Trace

Analog Morphing Scanner

User Manual

LIMITED WARRANTY

Vostok Instruments warrants this product to be free of defects in material or construction for three years from the date of purchase (invoice required).

During that period, any malfunctioning unit will be repaired, serviced, and calibrated on a return-to-factory basis, with the customer paying the transit cost to Vostok Instruments. 

Malfunctions resulting from wrong power supply voltages, backward or reverse power connections, abusive treatment, removing knobs, or any other obvious user-inflict faults are not covered by this warranty, and regular rates will apply. 

Vostok Instruments implies and accepts no responsibility for harm to persons or apparatus caused through the operation of this product. 

The device intended for repair or replacement under warranty should be shipped in the original packaging only. Vostok Instruments can not take any responsibility for damages caused during transport. So before sending us anything, contact us at vostokinstruments@gmail.com.

INSTALLATION

Trace needs a power supply capable of providing 70mA on each of the +12V and -12V rails, and 4HP of free space in your case. We strongly recommend you to check the current consumption of your system on the ModularGrid website and your power supply capabilities before plugging in the module.

To install it, turn your case off and connect the supplied power cable to both the module and your Bus Board, minding the polarity so that the RED Stripe on the cable is oriented to the -12V line on both the module and the Bus Board. Please refer to your case manufacturers’ specifications for the location of the negative supply.

Always turn your case off before plugging and unplugging any Eurorack module.

INTRODUCTION

Trace is a four-channel Interpolating Scanner created in collaboration with Ben Wilson “DivKid”.

Introduced by Jurgen Haible in 1994 and later improved by Donald Tillman in 1999, the Interpolating Scanning circuit is a hybrid between a signal selector and a crossfader. 

The circuit morphs between the inputs, fading from one to the next as the voltage control rises. The Trace version of this classic circuit comes with a custom, fine-tuned slope response that prioritizes a smooth transition between the inputs, providing interesting middle points between the channels and improving its behavior when controlled by external CV signals.

Following Ben’s unique vision and module design, Trace unifies the compact form that characterizes his modules with our hardware and aesthetics. 

From waveform morphing and CV-controlled transitions, to audio-rate scanning. Trace brings a new horizon of patching possibilities to any system.

TECHNICAL SPECIFICATIONS

  • Size: 4HP 

  • Current draw: +/-12V: 70mA, +5V: 0mA 

  • Depth: 32mm (including power cable) 

  • Input Impedance: 51kΩ (Signal Inputs), 100kΩ (SCAN CV Input)

  • Output Impedance: 1kΩ

OVERVIEW

  1. SCAN CV Input: CV control over the SCAN parameter. Range 5 Vp-p.

  2. Signal Output: DC-Coupled.

  3. Signal Inputs: DC-Coupled.

  4. SCAN Fader: morphs through the inputs from the bottom (1) to the top (4).

  5. LED Signal Indicators: shows the position of the scanning circuit.

  6. SCAN CV Input Mode Switch: selects the polarity of the signal plugged into the SCAN input between Original (left) and Inverted (right).

  7. SCAN CV Input Attenuator: controls the level of the signal plugged into the SCAN input.

FUNCTIONAL MAP

Scanning

Signal scanning is Trace's main function. By moving the SCAN slider from the bottom to the top, we can morph between the different inputs in ascendant order, having the first channel (1) at the bottom position and the last channel (4) at the top.

The figure shows the SCAN circuit behavior. The Scanner bank works as an array of four serial macro-controlled VCAs, which allows fading between the four channels.

Scan CV Control

The input scanning can be CV controlled using the SCAN CV Input, which sums the value of its incoming signal to the voltage value set by the SCAN slider. See figure below.

The circuit covers the whole scanning span with 5Vp-p signals. Thanks to the onboard attenuator, hotter signals can be adjusted to work within the desired scanning range. 

If the limit of 5Vp-p is exceeded, e.g., by applying a +/-5V LFO with the attenuator fully clockwise and the SCAN Fader at the mid position. The circuit will hold its position at the extremes till the input voltage turns down into the operating range, which can be interesting for creating an asymmetric scan. 

The incoming signal can be inverted using the two-position switch, allowing it to reverse the scanning direction concerning the incoming CV signal.

