The Kilpatrick format is a new kind of modular synthesizer system
for players that demand something better, different and
inspiring. Designed by Andrew Kilpatrick, the Kilpatrick format
represents a new generation of modular music making by offering the
right combination of look and feel, playability, excellent circuit
design, and the perfect blend of old and new concepts that make the
system easy and fun to use.
The Kilpatrick format system aims to provide all the building
blocks for experimental sound production in a way that is incredibly
intuitive and enjoyable. Discovering new sounds should be something
that happens in every session. After several years of research and
experimentation, the Kilpatrick format was chosen. Containing new
design ideas and the best of traditional modular synthesizer concepts,
the format aims to offer the best user experience possible.
We hope that you enjoy using your Kilpatrick format system for many
years to come!
Kilpatrick Format Features:
- 4U (7") panel height - each panel offers close to 30 in. of
- Simple plug and play module installation - rearranging a system
or adding new modules is easy
- Universal use of banana cables for patching of audio, CV and
pulse/gate signals - high quality cables are available in a variety
of colours and lengths
- Colour-coded jacks indicate different signal functions and
- Separate analog and digital grounds used for low noise signal
returns - plenty of power available for digital modules
- Total cabinet depth of less than 3" permits table top or rack
- High quality brushed anodized panels are rugged and feature
clean, futuristic graphics
- All modules and systems are hand-assembled and built-to-order in
our downtown Toronto workshop
Table of Contents
We want to make sure you get the most from your Kilpatrick
system. You'll find that this manual doesn't offer specific patch
ideas or tips on how to achieve certain sounds. That is left up to
you. This document aims to outline the various ins and outs
(literally) of each module and what all the controls do. Below we'll
begin with a basic overview of general signal and patching tips to
help you get started.
If you're an experienced synthesist then the following section will
be a review of basic concepts. Feel free to skip ahead to the Signals and Voltages section.
Basic Synthesizer Patching
When you first set up your system you'll need to make some
connections before any sound will come out. The modular aspect of the
system means that there are lots of tools at your fingertips, powered
up and ready to go, but it's up to you to connect them in some sort of
Many keyboard synthesizers are built with a fixed patch internally,
and you can make that patch too if you want to get started with
something familiar. A basic synth patch might look like:
The modules in the patch work as follows:
- MIDI INTERFACE - The MIDI input from the keyboard or
another device generates information about which note is being
played (pitch voltage) and whether or not a key is being pressed
down. (gate signal) The setup shown above is monophonic and can play
one note at a time. Polyphonic synths use multiple oscillators,
filters, etc. to play more than one note at at time, and software
determines which notes will play on which hardware.
- OSCILLATOR - The oscillator generates a waveform, usually
a basic waveform like a sawtooth, pulse wave, etc. but sometimes
more complex waves like sampled waves. The output is generated all
the time, the pitch determined by a voltage from the MIDI
interface. In analog synths this voltage is usually decided as
something like 1V per octave. That means for every 1V increase in
the pitch voltage, the output frequency will increase by 1
octave. (double in frequency)
- FILTER - The filter changes the timbre of the sound by
applying some kind of frequency-dependent transformation on it. The
most common filter type is the low-pass filter, which cuts off high
frequency sounds. Usually the cutoff frequency is adjustable by a
- LFO - The low-frequency oscillator (LFO) generates a
low-frequency signal, usually a triangle or sine wave. The LFO can
usually make signals from about 1 cycle per minute, up to maybe 40Hz
or so. The LFO is used to modulate some parameter of the sound to
create a constantly evolving and changing sound. In the example
above the LFO is used to modulate the filter cutoff frequency.
- VCA - The voltage-controlled amplifier (VCA) can adjust
the volume of a sound from muted to full volume under voltage
control. The VCA is the necessary component for making it possible
to have sounds that turn on and off when you press and release keys
on the keyboard.
- ENVELOPE - The envelope generator takes gate (on/off)
voltages from the MIDI interface and makes smoothly changing
voltages which fade up and down when a key on the keyboard is
pressed or released. This is usually used to turn the volume of a
sound up and down. Envelopes can also be used as sources of
modulation in many places where you might consider an LFO.
- MIXER - Most synths contain a mixer section just before
the sound comes out to a line output or headphone jack. In a
polyphonic setup this is used to mix all the notes together. It also
adjusts the master volume, and often contains circuitry for adding
reverb, delay or chorus effects to the final sound.
This is an overly simplified explanation, but this is the general
idea behind most synthesizers. Nearly all digital or analog
synthesizers follow a signal flow similar to what was described
above. But for experimental sound creation or ultimate flexibility,
breaking from this traditional type of patch will open the doors to a
world of sonic possibilities.
In a modular system you can build a traditional synth patch like
the one shown above, or you can patch in a totally different way to
create sounds never heard before.
Signals and Voltages
Everything patchable in the Kilpatrick system is
voltage-controlled. This concept of representing control parameters
with voltages was what made synthesizers practical for musicians back
in the 1960s. And now with the rebirth of the modular synthesizer in
the present day we can once again experience the flexibility that
player-patchable control signals presents.
We often speak of CV (control voltage) in which we usually
mean a signal that affects a performance parameter, instead of the
actual audio signals being generated. In the Kilpatrick format audio
and CV signals are interchangeable, and the only difference when
thinking about patching is the intended function. CV signals are often
held at steady DC voltages, or set up to be slowly changing. Audio
signals are usually faster changing signals or percussive
impulses. But there is no limit to using CV and audio signals
You should always monitor the output with speakers or headphones
connected to one of the mixer outputs. Connecting directly to a module
output might cause DC voltages to be sent to your headphones or
speakers which could damage them. Unlike most audio equipment, the
inputs and outputs on the Kilpatrick system are often designed to work
all the way down to DC. The headphone and line out jacks are designed
to block DC.
