Moog Music Subsequent 25 User Manual

IMPORTANT SAFETY INSTRUCTIONS

WARNING - WHEN USING ELECTRIC PRODUCTS, THESE BASIC PRECAUTIONS SHOULD ALWAYS BE FOLLOWED:

1. Read all the instructions before using the product.

2. Do not use this product near water - for example, near a bathtub, washbowl, kitchen sink, in a wet basement, or near a swimming pool or the like.

3. This product, in combination with an ampliﬁer and headphones or speakers, may be capable of producing sound levels that could cause permanent hearing loss. Do not operate for a long period of time at a high volume level or at a level that is uncomfortable.

4. The product should be located so that its location does not interfere with its proper ventilation.

5. The product should be located away from heat sources such as radiators, heat registers, or other products that produce heat.

6. The product should be connected to a power supply only of the type described in the operating instructions or as marked on the product.

7. The power-supply cord of the product should be unplugged from the outlet when left unused for a long period of time.

8. Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through openings.

9. The product should be serviced by qualiﬁed personnel when: a. The power supply cord or the plug has been damaged. b. Objects have fallen, or liquid has been spilled onto the product. c. The product has been exposed to rain. d. The product does not appear to operate normally or exhibits a marked change in performance. e. The product has been dropped or the enclosure damaged.

INSTRUCTIONS PERTAINING TO RISK OF FIRE, ELECTRIC SHOCK, OR INJURY TO PERSONS.

Do not open the chassis. There are no user serviceable parts inside. Refer all servicing to qualiﬁed personnel only.

GROUNDING INSTRUCTIONS: This product must be grounded. If it should malfunction or breakdown, grounding provides a path of least resistance for electrical current to reduce the risk of electric shock. This product is equipped with a cord having an equipment grounding connector and a grounding plug. The plug must be plugged into an appropriate outlet that is properly installed and grounded in accordance with all local codes and ordinances.

DANGER: Improper connection of the equipment-grounding connector can result in a risk of electric shock. Check with a qualiﬁed electrician or serviceman if you are in doubt as to whether the product is properly grounded. Do not modify the plug provided with this product – if it will not ﬁt in the outlet, have a proper outlet installed by a qualiﬁed electrician.

TABLE OF CONTENTS

UNPACKING & INSPECTION

SETUP & CONNECTIONS

ABOUT SUBSEQUENT 25

FEATURES & CONTROLS

PRESETS PANEL

BASICS OF SOUND

1 1

SIGNAL FLOW

OSCILLATORS

MIXER

FILTER

ENVELOPES

MODULATION

GLOBAL PITCH CONTROLS

SHIFT MODE

HIDDEN PARAMETERS

PITC H

DUO MODE

FILTER / MODULATION

FILTER ENVELOPE

AMPLIFIER ENVELOPE

MIDI GLOBAL SETTINGS

MIDI OPERATIONS & CHARTS

TIME VALUE

BASIC INFORMATION

MIDI TIMING & SYNCHRONIZATION

EXTENSIONS COMPATIBILITY

PARAMETERS

SPECIFICATIONS

WARRANTY

SERVICE & SUPPORT

SUBSUBSEQUENT 25

This 2-note paraphonic analog synthesizer is ideal for both performance and sound design use. It combines the classic, hands-on control of vintage Moog instruments with a dynamic and gritty new sound engine.

UNPACKING & INSPECTION

Check the contents of the shipping carton. Be careful when unpacking Subsequent 25 so that nothing is lost or damaged. Moog recommends saving the carton and all packing materials in case you ever need to ship the instrument for any reason.

The Moog Subsequent 25 ships with the following items:

1. Subsequent 25 synthesizer

2. Power cord

3. Owner’s manual

4. Quickstart guide

5. Registration card

What you will need:

1. A stand or table sufﬁcient to support Subsequent 25

2. Either a 1/4” instrument cable and ampliﬁed speakers or headphones with a 1/4” inch plug

3. A properly wired AC outlet

SETUP AND CONNECTIONS

Place Subsequent 25 on a stable surface such as a table or keyboard stand at a height suitable for playing comfortably.

