Features and Controls

The Minimoog Model D is a direct descendant of the Moog modular synthesizers that came before it. Although unified into a single body, the internal electronics still rely on individual circuits that perform a specific function. Arranged as an intuitive flowchart, the Minimoog Model D App groups similar components together by type – CONTROLLERS, OSCILLATOR BANK, MIXER, MODIFIERS, OUTPUT – and uses colored rocker switches in place of patch cords to create connections between these modules.

The Minimoog Model D App uses this same efficient panel design

OSCILLATOR BANK

The Oscillators are the primary sound source in nearly any synthesizer. The Minimoog Model D App provides three oscillators of almost identical design. This arrangement means each note played can sound up to three oscillators, each with its own Waveform and Frequency settings. The Mixer then controls the balance between the Oscillators.

Range

The RANGE knob selects the fundamental octave for each oscillator over a five octave range. A sixth LO setting brings the pitch down even further, allowing the Oscillator to be used for other purposes, such as modulation.

NOTE: If an Oscillator is set to the LO position and is set to ON in the mixer, it may sound like repetitive pops. This is normal as it is operating below the audio range.

Frequency

Oscillator–2 and Oscillator–3 are each equipped with a FREQUENCY knob that can be used to detune the Oscillator from the pitch of Oscillator–1. Slight amounts of detuning can create a rich, chorusing effect. Tuning the Oscillators to an interval (Perfect Fifth above; Perfect Fourth below, etc.) provides a powerful voice for playing lead passages or creating chords.

Waveform

The Waveform of the oscillator determines its harmonic content; harmonic content is in turn determined by the number, strength, and amount of overtones a waveform contains. Consider a vibrating guitar string. The entire length of the string vibrates at the fundamental pitch. Halfway down the string? Twice as fast, or an octave higher. One third the string length? Three times as fast, creating a perfect fifth above that, and so on. Not every sound caries the same numbered harmonics, in the same proportion, or at the same strength. The same is true for each Waveform; each one carries a unique harmonic content.

NOTE: The harmonic series is the basis for the pipe organ, the Hammond organ, additive synthesis, etc. The Minimoog Model D begins with a choice of harmonically rich Waveforms, and uses a low-pass filter to modify the tonal content using the process of subtractive synthesis.

Triangle

The Triangle wave has an extremely strong fundamental, yet contains only odd-numbered harmonics at very low levels. This makes the Triangle wave an ideal choice for creating soft, flute-like sounds that have a pure tone with little overtone activity.

Triangle/Sawtooth (Oscillator–1, Oscillator–2 only)

This waveform is a hybrid of the Triangle and Sawtooth waveforms. It contains more harmonic energy than the Triangle Wave and adds in some of the even-numbered harmonics, but it is not nearly as brash as the Sawtooth wave. This hybrid waveform can add a little more edge than the Triangle wave alone, allowing it to cut through the mix with a bit more clarity.

Sawtooth

The Sawtooth waveform is the most harmonically dense of the waveforms, containing all of the natural harmonics in relatively strong levels. In addition to creating thick, brassy sounds, the Sawtooth waveform lends itself to powerful lead and bass sounds as well.

Reverse Sawtooth (Oscillator–3 only)

The Reverse Sawtooth has a sound similar to the regular Sawtooth wave; it is included here as a waveform choice for when Oscillator–3 is being used as a modulation source.

Square

The harmonic content of a Pulse wave is based on the width of the top half of the wave in relation to the bottom half of the wave, also known as the duty-cycle. In the Square wave, the width of these two portions of the wave are equal. As with the Triangle wave, the Square waveform contains only odd-numbered harmonics, but with greater energy. A Square wave provides a rich starting point for string-like sounds.

Wide Rectangle

As the Pulse wave changes from Square to Rectangular, even numbered harmonics are introduced, but the overall harmonic mix is changed. The wide rectangle forms the basis for hollow, reedy sounds.

