Audio interfaces have revolutionized the way music is recorded. These accessible and easy-to-use devices allow musicians to essentially create their recording studios in any location or setting.
The question “how to connect a guitar amp to an audio interface” is important to many guitarists.
The simplest way to connect a guitar amp to an audio interface is by using an output labeled ‘line out’ on the amplifier. This is sent to the input on the interface using an audio cable, where the signal from the amplifier can be recorded.
How easy it is to connect your guitar amp to an audio interface depends on the specifics of the two devices.
The amplifier must have a suitable output on its control panel, and the audio interface must have an input that is capable of receiving the outputted signal.
In this detailed guide, I’ll explain all of the steps you need to take to do this successfully.
Can I Plug My Amp Directly Into an Audio Interface?
Connecting your guitar amplifier to an audio interface should be pretty straightforward, providing you have the necessary outputs and inputs. Many solid-state and combo guitar amplifiers include a line output, which is designed for sending the signal to another device.
If your amplifier does have a ‘line out’, all you’ll need to do is plug a ¼ inch jack cable into it, then connect the other end of the cable to one of the line-level inputs on your audio interface. The input may also be labeled as ‘instrument’ or ‘line/inst’.
Before turning on the guitar amplifier, it’s a good idea to turn the gain settings on the audio interface input to zero. That way you can gradually add gain to the signal until you reach the desired level, without experiencing clipping or digital distortion.
If your audio interface has direct monitoring capabilities, this should allow you to hear the signal from the guitar amplifier through your monitors or headphones. It’s important to make sure the levels aren’t too high when doing this, as you could damage your speaker cones if the signal is too hot for them to handle!
Once you’ve successfully connected the guitar amp to the audio interface via the line output, you can open your chosen DAW and hit record on an audio track. The input must be set to the correct number that the amplifier is connected to on the interface.
Next, you should do a test recording by playing your guitar and checking the level of the waveform. If the waveform is clipping, simply reduce either the gain level on the input or reduce the volume setting on your guitar amplifier or guitar’s volume control.
You should now be completely set up to record the output from your guitar amplifier directly into your DAW through your audio interface. Any effects or modeling settings you apply to the amplifier will be present on the recordings you make into the software, as will any pedals you run your guitar through.
Line Outputs Explained
A common mistake made when attempting to connect a guitar amp to an audio interface is confusing the speaker and line outputs. Some amplifiers don’t provide a line output, so it may seem logical to use the speaker output instead. However, this should be avoided as it is not suitable for this connection.
Check out the popular Scarllett Audio Interface (pictured above) here on Amazon
- Line outputs are specifically designed to send a line-level signal.
This is commonly referred to as the standard professional audio signal level because the vast majority of audio hardware facilitates it. Outboard gear such as compressors, EQ units, or delay and reverb machines predominantly operate at line level.
Audio interfaces are designed to accept line-level signals into their inputs. This is why sending the signal from the amplifier’s line output allows it to be successfully received by the audio interface.
From a technical standpoint, line-level signals produce the highest level before amplification. It’s therefore very important to avoid sending a line-level signal from your amplifier to an input on the audio interface which is only designed to accept instrument or microphone level signals.
Thankfully, most decent audio interfaces have multi-level inputs.
These may combine XLR and ¼ inch jack connector ports, or the instrument and microphone inputs may be kept separate. Be sure to check the label on the input and look for the word ‘line’ before connecting the output from your amplifier.
Can I Use a Speaker Output to Connect an Amp to an Audio Interface?
Speaker outputs produce a speaker-level signal, which is very different from the line-level signal I just explained. This signal has been subjected to amplification and is designed to be received by studio monitors or another type of speaker.
If your guitar amp has a speaker output, you should be very cautious not to connect this to a microphone, instrument, or line-level input on your audio interface. If you do this, there’s a high chance that your gear will be damaged beyond repair. Only speaker level inputs should receive speaker level outputs!
If you look at the back of your audio interface, you may find inputs for speaker-level signals. This isn’t the case with all interfaces but is common on larger, more extensive models.
The inputs on the front of the interface should never receive a signal from a speaker-level output, under any circumstances. This will not form the proper connection between your guitar amp and the audio interface, no matter which cable type you use.
- Speaker level outputs should only be used with speaker cables.
These differ from line-level jack cables because they are unshielded and the wires are thicker. Using a thinner cable, like an instrument jack, is not suitable because they are shielded and therefore could be melted or damaged.
The table below illustrates the differences between different audio signals commonly found on guitar amps and audio interfaces:
|Line-level||Amplifier outputs, outboard gear||Both|
|Instrument-level||Electric guitar, bass, keyboards||No|
|Mic-level||Condenser, dynamic and ribbon microphones||Yes|
Using a Microphone to Record Your Guitar Amp
If your guitar amplifier doesn’t have a line output, you might be wondering if there’s any other method you could use to record it using your audio interface. Thankfully, by using a microphone, this is easily possible.
Dynamic and condenser microphones are both great for recording guitar amplifiers, so it doesn’t matter which type you have at your disposal. Condensers will produce a brighter-sounding recording with more detail, while dynamic mics produce more mid-range heavy recordings and are better at handling loud volumes.
Firstly, you’ll need to connect your microphone to the relevant input on the audio interface. If you’re using a condenser mic, you’ll need to switch on the +48v phantom power on the interface, as these microphones are incapable of recording without this boost in voltage.
Check out my article on phantom power if you are unsure what this is. You can read it here.
Ideally, you should use a microphone stand to position the capsule in front of the amp’s speaker cone. You can adjust the positioning accordingly once you do a test recording, but for now, just place it in the center of the speaker around a foot away from the amp’s grille.
If you don’t have a microphone stand, it’s possible to thread the XLR cable through the handle on the top of the amplifier and allow the mic to hang down in front of the speaker. As long it’s stable and won’t move, this is a good temporary solution to not having a stand.
You can now turn on the amplifier, and play your guitar through it. Check the levels on the input on your audio interface to see that they’re not clipping. Once you’re happy with the levels, open up your DAW and do a test recording. If the waveform looks good and you’re happy with the sound, you’re good to go.
This video provides useful tips on recording a guitar amp with an audio interface.
The likelihood is that you’ll find you need to adjust the positioning of the microphone in relation to the amplifier a few times before you get the right levels and tone that you’re looking for. Condensers are more sensitive, and therefore you may find that they need to be positioned further away from the guitar amp’s speaker.
Can you plug guitar pedals into an audio interface?
Guitar pedals can be plugged straight into an audio interface, as long as you use the correct input. The output from the pedal signal chain should be sent into the hi-Z instrument input on the interface or used with an amplifier and microphone.
What are the outputs on an audio interface for?
The vast majority of audio interfaces offer a pair of stereo ¼ inch line outputs. These are designed to be connected to your monitor speakers. You may also find analog outputs that allow you to connect other audio hardware to the interface.
Can you plug your guitar directly into an audio interface?
If your audio interface has an input labeled “instrument” or “inst”, you can plug your electric guitar directly into it. This will record the signal from your guitar completely clean, and you may need to use an amp modeler to get an amplified tone.