Klavis Flexshaper Voltage Mapper User Manual

Klavis Flexshaper Voltage Mapper

Introduction

The Flexshaper is a highly versatile module when it comes to modify evolving voltages in other directions and levels. Five settings allow you to fold/expand/clip/compress/invert partially or completely any CV or audio signal. The module can act as an envelope-shaping tool, frequency multiplier, waveshaper, clipper, distortion, limiter, curve changer, and more. Five CV inputs offer limitless control over the placement of the voltage points for dynamic signal sculpting.

Features at a glance

• Process from DC to full audio range
• Unipolar/bipolar input mode switch
• Nominal & clip level LEDs
• Output signal LED
• Input gain knob for nominal level setting, allows clean flat clipping when overdriven
• Five manual voltage mapping potentiometers
• Five CV control of the voltage mapping points
• Simultaneously active unipolar and bipolar outputs
• Firmware update via a simple audio file
• Compact and skiff-friendly module

Installation and security

Purpose

This module is meant for installation in a Eurorack-compliant chassis. It adheres to Eurorack Doepfer mechanical and electrical specifications. Do not attempt using this module in other mechanical or electrical contexts.

Installation

Before the installation, disconnect the mains power supply from your modular system. Some power supplies are not safely isolated; there is a risk of injury!

See in the specifications if this module requires 5V from the supply rails. If 5V is needed and your rack is not providing 5V, do not attempt connection!

Check that the current consumption requirements of this module, when added to your installed set of modules do not exceed the available current from your supply. This is done by adding up the current draw of all modules (mA) separately for each of 5V, 12V and -12V rails. (1000mA = 1 amp). If any of these 3 sums exceeds the available current of your supply for that voltage, do not connect the module to your system; you need a stronger power supply.

The provided supply flat cable can only be inserted in the appropriate orientation at the back of the module, so there is no risk of error on that end. However, you should pay attention to the orientation of the cable in the socket of the supply PCB inside your chassis. Cheap sockets without shrouding may allow you to plug in the connector the wrong way!

The red stripe on the cable should match a stripe printed on the supply board. The stripe also indicates the -12V side. In case there is no stripe, a -12V marking is a safe indication of the orientation.

Double check that the connectors are fully inserted and correctly oriented before switching on the power supply. In case of an anomaly, switch off the power supply immediately and check everything again.

Firmware update

If needed, the product can be updated by playing an audio file such as “Flexshaper_1.00.wav”.
Not finding any file on Klavis web product’s page means there is no update available.

Procedure

• Connect a mono or stereo cable between your audio playing device headphone output and the Flexshaper input.
• Prepare to play the audio file
• Set the play level of your playing device at two thirds
• While pressing the Bipolar button, switch on your modular case supply
• The yellow LED will flash
• Start playing the audio file

If everything goes fine

• The yellow LED will goes steady on
• As the update is progressing, the output white LED will go brighter
• When the white and green LEDs are flashing, the firmware is updated successfully
• Press the button to restart the module

If the sound level is too low

• The red, yellow and white LEDs will blink
• Stop audio playback
• Slightly increase the audio playback level
• Press the button
• Start audio playback from the beginning

If there is an error during the playback

• The red and white LEDs will blink

It is possible that the sound setting was too loud to begin with. Diminish the sound level drastically and restart the procedure.

Playback error can also be due to various parasitic sound causes:

• Touching the cable
• Using sound-generating features of your phone or computer
• Some power saving feature affects the audio playback
• Surrounding noisy modules, bad electrical grounding or modular supply noise

Birth of the product

The idea of the Flexshaper comes from a feature in the Oberheim® Matrix synthesizers called Tracking Generator. This signal processor was part of the modulation matrix and meant to be virtually inserted between modulation sources and destinations in order to change the shape of the controlling signal.

The Flexshaper applies the same concept using the same 5 shaping points. However, it goes beyond Oberheim’s implementation on two main aspects:

• It goes fast enough to process signals at full audio rate
• The 5 points are dynamically adjustable (CV) in real-time

Besides, the Flexshaper can process adequately bipolar and unipolar Eurorack signals.

Concept of voltage mapping

Note: actually the input and output lines should superpose exactly; they’re here shown apart for clarity.