EXTERNAL AUDIO IN

POWER

SPEAKERS OR

AMPLIFIER

INPUT

CONTROL

VOLTAGE

5 PIN

DIN MIDI

USB MIDI

SETUP AND CONNECTIONS (Continued)

POWER

Plug one end of the supplied AC cord into the standard IEC power connector on the Subsequent 25 left-side panel. Plug the other end into an AC outlet. The Subsequent 25 universal power supply will operate with 50 or 60Hz AC power sources ranging from 100 to 240 volts. Flip on the power switch located next to the power connector.

NOTE: Your Subsequent 25 is an analog instrument and should be allowed at least 60 seconds to warm up before use. In cases where it has been left in a cold car overnight, for example, it may take as long as 10 minutes before oscillator tuning has stabilized. Do not operate Subsequent 25 in direct sunlight.

AUDIO OUT

With the MASTER VOLUME turned all the way down, plug one end of a 1/4” instrument cable into the unbalanced Subsequent 25 AUDIO OUT jack and the other end into an ampliﬁed speaker or mixing console input. Adjust the level by slowly turning the MASTER VOLUME knob clockwise while playing the keyboard.

If you’ll be using headphones, plug them into the headphones jack (on the front panel’s bottom-right corner) with HEADPHONE VOLUME turned all the way down. Adjust the level by slowly turning the HEADPHONE VOLUME knob clockwise while playing the keyboard. Note that MASTER VOLUME must be turned up as well.

EXTERNAL AUDIO IN

Located just above the AUDIO OUT jack, the jack labeled EXT IN allows Subsequent 25 to shape and ﬁlter external sounds. This is an unbalanced input that accepts a line-level signal. You can adjust the audio level using Shift mode (see page 26) or the plug-in editor.

NOTE: You must press a key to pass external audio through the Subsequent 25 electronics. You also can use a Moog FS-1 footswitch, or any 1/4” cable to open the gate. Simply connect to the 1/4” KB GATE jack.

USB

To use Subsequent 25 with a computer, connect one end of a USB cable to the Subsequent 25 USB port and the other end to an available USB port on your computer. Subsequent 25 supports MIDI I/O over USB, but not audio data.

MIDI

Using Subsequent 25 with an external MIDI device requires one or two MIDI cables. To use Subsequent 25 as a MIDI controller, connect one end of a MIDI cable to the Subsequent 25 MIDI OUT jack and the other end to another device’s MIDI IN jack.

To control Subsequent 25 from an external MIDI controller, connect one end of a MIDI cable to the Subsequent 25 MIDI IN jack and the other end to an external controller’s MIDI OUT jack. By default, Subsequent 25 is set to transmit and receive MIDI data on MIDI Channel 1.

CONTROL VOLTAGE IN

The PITCH CV, FILTER CV, and VOL CV inputs each accepts an expression pedal (such as the Moog EP-2) or a control voltage signal from 0 to +5 volts. If you connect an expression pedal to VOL CV, you can use your foot to control the Subsequent 25 output level. If you connect an expression pedal to F I LT E R CV, you can sweep the Filter Cutoff frequency in the same manner. The PITCH CV input is calibrated so that a one-volt change in the control voltage will result in a one-octave change in frequency.

The KB GATE input accepts a +5 volt signal, which causes the Subsequent 25 Envelopes to trigger.

ABOUT SUBSEQUENT 25

Subsequent 25 is a 2-note paraphonic analog synthesizer, built in the tradition of classic Moog synthesizers. It is housed in a rugged black steel chassis with aluminum extrusion, and ﬁnished with classic wood sidepieces. Equipped with 25 full-size, velocity-sensing keys, Subsequent 25 provides a highly expressive playing experience. The front panel delivers plenty of hands-on controls for designing, saving, and retrieving your own sounds. Subsequent 25 offers a 100% analog audio signal path with two exceptionally stable voltage-controlled oscillators, a square-wave sub oscillator, a noise generator, two ADSR envelope generators, and a voltage-controlled, ladder-type lowpass ﬁlter capable of self-oscillation. One feature that makes Subsequent 25 unique is MultiDrive, a variable multistage drive circuit that delivers overdrive and distortion. Virtually every Subsequent 25 function has its own dedicated knob, and every knob sends MIDI Control Change (CC) data.

As with its larger 37-key sibling, Subsequent 25 also has the ability to play more than one note at a time using the Duo Mode function. This allows each of the two Subsequent 25 oscillators to play independent pitches. In this case, Oscillator 2 can be designated to play either the higher or the lower of two keys played on the keyboard. Both oscillators are then processed through the single, classic 20Hz-20kHz Moog Ladder Filter.

