Koma Elektronik Field Kit FX User manual

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The KOMA Elektronik Team

1. Introduction 5
2. User Manual 6
2.1 Getting Started 6
2.2 Function Overview 6
2.2.1 Looper 7
2.2.2 Frequency Shifter 9
2.2.3 Bitcrusher / Sample Rate Reducer 11
2.2.4 Digital Delay 13
2.2.5 Spring Reverb 16
2.2.5.1 Spring Tanks 18
2.2.5.2 Choosing a Tank 21
2.2.6 4-Channel VCA Mixer 24
2.2.7 CV Interface 28
2.2.8 Roll-O-Decks 30
2.2.8.1 4-Step Mini Sequencer 30
2.2.8.2 The Envelope Generator 33
2.2.9 Field Kit FX In A Eurorack System 36
2.2.9.1 Power 36
2.2.9.2 Panel and Connecting to Eurorack 36
Table of contents

2.2.10 Open Source Software 39
3. 50 Ways to Use the Field Kit FX 41
3.1 Effect Patches: The Delay 41
3.2 Effect Patches: The Spring Reverb 46
3.3 Effect Patches: The Looper 51
3.4 Effect Patches: Frequency Shifter 56
3.5 Basic Patches 60
3.6 Plug It In 68
3.7 CV Patches 73
3.8 Feedback Patches 82
3.9 Field Kit FX with the Field Kit 86
4. Frequently Asked Questions 91
5. Warranty 92
6. Imprint 93
7. Who Made The Field Kit Possible 94
8. Glossary 97
9. Patch Sheets 100
Table of contents

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Berlin, February 1st 2018
Thank you so much for purchasing the Field Kit FX!
A year after we launched the electro-acoustic workstation the Field
Kit, we’re happy to introduce you its younger sibling – The Field Kit
FX. Instead of amplifying objects and experimenting with sounds from
everyday life, the FX is a multi-effect device to modulate your sounds
and apply various effects to them.
This manual serves as a guide demonstrating all the functions of
the Field Kit FX, descriptions and specifications of each part of the
device and which tools and instruments work best with it. You will also
get many tips on how to use the device. The Glossary at the end of
the manual explains some of the most important and commonly used
terms, which are underlined throughout the book.
For the hackers amongst you, we added a chapter about the open
source software, and there are also empty patch sheets to keep track
of your patches.
If you have questions about warranty and what to do if your Field Kit
FX is broken, please check the Warranty section towards the end of
this book. If you have a question about your device, please contact
us via [email protected] and we will help you get back
on your way!
Thanks again for your support, in particular the Kickstarter backers,
we could not have done this without you!
All the best from Berlin,
The KOMA Elektronik Team
1. Introduction

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2.1 Getting Started
The FX is a great device to apply effects on various instruments and
signals and works great with any of your electronic instruments, syn-
thesizers and (Eurorack) modular systems.
To get started, you will first need to bring the Field Kit FX to life. Grab
the included 9V PSU and plug the PSU into the DC connector on the
back side of the Field Kit FX.
For the Eurorack version, carefully connect your Field Kit FX to the
bus board of your Eurorack system with a ribbon cable, making sure
-12V aligns with the red stripe and eventually mount the module on
the rails of the case (for more detailed information with photos, skip to
the ‘Field Kit FX In A Eurorack System’ chapter).
2. User Manual
2.2 Function Overview
The Field Kit FX is an effect box which allows you to use several
effects at the same time including reverb, delay, an envelope genera-
tor, frequency shifter, looper, a bitcrusher, a sample rate reducer and
even a 4-step sequencer – all in one device! Its compact size makes
the FX ideal for touring and traveling, but the device is as useful in
the studio where you can explore its potential and experiment apply-
ing effects on various sounds, from acoustic instruments to synthesiz-
ers.
The Field Kit FX consists of seven different effect blocks of which
many parameters can be controlled with the CV Interface and its nifty
CV matrix.
All outputs are mono, except for the master output, which is dual
mono (“fake stereo”). If you have a Field Kit, you can connect the
two devices so they can instantly become friends! Use this manual
to check all the specifications on your device and get inspired by the
many possibilities the Field Kit FX has to offer!