Narrow Rectangle

As the Pulse wave continues to get narrower, lower numbered harmonics—both odd and even—are emphasized. The resulting timbre takes on a more nasal tone.

TIP: Mixing a Triangle wave from one Oscillator with the more complex wave of another Oscillator allows you to emphasize one particular harmonic without adding unwanted overtones. Changing the relative tuning of the Triangle wave Oscillator can enhance this effect.

Osc. 3 Control

Oscillator–3 is unique. Normally, all Oscillators are controlled directly from the keyboard and Pitch wheel. Setting this orange rocker switch to Off releases Oscillator–3 from keyboard control, allowing it to run free as a modulation source.

Oscillator Modulation

Setting this orange rocker switch to On creates a connection between the Oscillator Bank and the Modulation wheel. The amount of modulation is controlled by the position of the Modulation wheel. Sources that can be used for modulation and assigned to the Modulation wheel include Oscillator-3, the Filter Contour (Filter Envelope Generator/EG), the Noise Generator, and the dedicated LFO (Low Frequency Oscillator).

Controllers

In addition to setting the Glide rate, this panel allows you to select two modulation sources, set a mix between them, and assign that mix to the MOD. (Modulation) wheel. In this way, the Modulation wheel can be positioned to introduce a set amount of modulation that is saved per Preset. In addition, the Modulation wheel can be used to vary the amount of modulation as a way of adding expression to any performance.

Tune

The TUNE knob sets the global tuning for the Minimoog Model D App.

Glide

Glide produces a smooth, continuous change in pitch between notes as you transition from one note to the next. This knob determines the amount of time required to transition between the two pitches. Increasing the value of this knob sets a longer Glide rate; lowering the value sets a shorter Glide rate.

NOTE: The white rocker switch controlling the Glide effect (located on the Left-Hand Keyboard panel) must be set to ON in order to hear the effect.

Modulation Mix

Two modulation sources can be selected using the two black rocker switches labelled OSC.3/FILTER EG and NOISE/LFO. The MODULATION MIX knob then sets the balance between these two modulation sources. With the MODULATION MIX knob rotated fully counterclockwise, only the modulation source selected by the OSC.3/FILTER EG switch is applied. With the MODULATION MIX knob rotated fully clockwise, only the modulation source selected by the NOISE/LFO switch is applied. In the center position, both selected modulation sources are applied equally.

NOTE: In order for modulation to be audible, the MOD. wheel must be set above its minimum position and the OSCILLATOR MODULATION and/or FILTER MODULATION switches must be set to ON (Right).

Osc. 3 / Filter EG

This black rocker switch is used to choose the modulation source that will be assigned to the counterclockwise portion of the Modulation Mix knob. In the OSC. 3 position, Oscillator-3 will be assigned as the modulation source. Oscillator 3 is an excellent modulation source, with six selectable waveforms and a wide frequency range. Unlike the other two Oscillators, Oscillator-3 can operate free from keyboard control by setting the orange OSC.3 CONTROL rocker switch to OFF. Using OSC.3 as a modulation source also opens the door for FM effects. In the FILTER EG position, the shape defined by the Attack Time, Decay Time, and Sustain Level knobs in the Filter Contour can be used as a modulation source. Filter EG is ideal for creating synthetic percussion and other sounds.

Noise / LFO

This second black rocker switch is used to choose the modulation source that will be assigned to the clockwise portion of the Modulation Mix knob. Setting this switch to NOISE allows the Noise Generator to be assigned as a modulation source. Choosing NOISE provides a constantly changing and non-cyclic modulation source that is totally unique. The NOISE switch located in the mixer selection determines what type of noise is used for modulation. When WHITE is selected, Pink noise is actually the modulation sources, and when PINK is selected, Red noise is actually the modulation source. In the LFO position, the dedicated LFO located on the Left-Hand Keyboard panel is used as a modulation source, with Triangle and Square waveform selections available via the SETTINGS menu. This dedicated LFO is ideal for adding vibrato and trills to a sound.