Subsequent 25 provides both a straightforward signal path and a traditional one-knob-per-function user interface that is ideal for beginning synthesists. Nonetheless, Subsequent 25 stands as an extraordinary addition to any electronic musician’s studio setup or to any live performer’s stage rig. Equipped with vigorous MIDI capabilities, Subsequent 25 can be layered with other MIDI sound sources or integrated into a multitrack DAW-based studio. Your Subsequent 25 can even be used to process sound from other instruments, microphones, or other audio sources.

The Subsequent 25 internal Patches memory stores 16 user-rewritable Presets. The free editor/ librarian/controller plug-in allows your computer to store as many Presets as you like, and provides a graphical user interface for programming your own sounds. Like other synths in the Voyager and Little Phatty families, Subsequent 25 has syncable audio oscillators with continuously variable waveforms, as well as a low-frequency oscillator (LFO) that syncs to MIDI clock and offers a choice of modulation waveforms. In addition to a mono audio output with a dedicated volume knob, Subsequent 25 provides a front-panel headphone output with a separate volume knob.

FEATURES & CONTROLS

PRESETS PANEL

BANK AND PATCH BUTTONS

Subsequent 25 ships with 16 Presets, and you can replace any of them with your own Patches. (The word patch is a holdover from modular synthesis, which requires patch cords to connect the various modules.)

Presets are arranged in four Banks, each containing four Patches. On the front panel’s left side, you’ll see two rows of buttons in the PRESETS section. Use the row on the left to select Banks and the row on the right to select Presets within those Banks. For example, to select Preset 1 in Bank 2, ﬁrst press the second button on the left and then press the ﬁrst button on the right. You can tell at a glance which Preset is active because the corresponding BANK and PATC H buttons will be illuminated. If you select a new Bank, the new BANK button will pulsate slowly until a new Patch is selected.

Take your time, listen to all the Presets, and turn some knobs to get a feel for how you can use them to alter the sounds.

PRESETS PANEL (Continued)

(Bank and Patch Controls Continued)

Whenever you want to go back to the original stored Preset, just select it again using the same BANK and PATCH buttons.

NOTE: The buttons found in the PRESETS section also provide access to Shift mode, which allows you to access “under-the-hood” Subsequent 25 features directly from the front panel. To learn more, see page 27.

SAVING PRESETS

Saving Presets is a two-ﬁnger maneuver. Just remember that whenever you save a Preset to a particular location, the Preset previously stored in that location will be deleted. To save your changes, press and hold the BANK button corresponding to the Bank in which you want to store your new Preset. While holding the BANK button, press the PAT CH button corresponding to the location in which you want to store it, hold both buttons for at least one second, and then release them.

NOTE: Both buttons will ﬂash and then go solid again to indicate that your new Preset has been stored.

If you release both buttons before one second has elapsed, both buttons will continue ﬂashing. By pressing and holding the ACTIVATE PANEL button as they’re ﬂashing, you can listen to the Preset currently stored in the selected location to make sure it’s the one you want to replace. Releasing ACTIVATE PANEL returns to your unsaved Patches. At this point, you can either ﬁnish saving your Preset by repeating the save procedure or cancel saving by pressing any of the BANK buttons.

ACTIVATE PANEL

Pressing the ACTIVATE PANEL button puts Subsequent 25 in Panel mode. Pressing it again returns Subsequent 25 to Preset mode. In Panel mode, the front-panel settings determine the sound rather than a stored Preset. The current position of each knob and the status of each button determines the natures of the sound emanating from your Subsequent 25. Dialing up sounds in Panel mode is exactly like dialing up sounds in a classic synth without Patch memory, but when you’re ﬁnished sculpting your sound, you can save your work. Saving a Preset stores all the settings that deﬁne your new sound.

BASICS OF SOUND

If you’re new to the world of music synthesis, it helps to have at least a rudimentary understanding of music and acoustics. Even if you know this stuff like the back of your hand, it never hurts to approach it from a fresh perspective. Several qualities distinguish one musical sound from another, including pitch, loudness, duration, and timbre. Being able to manipulate those qualities allows you to turn raw sound into music.

