Always read the official Owners Manuals first
UPDATE: information about Fractal Audio's new FM9 and FullRes IRs has been added
- 1 Available on which products
- 2 Channels or X/Y switching
- 3 Tremolo/Panner types
- 4 Position of the Tremolo/Panner block on the grid
- 5 Factory presets
- 6 Parameters
- 7 Tips and tricks
Available on which products
- Axe-Fx III: 2 blocks
- FM9: 2 blocks
- FM3: 2 blocks
- Axe-Fx II: 2 blocks
- AX8: 1 block
- FX8: 2 blocks
Channels or X/Y switching
- Axe-Fx III and FM9 and FM3: 4 channels
- Axe-Fx II Mk I and II: no
- Axe-Fx II XL and XL+: X/Y
- AX8: X/Y
- FX8: X/Y
The block provides the following types in firmware Ares and later:
- Panner — stereo panning between left and right
- Bias Trem — tube emulation algorithm to replicate the bias tremolo used in vintage tube amps. As the FM3 does not support the Amp block’s Bias Tremolo, use this instead
- Harmonic Trem — recreates the famous sound of the tremolo circuit in the old “Brownface” amplifiers. This effect splits the spectrum and applies modulation to the two frequency bands. The Crossover Slope parameter selects the filter order for the crossover. The original circuit used a 6 dB/octave crossover. Higher slopes can give a more intense effect. The crossover frequency can be changed with the Crossover Frequency parameter. Note: unlike most implementations the Axe-Fx III version is full stereo and can be used before or after the Amp block without losing stereo separation. Additionally the effect supports LFO phase for the left/right which can be used to achieve unique sounds. Furthermore the effect supports LFO types other than Sine for even more unique sounds
- Optical Trem
Both Bias Trem and Harmonic Trem use nonlinear processing techniques and, as such, may add distortion to the audio signal, just as their tube-based counterparts would.
"I like the Harmonic Trem on clean and light crunch before an amp. It takes on a slight phaser vibe. Another cool thing to try is to put it near the end of the chain and set the LFO Phase to 180. Funky stereo tremolo." 
Position of the Tremolo/Panner block on the grid
If the Tremolo block is placed before the Amp block and there's a lot of amp gain, the tremolo effect will be less noticeable because of the compression of the signal. Adjust the waveform or the Duty parameter to emphasize the pulse. Or move the Tremolo block to a position after the Amp block.
The Panner pans the signal left and right, just like a ping pong delay. This requires the signal not being summed to mono after the Tremolo/Panner block.
The Tremolo/Panner block is showcased in many factory presets. Search the Factory presets page for "tremolo" or "panner" or "panned".
|Parameter||Axe-Fx III / FM9 / FM3|
|LFO Duty Cycle||yes|
|Harmonic — Crossover Slope||yes|
|Harmonic — Crossover Freq||yes|
|Panner — Width||yes|
|Panner — Pan Center||yes|
Set LFO Phase to 0 for mono output, and to any other value for stereo output.
There's no Mix parameter In the Tremolo block. Depth is the same as Mix, because a tremolo's modulation is volume-based.
"Mix makes no sense in a tremolo as it is the same as reducing the depth." 
Triggering the Tremolo
To trigger the Tremolo:
- when engaging the block: use the Start Phase parameter.
- when hitting the strings (synchronize the Tremolo to your playing): turn up the Trigger Threshold parameter (firmware Ares 12 and later). When the Tremolo is triggered, it will start and the LFO phase will start at the Start Phase value. Turn Trigger Threshold all the way down to defeat the trigger.
In earlier firmware without trigger Threshold, set Rate to “LFO1 SYNC”, sync LFO1 to a Tempo, and attach the LFO to the Envelope follower.
Use this parameter to change the character of the tremolo peaks, from a regular tremolo to electronic "blobs".
Tips and tricks
Tremolo in Amp block
The Amp block in the Axe-Fx II and III (not in the AX8 and FM3) provides its own Bias Tremolo.
Widen the Panner
Make the Panner effect appear fuller and wider, by adding the Enhancer block.
Alternative to Panner: LFO
As an alternative to using the Panner block, attach an LFO to a panning parameter in a block.
Ring Modulator as a tremolo
You can configure the Ring Modulator block to operate as a tremolo, by turning down Frequency all the way.
Flanger as a tremolo
You can turn a Flanger block into a tremolo.
Tremolo as an On/Off switch
Set the Tremolo's LFO to Square with Depth at 100%.
Vox Percussion Tremolo
To simulate the Percussion Tremolo effect on old Vox guitars, set LFO Type to Saw Down.