The Kilpatrick system uses four types of jacks which are colour
coded to make them easy to distinguish:
- CV / Audio Output - GRAY - Control voltages and audio
signals come out of gray jacks. These are normally in the range of
-5V to +5V. Most outputs are fed through 1K resistors to make them
protected from short circuits. The exception is pitch outputs from
MIDI to CV converters, which are fed through 100 ohm resistors to
provide better tuning accuracy. You should avoid shorting outputs to
the chassis or external equipment.
- CV / Audio Input - BLACK - Control voltages and audio
signals go into black jacks. All black inputs have an input
resistance of 20K-50K, with the exception being oscillator pitch
inputs which have an input resistance of 100K.
- Pulse and Gate Output - RED - Pulse, gate and clock
outputs and various other digital type of signals come out of red
jacks. These are nominally +5V when on, and 0V when off. They are
all fed out through 1K resistors. Pulse and gate output signals can
be fed into CV or audio inputs, but the signal will only change from
the mid point to the maximum value when the output turns on and off.
- Pulse and Gate Inputs - WHITE - Pulse, gate and clock
inputs go into white jacks. These type of inputs have a resistance
of 20K and generally detect any voltage greater than about +1V. Some
inputs like oscillator sync inputs might require a fast-changing
signal like a ramp or pulse wave to trigger. Any range of input
voltage can be input to these jacks making it possible to trigger
this type of input from an audio or CV signal.
Warning: The only thing to keep in mind when
patching is that outputs should not connect to other outputs. Although
it may be possible to connect two outputs together to achieve passive
mixing, it is not recommended to do this as it can overload the
outputs and may cause damage to the module.
Enclosure and Module Installation
The smallest size of one module is called a space and
occupies a quarter rack width. Larger modules may occupy two or more
spaces. An enclosure generally provides four spaces and fits into a
19" equipment rack. Other sizes such as five or six spaces can be
custom ordered. Rack ears are used for rack mounting, and stacking
brackets are used to attach two enclosures together for table-top use.
Enclosures can be ordered as active or passive. Active enclosures
take power from an external power supply and generate power for
modules internally. Passive enclosures take power from an active
enclosure to add additional modules to the same power supply. An
active enclosure can power approximately 8-12 modules.
When using multiple active enclosures together in the same system
it is necessary to connect a ground cable between systems. Banana
sockets are provided on each enclosure for
this purpose. Connect a short banana cable between the systems and
always ensure it is in place before powering up your system. Only
connect one of the enclosures to external equipment such as mixers or
amplifiers to prevent ground loops.
The Kilpatrick format system uses a single 15V regulated switching
power supply to feed the system. The power input is located on the
back of an active enclosure. Only use the included 15V regulated power
supply for powering the system. Use of other types of power supplies
could damage the system.
Modules use a plug-and-play system and requires no internal
cables. A single captive screw is used to secure the module to the
enclosure. Never install or remove modules with power applied!
To remove a module:
- Power down the system
- Loosen the captive screw with the included 2.5mm hex key
- Plug a banana cable into two jacks near the top or bottom of the
- Grip the banana plugs and gently pull the unit out at one end
- Gently lift the module up out of the enclosure until the
internal connectors are completely unplugged
To install a module:
- Power down the system
- Set the module into the internal connectors and make sure the
module is aligned correctly in the enclosure
- Gently press straight down to seat the module in the enclosure
- Use the included 2.5mm hex key and turn the captive screw
counter-clockwise until a small click is heard
- Turn the captive screw clockwise until it is finger tight - Do
not over-tighten the screw or you could damage the module
All patch cables used in the Kilpatrick system are of the 4mm
banana type. We supply an assortment of colours and lengths with each
new system and can offer additional cables upon request. All patch
cables supplied are high quality Pomona brand B-type stacking banana
cables. We use only Emerson Johnson banana jacks on modules. This
combination provides very solid connections, and the stacking function
is incredibly useful. Even if plugs are not inserted all the way they
can still make excellent contact, making it easy to try out patch
ideas just by touching the plug to various points in the system.
We offer the following unique patch cable colour and length
- 12" GRAY
- 12" RED
- 12" YELLOW
- 18" BLACK
- 18" GREEN
- 18" ORANGE
- 24" BLUE
- 24" BROWN
- 48" VIOLET
K1 // Mixer Interface
The K1 Mixer Interface module is a combination of a high quality
five channel audio mixer and MIDI to CV converter. The mixer is
designed for high level signals from other modules and offers both an
AUX send for use with effects, and dual stereo outputs on banana and
mini jacks, as well as a headphone amplifier with dedicated volume
The mixer circuit incorporates high quality low-noise inputs on
banana jacks. Three mono channels and one stereo channel all contain
input level indicators and input level controls. The stereo channel
offers an AUX send level control which sends a post-input level blend
of the left and right channels to the AUX output.
The mono inputs offer level controls, a post-input level AUX send,
as well as a pan control. Channel 5 offers a CV input for panning
instead of a pan control.
The master output contains a stereo level control and a pair of
banana jacks suitable for connection to other modules or
daisy-chaining several mixers. A pair of mini jacks offer line-level
signals that can be output to external audio equipment. Signal level
indicators show the levels at the output jacks and sense the levels
after the MASTER volume control. A ground jack provides access to the
analog ground on the system.
A dedicated headphone amplifier provides a stereo output on a mini
jack with a dedicated level control. This output can also be used for
powered speakers or stereo recorders that work more conveniently with
stereo mini cables.
MIDI Interface Section
The K1 also contains a small but useful MIDI to CV converter. Built
on the success of the K1600 MIDI Interface, the MIDI to CV converter
on the K1 supports a number of useful MIDI to voltage conversions,
plus a MIDI THRU jack for daisy-chaining. Outputs can be assigned to
note, control change and pitch bend messages. Note playing modes
include single (mono) mode, split keyboard mode, two-voice polyphonic
mode, which is expandable up to 16 voices with additional modules, Arp
Odyssey-style duo-phonic mode, and single (mono) mode with velocity
output on the second CV output jack.
