Tremolo/Panner block

Tremolo/Panner block

Axe-Fx III: 2 blocks, 4 channels
FM3: 2 blocks, 4 channels
FM9: 2 blocks, 4 channels
VP4: 4 blocks, 4 channels

Axe-Fx II: 2 blocks, X/Y
AX8: 1 block, X/Y
FX8: 2 blocks, X/Y

Tremolo/Panner types

Bias Trem 

Tube simulation algorithm that replicates the bias tremolo in vintage tube amps. As the FM3 does not support Bias Tremolo in the Amp block, 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 sound.

Neon Trem 

Replicates the optical tremolo in classic Blackface amps which used a neon bulb to illuminate the LDR.

Optical Trem 1 

Replicates optical pedal tremolos where depth controls the intensity of the LED.

Optical Trem 2 

Replicates optical pedal tremolos where Depth controls a mixer pot. This type has more throb than Optical Trem 1.

Panner 

Stereo left/right panning.

VCA Trem 

Previously known as Tremolo. Based on a voltage-controlled amplifier topology.

The Bias and Harmonic types use nonlinear processing techniques and, as such, may add distortion to the audio signal, just as their tube-based counterparts would.

For more information see:

• The forum's discussion: The Flint Tremolo Done Right
• Strymon's white paper: Amplifier Tremolo TechnologyPaper

FRACTAL AUDIO QUOTES

---

[1] 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.

Tremolo position 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.

Parameters

LFO Phase (mono/stereo)

Set to 0 for mono output, and to any other value for stereo output.

Depth

A tremolo's modulation is volume-based, so there's no mix parameter in the Tremolo block. Use DEPTH instead.

FRACTAL AUDIO QUOTES

---

[2] Mix makes no sense in a tremolo as it is the same as reducing the depth.

Duty

Use this parameter to change the character of the tremolo peaks from a regular tremolo to electronic blobs.

Start Phase, Trigger Threshold

To trigger the Tremolo when engaging the block, use the START PHASE parameter.

To trigger the Tremolo when hitting the strings (synchronize the Tremolo to your playing): turn up the TRIGGER THRESHOLD parameter. 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 firmware without the TRIGGER THRESHOLD parameter, set RATE to LFO1 SYNC, sync LFO1 to a tempo, and attach the LFO to the envelope follower.

FRACTAL AUDIO QUOTES

---

[3] You can adjust where in the waveform it starts with the Start Phase control.

Ducking

Added in firmware 28 for the Axe-Fx III.

Reduces the intensity of the effect as you play louder.

FRACTAL AUDIO QUOTES

---

[4] It's weird but when I first added bias tremolo in the Amp block I noticed it was ducking and was trying to figure out how to prevent that. Then I fired up a Princeton and noticed that the tremolo ducked. I came to appreciate the ducking aspect.
I doubt whoever came up with bias tremolo intended ducking to be desirable, it was just a side effect of the circuit design and the reason for that design is that it was inexpensive. Harmonic tremolo used two tubes and bunch of resistors and caps. Photocells hadn't been invented yet IIRC.
A bias tremolo only requires half a 12AX7A and a handful of passives. Of course it also beats the crap out of the power tubes.

Tips, tricks and troubleshooting

Factory presets

The Tremolo/Panner block is showcased in many factory presets. Search the Factory presets page for tremolo or panner or panned.

Bias Tremolo in Amp block

The Amp block in the Axe-Fx II and III and FM9 provides its own Bias Tremolo.

Widen the panning

Make the Panner effect appear fuller and wider, by adding the Enhancer block.

Alternative for Panner

As an alternative to using the Panner block, attach an LFO to a panning parameter in a block.

Ring Modulator as Tremolo

You can configure the Ring Modulator block to operate as a tremolo, by turning down FREQUENCY all the way.

Volume block as Tremolo

Attach the VOLUME parameter in a Volume block to an LFO to create a tremolo effect.

Tremolo as On/Off switch

Set the Tremolo block's LFO to Square with DEPTH at 100%.

Shuffle tremolo

See the forum's Shuffle tremolo tempo? discussion.

Vox Percussion Tremolo

To recreate the Percussion Tremolo effect on old Vox guitars, set LFO TYPE to Saw Down.

Sync to Metronome

See the forum's discussion about How to sync the Tremolo to a Metronome?.