Voltage Controlled Oscillator ^

The VCO is the source of all sound for the MS-10 synthesizer. It is here that all pitch and basic tone color elements are determined.

Waveform:This selects the various waveforms that determine the basic tone color (timbre).
Four waveforms are provided , , , .
Each waveform has its own unique characteristic sound.

	Scale: This control is an Octave selector. With each halving of the number displayed, the pitch goes up one octave. For example the 4' (foot) scale indication is one octave higher than the 8'; similarly, 16' is one octave lower that 8'.

(Triangle Wave): A very basic waveform having few harmonics, and possessing a soft, rounded tone color. Excellent for flute, vibes and other such effects. The Triangle Wave may be changed into a Sine Wave (having no harmonics) by the use of the Low Pass Filter.

(Sawtooth): A waveform rich in all the harmonics, and one of the most useful to the synthesist. Used for string, brass, voice and other harmonically rich sounds. The Voltage Controlled Filter (VCF) is highly effective on Sawtooth Waveforms.

(Rectangle Wave): A variable waveform having different timbres depending on the width of the top (called Pulse Width). When the top and bottom widths are equal, the waveform is called a Square Wave, and possesses the "hollow" qualities of the reed family (i.e., the clarinet). As the pulse width proportionately decreases, a strong shift in tone color occurs; the sound becomes "nasal" in quality. This waveform is called a Pulse Wave. Pulse Width is varied on the MS-10 using the PW / PWM control and any external controller patched into the PWM jack.

(White Noise): An unpitched sound consisting of equal amounts of all frequencies. Used for wind, surf, gunshot, percussion instrument and other such effects. The use of the filter will emphasize certain frequencies over others, creating many different sound effects.

- VCO waveforms

Pitch: This control varies the VCO's pitch over a range of +/- one octave. Once set, the pitch level remains extremely stable throughout the playing range, thanks to Korg technology.

PW / PWM:This control varies the Rectangle Wave's Pulse Width (PW), when no patch in the PWM jack. At "0", the waveform is symmetrical (i.e., a Square Wave). Rotating the control clockwise proportionately decreases the pulse width. Near the full clockwise position, the pulse width becomes so narrow as to virtually disappear, and no sound will be heard. This function is useful for eliminating the VCO when external sound sources are being processed through the MS-10 EXT signal in jack. In addition, pulse width may be varied externally by other parts of the synthesizer (e.g. Control Wheel, MG, EG, etc.) by patching the PWM jack to the appropriate controller output. This effect is called Pulse Width Modulation (PWM); the PW/ PWM control now varies the intensity of the modulation effect. For example, when connected to the MG Triangle Wave output on the patch panel, a "chorus" effect similar to the sound of two oscillators slightly detuned from each other is achieved, due to the constant shifting harmonic balance.

- pulse width modulation

Portamento: Varies the rate of "glide". . .the time it takes the MS-10 to go from note to note. The ability to make smooth transitions in pitch between notes is unique to the monophonic synthesizer, and adds to the creative effects available.

Frequency Modulation controls ^

These controls allow other parts of the synthesizer to affect the VCO's pitch, for such effects as vibrato, trills, pitch bends, "sweeps," etc.

Frequency Modulation by MG: Varies the intensity of vibrato from the Modulation Generator (MG) Triangle Wave output.

Frequency Modulation by EG / EXT: With no patch in the VCO's FREQ jack, this control varies the effect of the Envelope Generator (EG) on the VCO. Advance the control and play a note on the keyboard. Notice that the pitch of the note rises and falls corresponding to the envelope curve (see Envelope Generator). With any external controller patched in (e.g., Control Wheel, Reverse Envelope, etc.), this control now varies the intensity of the external device.

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Voltage Controlled Low-Pass Filter ^

The VCF alters the tonal quality of the VCO waveform by removing certain frequencies while passing others. The fact that the VCF can vary its characteristics dynamically gives the synthesizer enormous expressive powers. The MS-10 is equipped with a wide range Voltage Controlled Low-Pass Filter (VCLPF) which, as its name implies, passes lower frequencies while blocking, or filtering out, higher frequencies.

- low pass filter

Cut-off Frequency (Fc): Controls the point in the frequency spectrum where sounds start to be filtered out. At "10", the filter is wide open and sounds pass through unaffected. As the control is rotated counter clockwise, sounds passing through gradually become rounder and softer in tonal quality, as more and more higher frequency components are reduced and eliminated. At "0", the filter is almost completely "closed", and sounds passing through are barely audible.

Peak: This control varies the amount of the filter's Resonance or Emphasis ("Q") at the cut-off frequency. At "0" there is no Emphasis, and frequencies are rolled off smoothly at the cut-off frequency point. As the control is advanced clockwise, a "peak" rises in the filter's frequency response at the cut-off frequency. The effect of this function is to make the action of the filter more pronounced. "Wah" and "Twang" effects are produced using this function. At somewhere near its maximum setting, the filter itself begins to oscillate, generating its own pure sine wave . . . thus in effect becoming another sound source. Its pitch is affected by the cut-off frequency and cut-off frequency modulation controls.

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Cut-off Frequency Modulation Controls ^

These controls allow other parts of the synthesizer to vary the filter's cut-off frequency, in a manner similar to VCO frequency modulation.

