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Chopper tremolo / programmable LFO
In its simplest use, Chopper produces a very wide range of tremolo effects. The built-in LFO can produce a variety of waveforms that cover many of the waveforms produced by the tremolo circuits built into vintage guitar amplifiers.
The LFO is sent to an output so that it may modulate other modules. It is one of the few LFOs that can by synchronized with an external clock.
There is also a clock synchronizer and multiplier.
To use Chopper as a tremolo, send a signal to the in jack, and listen to the out jack. Leave the clock control at the default int setting. Most of the knob settings will now affect the tremolo effect.
Chopper LFO
To understand all the LFO settings, it helps to watch the outputs on a scope.
The LFO starts as skewed sawtooth. In the middle skew position it is a symmetric triangle wave, at one end a positive sawtooth and at the other a negative sawtooth. The signal is sent to the saw output.
The skewed saw then goes to a waveshaper. As the shape control is increased the LFO is gradually rounded and then flattened. The shaped LFO is send to the lfo output, and used internally to modulate the audio input.
LFO Controls:
- Shape Flattens the LFO waveform.
- Skew Dials in the amount of asymmetry in the LFO.
- Depth Shifts and scales the LFO.
When used as a tremolo effect, you will hear more tremolo when these controls are turned up.
Chopper clock
The LFO in Chopper may be synchronized with the ckin signal. There is a built-in clock multiplier. To use the synchronization, patch a clock to the ckin, and select x1 from the clock knob. To run at a multiple of the input clock, select x2, x3, or x4.
When Chopper is being synched, the Phase control sets the phase difference between the external clock and the synchronized LFO. This may be used to “dial in” the tremolo so that it sounds exactly on the beat (or off the beat).
There is also an internal LFO that is controlled by the Rate control. Set the clock control to int to use the internal clock.
More information
Here is a video by Artem Leonov on some non-obvious uses of Chopper: 7 REASONS to use a Tremolo in Modular Environment [VCV RACK]