Applies to Circuit and Circuit Tracks
This article describes every parameter available to the Circuit Synth Editor of Circuit and Circuit Tracks on Novation Components. While the guide aims to provide detailed information on the controls available, you will likely find using the editor to make patches is the best way to understand the effect of the control on a sound.
For a full guide to content management for Circuit and Circuit Tracks, please check out:
Simplified Block Diagram
The Synth Engine in the Circuit and Circuit Tracks are based on the Novation MiniNova synthesiser, but with fewer controls than the MiniNova offers. This diagram shows the synth engine's signal flow which is worth bearing in mind when creating a sound.
OSC 1/2 Wave
This selects the oscillator's waveform from a range of 30 options which includes 14 analogue synth-type waveforms and 16 Wavetables. The waveform defines the character of the sound and is usually the first consideration in designing a sound.
This control has two functions, depending on the waveform selected by OSC 1/2 Wave. With Pulse Width waveforms the pulse width is adjusted. You will hear the harmonic content varies and at high settings, the sound becomes quite thin and metallic. With Wavetables, setting the Index value to anything between -64 and 63 will transit between nine waveforms. The Interpolation parameter can be used to introduce further variation in the way WaveTables are used.
This parameter sets how smooth the transition is between adjacent waveforms in the same
wavetable. A value of 127 will create a very smooth transition, with the adjacent waveforms
blending together. With a value of 0, the transitions will be abrupt and obvious.
VSync (Virtual Oscillator Sync) is a technique of using an additional "virtual" oscillator to add harmonics to the first, using the virtual oscillator's waveform to retrigger the first. This technique produces interesting sonic effects. The nature of the resulting sound varies as the parameter is altered because the virtual oscillator frequency increases as a multiple of the main oscillator frequency as the parameter value increases.
When the Vsync value is a multiple of 16, the virtual oscillator frequency is a musical harmonic of the main oscillator frequency. The overall effect is a transposition of the oscillator that moves up the harmonic series, with values in between multiples of 16 producing more discordant effects.
This parameter sets the basic oscillator tuning. Incrementing its value by 1 shifts the pitch of every note the oscillator receives by one semitone, thus setting it to +12 effectively shifts the oscillator tuning up one octave. Negative values detune in the same manner.
This parameter lets you make finer adjustments to the tuning. The increments are cents (1/100 of a semitone), and thus setting the value to ±50 tunes the oscillator to a quartertone midway between two semitones.
The density parameter adds copies of the oscillator waveform to itself. Up to eight additional virtual oscillators are used for this, depending on the value of the parameter. This produces a "thicker" sound at low to medium values, but if the virtual oscillators are detuned slightly, a more interesting effect is obtained.
This parameter should be used with the Density control. It detunes the virtual density oscillators and you will notice not only a thicker sound but the effect of the beating of detuning as well.
This parameter sets the amount of Oscillator 1's signal present in the overall sound.
This parameter sets the amount of Oscillator 2's signal present in the overall sound.
This parameter sets the amount of Noise present in the overall sound.
The parameter sets the amount of the Osc 1 * 2 Ring Modulator output present in the overall sound. A Ring Modulator is a processing block with two inputs and one output, it "multiplies" the two input signals i.e. Oscillator 1 and Oscillator 2 together. Depending on the relative frequencies and harmonic content of the two inputs, the resulting output will contain a series of sum and difference frequencies and fundamentals.
This adjusts the level of the summed mixer inputs routed to the FX block in a level range between -12dB to +18dB. This control should be adjusted with care to avoid overloading the FX processing.
This parameter adjusts the level returned from the FX processor between -12dB and +18dB.
The Circuit filter sections offer six different filters: two Highpass, two Bandpass and two Lowpass (2 different slopes for each). Each filter type differentiates between frequency bands in a different way, rejecting some frequencies and passing others, and thus each imposes a subtly different character on the sound.
The engine has three options to bypass the Filter block for specific input signals. Noise is always routed to the Filter block.
This parameter sets the frequency of the Filter. In the case of Highpass or Lowpass filters, it is the "cut-off" frequency; for Bandpass filters, it is the "centre" frequency. Sweeping the filter manually will impose a "hard-to-soft" characteristic on almost any sound.
This parameter adds gain to the signal in a narrow band of frequencies around the frequency set by Frequency. It can accentuate the swept-filter effect considerably. Increasing the resonance parameter is good for enhancing the modulation of the cut-off frequency, creating an edgy sound. Increasing Resonance also accentuates the action of the Filter Frequency parameter, so as you move the Frequency, you'll hear a more pronounced effect.
This parameter alters the bandwidth of the peak created by Resonance. This feature enables the Filter section to emulate many filter responses found on various classic analogue and digital synths.
