Mutable Instruments Ripples User Manual

Mutable Instruments | Ripples

Ripples is a voltage-controlled filter. It provides 3 output modes: 2-pole band-pass, 2-pole low-pass and
4-pole low-pass. The filtering is achieved by a high-quality quad VCA. An OTA in the filter feedback path
brings the resonance under voltage control, and also serves as a soft-limiter to ensure a clean self
oscillation. Finally, a VCA allows the level of the 4-pole low-pass output to be modulated by a CV. This
makes Ripples a good “final stage” module for a subtractive synthesis patch.

The tonal character of the filter is inspired by japanese classics from the 80s.

Ripples is designed for Eurorack synthesizer systems and occupies 8 HP of space. It requires a +/- 12V
power supply, consuming 35mA from each supply rail. The red stripe of the ribbon cable must be oriented
on the same side as the “Red stripe” marking on the printed circuit board.

This device complies with part 15 of the FCC Rules. Operation is subject to the following
two conditions: (1) This device may not cause harmful interference, and (2) this device must
accept any interference received, including interference that may cause undesired
operation.

This device meets the requirements of the following standards: EN55032, EN55103-2,
EN61000-3-2, EN61000-3-3, EN62311.

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Mutable Instruments | Ripples

A. Resonance level. Self-oscillation occurs at about 80% of the course of this potentiometer.

B. Cutoff frequency.

C. Frequency modulation attenuverter. Adjusts the amount and polarity of frequency modulation from

the FM input.

1. RES: Resonance control voltage, added to the value set by the RES knob. A control voltage of +4V

starts bringing the filter to self-oscillation. Control voltages above +5V are compressed and only bring a
moderate increase of the loudness of the self-oscillation tone.

1. FREQ: 1 V/Oct cutoff frequency control. This input is very helpful for getting the filter frequency to track

the keyboard note. Notice that when resonance is set to its maximum value, with no input signal, Ripples
behaves like a sine wave oscillator. The LP2 and BP2 outputs produce a slightly distorted sine-wave. The
LP4 output produces a clean output.

1. FM: Cutoff frequency CV. This signal is attenuated and polarized by the corresponding knob.

2. IN: Signal input. This input is DC-coupled. However, the internal connection between the VCF output

and the VCA stage is AC-coupled.

3. GAIN: VCA control voltage. This voltage controls the level of the signal produced at the LP4>VCA

output. 0V silences the signal; 5V applies a unitary gain. Values above +5V are progressively compressed.

4. Outputs:

BP2 is a 2-pole band-pass output.
LP2 is a 2-pole low-pass output.
LP4 is a 4-pole low-pass output.
LP4>VCA is the 4-pole low-pass output sent into a VCA.

Set the FREQ knob to 10 o’clock (exact position does not matter).1.
Set the RES knob to its maximum position. Disconnect any input signal or FM modulation CV.2.
Connect the note CV output of a well-calibrated keyboard interface or MIDI-CV converter to the FREQ input.3.
Listen to the tone at the LP4 output.4.
Adjust the trimmer resistor at the back of the circuit board until the musical intervals played on the keyboard

5.
are correctly reproduced (actual note values do not matter, but when playing an octave, it must sound like an
octave).

The filter is designed to track well over 4 octaves, but is not temperature-stabilized.

This product is covered by Mutable Instruments’ warranty, for one year following the date of manufacture.
This warranty covers any defect in the manufacturing of this product. This warranty does not cover any
damage or malfunction caused by incorrect use - such as, but not limited to, power cables connected
backwards, excessive voltage levels, or exposure to extreme temperature or moisture levels.

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