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2.2.1 The Looper
2. User Manual
Under the inputs of the CV Interface, you can switch between two
different effects: Looper or Frequency Shifter.
We love loopers, they are an effective and simple tool to create
quick musical textures and more complicated rhythmical patterns.
With the Field Kit FX Looper you can loop your music up to 3.5 sec-
onds and create loops on top of each other (“overdubbing”). The
hi-fi looper can be controlled by the RGB loop button under the CV
Interface. Five different colours define its state:
Green = Armed
In this state, the loop is empty and the Looper is ready to accept
the audio and record a loop. The incoming audio is routed to the
output and that the looper acts as a passthrough for the Bitcrusher
/ SRR (see below).

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Red = Recording
When you press and hold the button while it’s green, it will start
recording the audio. In this state, the looper input is re-routed to
the output, so you can hear what you are recording.
Blue = Playback
After reaching the maximum loop time, the Looper will automatical-
ly go into playback mode, where the loop button flashes shortly at
the end/start of the loop.
Purple = Overdub
Because the incoming audio signal and the loop are mixed togeth-
er inside of the FX, you can record a loop on top of something else.
Just press and hold the LOOP button while playing back the loop.
They will be mixed and saved together. This has no limits, so you
can overdub as many times as you like! Note that the length of the
first recorded loop sets the maximum length of the overdubbed
section.
White = Delete
If you wish to erase the loop and stop the looper from playing, sim-
ply short press the loop button. It will shortly shine in white while
the loop is being played for the last time as an indication of delet-
ing the recorded loop. After deleting the loop, the looper returns
back in the armed state (green light).
Inputs
Control
Outputs
▪AC coupled input for different kinds of audio
signals.
▪CV Range: ± 5V
LOOP Button.
▪AC coupled output

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2.2.2 The Frequency Shifter
The Frequency Shifter allows you to shift the frequency instead of the
pitch to achieve an interesting change in timbre and texture of the
original sound. For instance, when you input a piano sound and shift
the frequency up, you will end up with a piano which is very metallic
sounding, perfect for those industrial techno expeditions!
Plug any instrument into the Input jack of the Looper/Frequency Shift-
er, flip the switch to the SHIFT mode and play with the two controls for
this effect: AMOUNT and CONTROL.
If the AMOUNT Control is in the middle position, it means it’s on
“neutral”: You get the original incoming signal and nothing is shifted.
By turning the pot to the right, you raise the frequency shift amount
by up to +1000Hz. By turning it to the left, you shift the signal down a
maximum of -1000Hz.

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The CONTROL pot sets the sideband characteristics of the output
signal, so you can tweak the harmonic structure to another dimen-
sion! With CONTROL turned fully clockwise, only the upper sideband
of the frequency shifter will be heard. Set at the middle position, the
output will be a double sideband signal. This allows the Frequency
Shifter to enable ring modulation. Fully counterclockwise, the output
of the effect only presents the lower sideband of the frequency shift-
er, meaning the harmonics are reversed compared to the input ones.
Inputs
Control
Outputs
▪AC coupled input for different kinds of audio
signals.
▪Input Impdenance: 100kΩ (Eurorack standard)
AMOUNT
Sets the frequency amount by which the incoming
audio will be shifted.
CONTROL
Sets the sideband characteristics of the output
signal.
▪CV Range: ± 5V
▪AC coupled output
▪Output impedance: 1KΩ (Eurorack standard)