Simply put, sound occurs when a vibrating object causes the air around it to vibrate. That object could be a guitar string, a loudspeaker, or anything capable of rapid movement. An individual vibration is called a wave or cycle, and the rate of vibration is called frequency. Frequency determines the sound’s pitch, and pitch determines how high or how low you perceive the sound on a musical scale. Frequency is measured in Hertz (abbreviated Hz), which describes the actual number of times that something vibrates every second. One thousand cycles per second is called a kilohertz (kHz).

WAVELENGTH

AMPLITUDE

LOW FREQUENCY HIGH FREQUENCY

BASICS OF SOUND (Continued)

Amplitude—the intensity of vibration—determines a sound’s loudness. A high-amplitude sound is loud, and a low-amplitude sound is soft. A vibrating source’s loudness depends on the amount of air it displaces, and that depends on how hard it vibrates.

It’s difﬁcult for anyone to identify a musical instrument simply by the pitch or loudness of the sounds it makes. Every musical sound also has a characteristic tone color or timbre (pronounced tam’–br, as in tambourine, not tim’–br, as in a tree falling). Differences in timbre make it possible to distinguish one instrument from another.

If you analyze a single cycle of a musical sound, you can perceive it as a complex combination of simple sine waves, each wave different in frequency and amplitude. When their frequencies are wholenumber multiples of each other (and in musical sounds, they usually are), those simple waves are called harmonics. A sound’s timbre depends on its harmonic content. The ﬁrst harmonic—the one with the lowest frequency and usually the greatest amplitude—determines its pitch. Higher harmonics are often called overtones. Normally, the higher the overtone’s frequency, then the weaker its amplitude.

When those harmonics are combined in a musical sound, a single cycle of that sound has a speciﬁc shape, which synthesists call a waveform. Just as the frequencies and relative amplitudes of the sound’s harmonics determine its waveform, the waveform determines the sound’s timbre.

Instead of producing sounds acoustically the way vibrating objects do, synthesizers generate electrical signals that are ampliﬁed and converted to sound. Just as sound has frequency and amplitude, so does the kind of alternating current produced by a synthesizer. An analog synthesizer’s primary sound source is called an oscillator.

The oscillator’s waveform, of course, determines the sound’s harmonic content. Some waveforms are rich in harmonics, while others have relatively few. Depending on the waveform, some overtones may be absent altogether. Waveforms with lots of overtones, such as sawtooth and square waves, are harmonically the most complex. Waveforms with fewer overtones, such as triangle and narrow pulse waves, are harmonically less complex.

Rather than building up waveforms one harmonic at a time, the way an additive synthesizer does, analog synthesizers like Subsequent 25 provide the means to shape and ﬁlter complex, harmonically rich waveforms to selectively remove, reduce, or emphasize speciﬁc harmonics—a technique called subtractive synthesis.

THE SUBTRACTIVE SYNTHESIS MODEL

KB: Keyboard (Pitch Voltage)

VCO: Voltage Controlled Oscillator

VCF: Voltage Controlled Filter

EG: Envelope Generator

LFO: Low Frequency Oscillator

VCA: Voltage Controlled Amplifier

BASICS OF SOUND (Continued)

The oscillators, ﬁlter, modulators, and other parts are connected in the most useful ways for producing and modifying electronic signals that result in sounds. Unlike the patchable connections made on modular synthesizers, many of the connections between the various Subsequent 25 circuits are hardwired, meaning that it is not possible to change the routing of the pathways that connect them.

The electrical signals within a synthesizer are either audio signals or control signals, depending on the pathway they follow. Typically, an audio signal begins with an oscillator and passes through the ﬁlter on its way to the audio output. Control signals are used to change things, like the pitch, timbre, waveshape, or loudness of an audio signal.

Any time a signal controls something, no matter whether it’s controlling an audio signal or another control signal, we say that it modulates it. In synth-speak, you could say that a steering wheel modulates a car’s direction and the accelerator pedal modulates its speed. When you play Subsequent 25 keyboard, the key you press modulates the instrument’s pitch. You can modulate ﬁlter cutoff by turning a knob manually, or you can apply a control signal from a low-frequency oscillator or envelope to modulate it electronically. It’s worth noting that a control destination can be modulated by more than one control source.