Incoming voltages are divided in 4 consecutive ranges defined by 5 points.
The floor and ceiling points define the minimum and maximum voltages processed. Voltages beyond those limits will be considered at the limit. Three other points are set equally between the floor and ceiling points.
The knobs tell for each point’s default place where the incoming voltage should go. In other words, the knob “Halfway” defines where a voltage entering at halfway will end up.
When the knobs are set as shown, outgoing voltages are replicating the incoming voltages. The module does “nothing”. With such default setting, we define that what comes at the top should go at the top, and so on for each setting point.

Another example helps understanding the Flexshaper’s mode of operation: If you set all five points very precisely to the same scale value (say, the 12 o’clock position), then a constant mid voltage will result at the output no matter which voltage level is present at the input jack.

Unipolar and bipolar considerations

The Flexshaper handles unipolar (positive only) and bipolar (mixed positive and negative) signals differently. To benefit from the entire control range, it is better to select the appropriate unipolar/bipolar setting. Usually, VCOs and LFOs are bipolar while envelope generators are unipolar.

Whatever the input setting, both unipolar and bipolar outputs are simultaneously available. The only differences between them are a voltage offset and the overall amplitude.

Nothing forbids you from entering a bipolar signal to use it as a unipolar result and vice-versa.
This might be useful for modulation signals such as a (bipolar) LFO you want to use as a positive modulation only. Bringing a bipolar signal with the input setting on unipolar will discard the negative part of the signal.

Here are examples of signal processing in both input modes.

Unipolar out

Bipolar out

Module description

Input

Bipolar button and LED

Selects the type of signal you bring to the module. When the bipolar LED is off, you are in unipolar input mode.

Gain button and level LEDs

To benefit from the best dynamics it is recommended to adjust the gain knob so that the green LED goes regularly on. If you want to avoid clipping, the red LED should never go on.

NOTE about clipping

Since signals beyond the valid range are clipped, they could not be handled differently from those reaching the top and bottom limits of the optimal range. Everything beyond a limit is considered at the limit.

However, clipping can be done purposely in order to achieve interesting wave shaping results.

The Flexshaper clips the signal in a perfectly flat and clean way; this feature is useful to purposely limit or flatten a signal.

Point setting knobs and CV inputs

The five setting knobs position the voltage for each level point. Default points are printed as black dots around the pots. When the pots’ cursors match the dots, the output signal is identical to the input signal (besides possible discrepancy due to bipolar<>unipolar in/out mismatch)
The CV inputs add up to the manual setting of the knobs. The knobs are an offset of the CV – they do not act as attenuators!

Outputs and LED

Both outputs deliver the same signal with only the offset and gain being different. They can be used simultaneously.
The bipolar output is typically used for audio signals or LFO; the unipolar output could be used for envelopes or similar positive-only signals.
The output LED amplitude represents the unipolar signal. On the bipolar output, the LED off represents maximum negative voltage, half brilliance is zero volt, and full brightness corresponds to maximum voltage.

Use tips

Shaping vs modulating CV signals – Setting the output level

Theoretically, the knob settings can modify a signal such as each setting point of the resulting signal is not only at the right place among other points, but also at the right overall level.

In practice, defining the shape and out level in a single operation is difficult to do. There is a permanent interdependence between these adjustments.

It is much easier to shape the signal on the Flex shaper using the full range of the pots and patch a gain control on the output signal. Otherwise, one would have to tweak most Flex shaper pots every time the resulting signal needs a gain adjustment.

What input signals give the best results?

Since the Flexshaper remaps the voltages, it is better to have signals that go through voltages progressively and/or present several intermediate levels – instead of being “high” and “low” as is the case with gate signals or pulse/square waves.

In this view, an audio square wave or gate signal are the poorest you can bring to the Flexshaper.

Given that there are only two different levels (one min and one max), all the Flexshaper can do is change the overall level, offset and possibly polarity.

However, a simple audio/LFO triangle will allow creating various levelling effects given that a triangle shape goes progressively through all levels between min and max.

The most interesting audio shapes to process are found in wavetable, additive synthesis, FM and other VCOs offering complex shapes. Processed or “final” sound are also interesting audio sources.