Outputs are programmed by pressing the SET button to select the
output mode to program and then sending a MIDI message to the
unit. The MIDI channel, output type and other parameters are stored
automatically in the module and restored at power-on.
Mixer Interface Connections and Controls
Audio signals are input on IN jacks 1-5. Jacks 1 and 2 are a stereo
pair and automatically wired to output to L and R respectively. Jacks
3, 4 and 5 are mono inputs.
LEVEL 1/2 controls the input level of the stereo input. LEVEL 3, 4
and 5 are used to control the input from the mono channels. Signal
indicators on each channel light regardless of the level control
setting. This can be used to detect if there is a signal present on an
input without having to raise the input level.
Each input has an AUX control. AUX 1/2 sends a mix of inputs 1 and
2 to the AUX OUT jack. Each mono channel also has a AUX send which
will send to the AUX OUT jack. Note that the AUX controls receive a
signal after the input level adjustment. (post-fader) If you turn down
an input level control the AUX control signal will also be turned
Channels 3, 4 and 5 support panning. Channels 3 and 4 have PAN
controls which position the signal between the left and right channels
on the output. Channel 5 contains a CV input instead of a panel
control. Inputting a CV signal of between -5V and +5V will pan the
signal from fully left to fully right.
The MASTER LEVEL control affects the output signal level on the L
and R banana and minijacks. The PHONES LEVEL control affects the
output level on the PHONES jack. Both output level controls work
MIDI Interface Connections
The MIDI IN jack received MIDI signals from a keyboard or other
equipment. Signals input to the MIDI IN jack are repeated on the MIDI
The CV / GATE jacks output a variable voltage (CV) and gate signal
(GATE) in response to MIDI input signals. The CV and GATE jacks always
operate together in pairs.
To set up the MIDI interface, press the SET button to select the
correct programming mode by observing the GATE1 and GATE2 indicators. Then
send the correct MIDI message to program the outputs. The settings are
stored internally and restored when the module is powered
Note: Channel 16 is reserved and cannot be used for
MIDI Setup Modes
The outputs are assigned by pressing the SET button until the
correct GATE indicator flashing pattern is observed, and then sending
a MIDI message to assign the outputs. The K1 automatically learns the
MIDI channel and other parameters based on the setup mode. Press the
SET button to cycle through the setup modes. If no MIDI message is
detected within several seconds no change is made to the current
Single (Mono) Mode - GATE 1 indicator flashes (CV1 / GATE1 assign) or GATE 2 indicator flashes (CV2 / GATE2 assign)
Single Mode provides monophonic playing on a single CV / GATE
output pair. When programming, if you send a note message the MIDI
channel will be set and pitch voltages will be output on the CV jack,
and gate (note on/off) will be output on the GATE jack. Last-note
priority is used and the last 8 notes pressed will be stored and
recalled as notes are pressed and released.
If you send a CC message when programming, the sent CC number will
be output as a variable voltage on the CV jack. The GATE jack will
output an on/off signal based on whether the CC level is above or
If you send a pitch bend message when programming the CV output
jack will output a voltage corresponding to the pitch bender position,
and the GATE output jack will be on if the bender is raised, or off
otherwise. If you bend down instead of up during programming the
polarity of the CV signal and GATE response level will be inverted.
Split Keyboard Mode - GATE 1 and 2 indicators flash alternating
In split keyboard mode both pairs of CV / GATE jacks work together
to provide a dual monophonic setup on the same MIDI channel. The note
sent to program determines the lowest note of the upper half (CV 2 /
GATE 2) of the keyboard. Last-note priority is used and the last 8
notes pressed on each half of the keyboard will be stored and recalled
as notes are pressed and released.
Polyphonic Mode - GATE 1 and 2 indicators flash together
Polyphonic mode makes it possible to play more than one note at a
time and have voices automatically assigned to different outputs as in
a polyphonic synthesizer. Multiple K1 units (theoretically up to 8)
can be used together for up to 16 voices of polyphony. Practically
speaking 4-6 is probably the maximum number which is reasonable.
While programming, the key pressed sets the voice unit number. This
tells the K1 which pair of voices it is responsible for playing. Press
the white keys from C4 (middle C) to C5 to assign voice unit
1-8. Always start with voice unit 1 and add more units depending on
the number of K1s you are using.
Voice unit 1 will produce voices 1 and 2. Voice unit 2 will produce
voices 3 and 4, and so on. As you hold down more keys more voices will
be assigned. Releasing a key will free up a lower numbered slot and
the next key pressed will produce an output on this free voice.
Arp Mode - GATE 1 indicator flashes and then GATE 2 indicator comes on
Arp mode emulates the duo-phonic behavior of the Arp Odyssey
synthesizer and offers a nice combination of mono and poly playing
with only two oscillators. When a single note is being played both CV
and GATE output pairs will play in unison. Due to small analog
variations in the CV output and oscillators, a rich chorused sound will
be heard when playing a single note at a time. When a second note is
pressed the CV 2 / GATE 2 pair will split off and play the second
note. If additional notes are played, monophonic last-note priority is
applied to the second voice while CV 1 / GATE 1 hold the first note
Velocity Mode - GATE 1 indicator flashes and then GATE 2 indicator fades up
Velocity mode offers monophonic playing with last-note priority on CV 1 / GATE 1 while the velocity of each last note played is output as variable voltage on CV 2. This allows expressive playing on a touch-sensitive keyboard. The velocity voltage can be used in all kinds of ways: adjust the volume, affect the speed of an LFO or filter cutoff frequency, etc.
