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V1.0
Pulse Synthesizers
Load Runner Granular
Synthesizer
Operating Manual
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V1.0
Table of Contents
Introduction .......................................................................................................................................... 3
Power Connections ............................................................................................................................... 3
Front Panel ............................................................................................................................................ 4
1.3.1 Granular Controls.............................................................................................................................. 4
1.3.2 Play Controls ..................................................................................................................................... 4
1.3.3 Navigation Controls .......................................................................................................................... 4
1.3.4 CV Inputs ........................................................................................................................................... 5
1.3.5 Output ............................................................................................................................................... 5
Importing Sounds .................................................................................................................................. 6
Playing Sounds ...................................................................................................................................... 9
1.5.1 Granular Controls.............................................................................................................................. 9
Recording ............................................................................................................................................ 11
Settings Menu ..................................................................................................................................... 11
Firmware Update ................................................................................................................................ 12
Specifications ...................................................................................................................................... 13
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V1.0
Introduction
The Load Runner module uses a form of granular synthesis to generate sounds from user audio sources.
The term ‘granular’ refers to small snippets of sound ranging from 10 milliseconds to 1 second; each short section
of sound is referred to as a grain. An amplitude envelope is applied to each grain in order to smooth out any
transients and to create different sonic textures. When multiple grains are played together, they can form a
continuous sound with different characteristics to the original source audio.
Power Connections
Please take careful note of the Eurorack power connection which is labelled on the circuit board and shown in
the picture below.
Please observe the correct polarity.
DO NOT connect Eurorack power to the blue CPU boards JTAG/SWD socket, this will damage the module.
Your module will arrive with all the switches and jumpers in the correct position however if for some reason
they are inadvertently changed please set them to the configuration shown below. The module will not be
damaged if the switches change position however the module may not power on.
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V1.0
Front Panel
1.3.1 Granular Controls
There are five front panel knobs which allow control over the granular generation.
Density
Density controls the number of grains playing simultaneously. Up to 15 grains can be played at a maximum
down to around 1 grain every 10 seconds depending on the grain length.
Start / Range Time
Each grain is generated or started from a randomly selected point in the audio sample between the start and
range positions. By moving the start and range position controls different sections of the audio can be
selected.
Length
Determines the length in milliseconds of each grain.
Pitch
Controls the pitch of all grains including ones that are already playing.
Env Button
Cycles through the different amplitude envelopes.
1.3.2 Play Controls
Play Button
Triggers granular sound generation. Grains will be generated whilst it is held on.
Latch Button
The latch button changes the function of the play button from momentary to toggle.
Record Button
Toggles recording to USB flash drive on and off.
1.3.3 Navigation Controls
Rotary Encoder Dial
For navigating and selecting samples in the file explorer and waveform display modes. The encoder has a push
button switch.
Mode Button
Changes between the WAV file explorer, playback and settings screens.
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V1.0
1.3.4 CV Inputs
Sample CV
Allows control voltages to select files in the internal memory for granular playback. A +5V pulse at the input
will increment the current playback sample whereas -5V will decrement the current sample.
Density CV
The density CV input value will be added to the current front panel density knob value. A +5V signal will allow
the density value to swing the full range in the positive direction whereas a-5V allows the density value to
swing fully negative.
Env CV
Allows control voltages to select the grain amplitude envelope from the 10 internal shapes. A +5V at the input
will increment the current envelope whereas a -5V will decrement the current envelope.
Start CV
The start CV input value will be added to the current front panel start knob value. A +5V signal will allow the
start value to swing the full range in the positive direction whereas a -5V allows the start value to swing fully
negative.
Range CV
The start CV input value will be added to the current front panel start knob value. A +5V signal will allow the
start value to swing the full range in the positive direction whereas a -5V allows the start value to swing fully
negative.
Pitch CV
The pitch CV input value will be added to the current front panel pitch knob value. A +5V signal will allow the
pitch value to swing the full range in the positive direction whereas a -5V allows the pitch value to swing fully
negative.
