MAKE NOISE STO (01) PDF DOCUMENT

Always turn the Eurorack case off and unplug the power cord before plugging or un-plugging any Eurorack bus board connection cable. Do not touch any electrical terminals when attaching any Eurorack bus board cable.

The Make Noise STO is an electronic music module requiring 40mA of +12VDC and 30 mA of -12VDC regulated voltages. To install, find 8HP in your Eurorack synthesizer case. Confirm proper installation of the included eurorack bus board connector cable on the backside of the module. Plug the bus board connector cable into the Eurorack style bus board, minding the polarity so that the RED stripe on the cable is oriented to the NEGATIVE 12 Volt line on both the module and the bus board. On the Make Noise 6U or 3U Busboard, the negative 12 Volt line is indicated by the white stripe.

The STO is a compact Voltage Controlled Oscillator (VCO) designed for generating Sine waves, Variable wave-Shapes, Sub-Octaves, Oscillator SYNC and Linear FM in the analog domain. It is described as a more subtle and melodic friend to the DPO’s complex harmonic lattice. The STO yields harmonically rich textures through the use of Hard Sync, Linear FM and Variable Shape, but is primarily designed for melody.

The STO uses a Triangle Core and has outputs for Sine, SUB, and Variable Shape. The Sine is shaped from the Triangle. The Sub-Oscillator has its own gate input that lets you turn it on/off at will. The Variable SHAPE ripples both Even and Odd Harmonics, resulting in subtle timbral shifts where the fundamental frequency is never masked. The STO is a 100% analog musical instrument that is not suitable for laboratory use.

1. Variable Shape Waveform Output: 10Vpp

2. Sub-Oscillator Output: 12Vpp

3. Sine Waveform Output: 10Vpp

4. Coarse Tune panel control: 9 octave range 8hz-4khz

5. 1V/Octave Scale Trimmer (Calibration Use Only)

6. Fine Tune panel control: +/-2.5 semi-tone range

7. Linear FM Level: uni-polar attenuator for Linear FM input

8. Linear FM Input: AC coupled, 10V range

9. Variable Shape: Ripples Even and Odd harmonics. With nothing patched to Variable Shape CV Input, it works as a standard panel control. With a signal patched to the Variable Shape CV Input, it works as an attenuator for that signal.

10. Variable Shape CV Input: Direct Coupled uni-polar control signal input, range 0V to +8V

11. Expo Input: Exponential frequency control input. Bi-polar, 10V range

12. 1V/Octave control Input: bi-polar pitch control, optimal range +/-5V

13. S-Gate: Resets and turns Sub-Oscillator ON at Gate High, turns Off at Gate Low. Just about any signal that exceeds 1V will work here.

14. SYNC: Resets Oscillator Core. Just about any 10Vpp audio rate signal works here.

The STO has three wave shapes derived from the oscillator core, all roughly 10V peak to peak and centered around 0V (bi-polar).

Sine Wave: Derived from the Triangle core, it has almost no harmonics. This makes it great for blending with signals of greater harmonic content to strengthen the fundamental, and it’s a good starting point for complex FM sounds because sidebands are not obscured by existing harmonics.

Variable Shape: This is a unique waveform derived from the Sine. It is more harmonically rich than the Sine, but the fundamental frequency remains very strong. It carries harmonics and sidebands from Hard SYNC and FM with greater presence than the Sine shape, making it a more aggressive signal. It’s also excellent for subtractive synthesis patching.

Sub-Oscillator: This is a stepped rectangular shape derived from the comparator on the core. Its sound is similar to a Square wave, but it is one octave below the frequency of the Variable Shape and Sine waveforms, making it pleasant to combine with them. It thickens the sound and provides more harmonics for filters.

EXPO CV Input: This input is similar to the 1V/Octave input and can be used for adding or transposing a sequence. It is also highly useful for sweeping the STO’s frequency to animate SYNC sounds or percussion patches. For wild textures, it can be used for Exponential FM. When using it for modulation, it is recommended to patch a VCA (like an Optomix) in series before the input, as there is no associated attenuator.

1V/Octave Input: This is typically used for controlling the pitch of the STO from a sequencer, CV keyboard, or MIDI to CV converter. It can also be used for all the functions described for the EXPO CV Input. As with the EXPO input, if used for modulation, a VCA should be patched in series before it.

S-Gate Input: This input turns the Sub-Oscillator ON, OFF, and also Resets it. Any signal can work as a gate. The Sub-Oscillator resets at the onset of the Gate High state (Sub On). This is useful for animating the Sub-Oscillator, allowing it to have rhythmic or percussive patterns not associated with the other outputs. Using a narrow signal, like a Saw wave from another VCO, can create a sync-type sound in the Sub-Oscillator without affecting the other outputs.