PATCH EXAMPLES BY BEN WILSON DIVKID

Hello, Ben (DivKid) here! For the manual I wanted to share 4 patches that we demonstrated in the first video about Trace. Do go watch the video and use this manual as a reference for remaking these patches for yourselves too.

Patch 1: Waveform Morphing & Complex Oscillator Tones

Basic Morphing Waveforms Patch

  • Patch four different waveform outputs from a standard VCO into the inputs of trace.

  • Use a common modulator such as an LFO or envelope to the scan CV input.

  • Adjust the scan CV input attenuation and manual scan slider to dial in your modulation.

  • Monitor the output of Trace and adjust the modulation to morph through the VCO waveforms to suit your patch.

‘Complex Oscillator’ tones from one VCO

  • Stick with four VCO waveforms as the inputs to Trace.

  • Swap the modulation source to another waveform from the VCO providing the Trace inputs.

  • Adjust the manual slider and CV attenuation on Trace to dial in new audio rate modulation ‘Complex Oscillator’ tones.

  • If you don’t have 5 waveform outputs on your VCO you can leave some of the Trace inputs empty. This will scan to 0V between the other waveform inputs and work well too.

Description

I really like this patch as it takes one oscillator and very easily gives you more control and animation over basic waveforms. Modulation can come from simple sources like LFO and envelopes or to use another oscillator waveform to lean into more ‘complex oscillator’ style tones.

Take any basic VCO that has multiple waveform outputs and patch those outputs into the four inputs. You may want to arrange them from the most simple to the more harmonically complex, such as sine wave to input 1, triangle to input 2, saw wave to input 3 and a pulse with PWM to input 4.

Patch the output of Trace like you would a typical oscillator output, this may be into a filter and VCA, a LPG, or droning into some FX depending on the goal for the patch. I like to skip the filter in this sort of patching as we can morph through the harmonics in the waveforms on Trace. However for this example I suggest starting with the output of Trace direct to your mixer/output while you set up the patch.

Start with a slow LFO into the scan CV, adjust the manual scan slider to the mid position and turn up the CV attenuation to let the typically bipolar signal from your LFO modulate above and below the slider position. While using your ears to dial in modulation is always recommended you can watch the LEDs on Trace to see how the modulation is affecting the output.

Try swapping the LFO for an envelope so you have a waveform morph that plays in time with each note in your sequences. If you arrange the inputs with waveforms with the least harmonics to most harmonics you can emulate a typical low pass filter sweep. Where on a filter an envelope would open the cut off and let in more harmonics and then remove them as the envelope decays away. We can have an envelope scan through sines and triangles to saws and squares, similarly increasing in harmonic content and then decreasing in harmonic content as the envelope decays.

To advance this patch further we can use audio rate modulation to gain what would typically be tones you’d find in more advanced patching or with ‘Complex Oscillators’ (those are usually Buchla 259 variants with two oscillators and a modulation section). As we have already patch multiple waveform outputs from one VCO into the Trace inputs then take an additional waveform output to the Scan CV. If you don’t have 5 waveform outputs on your VCO remove one of the inputs and use that as the Trace scan CV. This will scan through 0V (no input) between the waveforms and still work well to make new tones to work with. For example take a triangle waveform to input 1, saw waveform to input 2, nothing to input 3 and a pulse out to input 4, then use your sine waveform to the scan CV. Adjust the scan CV and manual scan slider to taste to explore new waveforms.

All of this is extra fun with a scope so you can see your waveforms morphing too.

Patch 2: Modulation Morphing

Modulation Source Scanning

  • Patch multiple modulation sources into the inputs of Trace.

  • We’re using an envelope generator, stepped random voltages, LFO and an audio rate VCO.

  • Patch the output of Trace into a filter cut off, alternatively try a folder, PWM or other waveshaper.

  • Manually sweep through the modulation sources with the slider as you’re patterns play.

  • Try using sequences, slow LFOs and random sources to drift through different modulation sources as your patches evolve.

Description

This is a really fun patch, I like mixing modulation, especially for filter cut off control but breaking out the different modulation sources into Trace we can morph between them and find interesting and often unique “in-between” positions as we morph and blend through them.