Pitch Bend Range
When in a note mode the pitch bend range of CV1 or CV2 can be
adjusted. Send a MIDI program change on either CV1 or CV2 assigned
channels to adjust the bend range from 1 to 12 semitones. Program
change 1-12 selects bend range of 1-12 semitones for CV1. Program
change 13-24 selects bend range of 1-12 semitones on CV2. Pitch bend
range for CV2 is only used in single mode.
Direct Control Mode (Channel 16 Only)
The Direct Control Mode on channel 16 uses continuous controller
messages to control any of the outputs. This includes the ability to
set the CV outputs to any voltage, as well as the ability to turn on
or off the GATE outputs.
|Direct Control Mode CC
CV1 DAC: 16 (MSB), 48 (LSB)
CV2 DAC: 17 (MSB), 49 (LSB)
CV1 / CV2 DAC Control:
- Use the MSB and LSB bytes to set 12 bits of resolution.
- MSB = top 7 bits (right justified)
- LSB = lower 5 bits (left justified)
- Value 0 = lowest output voltage
- Value 4095 = highest output voltage
Control of gate outputs:
- Value 0-63 = off
- Value 64-127 = on
System Exclusive (SYSEX) messages are used by Kilpatrick Audio
modules for vendor-specific commands that are not part of the MIDI
spec. The K1 MIDI interface channel and mode assignments can be sent
in a single SYSEX message. This can be used by sequencing software to
reset the interface to a known setting when loading a song.
SYSEX packet format:
0xf0 0x00 0x01 0x72 0x43 0x02 [11 setting bytes] 0xf7
The meaning of the 11 setting bytes are as follows:
|Byte Number / Meaning
|Byte 1 - CV1 Map
0 = unassigned
1 = note mode
2 = CC mode
3 = pitch bend mode
|Byte 2 - CV2 Map
0 = unassigned
1 = note mode
2 = CC mode
3 = pitch bend mode
|Byte 3 - CV1 Channel
||0-14 = MIDI channel 1-15 (channel 16 reserved)
|Byte 4 - CV2 Channel
||0-14 = MIDI channel 1-15 (channel 16 reserved)
|Byte 5 - CV1 Value
CC mode: controller number (0-121)
pitch bend mode: 1 = normal, 0 = inverted
|Byte 6 - CV2 Value
CC mode: controller number (0-121)
pitch bend mode: 1 = normal, 0 = inverted
|Byte 7 - Voice Mode
0 = single
1 = split
2 = poly
3 = arp
4 = velocity
|Byte 8 - Voice Split
||split voice mode split point: note number
|Byte 9 - Voice Unit
||polyphonic voice mode unit number: 0-7 = unit 1-8
|Byte 10 - Voice Bend CV1
||CV1 bend amount: 1-12 = 1-12 semitones
|Byte 11 - Voice Bend CV2
||CV1 bend amount: 1-12 = 1-12 semitones
K2 // Pitch Oscillator
The K2 Pitch Oscillator is a fully analog voltage-controlled
oscillator (VCO) with a traditional sawtooth core and waveshapers that
provide sine, triangle, ramp and pulse outputs. Two different pulse
modes offer either standard PWM pulse shaping or a unique multi-pulse
mode that generates different timbres by producing multiple narrow
pulses. Both modes can be pulse width modulated.
Front panel tuning is accomplished with coarse and fine tuning
controls. Additionally a range switch allows a second coarse control
to be added to the tuning signal allowing two ranges of tuning, or
offering even more tuning range.
A special blend mixing section allows mixing of sine, triangle,
ramp and pulse outputs. Two controls blend between sine and ramp, and
triangle and pulse waveforms. These two signals are fed into a voltage
controlled blending circuit which can be control with the BLEND MIX
control or input control voltage.
Inputs include a calibrated V/octave input, linear and exponential
CV inputs with bi-polar input level controls, a PWM input with level
control, and a sync input which can be used to hard sync the
oscillator with input pulses from another oscillator. Outputs are
provided for the blend mix circuit and also separate outs for sine,
triangle, ramp and pulse outputs.
Oscillator Connections and Controls
Oscillator Core and Tuning
The oscillator core is an analog sawtooth core. Tuning is affected
by the COARSE and FINE tuning controls. If the RANGE switch is in the
OFFSET position the RANGE OFFSET control acts as a second COARSE
tuning control, allowing the main tuning range to be shifted up or
down by a significant amount.
The V/OCT input provides a calibrated 1V/octave control over
oscillator pitch. The EXP FM IN provides exponential FM control of
pitch. The EXP FM DEPTH control affects the scaling of the input and
can be set to either + or - so that the input signal can be inverted.
(increasing voltage causes decreasing pitch) The LIN FM IN and LIN FM
DEPTH control works similarly except that the pitch change is linear
with input voltage instead of exponential.
Inputting a fast-changing waveform like a pulse wave into the SYNC
input will reset the oscillator core to the starting position. This
can be used to create unusual timbres by driving it from a second
The PWM section generates the PULSE output. The PWM OFFSET control
selects the duty cycle of the pulse waveform. PWM IN and PWM DEPTH
allow voltage control of the pulse duty cycle.
The signal from the oscillator core is processed by various analog
waveshaping sections before being output on the four main output
jacks. The nominal output level is 10Vp-p except the pulse output
which is intentionally slightly lower in amplitude. The jacks output
the following signals:
- RAMP OUT - A processed version of the internal ramp
signal from the oscillator core comes out of the RAMP OUT jack.
- TRIANGLE OUT - The triangle signal is generated from the
ramp signal using an analog waveshaper. This signal comes out of the
TRIANGLE OUT jack.
- SINE OUT - A smoothed version of the triangle signal is
produced to be somewhat sine-like. It is not a low-distortion sine
wave, but has a soft and interesting character.