SUBSEQUENT 25 SIGNAL FLOW

SUB 1 LEVEL

VCO 1 LEVEL

MULTIDRIVE

VCO 2 LEVEL

EXT AUDIO

Subsequent 25 can be controlled using control voltages and MIDI commands. When your Subsequent 25 receives either a control signal from the onboard keyboard or a Note On command from an external MIDI source, it responds by sending a gate signal to trigger the envelopes and a control voltage (CV) to control oscillator pitch. The envelopes respond by sending control signals to the ampliﬁer and ﬁlter.

Every Subsequent 25 knob and button transmits MIDI data. This functionality is useful for recording your knob turns and button presses into a computer-based DAW, as well as for controlling external devices using the Subsequent 25 front-panel controls. All the settings that make up a Patch are called its parameters, which is simply another name for settings.

OSCILLATORS

Oscillator 1 and Oscillator 2 are the primary Subsequent 25 sound sources. Each Oscillator generates four basic waveforms: triangle, sawtooth, square, and pulse.

The triangle wave consists of odd-numbered harmonics only. Its fundamental is very strong, and its overtones are very weak, making it less harmonically complex than other waveforms. By mixing a triangle from one Oscillator with a more complex wave from the other, you can emphasize one particular harmonic without mucking things up with unwanted overtones.

An unﬁltered sawtooth wave is much brighter, because it contains all the natural harmonics. As the harmonics ascend in frequency, they grow weaker in amplitude. Sawtooth waves are useful for synthesizing bass, simulating brass instruments, and more.

Although a pulse wave contains only odd-numbered harmonics, it offers the most ﬂexibility because you can change the balance of those odd-numbered harmonics by changing its shape. Think of a pulse-wave Oscillator as a switch you can turn off and on hundreds or thousands of times per second. In a single pulse wave, the “switch” is either on or off. Its pulse width is the proportion of the wave that’s on, usually expressed as a percentage. A square wave is simply a pulse wave with 50% pulse width, meaning that in a single

cycle, it is on half the time and off half the time. If its frequency is 440Hz, that means it goes on and off 440 times every second, and the result you hear is the pitch A above middle C. Every pulse width has its own characteristic sound, because each has a unique harmonic structure, making a variety of basic timbres possible.

Unlike most synths, which simply switch between basic waveforms, Subsequent 25 allows you to gradually change the Oscillator’s output from one waveform to another, so it can generate something partway between a sawtooth and a square wave, for example. We refer to such controls as continuously variable because there are no discrete steps between settings. In normal operation, either the keyboard or external MIDI data controls Oscillator pitch. You can also apply the LFO or the Filter Envelope to modulate Oscillator pitch and waveform.

OSCILLATOR CONTROLS

OCTAVE: This knob sets the pitch range for that Oscillator. Pitch range is expressed in feet, a

throwback to the age of pipe organs, when a pipe’s physical length determined its pitch. The Subsequent 25 O C TAV E knobs cover four pitch ranges corresponding to four octaves. The lowest setting is 16’, and the highest setting is 2’.

WAVE : This knob is used to control that Oscillator’s waveform from triangle to sawtooth to square to narrow pulse wave. Turning the knob clockwise from the triangle to sawtooth position increases the Oscillator’s harmonic content. Continuing to turn it to the square-wave position weakens and then eliminates even-numbered harmonics while strengthening odd-numbered harmonics. Turning it from the square to narrow-pulse position changes its harmonic content further by weakening the overtones relative to the fundamental frequency.

FREQUENCY: This knob is used to ﬁne-tune Oscillator 2’s pitch within its selected range. The knob’s range is seven semitones higher or lower than its center position. At its center position, Oscillator 2 is tuned to Oscillator 1. Turning it just slightly out of tune with Oscillator 1 can yield interesting detuned or phasing effects.

OSCILLATORS (Continued)

HARD SYNC OSC 2

This button locks Oscillator 2’s phase to Oscillator 1, eliminating any phase differences between them. The HARD SYNC OSC 2 button illuminates when it’s engaged.

When both Oscillators are in sync, every time that Oscillator 1 begins a new cycle, it forces Oscillator 2 to begin its cycle at the same instant, regardless of whether its previous cycle is complete. As a result, hard sync forces Oscillator 2’s waveform to take on a different shape—typically one with greater harmonic complexity. Because Oscillator 2 is in sync with Oscillator 1, their combined harmonic content depends on their pitch relationship, so that changing Oscillator 2’s frequency will have an immediate effect on timbre. For that reason, modulating Oscillator 2’s frequency opens up some outstanding waveshaping opportunities when HARD SYNC OSC 2 is engaged.

