Always consult the Owners Manuals first

Chorus block

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Chorus block.PNG

Available on which Fractal Audio products

  • Axe-Fx III: 2 blocks
  • Axe-Fx II: 2 blocks
  • FX8: 2 blocks
  • AX8: 1 block

X/Y and channels

  • Axe-Fx III: 4 channels
  • Axe-Fx II: X/Y
  • FX8: X/Y
  • AX8: X/Y

Position of the Chorus block

It's a matter of personal preference where to put the Chorus block: before (like a pedal) or after (like in a rack or studio) the Amp block. When placed before the Amp, make sure the Chorus is set to mono (LFO Phase is 0).


Parameters table

Parameter Axe-Fx III Axe-Fx II AX8, FX8
Type yes yes yes
Basic - Number of voices yes yes yes
Basic - Rate yes yes yes
Basic - Tempo yes yes yes
Basic - Depth yes yes yes
Basic - Delay Time yes yes yes
Mix yes yes yes
Level yes yes yes
Expert - Low Cut, High Cut yes yes yes
Expert - LFO Phase, LFO Type yes yes yes
Expert - Auto Depth yes yes yes
Expert - Phase Reverse yes yes yes
Expert - Drive yes yes yes
Expert - Width yes yes yes
Expert - LFO2 Rate, LFO2 Depth yes yes yes
Expert - Stereo Spread yes yes yes
Expert - Dimension Mode yes yes yes


(Axe-Fx II Owner's Manual) "Whenever the number of voices is set to more than two, the LFO type will be changed automatically to SINE. If the number of voices is greater than two and the LFO type is changed to something other than SINE, the number of voices will be reset to two."
(Axe-Fx III) "The Chorus block has up to 8 voices." source

Selecting more than 2 voices is useful only when LFO Phase is not zero. source

A single chorus voice, i.e. for a Vibrato effect, can be obtained by setting LFO Phase to 0.

Specific chorus types

Boss CE-1

Read this thread for a perfect description of the Boss CE-1 and how to emulate it using a LFO-driven Flanger block

Leon Todd dials in the Boss CE-1 sound, based on the 'Japan CE-2' type in the Chorus block. YouTube demo

Vintage tape

This type uses the tape delay algorithm from the Delay block. It sums the left and right block inputs into mono, so use caution as stereo cancellation may occur.

Dimension D

Based on Roland's SDD-320 Dimension D (original manual).

The Chorus block provides three Dimension types: Dimension 1, 2 and 3. These correspond to the modes on the original device.

"The Dimension Mode parameter turns on "Dimension Processing". This can be turned on in any type. However I highly recommend using the Dimension Type as it sets the correct base algorithm, LFO type, delay time, phase, etc., etc. as well as turning on the Dimension Processing. The Dimension D is really just a typical chorus. At the output, however, some special processing occurs that gives that unique sound. Turning Dimension Mode to one of the three settings engages the various aspects of that processing." source
"A Dimension D is a fairly typical chorus with some added analog processing on the outputs. The analog processing has a "normal" mode and a "boost" mode. The unit itself has four switches. These switches set the rate and the depth as well as turn on the boost mode. The switches do the following: Slow rate (0.25 Hz) and low depth, Slow rate and normal depth, Fast rate (0.5 Hz) and normal depth, Fast rate and normal depth and "boost" on. The depth is actually reduced in modes 3 and 4 to compensate for the higher rate. In the Axe-Fx this is done automatically when Auto Depth is on. Therefore I've indicated the depth as "normal" in modes 3 and 4 as the amount of pitch shift is roughly the same as mode 2. There is also an EQ that is present in all the modes on the dry signal. The LFO is a triangle wave and is 180 degrees out of phase between channels. The Dimension Mode parameter has three settings: Low, Medium and High. Low: Dry EQ off, boost off. Med: Dry EQ on, boost off. High: Dry EQ on, boost on. The Low setting has no equivalent on an actual Dimension D since the dry EQ is always active. The Dimension Type sets the LFO type, phase, Auto Depth, Hi Cut, etc., etc. and sets the Dimension Mode to Medium. With the appropriate settings of Rate and Depth you can duplicate modes 1, 2 & 3 on the actual Dimension D. To duplicate mode 4 you simply set the Dimension Mode to High. The Rates are given above. I've found a Depth of around 25% to be a good starting point. Increase or decrease to taste. The Type does NOT preset the Rate or Depth." source

According to Guitar World, SRV used the Dimension D to add thicken his solos and still keep the tone natural.

The Dimension C pedal was created by Boss to produce the Dimension D effect through a pedal. In 2018 Boss released its DC-2W Dimension C pedal, an update which is part of the Waza Craft Series. YouTube

Cooper Carter: try the "Dimension 1" type, with Mix at 35%.

BBD algorithm

This uses an algorithm which is based on the BBD algorithm from the Flanger block. All the “Analog” chorus types use this algorithm, as well as the "Dimension 2" type: Analog Mono, Analog Stereo, Dimension 2, Dimension (and probably Japan CE-2).

"Those types use “analog” delay lines. The delay lines are virtual bucket brigade devices with the delay time controlled by a virtual oscillator. That behavior is consistent with how they would work in the real world." source


There's no dedicated Vibrato effect in the Axe-Fx and AX8. You can create this effect by using a 100% wet chorus (no dry signal), a single chorus voice and Auto Depth off.

Mix at 100% is not a requirement. As documented here the Vibrato mode of the venerable Boss CE-1 depends on a variable Mix setting.

Yek's settings for a vintage Vibrato (source):

  • Chorus type: Japan CE-2
  • Rate: 4.294
  • Tempo: none
  • LFO: Sine (try Triangle for a more spiky sound)
  • LFO Phase: 0
  • Depth: 50
  • Delay Time: 10.00
  • Voices: 2
  • Width: 0
  • Auto Depth: High
  • Phase Reverse: None
  • LFO2 Rate: 0.050
  • LFO2 Depth: 0
  • Spread: 0
  • Mix: 100
  • Low Cut: 20.00
  • High Cut: 8000
  • Drive: 3.33.

Vibrato in Wikipedia


The Tri-Chorus is a very lush chorus that was very popular among studio players in the 80s and 90s. The original devices have been discontinued, but there are a few replicas.

AX8, FX8 and Axe-Fx II – Use the Chorus and/or Quad Chorus (Axe-Fx II only) effects, combined with Pitch Detune. Forum discussions here and here.

Axe-Fx III – The Chorus block has an authentic Tri-Chorus emulation type, based on a Dytronics Songbird TSC-1380. Forum discussions here, here and here. Demonstration by Camilo Velandia

Dual Chorus

Available on the Axe-Fx III only. This type has independent LFOs for the left and right delay lines. The delay lines are BBD emulations.

Creating a chorus with other blocks

The Multitap Delay block can create a lush multi-voice chorus.

The Pitch block and Plex Delay block can create a multi-voice detuning effect.


Avoiding phase cancellation and comb filtering

Some chorus types (such as 80s and Triangle) "invert" the wet sound on one side. If you're collapsing the signal to mono after the Chorus block, the wet side will completely cancel and you'll hear no chorus at all.

More information about phase cancellation

More information

The Chorus block is explained in the Owner's Manual.