- PULSE OUT - The PULSE OUT jack outputs the signal from
the PWM section described above.
Each of the waveshaped outputs is fed into the blend section where
they can be mixed to generate more complex waveshapes. Two controls
choose a blend of sine and ramp waves, and triangle and pulse waves
respectively. These two signals are sent into a voltage-controlled
blending circuit which can fade between each signal manually by using
the BLEND MIX control or by inputting a voltage into the BLEND CV IN
jack. The BLEND OUT jack outputs the final blended signal.
K3 // Digital Effects
The K3 Digital Effects module contains two different digital effect
units in a single module. The top REVERB / DELAY section produces high
quality reverb and delay effects, all processed at 24 bit. The lower
ITTI BITTI section produces lo-fi effects such as bit crushing and
sample-rate reduction, wavefolding, distortion and signal
multiplication. Reverb and delay effects are geared towards audio
signals, whereas the ITTI BITTI effects can be used for both audio and
low frequency control voltage signals.
Reverb / Delay
The REVERB / DELAY section provides high quality stereo reverb and
delay effects with a dedicated audio DSP. A mono input and level
control are used to feed audio into the processor. The output
generates a left and right channel which create expansive reverbs and
stereo delays. Three controls allow the reverb mix, delay mix and
delay time to be controlled. The delay time can also be controlled
with a voltage to create pitch shifted and sped up / slowed down
effects. Two reverb algorithms and three delay algorithms are selected
with the main PROGRAM control.
The ITTI BITTI section occupies the lower half of the module. It
generates low fidelity audio and CV effects using non-oversampled 12
bit analog converters to create a number of interesting types of
distortion and digital processing of both control voltages and audio
signals. It creates digital multiplication of two signals, sample and
hold with sample-rate and bit depth reduction controls, wave folding
with adjustable drive and break points, and a digital distortion
effect which creates harmonically rich timbres from simple
waveforms. The sample rate of the system is internally generated, or
can be fed from a pitch oscillator or other source of pulses.
Digital Effects Connections and Controls
Reverb / Delay
Audio is fed into the reverb / delay section through the IN
jack. The IN LEVEL control affects the input signal, and the CLIP
indicator will blink if the digital signal path is overloaded. The
REVERB MIX, DELAY MIX and DELAY TIME controls affect the currently
selected reverb and delay programs. The DELAY TIME CV IN jack allows
the DELAY TIME control to be adjusted with a control voltage. A stereo
output is generated on the L and R OUTS jacks.
The reverb and delay programs are selected together by using the
PROGRAM control. This control is used for selecting programs for both
parts of the module. Click the program control until the REV and DEL
indicators are flashing and then turn it to select a combination of
reverb and delay programs. There are two reverb programs and three
delay programs. The third delay program is shown by lighting both DEL
1 and DEL 2 indicators.
A pulse input to the PROG A jack will step through the reverb /
The ITTI BITTI section performs 12 bit audio or control voltage
processing using one of four algorithms. There are two inputs. The
main signal is fed into the SIG IN jack, and the level is controlled
by the SIG LEVEL control. The output is sent out of the SIG OUT jack.
Each effect has two parameters which can control the effect
response in real-time. The PARAM 1 control is manually adjusted. The
PARAM 2 control has a manual adjustment, but can also be controlled by
a voltage input into the PARAM 2 CV IN jack. The input level is
controlled by the PARAM 2 CV LEVEL control.
A pulse input to the PROG B jack will cycle through ITTI BITTI
The ITTI BITTI effects and parameters are as follows:
- MULT - Multiplies SIG IN by PARAM 2, which can be either
positive or negative. The PARAM 1 control adds a DC offset to the
signal. The PARAM 2 control or CV IN can be used to amplitude
modulate the SIG IN signal for digital ring modulation or VCA-like
- S/H - Sample and hold offers sample-rate and bit depth
reduction. The PARAM 1 control adjusts the bit depth from 12 bits
down to 1 bit. The PARAM 2 control or CV IN adjusts the sample-rate
from the maximum rate of approx. 29.7kHz down to less than 1kHz.
- FOLD - Fold offers digital wavefolding by applying
non-linear transformations to the signal at different
thresholds. The PARAM 1 control affects the overall wave folding
shape, and PARAM 2 control or CV IN affects the drive level, which
changes how hard the input signal hits the wave folding effect.
- DIST - Dist offers digital distortion by directly
manipulating the bits that represent the signal waveform. The PARAM
1 control chooses which distortion shape is used. The PARAM 2
control or CV input affects the drive level, which changes how hard
the input signal hits the distortion effect.
External Sample Clock
Normally the sample clock for the ITTI BITTI is generated
internally at approx. 29.7kHz. However external clock pulses can be
input into the SAMPLE CLOCK IN jack to drive the internal processing
at an arbitrary rate. The minimum sample frequency is 1 pulse every 30
seconds or less, and the maximum frequency is approximately
30kHz. Once a pulse is received the external clock mode will be
activated and the indicator next to the SAMPLE CLOCK IN jack will
light. If no clock pulse is received for more than 30 seconds, the
internal clock will be reactivated automatically.
K4 // Envelope Modulator
The K4 Envelope Modulator combines two envelope generators and two
LFOs into a single module. Each section supports a number of different
uses in many types of patches.
Envelope Generator Section
The two identical envelope generators can operate in one of three
modes: attack / hold / release, attack / release, and auto-repeat
mode. Both a gate input and manual trigger button can be used to start
and stop the envelopes, and the up and down times are voltage
controllable. The outputs generate both a variable voltage and a
pulse which activates during the release phase of the envelope.
A dual LFO section generates periodic signals of various speed and
amplitude. The speed can be controlled by a voltage as well as by the
panel control. The output level can be adjusted over a wide range
including the ability to internally clip the output to max and min
Both channels of the LFO section can be synchronized together and
the phase of the second channel can be adjusted ahead or behind by up
to 180 degrees. This can be used to generate waveforms which have a
known phase shift between them.
