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Computer audio and reamping

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Computer audio

Getting audio to and from the computer

To get audio into (and from) a computer, an audio connection has to be established.

Available options depend on the hardware. Read this: I/O specifications

Analog — To connect analog outputs and inputs to a computer (XLRs or jacks), a hardware audio interface is usually needed. The interface sits between the processor and the computer's I/O ports. This usually is a USB, Firewire or Thunderbolt interface. An analog connection means that the D/A conversion has to take place at the processor output and A/D conversiion at the computer's input.

Digital — A digital connection avoids the need for digital/analog conversion. To connect digitally, use one of the available options: USB Audio, SPDIF or AES. SPDIF and AES may require an additional audio interface between the processor and the computer. The AX8 and FM3 only support SPDIF output, not input. The FX8 does not support digital audio.

The I/O menu provides level controls for the digital signal.

When using a USB-C to USB adapter on a newer Apple computer, plug the USB-C adapter into a the port on the Mac first, allow it several seconds to “wake up” and then connect a USB cable and the unit into the adapter.

Read more:


When monitoring audio through the computer's output, latency (the time between playing a note and hearing it) depends on the computer and the USB driver. Higher buffer sizes = more latency. Some processors let you adjust the USB buffer size.

Read this: USB

When monitoring audio directly from the Fractal Audio hardware or hardware audio interface, latency is below 2 ms. Optimizing Latency with Computer Recording

Sample rate

All Fractal Audio processors use a fixed sample rate: 48kHz, 24 bit.

Read this: Sample rate

Mute hardware monitoring when listening to a DAW

If the processor is connected to a DAW through USB, you have monitors connected to the processor and you're recording, you may want to hear just the signal from the DAW (software monitoring), not the signal from the processor.

To accomplish this, use one of these methods:

  • Set USB/DIGI Out Source to Output 2, set Output 2 Echo to Output 1 and lower gain in Output 1's Global EQ gain slider.
  • Set USB/DIGI Out Source to Output 2, set Output 2 Echo to Output 1 and send a 0 value for Output 1 Volume's MIDI CC.
  • Set USB/DIGI Out Source to Output 2, put an FX Loop block at the end of the grid chain and connect your signal row(s) to it instead of the output block.

The Axe-Fx III's expanded I/O capabilities allow easier control.

If connecting the processor to a DAW drops the volume or puts it into bypass

Some DAWs send MIDI commands (intended for other devices) which lower the volume of the processor or put it into Bypass mode. To solve this, adjust the DAW settings. If not possible, force the processor to ignore those commands by setting the corresponding MIDI CCs in the I/O menu to "NONE". source

Simultaneous analog and digital audio

The Axe-Fx series allow combining digital input with analog output and simultaneous digital out. Also, you can use Input/Output 2 while using the digital input.

FAS-FX Reverb plugin

FAS-FX Reverb plugin is Fractal Audio's reverb plugin for the computer.

Control the processor in the DAW

Preset switching, scenes, X/Y switching, channels and other MIDI-controllable functionality can be controlled remotely in the DAW. MIDI Program Changes and Control Changes can be embedded in a track, enabling automated control.

Read this: MIDI


GarageBand always uses USB channels 1 and 2, even if Apple's system audio is configured to use channels 3 and 4.


What is re-amping

Re-amping is the process of recording a dry signal to be "processed" at a later time. This lets you experiment with different amp models, before deciding which one will be used on the final track.

The Axe-Fx II and III are suited best for easy re-amping, and the FM3 can do it too. It takes more effort with the AX8.

Axe-Fx III

Re-amping is covered in section 3 of the Owner's Manual.

Axe-Fx II

The USB output signal of the Axe-Fx II always contains 4 signals: 4 x mono / 2x2 stereo. There's nothing to set up in the Axe-Fx.

Channels 3 and 4 contain the raw data from the instrument input, without processing by the Axe-Fx. You record this on the computer by selecting input signals 3 and 4 as sources. This is known as the DI track.

Play this recording from the software back into the Axe-Fx, by setting the software's output source to Axe-Fx II, and selecting USB (or Digital) as input source in the Axe-Fx's I/O menu. Then tweak the signal on the Axe-Fx II by creating an empty preset and adding effect blocks, such as Amp and Cab. When you are happy with the result, record channels 1 and 2 again which contain the re-amped audio.

To record audio on the computer through USB, USB/Digi Out Source in I/O menu should be set to Output 1. If you want to route the guitar's dry input signal directly to the output (USB or digital), set USB/Digi Out Source to Input. To send dry signal only from the Axe-Fx II to the DAW through Output 2, set Echo Output 2 to Input.

"The DI signal level of channels 3 and 4 is fixed, for good reason. When you send that signal back into the Axe-Fx, it has the same level as the original signal sent to the grid. This means you don't have to adjust anything when re-amping. You simply send the signal back." source

"You are getting a bit-copy of the signal out of your guitar. Do not adjust the level. It may sound quiet because your guitar IS quiet when not amplified. When you put that signal back into the Axe-Fx it will be gained up and sound just like when you are playing through the Axe-Fx." source

Make sure to use the correct Input Mode when re-amping. For example, using Stereo instead of Left Only will attenuate the incoming signal.



Re-amping is covered in Chapter 3 of the Owner's Manual.

Walkthrough: source

  • Create a track and set its inputs to Input 1-2
  • Create a second track and set its inputs to Input 3-4
  • On the FM3 go into Setup > I/O > Audio and set USB 3,4 Record Source to INPUT 1
  • Arm both tracks and record.

The track set to Input 1-2 is recording the wet, effected signal from the FM3. The track set to Input 3-4 is the guitar signal as it appears at INPUT 1 on the FM3, this is the re-amp track. Route that track back to the FM3 to replay the recording and re-record it through a new preset or combination of settings on the FM3.

Greg Summer demonstrates recording and reamping with the FM3


  1. Adjust the routing in the grid to create a dry DI signal (no amp/cab processing).
  2. Use the FX Loop block to send that signal through Output 2 to the computer.
  3. Send the recorded DI signal back into the AX8 through Input 2 (analog), process it on the grid, and record it using SPDIF OUT or the analog outputs.

Another way to send out a dry signal through Output 2, is to set Echo Output 2 to "Input 1" in I/O.

Orbm1's illustrated guide to re-amping via SPDIF