scene and for fly-in promotional TV and video tours. In these scenarios, everything is mixed to a single stereo or even a mono output to feed the PA system and broadcaster. Some bands have done this with great success but this takes a lot of hard work to get the balance just right.
  • 'Moderate' Scenario' - Here, 16 backing tracks are mixed down into stereo subgroups. This is the most common form of backing tracks as the musicians are doing all of the main work and the playback machines are adding icing to the cake. In these systems, you'll see extra left and right drums, percussion & beats, keyboards and orchestration, guitars & backing vocals and often all of the vocal effects.
  • 'Superstar' Scenario' - Everything is on backing tracks: drums, electronic beats, instruments, backing vocals, vocal effects and in some cases, even lead vocals. Here we are talking about the various pop bands that incorporate huge, over-the-top production. Every track is broken out to individual channels so the monitor engineer can send different players different mixes & the front of house mixer has total control.

Radial SW8 8-Channel Line Level Auto Switcher Specifications
  • Technical Specifications
    • Audio circuit type: Passive signal path with active relay switching
    • Input impedance: 140k Ohms, balanced
    • Output impedance: 150 Ohms, balanced
    • Frequency response: 20Hz ~ 20KHz
    • Gain: -20dB
    • Dynamic range: >120dB
    • Total harmonic distortion: 0.002%
    • Noise floor: -115dBu
    • Signal to noise ratio: >94dB
    • Equivalent input noise: -95dBu
    • Maximum input: 26dBu
    • Phase deviation: -2° @ 20Hz
    • Intermodulation distortion: >0.002%
    • Common mode rejection ratio: -112dB at 50/60Hz
  • Features
    • Number of channels: Eight channels
    • Switching: Local, remote, and auto-switching with gate
    • Transformer: Eclipse ET-DB2
    • Pad -30dB
    • Ground lift: Disconnects XLR pin-1 at isolated output
    • XLR configuration: AES standard Pin-1 ground, Pin-2(+), Pin-3(-)
    • Connectors: ¼" TRS, DB-25 inputs; XLR-F, DB-25 outputs
  • General
    • Construction: 14 gauge steel chassis & outer shell
    • Finish: Durable powder coat
    • Size: (W x H x D) 17.5" x 6" x 1.75" (44.5 x15.25 x 1.75cm)
    • Weight: 9.2 lb (4.2kg)
    • Shipping Size: W x H x D: 10.25" x 4.5" x 22.5" (260 x 114 x 572mm)
    • Shipping Weight: 9.7 lb (4.4 kg)
    • Power: Two +15VDC/400mA power supplies included
    • Conditions: For use in dry locations only between 5°C and 40°C
    • Warranty: Radial 3-year, transferable