The pitch of the note played can be made to alter the filter's cut-off frequency. At the maximum value (127), this frequency moves in semitone steps with the notes played on the keyboard i.e. the filter tracks the pitch changes in a 1:1 ratio (e.g. when playing two notes an octave apart, the filter cut-off frequency will also change by one octave). At minimum setting value 0), the filter frequency remains constant, whatever note(s) are played on the keyboard.
Env 2 > Freq
The filter's action may be triggered by Envelope 2. Please check the Envelope section on how the shape of the envelope is derived. Env 2 > Freq lets you control the "depth" and "direction" of this external control; the higher the value, the greater the range of frequencies over which the filter will sweep. Positive and negative values make the filter sweep in opposite directions, but the audible result of this will be further modified by the filter type in use.
The drive processor for each filter is located immediately before the filter section itself. The type of drive (or distortion) generated can be selected with this parameter.
This parameter adjusts the degree of distortion treatment applied to the signal.
Envelope 1 is always routed to Amplitude control; Envelope 2 is routed to Filter control.
It sets the time for the note to increase from zero (e.g. when the key is pressed) to its maximum level. A long attack time produces a "fade-in" effect.
It sets the time for the note to drop in level from the maximum value reached at the end of the attack phase to a new level, defined by the Sustain.
This is an amplitude value and represents the note's volume after the initial attack and decay phases – i.e. while holding the key down. Setting a low value of Sustain can give a concise, percussive effect (with the Attack and Decay times being short as well).
It sets the time for the note's volume to drop back to zero after the key is released. A high value of Release will cause the sound to remain audible for a long time (though diminishing in volume) after the key is released.
Velocity (Envelopes 1 & 2)
This does not modify the shape of the envelope but adds touch sensitivity to the maximum value. The harder you play the keys with positive parameter values, the louder the sound will be (Envelope 1). With Velocity set to zero, the volume is the same regardless of how hard the keys are played. This value determines the relationship between the velocity a note is played and its volume. Note that negative values have the inverse effect. For Envelope 2, the greater velocity the greater frequencies that the filter will sweep.
Delay (Envelope 3)
This parameter delays the start of the entire envelope. When a key is pressed, its note sounds normally with Envelopes 1 and 2 acting as programmed. But it will delay any modulation effects triggered by Envelopes 3 with the time set by the Delay parameter. The maximum value of 127 represents a delay of 10 seconds, while about 85 represents a delay of approximately one second.
LFO stands for "Low-Frequency Oscillation" which is widely used as a modulation source. For this engine, classic LFO shapes like sine, sawtooth, triangle and square waveforms, as well as a wide range of preset sequences of various lengths, rhythms and melodic waveforms are available. A common use of an LFO is to modulate the parameters of the Oscillators, Filter, Mixer and Envelope, even the LFO itself.
LFO Waveforms Table
|Classic||Sine, Triangle, Sawtooth, Square||Classic waveform|
|Random S/H||Jumps to random values every cycle of the LFO|
|Time S/H||Jumps to min and max values each held for a random amount of time|
|Piano env||A curved sawtooth shape|
|Sequence||Sequence 1-7||These are sequences that jump to different values, holding each for a sixteenth of the LFO cycle rate.|
|Alternative||Alternative 1-8||These are sequences that jump between a minimum and a maximum value, each value held for a varying interval of time|
Chromatic, Chromatic 16, Major, Major 7, Minor, Min arp 1, Min arp 2, Diminished, Dec minor, Minor 3rd, Pedal, 4ths, 4ths x12, 1625 maj, 1625 Min, 2511,
|These are "melodic" sequences of various kinds. When modulating oscillator pitch, to obtain chromatic results, set the Modulation Depth to ±30|
It determines the start point of the LFO waveform when the key is pressed. A complete waveform has 360º, and the control's increments are in 3º steps. A halfway setting (180°) will cause the modulating waveform to start halfway through its cycle.
This modifies the shape of the LFO waveform. Sharp edges become less sharp as the Slew is increased.
This effect can be heard by selecting Square as the LFO waveform and setting a low rate so the output when a key is pressed alternates between two tones. Increasing the Slew value will cause the transition between the tones to "glide" rather than a sharp change. This is caused by the edges of the square LFO waveform being slewed.
Check this parameter to On causes the LFO to generate just a single cycle of its waveform.
When LFOs are in use for pitch modulation, Common Sync is only applicable to polyphonic voices. When it is On, it ensures the phase of the LFO waveform is synchronised for every note being played.
When to set Off, there is no such synchronisation, and playing a second note while one is already pressed will result in an unsynchronised sound as the modulations will be out of time.