Envelope Modulator Connections and Controls
Envelope Generator Section
The envelope generators are labeled 1 and 2. Both envelope
generator sections are identical and can operate in one of three modes
as set by the MODE switch: attack / hold / release, attack / release,
and auto-repeat. The signal on the OUT jack normally sits at the
minimum level (-5V) and ramps up to the maximum voltage (+5V) when the
envelope is triggered. The UP TIME control affects the time taken to
ramp up to the maximum level. The DOWN TIME control affects the time
taken to ramp back down to the minimum level. The time range on both
controls is approx. 1 millisecond to 10 seconds. The UP CV IN and DOWN
CV IN jacks can adjust the up or down times under voltage
control. During the release phase the CYCLE jack will turn on. Both
the GATE IN and adjacent trigger button cause the envelope generator
The envelope modes work as follows:
- ATTACK / HOLD / RELEASE - A gate signal will cause the
output to ramp up while the gate is held down. Once the maximum
value is reached the output is held at this level as long as the
gate is on. When the gate is released the signal ramps down. The
output ramps up and down in response to the gate signal.
- ATTACK / RELEASE - A gate signal will cause the output to
ramp up and then down, completing an entire cycle regardless of the
gate level. This can be used to extend the length of a short pulse
or produce percussive envelopes.
- AUTO-REPEAT - When this mode is first selected the output
will begin to ramp up and down, repeating automatically. This can be
used as an LFO with separately adjustable up and down times. If a
gate signal is input the auto-repeat mode will change to a momentary
behavior. When the gate is subsequently triggered the envelope will
ramp up and down a minimum of one time. (like ATTACK / RELEASE mode)
If the gate is continuously held the envelope will continue
The LFO units are labeled 3 and 4. The LFO section contains two
identical LFO units, except for the PHASE control which is only
available on channel 4.
An LFO is always operating and normally generates triangle
waves. The SPEED control adjusts the LFO speed from 1 cycle ever 60
seconds, to about 40Hz. The SPEED CV IN jack allows voltage control of
the speed. The GAIN control adjusts the output signal amplitude from
about 10% to 100% amplitude. Increasing the GAIN control fully
clockwise will cause the output to generate clipped waves that quickly
switch between minimum and maximum values.
The SYNC switch allows both LFO channels to output the same
frequency as controlled by either LFO channel 3 or 4. In this case the
PHASE control allows both outputs to generate the same frequency but
allows the phase of channel 4 to be adjusted from -180 to +180 degrees
relative to channel 3.
K5 // Filter Amp
The K5 Filter Amp is a quad VCA and low-pass filter
combination. Four identical channels offer manual or voltage
controlled wide-band VCA, and also a low-pass filter section with
controllable resonance. Both circuits operate in tandem with the same
CV and input signal, but producing two simultaneous outputs.
The K5 uses high-quality, low-noise VCA circuitry throughout. The
response is designed to smoothly track the input signal for
optimum fades for use with an envelope generator or other type of
modulation source. The LEVEL control can be used to tweak the response
to suit the type of CV control and input signal.
The low-pass filter output has a resonance control which adjusts
the response from slight peaking around the cutoff frequency, to
extreme settings. The filter is not designed to self-oscillate but it
does produce percussive pitched bursts when fed with very low
Filter Amp Connections and Controls
Four identical sections are marked 1, 2, 3 and 4. The basic
connection is to feed an audio or CV signal into the IN jack on a
channel and then obtain one or both of the AMP or LPF output
signals. The LEVEL control will simultaneously open and close the VCA
and also move the cutoff frequency of the low-pass filter up and
down. The LPF output can be used as a low-pass gate by allowing the
cutoff frequency to go all the way down to below the audio range.
The CV IN jack allows control voltages to be input. These are
normally in the range if -5V to +5V and the LEVEL control can be used
to adjust the offset of the input signal. For some types of effects it
might be desirable to input a smaller amplitude signal if the range of
control is too wide.
For the low-pass filter, the resonance control is used to adjust
how much feedback exists within the filter circuit. The minimum
setting has slight amount of peaking around the cutoff frequency, for
an interesting yet fairly mild effect. The maximum resonance setting
creates extreme oscillations on the edges of fast changing waveforms
such as ramp or pulse type waveforms. The output amplitude on the LPF
jack is lower than the AMP output jack to allow more headroom at high
K6 // Voltage Processor
The K6 Voltage Processor is a workhorse utility module. It has voltage
interfaces to convert audio signals to and from the outside world. It is
completely analog with carefully designed mixers and amplifiers designed
to offer maximum versatility in a single space module. With a very dense
panel that is still easy to use, the K6 Voltage Processor solves a number
of problems with simple, easy-to-use sections.
The audio buffers are used to get audio signals in and out of the Kilpatrick
Format system. If you want to interface CVs from other synths you should simply make
some patch cables from banana to your connector of choice. There are four input buffers
and two output buffers.
Line level signals are gained up 4x to bring a typical line level signal up the levels
required by the synth. Feed drum machines or other audio sources into the synth and pass them
through filters or other effects. There are four input buffers which are DC coupled.
Hot signals in the synth can be sent out to external gear. Use the output buffers to attenuate
the signal by 4x and provide a buffered version suitable to feed into other gear. Outputs are buffered
and AC coupled so you won't hurt your speakers or other equipment if you happen to try sending them
DC control voltages. There are two output buffers.
Buffered Mixers with Gain
There are four buffered mixers with gain controls. Each mixer has two buffered inputs labeled INS.
The GAIN control adjusts the gain from 0-2x. Both normal (+) and inverted (-) outputs are driven at
the same time. A bi-colour LED shows the signal level and polarity of the normal output.