NOTE: If Oscillator 1’s frequency is higher than Oscillator 2’s, Oscillator 2 will be unable to complete its cycle, resulting in little or no output from Oscillator 2.

TRY THIS

PATCH INITIALIZATION

1. Press the ACTIVATE PANEL button.

2. In the FI LT E R section, turn the CUTOFF knob all the way up, the EG AMOUNT knob to center

position, and the remaining knobs all the way down.

3. In the ENVELOPES section, turn the SUSTAIN knobs all the way up and the remaining knobs all the way down.

4. Set the OCTAVE knobs for both Oscillators to 16’ and center the OSCILLATOR section’s remaining knobs. The HARD SYNC OSC 2 and PITCH AMT OSC 2 ONLY buttons should be turned off.

5. In the MODULATION section, turn the LFO RATE to 8 and the remaining knobs all the way down. Make sure the MOD wheel is turned all the way down, too.

6. Next to the PRESETS section, FINE TUNE and O C TAV E should be centered and GLIDE RATE should be all the way down.

7. Finally, turn all the MIXER knobs fully counterclockwise.

When you play the keyboard with these settings, you shouldn’t hear anything. This procedure initializes the front panel and gives you a starting place for creating your own Patches and exploring the capabilities of your Subsequent 25.

EXPLORE THE OSCILLATORS

After patch initialization, turn up the OSC 1 knob in the MIXER section. Listen carefully as you play the keys while slowly turning Oscillator 1’s WAVE knob to the triangle, sawtooth, square, and pulse positions. Listen to what happens when you turn the WAV E knob quickly while playing.

Now turn up Oscillator 2 in the Mixer. While holding a key, turn Oscillator 2’s FREQUENCY knob to adjust its tuning relative to Oscillator 1. Notice the varied effects of adjusting them slightly out of tune, ranging from obvious beating between the pitches to mild phasing between the slightly detuned Oscillators.

If you turn the FREQUENCY knob all the way up, you’ll hear Oscillator 2 tuned seven semitones (an interval of a perfect 5th) higher than Oscillator 1. If you turn it all the way down, it will be seven semitones lower than Oscillator 1. (For extra credit, try to tune them a major 3rd and a perfect 4th apart, too.) Now tune the Oscillators as close to unison as you can by turning the knob to its center position again.

OSCILLATORS (Continued)

TRY THIS

OSCILLATOR SYNC

With the HARD SYNC OSC 2 button engaged, you can step through the harmonic series by turning Oscillator 2’s FREQUENCY knob. To begin, make sure both Oscillators are turned up in the Mixer. Turn both OCTAVE knobs to their lowest settings, and then press the HARD SYNC OSC 2 button so that it’s illuminated. Begin with the FREQUENCY knob turned fully counterclockwise and slowly turn it while listening for how the overtones change. Using your ears, try to step through each harmonic one at a time. Now turn Oscillator 2’s OC TAVE knob to its 8’, 4’, and 2’ settings and slowly turn the FREQUENCY knob again to hear the harmonic series in successively higher octaves.

MIXER

The Mixer lets you combine audio signals from each of the four Subsequent 25 internal sources. Each has a dedicated knob for controlling its relative level. In addition to level knobs for each Oscillator, the Mixer has level knobs for the Sub Oscillator and Noise Generator. When a level knob is turned fully counterclockwise, its input is effectively turned off. Turning it clockwise from 0 increases the level until it reaches its maximum at 12. Settings higher than 6 overdrive the Filter, meaning that you can specify which sources are distorted and which simply pass through the Filter.

MIXER CONTROLS

OSC 1: This knob controls the level of Oscillator 1. Settings higher than 6 push

the level beyond unity, imparting gentle Filter distortion. A setting of 6 or below delivers a clean signal to the Filter.

OSC 2: This knob controls the level of Oscillator 2. Settings higher than 6 push the level beyond unity, imparting gentle Filter distortion. A setting of 6 or below delivers a clean signal to the Filter.