Rate is the LFO's frequency. A value of zero stops the LFO, and most musical effects are likely to use values in the 40~70 range, though higher or lower values may be appropriate for certain sound effects.
This control allows the frequency of the LFO to be synchronised to an internal/external MIDI clock.
- When set to Off, the Rate parameter is set in frequency.
- When set to On, the Rate is set in the beat that is derived from the MIDI clock.
Each LFO runs continuously, 'in the background'.
- Setting Sync Style to Free, there is no way of predicting where the waveform will be when a key is pressed. Consecutive presses of a key will inevitably produce varying results.
- Setting Sync Style to Key Sync, the LFO starts at the same point on the waveform every time a key is pressed. The actual point is set by the Phase parameter.
Delay is a time parameter whose function is determined by Fade Mode (see below).
When this parameter is set to Off, the LFO delay is controlled by the Delay parameter.
When set to On, Delay is set in the beat that is derived from the MIDI clock.
The functions of the four possible settings of Fade Mode are as follows:
- Fade In - the LFO's modulation is gradually increased over the time period set by the
- Fade Out – the LFO's modulation is gradually decreased over the time period set by
the Delay parameter, leaving the note with no LFO modulation.
- Gate In – the onset of the LFO's modulation is delayed by the time period set by the Delay parameter and then starts immediately at full level.
- Gate Out – the note is fully modulated by the LFO for the time period set by the Delay parameter. At this time, the modulation stops abruptly.
This parameter works in conjunction with the Delay parameters.
In Single mode, it is only the first note of a legato-style passage which triggers the delay. The subsequent notes do not re-trigger the Delay function. The Single mode is only operative with mono voicing and it will not work with polyphonic voicing.
In Multi mode, every note played will trigger the Delay function and has its own delay time, as set by Delay.
Chorus // Phaser
Chorus is an effect produced by mixing a continuously delayed version of the signal with the original. The characteristic 'swirling' effect is produced by the Chorus processor's own LFO making very small changes in the delays.
The Chorus processor can also be configured as a Phaser, where the varying phase shift is applied to the signal in specific frequency bands, and the result is mixed with the original signal. The familiar 'swishing' effect is the result.
Configures the FX processor as either a Chorus or Phaser
The Rate parameter controls the frequency of the processor's dedicated LFO. Lower values give a lower frequency, and hence a sound whose characteristic changes more gradually. A slow rate is generally more effective.
The rate can be synchronised to the internal or external MIDI clock, using a wide variety of tempos.
The processor has its own feedback path between output and input, and a certain amount of feedback will usually need to be applied to get an effective sound. Higher values will generally be needed when Phaser mode is selected. Negative values of Feedback mean the signal being fed back is phase-reversed.
The Depth parameter determines the amount of LFO modulation applied to the processor delay time, and thus the overall depth of the effect. A value of zero produces no effect.
Delay is the actual delay used to generate the chorus/phaser effect. Dynamically altering this parameter will produce some interesting effects, though the difference in sound between different static settings is not marked unless Feedback is at a high value. The overall effect of Delay is more pronounced in Phaser mode.
This parameter sets the amount of Chorus//Phaser's signal present in the overall sound.
The Equaliser is a three-band 'swept' type, with cut/boost and frequency controls for each band. The Low Freq and High Freq sections are shelving filters(slope of 12 dB/octave), and the Mid Freq section is a bell-response filter.
This parameter controls the Low Freq response of the equaliser; positive values will give a rise in the Low Freq response i.e., more bass, and negative values will have the opposite effect. The range of adjustment is ±12 dB.
This parameter controls the Mid Freq response of the equaliser; positive values will give a rise in the Mid Freq response – i.e., more mid frequencies (the voice region of the audio spectrum), and negative values will have the opposite effect. The range of adjustment is ±12 dB.
This parameter controls the High Freq response of the equaliser; positive values will give a rise in the High Freq response – i.e., more treble, and negative values less treble. The range of adjustment is ±12 dB.
Increasing the value of Low Freq increases the frequency below which Low Gain is effective, so in general, Low Gain will have more effect on the sound the higher the value of Low Freq. Decreasing the value of Low Freq will lower the frequency below which the Low Gain control is effective. The range of adjustment is from 140 Hz (value = 0) to 880 Hz (value = 127). The default value of 64 corresponds to approximately 500 kHz.
Increasing the value of this parameter increases the "centre" frequency of the Mid Freq response. The centre frequency is the one that gets the maximum amount of cut or boost as you adjust Mid Gain, and this control will have a proportionately decreasing effect on frequencies above and below the centre frequency. The range of adjustment is from 440 Hz (value = 0) to 2.2 kHz (value = 127). The default value of 64 corresponds to approximately 1.2 kHz.
