How many times has a line check problem been the results of a DI box issue? DI boxes, while simple in functionality, do present the opportunity to cause problems. Here are the three common line-check-related issues where the DI box is to blame;
- No sound coming through the channel.
A DI box won’t pass sound through when the input cable is incorrectly plugged into an output jack. An active DI box won’t pass sound through if there is no power. Make sure that either the phantom power is on, or the active DI box has its AC adapter plugged in or it’s running on fresh batteries.
- The sound coming from the DI box is less than expected.
Some DI boxes allow for control of the input signal strength or the output signal strength. Check the settings on the DI box. This could be a knob labeled “gain” or “volume.” Some DI boxes have controls for both. Also, you might have a pad switch enabled on the DI which drastically cuts the signal strength. These can even exist on passive DI boxes.
- A hum can be heard through the channel with the DI box.
Once you flip the ground lift switch, the noise goes away. The ground lift switch is used to eliminate the hum caused when you have a grounding problem that’s made evident by a looped signal. While you can use the ground-lift switch, consider it an indication that there is a problem in the sound system or with a component like an electric guitar. Therefore, make note when this occurs and spend time looking for the source of the problem after the service. It could be an electric guitar has a grounding problem or something else. In the case of the guitar, if the guitarist touches the strings and the hum goes away, then the guitar has a grounding wire loose inside.
DI boxes are great little electrical signal transformers. Most of the time, the issues you encounter will be caused with improper cabling or setting issues. Don’t overlook them when reviewing your signal chain for the source of a problem. They might be small, but they are mighty.
Question: Have you ever had a DI box go out completely?