The built-in microphone jack on a computer is usually not the correct input for an electric guitar. An interface provides the right connection, better converters, lower latency and level controls.
For one guitarist, a two-channel interface with one instrument input and one headphone output can be enough. An audio interface converts the analogue guitar signal into digital audio for a computer and converts computer audio back to headphones or speakers. It also provides the correct input impedance, gain control and low-latency monitoring path.
Instrument input is designed for pickups
A Hi-Z or instrument input presents a high impedance that preserves the guitar pickup response. A line input expects a stronger, lower-impedance signal and may make a passive guitar sound weak or dull.
Preamplifier and gain
Input gain raises the signal to a useful level before conversion.
Converters
Analogue-to-digital conversion sends audio into the computer; digital-to-analogue conversion returns it for listening.
Drivers and latency
Good drivers and buffer settings reduce delay.
Direct monitoring and software monitoring are different
Direct monitoring sends the input to the outputs inside the interface with almost no computer delay. Software monitoring lets you hear amp and effects processing but adds latency determined by the system and buffer size.
Driver support affects real performance
Two interfaces with similar inputs can behave differently because of driver quality and firmware. Stable low-latency drivers are especially important for live amp simulation and browser or recording work.
Check your own setup
- Install the manufacturer driver if required.
- Select the interface in system and app settings.
- Connect the guitar to an instrument input and select Hi-Z if the interface requires it.
- Set gain while playing your loudest part and leave headroom below clipping.
- Test latency before recording.
When you are unsure what to change
The guitar is very quiet
The input may be in line or microphone mode instead of instrument mode.
The sound is delayed
Reduce buffer size and use the correct low-latency driver.
The meter moves but the sound is only on one side
Record the guitar to a mono track or choose a mono input in the application. A single guitar jack is normally one mono source, not a stereo pair.