SONIC-POTIONS Erica Synths LXR-02, Руководство пользователя

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In this chapter we will take a closer look at the synth modules used in the
different voices.
8.1. OSCILLATOR
The oscillators provide 6 different waveforms:
> Sine
> Triangle
> Saw
> Rectangle
> Noise
> PWM
The waveforms are classic analogue waveforms realized using bandlimited
wavetable oscillators.
8.2. FILTER
The filter is a 2 pole (12dB) state variable filter (SVF). It's used to shape the
harmonic content of the sound. For example a hihat sound consists of high
frequencies and no low frequencies, so you want to use a highpass filter. A clap
has lots of mid sounds, here a bandpass filter is useful.
There are 3 parameters that control the filter response. Frequency, resonance
and drive.
FREQUENCY
The frequency determines the operating point of the filter in the spectrum. For
example a low pass filter will cut off all frequencies above its set cutoff frequency
(all frequencies below it pass the filter unaltered – hence the name).
RESONANCE
The resonance controls the feedback path of the filter. With higher resonance
settings the frequencies around the operating point (i.e. the set frequency) will be
amplified more and more.
It becomes clear if we look at the filter amplitude response plots in the next
section.
DRIVE
Controls how 'hot' the filter is driven. More drive yields more distortion. In the
normal operating range, when drive is set to 0, the filter is quite clean and nearly
linear. With higher input levels/drive settings, a soft clipper as well as the slew rate
limit of the integrators comes into effect. Low settings will only affect the
resonance peaks, higher settings will distort the whole signal. Since the soft clipper
is scaling down excessive peaks in the signal, the audible resonance is reduced with
higher drive settings.
FILTER TYPES
There are several different filter types available, each with it's own characteristics.
Let's have a closer look at each one of them. The filters are plotted with 3 different
resonance settings. No resonance, medium and high. The cutoff frequency is the
same in every plot and marked by the vertical dashed line. The x axis shows the
frequency from 0Hz to 22kHz, the y axis shows the gain for the specific frequency –
both on a logarithmic scale.
OPERATION MODES
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LXR OWNERS MANUAL 28