Make Noise XPO

MUSICAL FEATURES

The XPO (Stereo Prasmatic Oscillator) is a fully analog stereo oscillator.In addition to the basic waveforms of sine, triangle and sawtoothspike waveand SUB outputs, stereo timbre modulation including stereo PWM and wavefolding, frequency modulation, and unique oscillator sync in the analog domain.

XPO is a complex circuit that is multilaterally controlled by several powerful parameters within the stereo field.QPasWe have a common philosophy and high affinity with

• Stereo analog VCO with 5 mono outputs and 3 stereo pair outputs
• Modulate timbre via stereo PWM, stereo Vari-Timbre, and stereo Wave Folding
• Equipped with sine, triangle, sawtooth, spike and SUB mono outputs
• Unique mono versions of all stereo waveforms available with normalization between channel outputs
• Modulate left and right channels simultaneously or independently
• Center parameter for expanded timbral control on both sides of the Vari-Timbre and Wave Folded outputs
• Linear FM bus with FM index control input
• Internal wiring from SUB output to FM input
• Proprietary SYNC circuit
• Two 2V/Oct inputs for transposing sequences and rich FM
• Expo FM input with Athenuverter
• QPAS, Mimeophon, X-PANDesigned with compatibility with

HOW TO USE

Interface

The Waveform Outputs

Mono Outs

At the top of the XPO are five mono waveform outputs derived from the oscillator core.

A sine wave isDPOandSTOis shaped from a triangular wave identical to that of the circuit that implementsSawtooth, spike, and sub outputs are new for XPO.These outputs are useful for applications where they are individually processed through VCAs, filters, etc., like conventional VCO outputs.They areOPTOMIX,X-PANIt can be mixed using a mixer such as , panned to any position on the stereo output, or used as a tonal modulation source to modulate the XPO's own Center and Modulate parameters.It can also be used as audio rate modulation to processors like QPAS running on the output of the XPO, always showing the same frequency on all outputs.

• Sine: A sine wave is derived from the triangle wave core of the oscillator and is provided as one of the outputs.This is because the fundamental can be boosted by blending it with a signal with more overtones.The sine shape is almost free of overtones, so it's also a good starting point for creating complex FM sounds.This is because the sidebands that occur during FM are not obscured by the harmonics present in the utilized signal.
• Triangle: A triangle wave is the core shape of the oscillator.A triangle wave has slightly more harmonic content than a sine wave, has a stronger fundamental, and cuts through a mix better than a sine wave.Triangle waves are also useful as a modulation source when more harmonic creation is desired, such as audio-rate modulation of filter cutoffs.
• Sawtooth: Containing all overtones and suitable for shaping in filters, the sawtooth wave is a classic thumping East Coast synthesis waveform often used in subtractive synthesis.
• Spike: The Spike wave has a thin, long spike shape and a low fundamental wave, resulting in a thin, 'buzzy' sound.This not-so-common waveform can be found on the classic West Coast synthesizer 'Music Easel'.It can add or subtract impressive overtones to waveforms with few overtones, such as triangle waves, and is also a useful shape for modulating parameters with 'ringing' potential, such as resonant filters.
• Sub: The Sub Oscillator is a classic Far East coast waveform that has been used to thicken the sound when mixed with other waveforms from the same VCO.
  The XPO's Sub waveform output is a mix of multiple square waves derived in low octaves (sub-harmonics) from the oscillator core.Suitable for subtractive synthesis with filters, this output is great as a modulation source as well as for creating basslines and other 'fat' sounds.
  When patched to QPAS' filter cutoff, the filter creates a roaring sub-harmonic superimposition. In XPO, another version of the Sub waveform is normalized to the linear FM input.If this input does not have a patch, FM Depth can be used as an additional VC timbre parameter to generate sub-harmonic FM.

Stereo Outs

On the right side of the XPO are three pairs of stereo outputs derived from the oscillator core.These outputs are QPAS andMimeophonProvides an excellent audio source for stereo processing modules such as
All output pairs receive tonal modulation from the Modulate L/R parameters, and are available mono through their respective Left outputs when there is no patch on the Right output.
Note that the Vari-Timbre and Folding outputs receive timbre modulation from the Center parameter on both LR outputs.

Pulse Width ModulationThe output uses a classical PWM circuit to continuously modulate the width of the square wave. The Modulate control has a minimum value of 0% (no sound), 12% (square wave) around 50 o'clock, and a maximum value of about 99% (fine pulse).When using a control voltage, the pulse width can be increased up to a value of 100% (again silent).

Pulse width modulation can alternate between even and odd harmonics. The XPO has two independent PWM parameters for the two outputs, so you can listen to interesting combinations by monitoring in stereo and modulating both sides with the same period and modulation amount, or different values ​​at the same time. increase.

Left and Right, each PWM output is independently controlled by the Modulate control. If the Right output has no patch, the Left output will give the sum of the Left output and an inverted copy of the Right output.If you use only the Left output for a mono signal, you can get interesting fading behavior by modulating one or both waveforms.

