Also referred to as Direct Injection, DI refers to a device used in audio recording and live sound to connect high-impedance, unbalanced signals from instruments directly to a mixing console or recording system, converting them into low-impedance, balanced signals.
This conversion allows the audio signal to be transmitted over long cables without losing quality or introducing noise. DI boxes are particularly useful for connecting electric instruments directly to mixing consoles or recording devices without an amplifier. There are two main types of DI boxes:
- Passive DI boxes: These do not require external power and are simpler in design, typically using a transformer to convert the signal. They are generally used for strong output instruments and are known for their durability and reliability. However, they might not be suitable for all instruments, especially those with weaker outputs.
- Active DI boxes: These contain a preamplifier and require a power source, which could be batteries, an external power supply, or phantom power from a mixer. Active DIs are more versatile and can handle a wider range of signal levels and sources, especially useful for instruments with lower outputs.
DI boxes also provide other benefits like ground loop elimination, which reduces buzz and hum in audio signals and allows for balanced signal transmission, which is less susceptible to noise and interference over long distances.