Linear FM: This superimposes the frequency of a modulating oscillator onto the STO. It attempts to preserve the base frequency of the STO, allowing for harmonically rich waveforms that can still track the 1V/Octave scale properly. The Linear FM input is AC coupled and has a Level control. As you increase the Level, the resulting signals at all outputs become more complex. At greater than 80% Level, the Linear FM bus goes into overdrive, and the STO will not track accurately.

Exponential FM: This is achieved by patching a modulating oscillator to the EXPO input. For dynamic control over the FM amount (index), you should patch a VCA in series before the EXPO input. Exponential FM is much deeper and more complex than Linear FM; however, it severely changes the base frequency of the oscillator, causing it to no longer track the 1V/Octave scale properly. It is highly useful for creating complex signals where precise pitch tracking is not required, such as percussion sounds.

SYNC patches introduce strong harmonics to all of the STO’s outputs. It uses a modulation method where the STO’s core is made to conform to an external VCO. Once SYNC’d, the STO core restarts its period at each cycle of the external VCO signal, so they share the same base frequency.

Additional harmonics are created when the STO’s frequency is set higher than that of the external VCO it is SYNC’d to. In a SYNC patch, the timbre of the STO can be altered by varying its frequency against the master frequency set by the external VCO. Slow sweeping modulation of the STO’s frequency (e.g., from an envelope or LFO patched to the EXPO Input) results in sweeping harmonics. Best results are achieved by setting the external VCO to a base frequency of at least 100Hz (around A2) and sweeping the STO’s frequency from 100Hz upward. SYNC tracks more reliably than Linear FM but produces a much more aggressive sound.

This circuit is unique to the STO. It gently ripples both Even and Odd harmonics while always maintaining a strong fundamental frequency. At 0% modulation, the Variable Shape output is a Sine shape, and at 100% it becomes a glitched triangle. While capable of audio rate modulation, it is best served by slower modulations like logarithmic envelopes and LFOs from modules like MATHS or FUNCTION, or Smooth Random Voltages from a WOGGLEBUG. When modulated and combined with the Sub-Oscillator, this output creates a very strong voice for melodic sequencing.

1. Patch the Variable Shape output to the AC input of an MMG module.

2. Patch the Sub-Osc output to the DC input of the MMG.

3. Set the STO Freq knob to around 12:00.

4. Set the MMG input attenuator to 1:00, MMG Freq full counter clockwise, MMG Q to 11:00, and Mode to LP.

5. Patch a slow logarithmic LFO from a module like MATHS to the Shape CV Input on the STO and set the Shape attenuator to about 60%.

6. Patch a sequencer or keyboard CV to the 1V/Octave input on the STO.

7. Patch a sequencer or keyboard gate to an envelope generator (like MATHS or FUNCTION) programmed for a fast Rise, slow Fall, and Exponential shape.

8. Patch this exponential envelope to the Freq 2 CV Input on the MMG.

9. Monitor the MMG Output.

1. Patch the Sine output of the STO to an Optomix CH. 1 Signal Input.

2. Patch a Gate signal to both the Linear FM Input on the STO and the Optomix CH. 1 Strike Input.

3. Set the Linear FM amount on the STO to 12:00 and the Frequency panel control to roughly 9:00.

4. On the Optomix, set the CH. 1 Damp and Control panel controls to full Counter Clock-Wise.

5. Monitor the Optomix CH. 1 Signal Output.

Adjusting the Linear FM amount, Frequency setting, and Damp settings will allow you to create many different Bass Drum sounds. Adding Expo FM from another VCO expands the possibilities.

Patch a sequence (e.g., from a Rene) to the STO’s 1V/Oct input. Then, patch another sequence of a different speed, or control voltage from a keyboard, to the Expo input. The two sequences will be “added” together for transposition. Variations include clocking the transposing sequence at an odd division of the master clock for long periods between repetitions, deriving the transposing sequence from the master sequence via sample and hold, or tuning a square wave LFO to +/- 1V for double octave leaps.

Patch an audio-rate square or sawtooth wave to the STO’s S-Gate input, and another to the Sync input. The Sub output will be “pseudo-synced” to a different frequency from the Sine and Variable outs. If the Sync sources are related, such as from two sides of a DPO with Following engaged, so will be the STO’s outputs.

Mult the control voltage going into the 1V/Oct input to the Shape CV input as well. Take your audio output from the Variable Wave Output. This results in higher pitches having more harmonic content, similar to keyboard tracking on a low-pass filter.

1. Patch a low-frequency square wave (or an EOR/EOC gate from a cycling MATHS, FUNCTION, or CONTOUR) to the S-Gate input.

2. Take the audio output from the SUB Out.

3. Mult the same square wave to the Clock input of a sequencer.

4. Patch the sequencer’s CV output to the STO 1V/Oct input.

5. Adjust the square wave’s pulse width (or the Rise/Fall times on the function generator) to change the length of the “notes.”