Simple Buffered Mixers
There are two simply buffered mixers. These are used to mix two signals together properly. A single
output (OUT) provides the sum of both inputs. (INS) A bi-colour LED shows the signal level and polarity
of the output.
The source selector can select or swap signals. Two inputs (IN A and IN B) and two outputs
(OUT A and OUT B) are either connected A->A, B->B or A->B, B->A depending on the setting of the switch
or SEL input. When the switch is in the A-A mode, the inputs and outputs are patched A->A, B->B. When the
switch is in the A-B mode, the inputs and outputs are patched A->B, B->A. When the switch is in the CV
mode, the inputs are patched A->A, B->B unless a voltage is presented on the SEL input. Any voltage more
than about +1.2V will cause the outputs to be swapped.
Dual Voltage Source
Sometimes it's nice to have a manually controlled source of voltages. Two pots labeled VOLTS are used
to select a voltage from about -5V to +5V. The centre position is 0V. The voltages are output on the adjacent
jacks labeled OUT.
K7 // Entropy Sequencer
In the quest to revisit sequencers in a totally new way to previous attempts, the entropy sequencer combines
an analog noise source with a powerful sequencer to create a flexible and inspiring module. Use it as a straight-ahead
step sequencer, source of random voltages, gates and pulses, and real analog noise.
The sequencer section of the K7 is a step sequencer that supports up to 32 steps. You can program each of the steps
manually, but the real strength of the sequencer is to be able capture and loop random levels. These levels come from
an internal random number generator which is continually seeded from the analog noise source that is used to generate
the noise output. The sequencer outputs the voltages on the VOLTAGE jack. The GATE jack outputs gates which start at the
beginning of every step, and the PULSE output produces random pulses while the sequencer is running, but is otherwise
unaffected by other sequencer controls.
The STATUS display normally shows the step position. When changing some controls or using the EDIT modes the display
will show other information for a short time. When changing modes a
"--" is shown on the display for
a moment. When the sequencer is in the reset state waiting to start, a
"__" is shown on the display.
The sequencer does not have a built-in clock. You can patch the PULSE output into the CLOCK input for totally wacky
performances, but if you want constant step speed use a source of pulses or square waves for the most accurate triggering.
When the RUN/STOP switch is set to RUN the sequencer will accept clock input. When set to STOP the clock is ignored. The
RUN/STOP jack will start the sequencer when a positive voltage is input. When the RUN/STOP switch is in the RUN setting,
the jack will have no effect.
The step direction is set with the DIRECTION switch. NORMAL runs forward, and FLIP runs backwards. If a positive voltage
is input to the DIRECTION jack, the direction is reversed from the switch setting. The up and down LEDs show the current
The RESET jack and small adjacent pushbutton is used to reset the sequencer playback to just before the first step. The
next clock pulse issued will start the sequencer at the first or last step depending on the current step direction.
MODE and EDIT
The MODE switch is used to select whether the level of each step is seeded from the random number source, or looped
from the internal RAM. When in SEED mode as each step is taken the value of that step is replaced with a new random number.
When the LOOP mode is used, the previously set or seeded steps are used when each step is taken.
The edit functions allow the actual step levels to be edited, as well as the ability to select preloaded scales and
rhythms for playback. Click the EDIT knob to cycle through the edit modes. The STEP mode is used to select one of 32 steps
to edit. The LEVEL mode is used to adjust the level of the previously chosen step. Once editing a step or level the editing
function will toggle back and forth between these. To access the SCALE and RHYTHM functions you must let the edit mode
time, which takes about 5 seconds.
Note: Edit functions are not stored when the power is removed.
The SCALE mode allows the selection of different scales. The levels are normally quantized to semitones, but choosing a
different scale will shift the notes down to the nearest scale member to create other tonalities, regardless of the level
of the step in memory. The available scales are:
- Natural Minor
- Harmonic Minor
- Major Pentatonic
- Minor Pentatonic
- Man Gong
The RHYTHM mode allows steps to be played back with a rhythmic element by ignoring some clock pulses. There are
64 different rhythms. Rhythms are repeated every 8 steps.
Sequence Playback Controls
The SEQ LEN pot controls the length of the sequence from 1 to 32 steps. The associated SEQ LEN CV IN jack offsets
the SEQ LEN pot and allows voltage control over the sequence length.
The SEQ START pot changes the starting position of the sequence from between 1 and 32. By adjusting the SEQ START
and SEQ LEN together, small ranges of steps can be chosen in real time. The SEQ START CV IN jack offsets the SEQ START
pot and allows voltage control over the sequence start.
The SPREAD pot affects the range of output voltages produced on the VOLTAGE jack. Reducing the spread will shift
up or down levels which are outside this range. These are shifted by octaves if the spread is greater than 12, and
by smaller intervals as the spread is reduced to 0. The SPREAD CV IN jack offsets the SPREAD pot and allows voltage
control over the spread.
The VOLTAGE SLEW pot affects how the rate of change of voltage between steps. This can be used to create a
portamento effect, or generate wandering voltages that are continuously changing. The setting affects the rate
not the speed, so longer jumps between steps will take longer.
The GATE LEN pot affects the length of the gates issued at the start of each step. The lengths are set in time
so changes in the clock input rate will not change the gate length. Gates can be as short as 1 millisecond or as
long as 9 seconds.
The pulse generator produces random pulses when the sequencer is running. The PULSE DENSITY pot affects relatively
how often pulses are produced. The DENSITY CV IN jack offsets the PULSE DENSITY pot and allows voltage control over
Analog Noise Source
The analog noise source section of the module produces white noise internally using a transistor noise source
which is amplified and filtered to provide one of three kinds of noise at the output. The NOISE TYPE switch selects
the kind of noise generated at the output. The white noise setting provides a flat noise spectrum. The blue setting
provides noise that rises 3dB per octave and contains mostly high frequencies. The pink setting provides noise that
falls at 3dB per octave and has a musically smooth frequency response. The NOISE LEVEL pot controls the output level
at the NOISE output jack.