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2.2.3 Bitcrusher / Sample Rate Reducer
Not only can you use the looper to record loops, it also offers ways to
add spectral folding to sounds running through the effect and achieve
truly unique sounds from outer space! The Sample Rate Reducer knob
decreases the sample rate of the output audio. The higher the SRR
amount is set to, the more aliasing artifacts will appear and thus change
the timbre of the output audio.
The Crush Control pot reduces the number of bits per sample of the loop
and doing so introduces quantization noise to the sound (bitcrushing).
When the Bitcrusher is turned off, the audio signal is 12bit, which is
reminiscent to the early samplers like the SP-1200. The higher the crush
amount, the less bits are assigned. The bit crushing effect can heavily
distort the output audio, bringing its sonic characteristics into harsh,
noisy territories.
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Inputs
Control
Outputs
▪AC coupled input for different kinds of audio sig-
nals.
▪The signal is recorded at 12 bit resolution, 48KHz.
▪Input impedance: 100kΩ (Eurorack standard)
SRR
▪Decreases the sampling rate of the output audio.
CRUSH
▪Sets the number of bits of the audio signal in the
looper’s memory.
▪CV Range: ± 5V
AC coupled output
▪Output impedance: 1KΩ (Eurorack standard)
Both SRR and CRUSH can be automated by the CV interface. Also,
both effects are applied to the audio output regardless of the looper’s
state. They do not become part of the recorded audio unless you also
recorded the loop with these effects engaged. This allows you to use
the looper of the Field Kit FX in an armed state as a real time bitcrush-
er and sample rate reducer.
DSP Input Gain Setting
You might have noticed that unlike the digital delay and the spring re-
verb, the DSP part of the Field Kit FX does not feature a Gain In knob.
Since you want to be able to accomodate signals with different vol-
umes there is a feature that lets you set the internal gain of the DSP
circuit. The DSP circuit includes the Looper, the Frequency Shifter, the
Sample Rate Reduction and the Bitcrusher.
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2.2.4 Digital Delay
The Digital Delay of the FX is based on the amazing PT2399 Delay
chip and the configurations were tweaked to achieve a delay with a
strong attitude and true KOMA character. The frequency response is
optimized to suit the natural response of the PT2399 and the results
can be heard! You can go for anything from slightly delayed sounds
to creating Feedback loops and even harsh noise. Tweak that Feed-
back!
Just like with the Spring Reverb you can manually feed the signal
into the delay path with the GAIN IN control. With TIME, you control
the delay time. The FBACK knob routes the delayed signal back into
the input of the delay block, increasing the number of echoes. This
allows you to create anything from a single echo to infinite repeating
mayhem.
Both TIME and FBACK can be controlled manually or with the CV In-
terface. The feedback path also has an insert point, labeled FBACK,
allowing you to break the signal path and process the sounds further
with external effects – just plug in the special stereo to mono in/out in-
sert cable from our FX Expansion Pack and you’re free to experiment!

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2. User Manual
Inputs
Control
Input
▪AC coupled input for different kinds of audio sig-
nals.
▪Input impedance: 100kΩ (Eurorack standard)
GAIN IN
▪Serves as a pre-gain for the signal connected to
Digital Delay input.
▪Range:
Fully CCW - 0x gain / silence (-inf dB)
12 o’clock - unity gain (0dB)
Fully CW - 2x gain (+6dB)
TIME
▪Controls the delay time.
▪Range:
Fully CCW - ~ 30ms
Fully CW - ~ 5.5s
Longer delay times also gradually degrade the audio
quality of the echoes and introduce additional sonic
artifacts into the mix.
TIME CV
▪Automated delay time control via external CV.
The CV is mixed with the value set with the Time
control.
▪Range: -5V to +5V
FBACK
▪Controls how the echoes decay over time
▪Range:
Fully CCW - a single echo
Fully CW - self-oscillation

