Kern
Performance Synthesizer
Version 1.1
© 2015-2019 by Björn Arlt @ Full Bucket Music
http://www.fullbucket.de/music
VST is a trademark of Steinberg Media Technologies GmbH
Windows is a registered trademark of Microsoft Corporation
The Audio Units logo is a trademark of Apple Computer, Inc.
Kern Manual Page 2
Table of Contents
Introduction....................................................3
Why Kern?......................................................3
User Interface.................................................4
Sound Engine..................................................5
Oscillators......................................................5
Filter and Amp................................................5
LFO and Envelopes..........................................5
Chorus...........................................................5
Performance Controls.......................................6
Program Menu.................................................6
MIDI Learn.....................................................6
Options Menu..................................................6
The kern.ini Configuration File...........................8
Skinning Support.............................................8
MIDI Control Change Messages.........................8
Parameters.....................................................9
Oscillators......................................................9
Filter..............................................................9
LFO..............................................................10
Amplifier.......................................................10
Chorus.........................................................10
Frequently Asked Questions.............................11
Kern Manual Page 3
Introduction
Kern is a software synthesizer plug-in for Microsoft Windows (VST) and Apple macOS
(VST/AU) designed to run with and to be fully controlled by modern MIDI keyboard
controllers like the Novation® Impulse™. It is written in native C++ code for high
performance and extremely low CPU consumption. The main features are:
● Streamlined to be used with MIDI keyboard controllers;
all parameters can be controlled by MIDI CC
● MIDI Learn
● Two alternative user panels
● 32 voices polyphony
● Two band-limited oscillators including Hard Sync
● 4-pole zero-delay feedback lowpass filter (two types)
● Two envelopes, one LFO
● Chorus effect
● Double precision audio processing
● Plug-in supports Windows and macOS (32 bit and 64 bit)
Why Kern?
Ask yourself:
● Do you have a MIDI controller with all those shiny sliders, knobs, and buttons?
● Do you feel the urge to use it to twiddle the parameters of your favorite
(software) synth?
● Do you get frustrated because moving a knob here changes a knob there, but
the mapping seems not to be intuitive?
● Or maybe the parameter you want to access isn't even mapped?
● And, to even increase frustration, do you remember the good old days when
synthesizers had exactly one dedicated slider/knob/button for each parameter?
If your answer is always “No” then ask yourself:
● Do you want a light-weight, easy-to-use, CPU-friendly, cool sounding synth?
If it is “No” again then Kern may be not the right thing for you.
… but now you know why I created Kern. Together with my V-Machine (which is
grateful for CPU-friendly plug-ins!) I have a fully controllable stand-alone synthesizer
that does not need a PC.
Of course there are drawbacks: Since today's MIDI master keyboards typically do not
have more than 30 hardware controls I had to limit the number of Kern's parameters
to (what I believe – you may have a different opinion here, that's OK –) the minimum
of what is absolutely required. That is why Kern is named “Kern” which is German for
“core”.
Kern Manual Page 4
User Interface
Two alternative user panels (“views”) are available: The standard (“traditional”) view
is in line with the architecture of subtractive synthesizers while the second view
reflects the typical layout of the sliders, knobs, and buttons of today's MIDI hardware
controllers. If you own a Novation Impulse (like I do) or a similar machine you will
find the latter view very helpful since it visually maps the hardware controls to Kern's
parameters.
You can switch between the views via the Options menu or via the Switch View button
(only available on the standard view).
Kern's standard view
Kern's alternative view
Kern Manual Page 5
Sound Engine
Oscillators
Kern has two band-limited oscillators that can create Sawtooth or Square waves; the
waveform has to be selected for both oscillators together. Oscillator 2 can be
transposed by ±24 notes and detuned by ±1 note. Furthermore, it is possible to hardsynchronize Oscillator 2 to Oscillator 1.
The frequency of the oscillators can be modulated either by the LFO or the filter
envelope (positively or negatively). If Hard Sync is activated, only Oscillator 2 will be
modulated to produce the classic rich harmonic “Sync” spectra we all love. Apart from
that, frequency modulation of both oscillators by the LFO (“Vibrato”) can always be
applied via the modulation wheel. Portamento is on board, too.
Finally, it is possible to switch Kern into monophonic mode (e.g. for lead and/or bass
sounds). By default the envelopes are single triggered meaning that they are not
restarted when playing legato (also known as “Minimoog mode”). However you can
change the trigger mode to multiple using the context menu that opens when you
click on the Mono switch.
