Quad programmable Volt/Octave calibrator and transposer
  • Four V/Oct processing channels, each with
    • Curve correction and range expansion for any VCO, VCF or other oscillating circuit with a CV acting on pitch
      Works with other range systems (e.g. Buchla)
    • 1:1 in/out V/Oct mode for use without calibration
    • Switchable semitone quantizer
    • Adjustable portamento time
    • Adjustable glissando time
  • Separate semitone and octave transpose click-encoders
  • Inputs cascading with no added load for stable pitch control
  • Four user presets storing transpose, portamento and glissando
  • Storage of the calibration profile for each channel
  • Maximum voltage range covering 10 octaves
  • Presets, calibration and current state retained over power cycle
  • Volt/Oct inputs factory-calibrated in flash memory
  • User adjustable input scaling to correct voltage inaccuracies in your sources
  • Settings restored after power cycle
  • Easy firmware update via a simple audio file
  • High-quality push-encoders with metal shaft
  • Skiff-friendly & compact module
  • User manual in English and German

The CalTrans solves issues encountered when playing tonal music with a modular system: tracking problems, curves unrelated to Volt per octave ratio, limited octave range, cumbersome transpose, ...
The Caltrans corrects and expands the range of troublesome VCOs and brings V/Oct tracking to anything that oscillates.
Besides calibration, the CalTrans offers live play features. Each channel can be quantized and any combination of them transposed jointly.
VCOs that don't require calibration can be used simply in "Neutral" mode to benefit from the transposition and other musical features.
A pair of rotary encoders with detent allow a precise selection of octaves and semitones.
VCOs whose tracking doesn’t go high (low) enough to follow the leader will see their pitch repositioned in their highest (lowest) possible octave so that the global harmony is unaffected.
You can add a pinch of portamento and glissando to each channel and save the whole in user presets.
The latest firmware adds user editable scaling of the inputs to match sources that do not generate perfect 1V per octave signals.


Dimensions mm inches Eurorack
Height 128.40 5.06 3HE
Width 30.00 1.18 6HP
Depth behind panel
(with supply cable inserted)
36.00 1.41


Supply rail Current draw
+12V 44mA
-12V 8mA
+5V 0mA

This module is so insanely useful and awesome!!
I've been tuning everything by ear and it's been a faff to say the least.. also tracking was out on two of my three oscillators so I was constantly having to rebalance pitches.
This little module automatically gets everything perfectly lined up and tracks them nice and evenly, and then becomes a really neat and easy octave and semitone shifter for each separate channel.
It's ace!
The more I think about it, the more I like it.
It definitely would solve some tracking issues while also opening up new posibilities and it optimizes my workflow.
Very nice module considering its size, functionality and price.
I've spent quite a few hours now with the Caltrans; really great module that does it's job well!
I didnt realize how much time I was spending tuning until that module removed tuning from the work flow.
Highly recommended.
It really changed a lot for me when it comes to playing tonal with my Eurorack.
Once calibrated, the oscillators will stay in tune (with each other) over several octaves, even after turning the synth off and on again.
Love it, makes things so much easier!
Overall I’m really impressed with how this all turned out...
So the CalTrans is an excellent module which does deliver what it promises.
CalTrans is amazingly helpful.. wish I would have gotten it early on in my rack build.
It would have saved me some headaches for sure.


The 3 minutes video ...
... for those in a hurry ! by Synth Music Blog

A hands-on demo by KNH

La demo pratique de KNH en français.

Playing a KOrg MS-20 with a V/Oct keyboard.
The MS-20 is designed to play in Hetz/V which makes it incompatible with V/Oct Eurorack.

Parallel tracking demo with four analog VCOs
by ALEQ Modular

The commented full featured presentation by Marcin.
Since then, the latest firmware offers more features.

Inspiration technology to let you create the difference
Klavis Modular Systems
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