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Outputs
FBACK CV
▪Automated control of feedback via external CV
▪The CV is mixed with the value set by the Fback
control.
▪Range: -5V to +5V
FBACK (insert point)
▪Breaks the feedback path and allows processing
of the echoes with external effects.
▪Use a stereo to 2 x mono - insert cable to tap the
signal
▪Tip - from Digital Delay
▪Ring - to Digital Delay
Output
▪AC coupled output containing only the wet, de-
layed signal.
▪Output impedance: 1KΩ (Eurorack standard)

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2. User Manual
2.2.5 Spring Reverb
The Spring Reverb section is an attractive take on classic Spring Re-
verb circuitry: not only can you manually play around with the spring
tank, but you can also control the harmonic structure by playing
around with the on-board resonant low-pass and band-pass filters.
The Feedback section, which is based on an analog VCA, sends wet,
reverberated, signal from the spring tank back to the input filter and
again back to the spring, enabling you to create endless feedback
loops and control the reverb time.
To get going, always make sure a reverb tank is plugged in between
the TO and FROM.

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The GAIN IN controls the amount of signal sent into the effect. Center
position corresponds to unity gain. Next, use the CUTOFF control to
set the cutoff frequency of the filter. Use the FILTER control switch
to select either a low-pass (LP) or a band-pass (BP) response. After
the signal has travelled through the spring tank, the wet, reverberat-
ed signal comes out the Output. Finally, the FBACK control lets you
send the reverberated signal back into the input filter.
Both the CUTOFF and FBACK can be controlled via the CV Interface,
giving your hands the freedom to nudge and stroke the spring with
your fingers or play any instrument while the spring is doing its thing.
Please note: The Field Kit FX itself doesn’t have a build-in spring
reverb tank. You can use a whole scala of reverb tanks and connect
them to the TO and FROM. We offer a high quality reverb tank in our
FX Pack to get you going!

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2. User Manual
The reverberation effect in a spring reverb is created by transmit-
ting audio-signals mechanically through a number of springs. The
mechanical properties of the springs mangle the sound being trans-
mitted creating an artificial but, as their popularity has proven, very
pleasant reverberation effect.
Spring tanks come in a variety of electro-mechanical properties,
defining the produced reverberation effect. When selecting a spring
tank to use, a careful examination to these properties should be
taken.
Spring Tank Properties
Commercially available spring tanks are most often specified follow-
ing the Accutronics part-numbering scheme. The properties specified
in this scheme are:
Tank type
Input impedance
Output impedance
Decay time
Input/output electrical coupling
Locking devices
Mounting type
Out of these properties, a 7-digit part-number is formed, for example
8BB2C1A. In the following sub-chapters, the aforementioned proper-
ties are given a brief look.
2.2.5.1 Spring Tanks

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Tank Type
Essentially determines the size of the tank and the number of springs
used for reverberation. This is one of the most important parameters
in defining the overall reverberation effect. The number of springs
used for transmitting the sound changes the density of the perceived
reverberation, with early spring tanks having only one or two springs,
and the modern ones up to six. On multi-spring spring tanks, the
springs are often chosen to complement each other’s natural re-
sponse, leading to more natural reverberation effect.
Input Impedance
Determines the impedance seen by the spring driver circuit. Practi-
cally defined by the spring driver circuitry used.

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Output Impedance
Determines the impedance seen by the spring recovery circuit. Prac-
tically defined by the spring recovery circuitry used.
Decay Time
Decay time specifies, as its name suggests, how long it takes for the
reverb tail to fade into inaudibility. Different decay times often suit
different applications better than another.
Input / Output Electrical Coupling
Spring reverb driver / recovery circuits are designed following a num-
ber of common circuit topologies. In order for the chosen topology
to work, the input and output coils inside the spring tank should be
either insulated or grounded, depending on the used design.
Locking Devices
Determines whether the spring tank has a locking device in order to
fix the springs in place during transport.
Mounting Type
Since the spring tanks are mechanical in their operation, they are also
fabricated having a specific mounting direction in mind. Having the
tank mounted any way other than the originally intended affects the
characteristics of the perceived reverberation effect.