For modulation signals, LFO’s sine, saw and triangle are interesting enough to be remapped; even better if they offer some waveshaping on their own. When using envelopes, non-zero attack, decay and release times as well as a sustain level away from min or max will allow more creativity.

Dynamic clipping for more waveshaping – Adding a VCA
When doing audio waveshaping, we suggest setting up a modulated VCA in front of the Flexshaper and adjust the Flexshaper gain such as to clip deliberately. This will also change the relation between the signal and the setting points which will all move at once, creating drastic changes.

Adjusting a keyboard’s dynamics

The Flexshaper is perfectly suited to modify the velocity curve of a touch- sensitive keyboard, especially if it lacks adjustable dynamic curves. If you find that your keyboard generates too strong velocity values while you are playing pianissimo, try processing the velocity CV with the Flexshaper by setting all knobs to their default settings, and then experiment with the “Middown” and “Halfway” knobs. By adjusting them to lower values, you can mimick a keybed action that responds to softer playing styles.

It also works the other way round: To reduce the velocity when you hit the keys hard, turn down the “Halfway” and “Mid-up” knobs to your liking – probably it will require some trial and error todiscover the suitable dynamic response.

This also applies for other creative effects and playing techniques if your controller keyboard has the corresponding output jacks: You could for instance adjust the channel aftertouch or the sensitivity of the modulation wheel in order to apply extremely smooth amounts of vibrato in the lower range.

Applications

The examples are deliberately “academic” to help you understand the logic of the system. Any deviation from these examples and adding CV might result in more interesting results! ☺

Since the Flexshaper checks the various voltage levels to remap, waves with slopes tend to offer more interesting results. This is why the examples rely on sine, sawtooth and triangle rather than square or pulse waves.

Triangle to sine

Altering the Ceiling and Floor settings inflects the min and max voltages for a rounder shape.
A subtle touch of clipping finishes the rounding off by shaving the top and bottom peaks.
If you can’t look at the wave on an oscilloscope to fine tweak the settings, you can tell that you tend to a sine wave when sounds gets softer.

Frequency doubling saw to triangle

Alternating the settings to min and max all along the slope creates a pair of perfectly shaped triangles.

This processing is also useful to create a second set of random levels behind a [sample& hold + noise] patch doing random steps.
The derived signal will be in perfect time relation but providing seemingly unrelated levels.

Frequency doubling – triangle to triangle

The floor setting at the opposite of the incoming wave makes the doubling. The two mid knobs are put halfway to linearize the slopes around the newly created triangle.

Frequency Tripling – sine/triangle to mixed wave

By mixing slopes derived from doubling and quadrupling we end up with a signal that presents 3 cycles over the time of one incoming cycle.
There are two variations with a different timbre. By modulating the two related CVs with inverted polarity voltages, the timbre change can be automated.

Frequency quadrupling – triangle to triangle

Based on the Saw doubling example, both the rising and falling slopes of the triangle will each create two waves resulting in a triangle signal at four times the incoming frequency.

Half wave rectifying

By pretending that the wave is unipolar, the bottom half will be cut off.
The 5 settings will now apply to the remaining positive half of the incoming signal.
On the bipolar output, the resulting signal will be balanced around zero as a typical bipolar wave.

Deriving a melody

When fed with the V/Oct signal from a sequencer, it is possible to remap the incoming voltages to derive a second melodic line from the incoming one. If harmony needs be maintained, a melodic quantizer is required. Input and output can be used in unipolar or bipolar as needed.

Doubling a decaying envelope

This trick can be used for percussive sounds where a single decaying envelope becomes a pair of consecutive envelopes.
The peak level of the two envelopes can be set independently by the Ceiling and Halfway pots.

Several variations are possible by using the 5th pot and reassigning the role of the pots 2 to 5. Flats (holds) or two stepped-decay are then possible.

Specifications

Mechanical

Supply

The supply socket is protected against reverse insertion.

Input/output

All inputs and outputs can withstand signals between -12V and +12V without harm.

Signals

Packing list

The box contains:

• Flexshaper module
• 2x M3 black mounting screws + washers
• Eurorack-compliant 16-pin supply cable
• Quick setup notice

Klavis products, including PCB and metalwork, are designed and manufactured in Europe.

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