A clean audio feed for cameras and journalists means solving two things: level, because the mixing desk sends line level and many cameras expect mic level, and ground loops, which appear when equipment plugged into different sockets is connected together and cause hum.
For one or two cameras, one transformer isolator with an attenuator per camera is enough. For several outlets at once, the right tool is a press splitter with isolated outputs.
Why it distorts
If the camera expects a weak mic signal and receives the desk’s line level, it overloads even with its gain turned down. The signal has to be attenuated before the camera, or the camera switched to its line input if it has one.
Why it hums
Hum appears when two pieces of equipment connected by audio are plugged into different earth points. A transformer separates them electrically and breaks the loop without touching the installation’s safety earth.
Y-cables and chained DI boxes
A Y-cable loads the signal and ties every device’s ground together: if one journalist plugs in something faulty, everyone hears it. Chaining passive DI boxes can work for a few outlets, but every box adds a point of failure and it is not practical when ten cameras turn up.
What to use
For one camera: the Pinanson audio isolator, one XLR channel with a Lundahl transformer and 116 dB common-mode rejection, also available with an attenuator. For the press: a press splitter with transformer-isolated outputs; on the SAI series every output has its own gain control, and the SAI IT adds a transformer on each output. Press splitters deliver line level: a camera that only accepts mic level needs an attenuator in front of it.
How to choose
- Count the outlets: One or two cameras, or a full press table.
- Check the level they expect: Mic or line: if the camera only accepts mic level, it needs an attenuator in front of it; Pinanson press splitters deliver line level.
- Isolate: A transformer isolator for one camera; a press splitter for several.
- Format: Portable box for events or fixed installation in the press room.
Frequently asked questions
Why does the camera hum when connected to the desk?
Because of a ground loop between devices plugged into different sockets. A transformer breaks it.
Why does it distort even with the gain down?
It receives line level and expects mic level: attenuate before the camera.
Is a Y-cable OK?
For a quick test, but it ties the grounds together and one faulty device affects everyone.
When do I need a press splitter?
When several outlets take audio at the same time and each one must get its own isolated copy.
