LFO

Katla’s five per-voice LFOs share a single rate knob and can be offset using the key-tracking knob. The LFO also includes a rate-switch button toggling between slow and fast ranges. When the key-tracking knob is centered, the LFO rate is tuned to C at both its slowest and fastest settings.

The slow range spans from 0.064 Hz (C-8) to 4.8 Hz (C-2), while the fast range covers 1.02 Hz (C-4) to 65.4 Hz (C2), giving you a total of ten octaves of modulation range.

Tip

Try setting the LFO rate to its maximum value while in the Fast range, then turn the key-tracking knob fully clockwise. This enables audio-rate modulation that tracks the pitch of each note.

The available LFO waveshapes are sine, sawtooth, reverse sawtooth, square, and Volcano. The Volcano waveshape is a slewed sample-and-hold that generates two random values per cycle.

Phase Distortion

The LFO Phase Distortion works the same way as the Mod Envelope’s Phase Distortion. Pushing the slider upward introduces phase distortion, while pushing it downward inverts its direction.

Filter Cutoff

Pushing the slider upward increases the filter cutoff frequency, while pushing it downward reduces it.

Reverb Mix

Pushing the slider upward increases the reverb mix, while pushing it downward reduces it. This parameter is the first place where we encounter a feature called LFO min-maxing. Because five LFOs share control of a single stereo parameter, and because their rates can differ dramatically, Katla calculates their combined outputs and uses that to drive the modulation. The result is a uniquely complex, non-repetitive movement.

When you press the slider upward, Katla uses the combined maximum outputs of the five LFOs. When you press it downward, it uses their combined minimum outputs. This min-maxing behavior applies to the Reverb Mix, Drive Mix, Effects Amount, and Effects Color destinations.

Drive Mix

Pushing the slider upward increases the drive mix, while pushing it downward reduces it. This parameter also uses LFO min-maxing.

Effects Amount

Pushing the slider upward increases the reverb and drive amounts, while pushing it downward reduces them. This parameter also uses LFO min-maxing.

Effects Color

Pushing the slider upward increases the Effects Color value, brightening the reverb and drive signals, while pushing it downward darkens them. This parameter also uses LFO min-maxing.

Rökkur

Applies stereo movement to each voice independently.

Rústir

Rústir is Katla’s wavefolder. Pushing the slider upward increases wavefolding, while pushing it downward reduces it. This control signal is also wavefolded when pushed beyond its upper or lower limits, causing its direction to invert.