Play CV
A +5V signal will trigger playback whilst the signal is on. When the voltage is return o 0V playback will stop. The
play CV input is not latched by the latch button.
Length CV
The length CV input value will be added to the current front panel length knob value. A +5V signal will allow
the length value to swing the full range in the positive direction whereas a -5V allows the length value to swing
fully negative.
1.3.5 Output
The output provides a mono audio signal at Eurorack voltage which is adjustable from the master volume
section under the setting menu.
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V1.0
Importing Sounds
Audio samples must be loaded into the modules internal memory before they can be played. From the USB
explorer screen all valid 16-bit WAV files will be listed regardless of sample rate. Both mono and stereo files
will be shown in the list however by default on the left channel is loaded. Via the settings menu it is possible to
select the right channel.
When the USB flash drive is inserted it will automatically be scanned for valid WAV files. The number of files
will be shown at the top of the screen. Having more WAV files on the USB flash drive will take longer to scan
and validate.
A maximum of 200 WAV files can be displayed at any one time with 20 files per page.
A maximum of 200 WAV samples can be stored in the internal memory space permitting.
Only WAV files on the root directory are displayed and available for loading into internal memory. Files stored
in folders are not shown.
A maximum of 40 characters are displayed for each file name including the file extension.
Loading Files
The rotary encoder allows selection of the files to be loaded. The currently selected file will be highlighted in
green. Once the desired file is selected, push the rotary encoder to load it. A popup will appear showing the
file loading progress. When completed push the encoder to clear the popup and return to the file explorer.
Sample Already Loaded
Attempting to load a file twice is prevented and a popup will display “Sample Already Loaded”. Push the
encoder button to clear this message.
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V1.0
Internal Memory
A maximum of 90 seconds of mono 44.1kHz audio can be loaded into the internal memory. The percentage of
memory currently used is displayed in the top right-hand corner of the screen. Prior to loading the sample size
is compared against the available memory. If there is insufficient remaining capacity a popup with display “Not
Enough Memory”. Push the encoder button to clear this message.
Clearing Sample Memory
The entire internal sample memory can be cleared by selecting “Reset Sample Memory?” option. A popup will
be displayed requesting confirmation; select yes to clear and no to return back to the explorer screen. If
memory clearing is selected, then a popup screen will show “Sample Memory Cleared”. Push the encoder
button to clear this message.
Power Cycling
Note: When the power is cycled to the module all samples loaded will be cleared.
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V1.0
No USB
If there is no USB flash drive inserted the screen will display “Insert USB”.
Only FAT32 file system formatted flash drives can be read.
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V1.0
Playing Sounds
From the waveform screen a visual representation of the selected sample is shown with several granular
parameters linked to the front panel controls.
Sample Selection
When each sample is loaded into the internal memory it is assigned a sample number that is displayed to the
left of the file name at the top of the screen. Using the encoder, the selected sample can be incremented by
rotating clockwise and decremented by rotating counter clockwise. The sample can be changed on the fly
during playback.
When only one sample is loaded it will be selected automatically.
All Samples
When more than one sample is loaded it is possible to switch between playback of a single sample or all
loaded samples. From the waveform display screen push the encoder button to toggle between single sample
mode and all samples mode.
1.5.1 Granular Controls
The granular parameters are shown below the sample name.
Start Time
The start time defines point in the current sample after which grains will be generated. It is shown in seconds
numerically and graphically as a red line on the waveform. The waveform representation of each sample
automatically scales the sample across the display. Therefore, the start time will vary depending on the sample
loaded and the position of the controls.
The start time can range from approximately 1% to 99% of the sample allowing virtually any part of the sample
to be targeted.
Range Time
Between the start and range times the start point of each grain is randomly generated. The range time is
shown numerically and graphically on the waveform as a blue line. The range line can wrap from the end of
the sample back to the start which allows the selection of any part of the sample.
Pitch
The pitch control will modify the playback speed of all grains including those already playing. In the centre
position there is no pitch change which is shown as a “1” on the screen. There are three pitch scales available
selectable via the settings menu, plus the ability to lock to +/- 5 octaves.