Left-Hand Keyboard Panel

Located to the left of the keyboard, this panel contains a number of controls that address performance related functions. The most important of these are the PITCH (Pitch Bend) wheel and the MOD. (Modulation) wheel. The PITCH and MOD. wheels may be used to add articulation and expression to any performance.

Glide

Glide produces a smooth, continuous change in pitch between notes as you transition from one note to the next. Setting this white rocker switch to the On position turns the Glide effect on. The Glide rate is determined by the Glide knob on the Controllers panel.

Decay

The Contour controls determine how the sound changes over time – how fast the sound comes on (Attack Time), and how fast the sound falls (Decay Time) to a preset level (Sustain Level). When this white rocker switch is set to ON, the Decay Time is also used to determine how the sound dies out after the key is released.

LFO Rate

The LFO RATE knob sets the speed for the dedicated LFO (Low Frequency Oscillator) modulation source that was added to the Minimoog Model D in 2016.

NOTE: The Default selection for the LFO is a Triangle wave. A Square wave can be selected by opening the SETTINGS menu, tapping CONFIGURATION, and under the SYNTHESIZER heading choosing SQUARE as the LFO WAVEFORM.

NOTE: The LFO WAVEFORM selection is saved per-Preset.

Pitch

Touch and drag the PITCH (PITCH BEND) wheel to bend the pitch of the oscillators up or down for as long as the wheel is held. When released, the PITCH wheel will return to its original position. The range of this control can be specified per-Preset via the SETTINGS menu.

Mod

Touch and drag the MOD. (MODULATION) wheel up to introduce modulation to the Pitch of the Oscillators and/or to the Cutoff Frequency of the Filter. The position of the MOD. wheel is saved with each Preset. Unlike the PITCH wheel, the MOD. wheel must be manually returned to its minimum position.

CRITICAL NOTE: With the OSCILLATOR MODULATION switch and FILTER MODULATION switch set to OFF (left), the MOD. wheel will appear to have no effect on your instrument.

Mixer

The mixer is where all of the sound sources within a synthesizer are blended together. All three Oscillators, the Noise Generator, and the External Audio Input have their own individual channel with a dedicated VOLUME knob and a blue On/Off rocker switch. The VOLUME knobs not only set the levels for each sound source, but also determine how hard the input of the filter is driven. The blue On/Off rocker switches allow you to quickly add and remove sound sources without having to change the individual volume levels.

Oscillator Volume

The VOLUME knobs for all three Oscillators line up on the left side of the mixer, while each On/Off switch is found in the center column.

External Input Volume

Just as on the Minimoog Model D hardware synthesizer, the Main Audio Output of the Minimoog Model D App is attenuated slightly, and then sent back to the External Input of the Mixer. By increasing the  EXTERNAL INPUT VOLUME knob setting far enough, the Mixer will overload, introducing varying levels of overdrive or distortion. When this occurs, the Overload indicator lamp will illuminate.

IMPORTANT NOTE: The EXTERNAL INPUT VOLUME control is located after the Main Output VOLUME on the Minimoog Model D App. This means that the Main Output VOLUME knob will also affect the overall amount of overload. Mixer overload is only audible if the External Input is set to ON.

Noise Volume

While most of us think of noise as just that – noise – the noise generator can be a very desirable sound source, either alone, or mixed in with other sound sources. It can be used to create anything from a rocket launch to the subtle breath of a flute sound. The NOISE VOLUME knob sets the level of the Noise generator.

White/Pink

In addition to the NOISE VOLUME knob, there is a blue rocker switch for selecting either WHITE or PINK noise as a sound source. White Noise contains all audible frequencies at equal amplitude levels, much like white light. Pink Noise contains equal energy in each band of the audio spectrum, and is perceived as having more low-frequency components. If you think of White Noise as TV static, consider Pink Noise more as a waterfall pounding the rocks below.