	Cut-off Frequency Modulation by MG: The Modulation Generator's Triangle Wave output modulates the filter frequency, for filter vibrato, automatic "wa-wa", etc.
	Cut-off Frequency Modulation by EG / EXT: This control varies the modulation intensity from the Envelope Generator (when no patch is in the VCF's "CUTOFF FREQ" jack). This highly useful effect is called "filter contouring", and allows you to obtain changes in tonal quality over time. Learn to use this function, and to experiment with different settings of the Envelope Generator controls. When an external device (e.g., Control Wheel, Pedal, Reverse Envelope, etc.) is patched into the CUTOFF FREQ jack on the patch panel, this control varies the intensity of the external modulation effect.
	Voltage Controlled Amplifier (VCA): This device varies the volume of sound passing through it in accordance with the sum of control voltages from the Envelope Generator (EG), and from any external controller patched into the patch panel VCA INITIAL GAIN jack.

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Envelope Generator (EG) ^

This device generates a rising and falling voltage which when applied to the VCA and VCF produces corresponding changes in volume and tone color respectively. The MS-10 features a unique 5-part Envelope Generator for added flexibility. When "triggered" (usually by depressing a note on the keyboard), the EG voltage rises to a peak at a rate set by the Attack Time control, then falls at the Decay Time control rate to a level set by the Sustain Level control and eventually falls back to zero at the Release Time control rate following termination of the trigger signal.

	Hold Time: Extends the trigger signal by a variable amount of time. In effect, it "remembers" the trigger for a specified amount of time.
	Attack Time: Sets the time the voltage takes to rise to a peak.
	Decay Time: Sets the time the voltage takes to fall from the peak to the sustain level.
	Sustain Level: Sets the voltage level which will be sustained for the duration of the trigger signal (plus time set by Hold control).
	Release Time: Sets the time the voltage takes to fall to zero after the trigger signal ends. The EG output is internally patched to the VCA so that changes in volume over time will occur to sounds according to the EG control settings. In addition, another EG output is sent to the Filter Modulation controls (EG / EXT) so as to modulate the VCF's cut-off frequency. In this mode, the filter's "steady state" is the Sustain Level. The filter's cut-off frequency will start below this level, initially will rise above the Sustain Level during the Attack cycle, will fall to the Sustain Level, and then will fall below to the initial level again following trigger release.
	- envelope

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	Modulation Generator (MG): ^ This device generates a variable speed low frequency modulation signal, and is also known as a Low Frequency Oscillator (LFO). Its main purpose is to provide vibrato, trills, repetitive attack, and other cyclic (i.e., repeating) types of modulations. The MS-10 features two different simultaneous waveforms - Triangle and Rectangle - both of whose shapes are continuously variable by means of the Waveform Control (see figure). The MG frequency is selected by the Frequency Control and is displayed via a flashing red LED for easy visual confirmation. Both waveforms are available via patch panel connections. In addition, the MG's Triangle Wave is internally patched to the VCO and VCF via their respective MG Modulation Intensity controls. The MS-10 features either continuous modulation or modulation which is switched by a momentary pushbutton located to the left of the keyboard in front of the Control Wheel, for easy addition of the vibrato effect while playing. A slide switch on the patch panel selects the modulation mode desired. [ n.b. see below]
	- modulation output waveforms
	External Signal Level: The MS-10 provides an external Signal In jack on the patch panel, allowing external sound sources to be processed through the MS-10's VCF and VCA sections. This control varies the level of the external source, which may be combined with the VCO sound, or the VCO may be eliminated by selecting the Rectangle waveform () and turning the PW / PWM control to the extreme clockwise position.
	Programmable Control Wheel: This control produces a voltage from -5 to +5 volts, depending on the wheel position. Its output appears on the patch panel, and may be connected to various control input jacks as desired, for such effects as Pitch Bend, Pulse Width Modulation, Filter "Sweeps", etc.
	Patching Panel: ^ The flow chart on the patching panel shows the structure of the MS-10 and the way the internal patch is connected. Think of this chart as the starting point for discovering the multitude of hidden possibilities of the synthesizer.
	VCO Control Voltage In (VCO CV IN): Instead of using the keyboard, you can use the control voltage from an external source (another synthesizer or sequencer) to operate the VCO through this input jack.
	TRIG IN: The MG output () or trigger signal from an external source can be connected to this input to control beginning and end of EG operation.
	KBD CV OUT: This output allows you to use the control voltage (control signal) from your keyboard to control the VCO or VCF cut-off frequency of another synthesizer.
	KBD TRIG OUT: Whenever you play a key on the keyboard a trigger signal is generated. Ordinarily, this trigger signal output is used along with the KBD CV OUT to operate another synthesizer.
	INITIAL GAIN: Although the VCA and EG are connected by the internal patch, this input permits you to use an external input along with the EG to control the VCA. However, when the sum of the input control voltages goes above 5V no further change in volume will occur.
	Envelope Generator Reverse Out (EG REV OUT): While the normal envelope () is ordinarily connected internally to the VCO, VCF and VCA, the reverse of this envelope () is available at the REV OUT jack. Patching this into one of the inputs gives many new possibilities for creating sounds.
	Noise Generator: Noise is also available as one of the VCO waveforms but these outputs give you both pink and white noise which may be used as modulating signals. Pink noise is white noise with reduced high frequency components.

The later edition of the MS-10 has a momentary switch, like on the MS-20. and a slider switch to select the modulation source from the MG. Click here for a picture of a fairly well-used example.

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