October 2024: Fractal Audio's VP4 Virtual Pedalboard has been added to the wiki.
Chorus block
Contents
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
Parameters table
| Parameter | Axe-Fx III | Axe-Fx II | AX8, FX8 |
|---|---|---|---|
| Type | yes | yes | yes |
| Number of voices | yes | yes | yes |
| Rate | yes | yes | yes |
| Tempo | yes | yes | yes |
| Depth | yes | yes | yes |
| Delay Time | yes | yes | yes |
| Mix | yes | yes | yes |
| Low Cut, High Cut | yes | yes | yes |
| LFO Phase, LFO Type | yes | yes | yes |
| Auto Depth | yes | yes | yes |
| Phase Reverse | yes | yes | yes |
| Drive | yes | yes | yes |
| Width | yes | yes | yes |
| LFO2 Rate, Depth | yes | yes | yes |
| Stereo Spread | yes | yes | yes |
| Dimension Mode | yes | yes | yes |
Voices
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
Specific chorus types
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.
"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), low depth. Slow rate, normal depth. Fast rate (0.5 Hz), normal depth. Fast rate, normal depth, "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.
"Dimension 1 is the same as previous firmware and is "digital". Dimension 2 (firmware 17 and later) uses the new BBD algorithm." source
Tip: 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.
Vibrato
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.
A single chorus voice can be obtained by setting LFO Phase to 0.
A classic "VB" pedal vibrato effect typically uses a TRIANGLE waveform for the LFO, but the classic "CE" vibrato uses a SQUARE one.
(forum member Scarr) "The rumour is the Boss VB-2 was a CE-2 without the dry signal mixed in (and pedal ramp on depth). A switch to disable the dry signal is a popular CE-2 mod."
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.
Tri-Chorus
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, based on a Dytronics Songbird TSC-1380. Forum discussions here, here and here. Demonstration by Camilo Velandia
Troubleshooting
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.