With that in mind it’s worth thinking about which modulation sources you use in each input. In this patch we’re using an envelope generator, stepped random voltages, an LFO and an audio rate VCO. I’m particularly fond of percussive decay envelopes blended with stepped random voltages. It gives the impression of velocity and accents and creates dynamic and excitement movement in a filter or wavefolder. So I was sure to place those sources as inputs that will scan into each other. Following that the contrast of the hard edged stepped random and a smooth slow LFO is good fun before finally introducing audio rate overtones.

This example also works nicely with multiple envelopes playing different gate patterns, morphing through multiple simple LFOs to create more complex ones or a combination of clocked sources.

Patch 3: Sound Selector & Pattern Maker

Sound Selection & Scanning

  • Take multiple percussion samples playing the same clock or trigger rhythm into the 4 inputs of Trace. This could be 4 hi hats for example, or different sounds.

  • Patch the output of Trace into your mixer or system output.

  • First manually scan through the sounds, listening to how they sounds mix and blend into each other rather than hard switch between the inputs.

  • Use a clocked LFO to scan through the inputs that plays in time with your input sounds. You’ll have an evolving musical shift in sound selection.

Unique pattern generation

  • With the patch set as above, change the scan CV to CV sequencer.

  • Adjust the Scan CV attenuation to suit your sequence voltage levels & dial in a value per step to select different sounds and the sequence plays.

  • Working this way you can shift between open and close hi hats, different drum machines or custom sample sounds and create unique patterns that you may not otherwise sequence.

Description

I really like this patch with a drum sampler module and using 4 of the same types of sounds, I’ve had great results using different hi hat sounds whether they’re synthesized or samples. Using just a clock signal to all 4 sounds so they all fire on every step of a beat we can then scan between them to create a musical pattern in a unique way.

Take your time to dial in the attenuation levels and the value on each step of your CV sequencer. You can play with not just selecting which input is used like a switch but between blends/mixes of two inputs at once for a seemingly infinite variety of sounds for your hi hats.

This patch also works well with other percussive style patching, such as complex bassline or melodies where the ‘hook’ isn’t just the pitch of the notes but the sonic qualities of scanning through multiple oscillators, waveforms or FX processed versions of your patch.

Patch 4: Make Complex Melodies from Modulation

Making melodies from quantising scanned modulation

  • Create a variety of clock synced LFOs of different clock divisions and patch these into the inputs of Trace.

  • Patch the output of Trace into an attenuator and then into a quantiser to force the modulation into a musical scale.

  • Patch the output of your quantiser into the v/oct input on an oscillator.

  • With the Scan set to its lowest value (so it only plays input 1) adjust the external attenuator to set the musical range you want to work within.

  • Trigger the quantising of new notes on your quantiser with a steady clock that works with your clocked modulation sources.

  • Manually scan through your inputs to listen to how each different LFO creates musical patterns. A ramp up would create a rising scale like sound, a triangle LFO an up down arpeggio and so on.

  • Patch a slower LFO (either a much slower clocked LFO, or a free running source) into the Scan CV and adjust Scan CV attenuation to morph through the LFOs, creating new evolving melodies from your modulation.

Description

Creating scale runs and arpeggiator type patterns from LFOs is good fun in modular and it can lead to creating melodies you wouldn’t otherwise program in a sequencer. Like with lots of things in modular attention is key here. Attenuating the output of Trace to work within a musical range (most patterns are fine with 2 octaves, so a 2V range) but also attenuating the Scan CV on Trace to move through the inputs appropriately for the patch.

This patch works great with something like a Pamela’s Workout. Where you can have inputs that are clock synced but as a range of speeds and shapes. One example maybe input 1 - a /8 triangle wave, input 2 a /16 ramp, input 3 a /32 sine wave and input 4 a /56 ramp down.

You can then take an even longer division (say /128) and slowly scan through these sources to create musically relevant, tempo synced patterns that will repeat over a longer step count.

Changing the divisor to odd numbers can create further generation as each LFO isn’t repeating with standard divisible 4/4 style step counts.

Typically I’d use a x1 trigger on my quantiser to create a new note on every step while the LFOs are moving within their divisions of those note triggering on the quantiser. However you can try with different rhythms and be playful with how you trigger your quantiser to pull new notes from the scanned modulation.