Filter and Amp
The filter is based on a (attention: buzz words!) Zero-Delay Feedback design and
provides two modes: Smooth, a 4-pole lowpass with moderate non-linearities and
potential self-oscillation, and Dirty, a punchy 2-pole lowpass with potential but no selfoscillation. Cutoff and Resonance of course are editable.
The cutoff frequency of the filter can be modulated simultaneously and both positively
or negatively by four sources: filter envelope, LFO, key track, and velocity.
The amplifier just offers Volume and Velocity parameters; the latter controls the
influence of the velocity to the output volume.
LFO and Envelopes
The LFO offers three waveforms: Triangle, Square, and S/H (random); its' speed rate
ranges from 0 to 100 Hz.
The filter envelope is a simplified ADS generator: The Decay parameter controls both
Decay and Release rates together while Sustain can only be switched on or off. The
amplifier envelope is similar with the exception that here Release can be controlled
independently from the Decay rate.
Chorus
The Chorus can be switched on or off. Furthermore it is possible to set the speed rates
of the two triangle-shaped LFOs modulating the Chorus as well as the modulation
depth.
Kern Manual Page 6
Performance Controls
Program Menu
If you know my other plug-ins then there will be no surprises: To select one of the 64
patches just click on the program number, and edit its' name by clicking in the text
field.
MIDI Learn
Every parameter of Kern can be controlled by one MIDI controller. If you want to
change the assignment of MIDI controller (CC; MIDI Control Change) to Kern
parameter the MIDI Learn function comes in quite handy: Just click the MIDI Learn
button on Kern's control panel (caption turns red) and wiggle both the MIDI controller
and the parameter you want to assign (you can abort MIDI Learn by clicking the red
button). To save the controller assignments use “Save Configuration” in the Options
menu (see next section).
Options Menu
When clicking on the Options button, a context menu opens with these options:
Copy Program Copy current program to internal clipboard
Paste Program Paste internal clipboard to current program
Load Program Load a program file containing a patch to the Kern's
current program
Save Program Save the Kern's current program to a program file
Load Bank Load a bank file containing 64 patches into the Kern
Save Bank Save the Kern's 64 patches to a bank file
Init Program Initialize the current program
Reload Configuration Reload the Kern's configuration file (see section The
kern.ini Configuration File)
Save Configuration Saves the Kern's configuration file (see section The
kern.ini Configuration File)
Select Startup Bank Select the bank file that should always be loaded when the
Kern is started
Load Startup Bank Load the Startup bank file; can also be used to check what
the current Startup bank is
Unselect Startup
Bank
Unselect the current Startup bank
Check Online for
Update
When connected to the Internet, this function will check if
a newer version of the Kern is available at fullbucket.de
Switch View Switches between the views (see section User Interface)
Visit fullbucket.de Open fullbucket.de in your standard browser
Kern Manual Page 7
Note: If the Kern DLL and the kern.ini configuration file are located in a “protected”
Windows folder (for example somewhere under “C:\Program Files\...”) then it may
not be possible to save the configuration. In this case it is strongly recommended to
use a VstPlugins directory that lies “outside” the protected folder.
Kern Manual Page 8
The kern.ini Configuration File
Kern is able to read some settings from a configuration file (kern.ini) located in the
same directory as the as the Kern VST DLL (kern.dll or kern64.dll) or Mac VST/AU
(Kern.component or Kern.vst) itself. After you have edited this INI file in a text
editor, you have to reload it using the Reload Configuration command from the
Options menu (see section Performance Controls).
Skinning Support
Kern features some very rudimentary skinning support. Within the INI file, each of the
bitmaps used in the UI can be replaced by specifying the full path to an alternative
bitmap file; bitmaps that you don't want to replace can be set to default (see example
below), or left out of the INI file completely.
[Editor]
Bitmap_Back = C:\myCoolSkins\flashy.png
Bitmap_Back2 = C:\myCoolSkins\nerdy.png
Bitmap_Handle = default
Bitmap_Knob = default
Bitmap_SmallKnob = default
Bitmap_Button = default
Bitmap_MidiLearn = default
Important: The replacing graphics need to have the same size and control placement
to work correctly. Also knob/button/slider graphics need to have the exact same size
and number of frames to work correctly. It is not possible to alter the placement of
controls, as that is handled by code in the plug-in.
MIDI Control Change Messages
All parameters of the Kern can be controlled by MIDI controllers, or more precise:
Each MIDI controller (except Modulation Wheel and Sustain Pedal) can control one of
Kern's parameters. The mapping is defined in the kern.ini for example like this:
[MIDI Control]
CC41 = 12 # Filter Cutoff
CC42 = 13 # Filter Resonance
CC43 = 21 # Filter Env Attack
CC44 = 22 # Filter Env Decay
CC45 = 24 # Amp Env. Attack
CC46 = 25 # Amp Env. Decay
CC47 = 27 # Amp Env. Release
...