SUB OSC: This knob controls the level of the Sub Oscillator signal. Settings higher than 6 push the level beyond unity, imparting gentle Filter distortion. A setting of 6 or below delivers a clean signal to the Filter. The Subsequent 25 Sub Oscillator is always tuned exactly one octave below Oscillator 1’s pitch, and its waveform is always a square wave. Typically, the Sub Oscillator adds a solid foundation to the Subsequent 25 sound. It is especially useful for crafting monstrous Moog bass Patches.

NOISE: This knob controls the level of the Subsequent 25 Noise Generator. Settings higher than 6 push the level beyond unity, imparting gentle Filter distortion. Noise is useful for programming punchy percussion and other unpitched sounds.

Whereas an Oscillator generates a pitched waveform, Noise is an unpitched sound source. Just as white light contains all colors of the visual spectrum in equal proportion, white noise contains a random distribution of all audible frequencies. Every frequency has equal amplitude. We hear white noise as a constant ssshh sound, like an FM radio between stations. Because of the way our brains respond to white noise, the higher frequencies sound more prominent than the lower ones.

The Subsequent 25 Noise Generator produces a signal called pink noise. Pink noise has equal amplitude in every octave, making it sound deeper than white noise—more like the sound of a waterfall. Most synthesists consider pink noise more useful than white noise.

FI LTER

The number and relative strengths of a sound’s harmonic frequencies determine its tone color or timbre. Subsequent 25 contains a Filter for removing certain frequencies from audio signals. Because ﬁltering gives you control over an audio signal’s harmonic content, it physically alters the waveform being ﬁltered.

Subsequent 25 uses the classic Moog lowpass Ladder Filter with four selectable slopes (see Hidden Parameters on page 30). Lowpass ﬁlters pass all frequencies up to a point called the Cutoff frequency and gradually roll off, or attenuate, frequencies above that point. You can change the Cutoff manually using a knob, or you can change it by applying a signal from a control source such as an Envelope or LFO.

Turning the Cutoff all the way down closes the Filter so that nothing passes through it. Raising the Cutoff opens the Filter. As you turn the CUTOFF knob clockwise from its lowest position, ﬁrst you’ll hear only the audio signal’s lowest frequencies, and then the timbre will grow gradually brighter. The Filter Envelope, in combination with the CUTOFF knob’s setting, is the Filter’s primary control source.

Another characteristic of the Subsequent 25 Filter is Resonance. Resonance increases the level of audio frequencies closest to the Cutoff frequency by making the Filter roll off frequencies less gradually. It regenerates those frequencies by feeding them back to the Filter. Turning up the Resonance emphasizes harmonics closest to the Cutoff frequency and exaggerates any changes to the Cutoff frequency.

FILTER CONTROLS

CUTOFF: The Cutoff frequency of the Filter is controlled by this knob. Its lowest setting is 20Hz, which

effectively closes the Filter and doesn’t allow any audio to pass through. Its highest setting is 20kHz, which opens the Filter completely and allows all audio to pass through.

RESONANCE: Rotating this knob controls how much signal is routed from the Filter output back to its input. Turning it clockwise increases the Resonance, causing a peak in amplitude at the Cutoff frequency. Settings above 7 cause the Filter to self-oscillate.

MULTIDRIVE: MultiDrive acts as the Subsequent 25 distortion processor, offering effects ranging from asymmetrical, tube-like warmth to aggressive hard clipping, with a smooth continuous transition in between. The MULTIDRIVE knob controls how hard you drive the OTA and FET stages, which are located between the Filter and the Ampliﬁer in the signal path. The higher the setting, then the more aggressive the clipping effect. Varying amounts of MultiDrive can give your sounds a distinct tonal edge, as well as make them more responsive to changes in Filter Resonance, waveform, and Oscillator level.

EG AMOUNT: This knob determines how much the Filter Envelope modulates the Filter’s Cutoff frequency. In other words, EG AMOUNT controls the depth of the Envelope Generator’s effect on the Filter.

Notice that the EG AMOUNT knob is bipolar, meaning that its control value is positive when it’s turned up and negative when it’s turned down. Turning it clockwise from center causes the Envelope to raise the Cutoff frequency from the CUTOFF knob’s setting. Turning it counterclockwise from center causes the Envelope to lower the Cutoff frequency from the CUTOFF knob’s setting.

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