There can’t be many of us who have managed to avoid an annoying mains hum at some point or other in our careers. You have just finished a set up on location with a long cable run back to the OB van, you sit down to monitor the signal and there it is. It’s not the end of the world but you do now face rummaging through your tool box to find an isolation device of some kind, all the while keeping your fingers crossed someone has not borrowed it or that you remembered to bring it. It would be so much better if it was always set up ready and waiting. Well, just such a device is now available.
Tucked away on the Canford stand at PLASA Focus I discovered their interestingly named Zero-U Rack Mounted Line isolation unit. The devices each feature 8 channel s and are designed to provide that desperately needed isolation between input and output, we were just talking about. They come in either 110 ohm balanced or 75 ohm unbalanced circuits. Each channel has a 1:1 transformer; balanced circuit versions have an ‘earth-lift’ switch. They are housed in a 1U rack-mounting enclosure with innovative mounting options. The balanced circuit version has XLR connectors for input and output, one female, one male, located in pairs on one face. Earth-lift switches for each channel are located on the opposite face of the fully-screened case.
The unbalanced circuit version has BNC female connectors for input and output, located in pairs on one face; there is no earth lift facility on this type. They are designed to be mounted in a number of different ways within a 19 inch rack and this is the bit I really like and where the Zero U name comes in. Using clever little L shaped mounting plates, you are able to mount the isolators into the rack at a depth that enables you to fill all available rack space at the front with all the devices you need immediate access to whilst the isolators sit behind them, out of the way. Once set up there is no reason to ever have to move it and if you ever do get that hum it is taken care of straight away.