Hi,
Recording a guitar is much the same as any source signal and one section from the support article below ...
http://support.presonus.com/hc/en-us/articles/210044653-Why-won-t-my-AudioBox-record-or-play-back-audio-
... gives a step by step for recording with the AudioBox.
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Verify that you have set the gain for your inputs properly. Use this method to receive a usable signal in your DAW:
- Plug your input source (mic, guitar, etc.) into an input on your AudioBox. If using a condenser microphone, see step 9.
- Set the Mixer knob to Inputs
- If you are using headphones, turn the Phones knob to the 12 O'clock position
- If you are using speakers, turn the Main knob to the 12 O'clock position
- Speak into your mic or play your instrument, then SLOWLY turn up the gain for the channel you are using until you begin to hear a signal. For instance, if you have a microphone plugged into the left input on an AudioBox USB, this would be knob 1.
- Continue to turn the gain up for that channel until the red "clip" LED illuminates
- Roll the channel back while inputting a signal until the "clip" LED ceases to illuminate
9. If you are using a condenser microphone, make sure that the 48V button on the front of the AudioBox is pressed and illuminated. This will supply energy, called "phantom power" to your condenser mic.