Decreasing the value of High Freq decreases the frequency above which High Gain is effective, so in general, High Gain will have more effect on the sound the lower the value of High Freq. Increasing the value of High Freq will raise the frequency above which the cut/boost control is effective. The range of adjustment is from 650 Hz (value = 0) to 4.4 kHz (value = 127). The default value of 64 corresponds to approximately 2 kHz.
Distortion arises when a signal is passed through a non-linear channel of some kind, the non-linearity producing alterations to the waveform which we hear as distortion. The nature of the circuitry exhibiting non-linearity dictates the precise nature of the distortion. The distortion algorithms used here are able to simulate various types of non-linear circuitry, with results ranging from a slight thickening of the sound to something really quite nasty.
- Diode - Simulation of analogue circuitry producing distortion where the waveform is progressively "squared-off" as the Level of distortion is increased.
- Valve - Simulation of analogue circuitry producing distortion similar to Diode, but at extreme settings alternate half-cycles of the waveform are inverted.
- Clipper - Simulation of a digital overload.
- Cross-Over - Simulation of the crossover distortion generated by bipolar analogue circuitry, e.g., amplifier output stages.
- Rectify - All negative-going half-cycles are inverted, simulating the effect of rectification.
- Bit Reducer - Reproduces the "grainy" quality associated with lower bit rates, as found in older digital devices.
- Rate Reducer - Gives the effect of reduced definition and high-frequency loss, similar to the use of a low sample rate.
This parameter controls the amount of distortion added to the synth output.
Distortion Compensation only has an effect on Diode and Valve distortion types. Increasing compensation reduces the harshness of the distortion effect.
The synth engines used for Circuit and Circuit Tracks are 6-voice polyphony, you can play up to six notes at once at any step in the pattern if the Patch you've selected is polyphonic. But you can change the synth to the monophonic mode which is good for playing the bass line.
- Mono – This is standard monophonic mode; only one note sounds at a time and the "last played" rule applies. Portamento and Pre-Glide apply both if notes are played separately, or in a legato style (when one note is played when another is already held down).
- Auto-Glide– This is an alternative monophonic mode, which differs from Mono in the way Portamento and Pre-Glide work. In Auto-Glide mode, Portamento and Pre-Glide only work if the keys are played in a legato style. Playing notes separately produces no glide effect.
- Poly – In this mode, you can play up to six notes at once. Successively playing the same note(s) uses separate voices so the notes will be 'stacked' and the sound gets louder as more notes are played. The effect will only be evident on patches with a long amplitude release time.
With Portamento active (0 = Inactive; > 1 = Active), notes played sequentially glide from one to the next, rather than immediately jumping to the desired note pitch. The synth remembers the last note played and the glide will start from that note even after the key has been released. The Portamento parameter is the duration of the glide.
Pre-Glide takes priority over Portamento, though it does use the Portamento parameter to set its duration. Pre-Glide is calibrated in semitones, and each note played will begin on a chromatically related note up to an octave above (value = +12) or below (value = -12) the note corresponding to the key pressed, and glide towards the 'target' note.
This parameter sets the initial pitch range of the synth keyboard. Please note that the pitch range of each track is adjustable independently.
You can modify Circuit's synth sounds extensively with the eight Macro controls. Each Macro has four parameters that are available to alter the sound. Once the Marcos are assigned and saved in a synth patch, you can still change the synth sound when you are using the Circuit outside Novation Components.
The engine has a Modulation Matrix like the Mininova Synth. You can route multiple modulation sources (Source 1 & 2) to a controlled parameter (Destination) which is defined in each slot (20 modulation slots are available), and control the "magnitude" of the control with Depth. A controlled parameter may be varied by more than one source. Each slot allows for two sources to be routed to a parameter, and their effects are multiplied together. This means if either of them is at zero, there will be no modulation. The control signals from different slots "add" to produce the overall effect.
Delay and Reverb
Circuit and Circuit Tracks includes a digital effects processor (FX) which lets you add delay and/or reverb effects to any or all of the tracks making up your Project. Sixteen delay and eight reverb presets are provided, and you can select any one of each type. The send levels from each track – i.e., how much reverb and/or delay is added – are individually adjustable for each track using the Macro controls. Any effects added can be saved to the Project in the usual way. Press FX button to open FX View.
Master Compressor (Circuit Tracks only)
Circuit Tracks includes a master compressor, which is applied to all audio outputs from the device. It can be enabled or disabled by pressing the FX button while in in Advanced Setup View. When the compressor is enabled, the FX button lights bright green: when it is disabled, it lights dim red.
To enter Advanced Setup View. It is entered by holding down SHIFT while powering the unit on, and exited by pressing the PLAY button.