Vari-Timbreis derived from sine, triangle, and sawtooth waves.Crossfade both left and right Vari-Timbre signals from sine to sawtoothCenterParameters are features found in the circuitry of classic West Coast synthesizers such as the Buchla 158 and 258.It can also be used in a manner similar to a lowpass filter, changing the sound from smooth and soft to sharp and bright.The resulting Sine/Saw shape is further processed with the Modualte L/R parameters to cut the triangle wave into the waveform defined by the Center parameter (Sine/Saw).At a minimum value of 0%, at approximately 12 o'clock 50%, at a maximum value of 99%, the presence of a triangular wave can be increased to 100% when using a control voltage.

The Left and Right Variable outputs are independently controlled by each Modulate control. The Center parameter behaves identically for both outputs.

If the Right output has no patch, the Left output will give the sum of the Left output and an inverted copy of the Right output.If you use only the Left output for a mono signal, you can get interesting fading behavior by modulating one or both waveforms.The effect of the Center parameter when in mono tends to be more subtle due to more phase cancellation in the center of the generated waveform, but can still result in strong overtones when modulated at audio rates. I have.

Wave foldingThe output is the Final output of the DPO, and0-CoastA circuit similar to the Multiply circuit of

When modulated at its minimum value, the wavefolder gain is sufficiently low that the output is functionally silent. Increasing the value of Modulate L/R causes the waveform to appear and then collapse onto itself.The number of folds increases from zero to five through the operating range of each Modulate L/R parameter. The Center parameter modulates the shape of the waveform sent through the wavefolder, as well as the folding point.The lowest parameter value produces the simplest saturated sinusoidal wave, while the highest value produces a series of light, crisp spikes.

Left and right Folded outputs are independently controlled by the Modulate control. The Center parameter behaves identically for both outputs.

If the Right output has no patch, the Left output will contain the combined signal of the left and right wavefolding circuits.If you use only the Left output for a mono signal, you can get interesting fading behavior by modulating one or both waveforms.

Control inputs

Frequency controls

2 つ の1V / OctInputs are used for XPO pitch control/sequencing via a sequencer, keyboard, etc.They are factory calibrated to track at 1 volt per octave,KidneyA CV source quantized to 1V/Oct, such as0-CTRLGreat for creating sequences with unquantized analog voltage sources like Two 2V/Oct inputs are summed with a large Pitch knob, and an FM input to determine the oscillator frequency at any given moment. A second 1V/Oct input is very useful as a transpose input or as an additional exponential FM input.

Exponential FMThe input can be used for vibrato or audio rate FM, pitch envelope or sync sweep, and features an attenuverter that acts as an intensity and polarity control.

Linear FMInput can be via another VCO orMATHPerfect for fast cycling functions from XPO or audio rate FM with self-patching from XPO itself.This input is normalized to a variation of the Sub Oscillator output, allowing the creation of superimposed sub-harmonics without mixing the Sub Oscillator with other waveform outputs.

FM Depthis the parameter that sets the amount of linear FM applied, and can be voltage controlled via the accompanying CV input. Dynamic FM is useful for creating dynamic harmonic profiles with voltage control, which can range from very rich overtones to simple, overtoneless sounds.Input Attenuator is a multi-function knob that acts as a panel control as well as an attenuator that scales the incoming CV if there is a patch. The state of FM Depth isFM Depth Activity Windowshown in red through .Note that even if the Linear FM input is unpatched, the FM Depth control remains active, controlling the amount of FM coming out of the XPO's Sub oscillator.

XPO is uniqueSyncimplement the circuit. The XPO will attempt to match the frequency of the signal incoming to the Sync input.This actually makes every pitch/frequency control on XPO a timbre control as well.This synchronization circuit can be described as "medium sync".This is because it allows a wider range of oscillator resets than "soft sync", which has few resets, or "hard sync", which always resets, creating a ripple effect as the pitch of the sync source sweeps. From the XPO's output you can hear 'mountains' of hard sync and 'valleys' of missing resets.

Timbre Controls

PWM, Vari-Timbre, Wave folding, Each of these three stereo output pairs is affected in a unique way by the Modulate L/R control.For all stereo pairs, Modulate L affects only the Left output and Modulate R only affects the Right output. When using only the Left output jack, both outputs are mixed to create a mono signal, which is affected by both Left and Right Modulate controls.Each Modulate control has a knob and attenuverter, and the Modulate L input is normalized to Modulate R.This makes it possible to modulate both sides using a single CV source to Modulate L, with modulation depth and polarity set independently by their respective knobs and attenuverters.

CenterThe parameters are combo knobs that act as panel controls or as attenuators for incoming CVs if you have a patch.This parameter affects the Vari-Timbre and Wavefolding outputs in different ways.

Vari-TimbreOn the output, when Modulate is at its lowest value, Center performs a crossfade from a sine wave at its lowest value to a sawtooth wave at its highest value.The resulting shape is used to 'feed' the Vari-Timbre parameter with higher Modulate values.Note that if only the left Vari-Timbre output is patched and used in mono, the center parameter of the low-frequency modulated mono Vari-Timbre tends to be delicate due to the interaction of the two outputs.This makes an excellent source for audio rate modulation as it does not create pitch bend even at maximum applied amounts.

Wave folding, the Center parameter adjusts the shape and angle of the waveform sent to the left and right wavefolders as the value of the Modulate control is increased.The resulting sound can be bright and light or dark and rich at various points of the Center parameter value.