NOTE: When WHITE NOISE is selected, Pink Noise is actually the modulation source. When PINK NOISE is selected, Red Noise is actually the modulation source.

Modifiers

The Modifiers Panel contains three of the most important elements of any synthesizer – the Filter, the Filter Contour controls, and the Loudness Contour controls. Together and independently, these modifiers provide the tools you need to sculpt sound into a custom creation.

Filter

A Filter is one of the most crucial elements in synthesis and electronic sound design. The Minimoog Model D App employs a classic 24dB/Octave Moog Low-Pass Ladder Filter. The term "Ladder" stems from the hardware design of the original filter, which has transistors wired in a type of ladder configuration. Low-pass indicates that the filter is selectively removing harmonic content in the upper part of the audio spectrum, while allowing the lower frequencies to pass unaffected. Finally, the 24dB specification indicates how frequencies are attenuated above the Cutoff Frequency. In this case, harmonic content is rolled off at a rate of 24dB per octave.

Cutoff Frequency

Harmonic content occurring above the Filter Cutoff Frequency is reduced by the Filter at a rate of 24dB/Octave. Harmonic content, or sound, below the Filter Cutoff Frequency will pass unaffected. This is the foundation of subtractive analog synthesis. While the Filter Cutoff Frequency can be set manually using the CUTOFF FREQUENCY knob, the value is also affected by the Keyboard Control switches, Filter Modulation switch, Filter Contour controls, and the Amount Of Contour knob, which are discussed below. When closing the Filter by lowering the Cutoff Frequency, the sound will be perceived as darker, while increasing the Filter Cutoff Frequency will create a progressively brighter sound as more upper harmonic content is allowed to pass through.

Emphasis

Often referred to as resonance, the EMPHASIS knob takes a portion of the output of the Filter and sends it back to the input of the Filter, creating a resonant peak that occurs at the Filter’s Cutoff Frequency. By turning the Emphasis control up and lowering the Filter's Cutoff Frequency, the Filter can be coaxed into a self-oscillating state, acting as a sine-wave oscillator whose pitch can be controlled or played via the keyboard by using the Keyboard Control switches defined below.

Filter Modulation

When this orange rocker switch is set to ON (right), the Filter Cutoff Frequency can be modulated by the Noise Generator, Filter Contour, Oscillator 3, and the LFO (Low Frequency Oscillator). The modulation source and amount are defined by the CONTROLLERS settings and the Modulation Wheel position.

Keyboard Control 1&2

The KEYBOARD CONTROL switches allow the note played on the keyboard to affect the Filter Cutoff Frequency, a process also known as key tracking. This allows notes played higher on the keyboard to produce a brighter sound, while lower notes will produce a darker sound. Keyboard Control 1 provides 1/3 of the total amount of available key tracking. Keyboard Control 2 provides 2/3 of the total amount of available key tracking. By using both switches together, the full amount of available key tracking (1/3 + 2/3 = 1) is applied.

TIP: With KEYBOARD CONTROL switches 1 and 2 set to ON and RESONANCE set to maximum, the Filter Cutoff Frequency can be played from the keyboard similar to an oscillator.

Contour Controls

Sounds change over time. Some sounds begin abruptly, like the strike of a drum. Some sound build slowly, like a soft note on a cello. Some sounds end just as quickly, and some linger like a held chord on a piano. Some sounds begin with emphasis, and settle to a smooth, warm tone like a trumpet solo. In any case, the sound is changing over time. We call this the envelope, or the contour, of the sound. The Minimoog Model D App uses the Contour Controls to similarly change the sound over time. The Loudness Contour settings change the volume of the sound over time. The Filter Contour settings change the Cutoff Frequency of the Filter over time, creating a change in timbre, or tone. In either case, there are three main Contour controls: Attack Time, Decay Time, and Sustain Level.