For years, the Radial Custom Shop has been manufacturing large concert splitters for broadcasters, venues and touring sound companies.
At the high end, these systems employ mic bridging or splitting transformers that allow the main, front of house (FOH) console and monitor console to connect to the same source microphone while eliminating any ‘hard’ connection between the two desks. This eliminates so called ground loops, thus providing each system with a clean, noise-free source.
From time to time, we have been asked to produce smaller ‘custom’ splitters to allow a performance to be recorded. These range from 2 channels for a stereo feed to 8 channels or more. The problem is that custom manufacturing a single steel frame is expensive and at the other end, having expensive transformers in a box that are not being used, is also a waste.
The Radial JS•2 and JS•3 splitters offer a solution whereby they can be rack-mounted in the Radial J-Rak to provide the user with a ‘custom’ solution that can meet their needs today and expand as needs increase
Using the Radial JS•2 and JS•3
The Radial JS•2 and JS•3 signal splitters are easy-to-use problem solvers that are a must for all audio engineers. Both the JS2 and the JS•3 feature an input, a direct coupled thru-put and two outputs. The Radial JS•2 employs the Jensen JT-MBC transformer and features one isolated output and an auxiliary direct-coupled output with ground lift while the Radial JS•3 employs the Jensen JT-MBD with two isolated outputs.
Reading from left to right on the block diagram, the Radial JS•2 features an input and a direct-coupled main output for the main console and provides a direct return feed for 48V phantom powering of microphones and active direct boxes. The isolated output is designed to connect to the monitor console or recorder, thus providing transformer isolation to eliminate hum, buzz and noise caused by so-called ground loops. A second auxiliary output is also directly coupled with the input but features a ground lift switch to reduce ground path contamination. This may also be used to feed a device such as a broadcast console.
As shown in the block diagram, the JS•3 features an input and direct coupled main output for the main console. This provides a return path for phantom power and is also the primary safety ground path. Two isolated outputs provide 3-way isolation to simultaneously feed monitor and recording consoles without interaction. This provides maximum isolation against noise, buzz and hum caused by ground loops in larger systems.
Using the JS•2 and JS•3 is simple: before connecting, make sure all levels are off to avoid connection pops. If you are using condenser or capacitive microphones, make sure you turn on the phantom power before turning up the levels as the turn-on transient can cause severe system damage to your system. All connections to the JS•2 and JS•3 are wired using AES standard XLR configuration whereby pin-1 is ground and pin-2 is hot.
Generally, transformer isolated outputs are used to prevent noise caused by the interaction of two electrically charged devices that may have differing ground reference voltages. When connected together, these can cause hum or buzz which is commonly known as a ground loop. By isolating the devices across a magnetic bridge (aka an audio transformer), the audio signal is able to pass while the offending noise is eliminated.
The JS•3 features two identical isolated outputs for 100% isolation while the more affordable JS•2 features one isolated output and a direct-coupled auxiliary output with ground lift switch. This feature allows the JS•2 to be used as a 3-way splitter where the 3rd auxiliary output may feed an isolated broadcast split or used in a less critical application.
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