K9 // Dynamic Filter
The K9 filter offers a multi-mode filter with nine different response types as well
as an envelope follower for tracking audio signals. Both can be used at the same time.
Both sections can be used completely independently.
The filter occupies most of the module panel. Signals are input to the SIG IN jack. The
input level is set with the SIG IN LEVEL control.
The cutoff frequency can be manually set using the FREQUENCY control. The V/OCT IN jack
is internally calibrated for approx. 1V/octave response and is used for pitch tracking. The K9
filter cannot be used as an oscillator because it is not designed to self-oscillate. The FM IN
and FM DEPTH control offer exponential FM control with variable depth.
The RESONANCE control sets the resonance level. The RES CV IN allows voltage control of the
The AM CV IN and AM LEVEL allow the built-in VCA channel to be control with an external voltage.
The VCA GAIN manually adjusts the VCA. This must be turned up to get any sound from the filter.
The FILTER OUT jack outputs the currently selected filter mode.
The FILTER MODE control selects the current filter mode. The setting is stored after several
seconds and will recall the last-used filter setting when the system is powered off.
The envelope follower can track audio signals and provide an average level output signal
which can be used to convert volume information into control voltages. This can be used to track
the level of microphone or guitar signals, or to make pulses and gates from drum machine outputs
for synchronization purposes.
The INS are used to feed a signal in. It is recommended to only one one input at a time. The HIGH input takes signals from other high-level synth modules. The LOW input takes signals via a mono 3.5mm minijack input. This can be used to track line level signals from external equipment.
The FOLLOW IN LEVEL sets sensitivity of the input. The SMOOTHING control affects how fast the
envelope follower reacts to changes at the input. At the lowest setting the follower will track the actual waveforms of some bass signals. At the slowest setting it may take many seconds for the output to reach the peak input.
The ENVELOPE outputs (+ and -) output the tracked envelope signal with both normal (+) and inverted (-) versions available at the same time. The GATE output turns on when the envelope is above a preset threshold. The PULSE output pulses when the envelope exceeds a preset threshold. By adjusting the controls these can be made to track percussion signals for use as a clock or trigger signal.
K10 // Dual Envelope
The K10 Dual Envelope offers an easy to use dual channel ADSR envelope
generator with many useful additional features. With the SHAPE control set at
the centre position, and the PEAK control set at maximum, the ATTACK, DECAY,
SUSTAIN and RELEASE controls can be used to create the envelope shape in the
The TIME switch offers two different time ranges for the A, D and R slopes.
HIGH offers approx. 1ms to 32 seconds, and LOW offers approx. 1ms to 8 seconds.
The use of the SHAPE control will have an impact on the maximum or minimum time,
which are measured with a perfectly linear SHAPE setting. (centre position)
GATE IN and RETRIG IN
The GATE IN jack accepts a gate signal that controls the envelope generator.
When the GATE IN is high, it will generate the ATTACK, DECAY, and SUSTAIN
phases, holding on sustain. When the GATE IN is low it will run the RELEASE
phase and then go back to idle. A button under each GATE IN jack allows the
gate to be stimulated manually without an input signal. This is very useful
for testing and tuning the envelope.
The RETRIG IN jack will accept a rising-edge pulse and cause the envelope to
be retriggered immediately back to the ATTACK phase.
ADSR Controls and Voltage Inputs
The ATTACK, DECAY and RELEASE controls affect the slope times in each of the
phases. The SUSTAIN control affects the sustain level. Each of the A, D, S and
R phases has a voltage input which will add or subtract from the current setting.
Additionally an LED over each CV IN jack shows if the particular phase is active.
PEAK Control and Voltage Input
The PEAK control allows the overall size of the envelope to be adjusted. It is
a real-time control that alters the maximum peak size, but also scales the
entire output so that velocity-sensitive playing or realtime adjustment is
possible. The PEAK CV IN jack accents a voltage which is used to add or subtract
from the current PEAK setting.
When the SHAPE control is in the centre position linear ramps are generated.
When coupled with the K5 Filter Amp this will produce proper VCA or filter
control. If the SHAPE control is turned up, the linear ramps will be bent into
a more logarithmic shape, spending more time at higher voltages. When turned
down, an exponetial shape will be generated, making short fast peaks.
Kilpatrick Audio will warrant all parts of the system against
manufacturing defects for a period of one year from the date of
purchase. If you have a problem with a module, contact us and arrange
to return it to us for repair. After one year, we will offer low cost
service on modules for as long as possible. If you have trouble at any
time please contact us and we will do our best to help you. No
warranty is offered for damage caused by the end user or other
Note: This warranty applies to Kilpatrick format
products and takes precedence over our general warranty policies in
the case of any differences.
Hardware Repair Policy
Kilpatrick Audio will repair modules free of charge for the first
year after purchase provided that the failure was caused by
manufacturing defects. After 1 year, or for damage caused by the user,
a minimum charge of $25 is applied to cover transport costs. Do not
send items for repair before getting in touch with us. We can usually
handle repairs within 1 week.
Software Update Policy
Some modules have embedded software which we test thoroughly
before releasing each product. However, all software contains bugs and
thus is not covered by the warranty. Software updates are free for all
customers no matter when a module or system was purchased. Shipping
to/from Kilpatrick Audio is the responsibility of the customer. We
charge a flat rate of $25 to handle return shipping and can usually
turn around software updates in 1-2 days.
Need More Help or Support?
Kilpatrick Audio provides help for customers exclusively by
email. If you have any questions or problems we would be happy to help
you. Contact us and we will do our best to answer your questions.