The syntax is straight forward:
CC<controller number> = <parameter ID>
Given the above example, controller 41 directly controls the overall Filter Cutoff
parameter, controller 42 the Filter Resonance etc. As you can see, comments are
introduced by the Pound sign (#); they are here just for description purposes and
completely optional.
Kern Manual Page 9
The parameter ID of one of the Kern's parameters is given in the section Parameters
below. Note that the controller number can run from 0 to 119, with the exception of 1
(Modulation Wheel) and 64 (Sustain Pedal); the latter two are simply ignored.
Of course, instead of editing the controller/parameter assignments in kern.ini with a
text editor it is much easier to use the MIDI Learn function and save the configuration
(see sections MIDI Learn and Options Menu above).
Parameters
Oscillators
parameter ID description
Mono 1 Switches between polyphonic and monophonic mode
(Single or Multiple Trigger)
Master Tune 4 Master tune (hidden parameter)
Wave 5 Selects the waveform (Sawtooth or Square)
P.Bend 2 Pitch Bend range (in notes)
Porta 3 Portamento time
FM 6 Frequency modulation depth
FM Src. 7 Frequency modulation source
Trans. 8 Oscillator 2 transpose (in notes)
Tune 9 Oscillator 2 tuning
Sync 10 Oscillator 2 Hard Sync
Filter
parameter ID description
Cutoff 12 Cutoff frequency
Reso. 13 Resonance
Mode 11 Filter mode (Smooth or Dirty)
Env 14 Cutoff frequency modulation by filter envelope
LFO 15 Cutoff frequency modulation by LFO
Key 16 Cutoff frequency modulation by note number
Velocity 17 Cutoff frequency modulation by velocity
Attack 21 Attack time of filter envelope
Decay 22 Decay/Release time of filter envelope
Sustain 23 Sustain of filter envelope (Off or On)
Kern Manual Page 10
LFO
parameter ID description
Rate 19 Rate of the LFO (0 to 100Hz)
Wave 20 Waveform (Triangle, Square, S/H)
Amplifier
parameter ID description
Attack 24 Attack time of amplifier envelope
Decay 25 Decay time of amplifier envelope
Release 27 Release time of amplifier envelope
Sustain 26 Sustain of filter amplifier (Off or On)
Volume 0 Master volume
Velocity 18 Velocity amount
Chorus
parameter ID description
Enable 28 Chorus on/off
Rate 1 29 Rate of first Chorus LFO
Rate 2 30 Rate of second Chorus LFO
Depth 31 Depth of Chorus modulation
Kern Manual Page 11
Frequently Asked Questions
How do I install the Kern (Windows 32 bit version)?
Just copy the files kern.dll and kern.ini from the ZIP archive you have downloaded
to your system's or favorite DAW's VST plug-in folder. Your DAW should automatically
register the Kern VST plug-in the next time you start it.
How do I install the Kern (Windows 64 bit version)?
Just copy the file kern64.dll and kern.ini from the ZIP archive you have
downloaded to your system's or favorite DAW's VST plug-in folder. Your DAW should
automatically register the Kern VST plug-in the next time you start it.
Note: You may have to remove any existing (32 bit) kern.dll from your VST plug-in
folder or else your DAW may screw the versions up...
How do I install Kern (Mac VST/AU universal 32/64 bit)?
Locate the downloaded PKG package file kern_1_1_4_mac.pkg in Finder (!) and do a
right- or control-click on it. In the context menu, click on “Open”. You will be asked if
you really want to install the package because it comes from an “unidentified
developer” (me J). Click “OK” and follow the installation instructions.
What is the plug-in ID of the Kern?
The ID is k e r n .
I spent a lot of time customizing the MIDI controller/parameter
assignments. Can I save these assignments?
Yes, by using “Save Configuration” in the Options menu (see section Options Menu).
Why doesn't the configuration file (kern.ini) get saved?
Maybe you have placed the Kern files kern.dll/kern64.dll and kern.ini into a
“protected” folder somewhere under ”C:\Program Files\...”? In this case you
should use a VstPlugins directory that lies “outside” the protected folder (also see
section Options Menu).
How do I know if a new version of the Kern is available?
When connected to the Internet, open the Options menu (see section Options Menu)
by clicking the disk icon and select the entry “Check Online for Updates”. If a new
version of the Kern is available on fullbucket.de the respective information will be
shown in a message box.
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