Soleo Vero#

Patch-through stroboscope tuner


Soleo Vero is a 4HP stroboscope tuner for up to three oscillators. Patch directly through the Soleo Vero to avoid patching and repatching. Stroboscope allows tuning across a range of octaves on the fly - and even without audio monitoring. No more bumped oscillator surprises! Optional mode allows tuning to either the 440 Hz or 432 Hz standards.

  • Type: Tuner
  • Size: 4HP Eurorack
  • Depth: 0.8 inch
  • Power: 2x5 Eurorack
  • +12 V: 42 mA
  • -12 V: 5 mA


Soleo -- from Latin solere: "to be accustomed to"

Vero -- from Latin vero: "without a doubt"

"I am in the habit of truth"

Tuning range#

Soleo Vero tunes from the lowest A of 27.5 Hz to a highest A of 3520 Hz.


Power connector

To power your Noise Engineering module, turn off your case. Plug one end of your ribbon cable into your power board so that the red stripe on the ribbon cable is aligned to the side that says -12 V and each pin on the power header is plugged into the connector on the ribbon. Make sure no pins are overhanging the connector! If they are, unplug it and realign.

Line up the red stripe on the ribbon cable so that it matches the white stripe and/or -12 V indication on the board and plug in the connector.

Screw your module into your case before powering on the module. You risk bumping the module's PCB against something metallic and damaging it if it's not properly secured when powered on.

You should be good to go if you followed these instructions. Now go make some noise!

A final note. Some modules have other headers -- they may have a different number of pins or may say "not power". In general, unless a manual tells you otherwise, do not connect those to power.


illustration of Soleo Vero's interface

Three inputs, each normaled horizontally across the module to its output.
1/2/3 Switch
Selects which input is being tuned.
Chooses which note you wish to tune to. Tap once to see current setting. Tap again to select another note. The selected note will be applied to all three channels.
The green octave readout gives a quick indication of the octave of oscillator's pitch. Use to cross reference across channels.
Blue LEDs that illuminate when coarse tuning an oscillator to tell you whether the oscillator is flat or sharp.
The stroboscope portion of the display is the fine tuning readout. As with other stroboscope tuners, when the display stabilizes, the input oscillator is identical in pitch to the internal reference. As long as the strobe is stable or moving very slowly, the input oscillator will be in tune.

Patch tutorial#

  1. Patch the output of an oscillator into In 1.
  2. Choose In 1 with the Input switch.
  3. Choose a note you'd like to tune to using the Note button.
  4. Use your oscillator's pitch control to move to the octave you'd like to be in. When the pitch is close, the sharp or flat indicator LED will illuminate.
  5. Adjust the oscillator in the opposite direction and continue to tune up or down until the strobe stops moving.

Optional: plug the output into a mixer to listen, too.


Tuning percussive sounds can be difficult. If possible, temporarily disable any pitch modulation on sounds before tuning. For instance, if using the Basimilus Iteritas Alter, use Skin mode when tuning, then switch back to the desired mode. The module will still be in tune.

Changing modes#

To change between A = 440 Hz and A = 432 Hz tuning standard modes, power cycle the Soleo Vero while pressing the Note button. The illuminated lights on the stroboscope at startup will indicate the current mode:

Illustration of Soleo Vero in 400 Hz mode and 432 Hz mode

Technical details#

Stroboscopes are a really clever electro/mechanical/visual hybrid device that allow one to measure relative frequency with extremely high accuracy. A signal is generated from an accurate reference clock; this can modulate the signal to be measured. In older mechanical strobes, this modulation was performed by a disk with stripes painted on it rotated at an accurate speed while the input signal controlled the brightness of a lamp. This setup is a mechanical/optical computer that determines the correlation between the reference signal (a square wave at a particular frequency) and the input signal. Adjusting the input signal to have a stable correlation to the reference will minimize the frequency difference for clean input signals.

Soleo Vero uses similar principals but ditches the motor and disc with LEDs that are driven by the input signal and modulated by the reference clock. An accurate, precise and temperature/time stable crystal timebase forms the basis of this control and a microcontroller manages the various time base divisions and coarse measurements required for the display.

The user's eye performs the final "calculation" which is significantly more precise than the ability of the ear to hear pitch differences.

Soleo Vero will work with any oscillator, but some with very complex waveforms may be tricky. For example the Loquelic Iteritas, with two oscillators, can be tuned through the following process:

  1. Use the Master switch to choose the oscillator (A or B) you which to tune.
  2. Turn all tone settings low (if you are in PM Mode, turn Damp counterclockwise for A and clockwise for B).


No calibration is needed during the lifetime of Soleo Vero.

Design notes#

This module was borne out of the continuous feedback we both received from modular users on the difficulty of tuning oscillators (and keeping them in tune through transport, long patches, temperature changes, etc.). Tyler and Alex of WMD made a lot of helpful suggestions that affected the initial design. The idea of doing an electrical/optical correlation computer involving human perception as an integral feature was also of purely personal interest to Stephen as he has been deeply fascinated by analog, mechanical and various hybrid-technique computers for much of his adult life.


We will repair or replace (at our discretion) any product that we manufactured as long as we are in business and are able to get the parts to do so. We aim to support modules that have been discontinued for as long as possible. This warranty does not apply to normal wear and tear, including art/panel wear, or any products that have been modified, abused, or misused. Our warranty is limited to manufacturing defects.

Warranty repairs/replacements are free. Repairs due to user modification or other damage are charged at an affordable rate. Customers are responsible for the cost of shipping to Noise Engineering for repair.

All returns must be coordinated through Noise Engineering; returns without a Return Authorization will be refused and returned to sender.

Please contact us if you think one of your modules needs a repair.

Special thanks#

  • Joey Blush
  • Matt Lange
  • Instagrammers Deweythomas & Pozzetronics for the 432 Hz suggestion
  • Alex Anderson
  • Tyler Thompson