The internal sample rate is fixed at 44.1kHz. Therefore, if samples with higher or lower sample rates are
imported, they will be pitched down and up respectively.
Grain Length
The grain length is adjustable from 10ms to 1 sec and is applied to all grains. The grain length will not alter
grains already playing, once generated the grain will playout with the length value at the time of generation.
The length is shown in milliseconds numerically.
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V1.0
Grain Density
The grain density controls the number of simultaneously playing grains ranging from 0.01 to 15. With values
less than 1 there will be no overlap between grains with audible gaps between them. By increasing the density
greater than 1 the grains will begin to overlap forming a continuous sound.
Grain Envelope
An amplitude envelope is applied to all grains and is shown graphically on the right-hand side of the screen.
Pressing the “Env” button will cycle through the 10 envelope shapes.
Tips
To obtain a more consistent sound reduce the range time close to the start time which forces grain generation
from a smaller section of the sample.
Time stretched type sounds can be obtained by reducing the grain length below 100ms, setting the range time
as low as possible and moving the start time through the sample. This works particularly well for vocal
samples.
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V1.0
Recording
The audio output can be internally recorded onto the USB flash drive. The audio is mono, 16-bit 44.1kHz.
Recordings are stored on the root directory of the flash drive and are automatically named.
A maximum of 100 recording files can be created.
Filenames: “REC_001.wav”, “REC_002.wav” etc.
Recording is initiated by pressing the “Rec” button on the front panel. When recording is active the button
light will be illuminated. To stop recording press the “Rec” button again.
Please ensure there is sufficient space on the USB flash drive when recording as the entire recording file may
be lost otherwise.
Settings Menu
The settings menu is accessed by holding down the mode button for 1 second where additional parameters
can be accessed.
Master Volume
This applies to the audio output and is settable from 0 to 100. If the volume is set to maximum it may be
possible that output is clipped with certain high-volume audio samples.
Pitch Control
There are four pitch control settings which apply to the front panel and CV controls.
• +/- 2 Octaves
• 1V/Oct or +/- 5 octaves.
• Fwd/Rev allows the grains to be played back forward and reverse with centre or 0V being essentially
stopped.
• 1V/Oct locked locks the pitch to the nearest octave.
Grain Wrap Mode
When playing grains towards the end of the sample it is possible that the grain will extend past the end. The
default setting will wrap the grain back to the start of the sample however it can be set to silence which will
play out the available audio at the end and then play silence.
Stereo File Load
Allows selection of the left or right channel to be loaded when importing samples.
Waveform Colour
Allows choice of 15 colours for the waveform display.
Record Time
The record time can be displayed on the waveform screen in hours : minutes : seconds format.
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V1.0
Firmware Update
The Load Runner can install new firmware via the USB interface from flash drive. It is recommended to use a
flash drive with only the firmware file on it to reduce the chance of error. There must however be only 1
firmware file on the flash drive otherwise the incorrect file may be loaded.
Update Process:
DO NOT remove the flash drive during the firmware update process.
1) Ensure only one *.bin file on the flash drive as the module will select first *.bin file it finds.
2) Power down the module.
3) Insert the flash drive with firmware on it.
4) Power up the module whilst holding the mode button ON.
5) You should see the latch button illuminated indicating it is in update mode. You can now release the
mode button.
6) The record button may be illuminated which indicates the flash drive is in the process of connecting.
7) The envelope button will be illuminated whilst the firmware update is in progress.
8) When the update has completed the play button will be illuminated.
9) Press the mode button and the module will reboot as per normal with the updated firmware.
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V1.0
Specifications
Audio output amplitude +/-5V
Sample rate 44.1kHz
Internal Memory: 90 seconds, 44.1kHz, mono audio
Wav files, 16 bit mono or stereo (only 1 channel loaded)
All CV's bipolar +/-5V
Panel width 25HP
Module Depth 45mm
Power consumption 240mA@+12V, 20mA@-12V
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