State Zero
Reference Manual
Copyright 2010, Mungo Enterprises
State Zero
1
State Zero
2
Contents
Connections 4
Power 6
Display 6
Audio 6
Midi 6
Patchfield 6
Module Reference 8
Introduction 9
Oscilloscope 10
Master 12
Oscillator 14
Low Frequency Oscillator 16
Envelope 18
Filter 20
Amplifier 20
Comparator 22
Sample and Hold 22
Slew Rate Limiter 24
Curve and Quantize 24
Mixer 26
Sources 28
Tempo 30
Audio 30
Memory 32
Voice 32
Synthesis Techniques 34
Normalling 35
Portamento 35
Legato 36
Fingered Portamento 36
Filter Resonance 37
Envelope Curves 37
Envelope Variations 38
Envelope Hold 38
Service Notes 40
Shipping 41
Wood Care 41
Routine Maintenance 41
Case Access 42
Part Replacement 42
Repairs 42
Appendix 44
Schematics 44
State Zero
3
State Zero
4
Connections
State Zero
5
State Zero
6
Power
The synthesiser is powered by a regulated 9V DC power supply, connected
by a 2.1mm DC plug tip positive polarity. The power supply needs to be tightly
regulated and should not exceed 10V at any time. Earthing is not
recommended.
Display
An SXGA video output is available on a standard HD-15 connector. The
1024x1280 pixel image is oriented 90 degrees counter-clockwise from the
typical format, and is often described as the portrait orientation (as from the
typical landscape orientation). Connections to this socket should only be
made when the power is switched off at the wall for both State Zero and the
monitor.
Audio
The stereo inputs and outputs are via balanced !” TRS plugs. Both inputs
and outputs are DC coupled to allow interfacing with CV signals to/from
modular synthesisers.
Midi
Midi input and output is on standard 5 pin 180 degree DIN connectors. The
synthesiser only responds to messages on channel 1.
Patchfield
The patch points of the synthesiser are connected with 3.5mm TS plugs. They
do not provide or accept analog signals and should not be patched to or from
any other piece of equipment. Within their field, connecting outputs together
will cause no damage but may patch to unpredictable locations. Also each
output has infinite fanout and can be connected to as many inputs as needed
without buffering.
State Zero
7
State Zero
8
Module Reference
State Zero
9
Introduction
State Zero represents a new class of synthesiser, bringing together the
complete flexibility in the signal path of patchable systems with modern
polyphony and memory capabilities.
Signal flow is handled in the traditional method using physical patch cables to
connect modules together. The entire system follows the convention of signal
flow being from left to right, with inputs on the left of modules and their output
being on the right.
Patching is simplified by the absence of “multiples”, rather every input and
output is a pair of connected jacks allowing a signal to be endlessly chained
between inputs.
Most modules have several parameters that are continuously variable, each of
these are available as a pair of knobs and a signal input. Called “control
voltages” in conventional synthesisers there are no restrictions to signal
routing and these will be referred to as modulation inputs. The pair of knobs
set the base level of the parameter (right) and the amount by which the
modulation input signal will vary the parameter (left).
State Zero
10
Oscilloscope
The most prominent function of the video output is a dual timebase, 3 channel
oscilloscope.
The primary channel (green trace) follows whatever patch connection was last
made, allowing visualisation of any signal within the system. Triggering is
fixed and occurs on positive going zero crossings, while the timebase is
automatically adjusted to maintain several cycles on the screen at any time. If
the signal is too slow to effectively display as a periodic waveform, the
oscilloscope will ignore triggering and operate in roll mode.
A period counter is integrated with the primary channel to allow frequency
measurement or tuning, and operates from the same positive going zero
crossing trigger. The output is always displayed in microseconds, and is
disabled while the oscilloscope is in roll mode.
Further, a simple spectrum analyser (red trace) is available on the primary
channel. Operating from the waveform captured on screen it is scaled in
decibels vertically and octaves horizontally. Again it is disabled while the
oscilloscope is in roll mode.
The second timebase of the oscilloscope displays the left audio output (blue
trace) right audio output (yellow trace). Triggering is again fixed and occurs on
positive going zero crossings of the left audio output. An automatic timebase
the same as the primary channel is used, but operating independently.
These two channels are also applied to an X-Y trace (red) in the upper left of
the display, where the X and Y directions are driven by the left and right
channels respectively. This can be used for tuning oscillators by Lissajous
curves, or plotting transfer functions by viewing the relationship of the input
and output of a module.
State Zero
11
State Zero
12
Master
Zoom
Displays the zoom level of the last knob adjusted.
Increment/Decrement
Zoom
Increases/decreases the zoom level of the last knob adjusted. Pressing both
together zeros the value.
Number
Increases/decreases the value of the last knob adjusted by a single step,
regardless of zoom control. Pressing both together zeros the value.
Program
Selects program number.
Mode
Selection of zoom, number, and program modes.
State Zero
13
State Zero
14
Oscillator
Frequency
Exponential response, modulation of 50% from the master pitch source
achieves natural scaling and A440 tuning. Offset is displayed in
Octave/Semitone/Cent quantities.
Phase
Advances or retards phase of the oscillator up to 1 period. Offset is displayed
as a percentage.
Symmetry
Square:
Pulse width from 0 to 1, expressed as a percentage of full range from 0.5.
Sawtooth:
Ramp shape from negative going sawtooth to positive going sawtooth,
expressed as a percentage of full range from symmetric triangle.
Sinusoid:
No effect.
Waveform
Output selection of sinusoid, ramp, or square waveform.
Synchronization
Resets the phase of the oscillator to zero plus/minus phase offset. Triggered
by a positive going edge through zero.
State Zero
15
State Zero
16
Low Frequency Oscillator
Frequency
Exponential response, modulation of 50% from the master pitch source
achieves natural scaling and A440 tuning down 6 octaves. Modulation of 50%
from the tempo rate source achieves an eighth note period. Offset is displayed
in Octave/Semitone/Cent quantities.
Phase
Advances or retards phase of the oscillator up to 1 period. Offset is displayed
as a percentage.
Waveform
Output selection of sinusoid, triangle, or positive going sawtooth waveform.
Synchronization
Resets the phase of the oscillator to zero plus/minus phase offset. Triggered
by a positive going edge through zero.
State Zero
17
State Zero
18
Envelope
Rate
Exponential response, expressed in nominal units from 0 (infinite hold) to full
scale per sample.
Level
Final level of envelope stage expressed as a percentage of full scale from
zero.
Synchronization
The first stage of the envelope is triggered on a positive going edge through
zero and two stages follow it. The final stage is triggered on a negative going
edge through zero.
State Zero
19
State Zero
20
Filter
Frequency
Exponential response, modulation of 49.249% from the master pitch source
achieves approximately natural scaling about A440 down 1 octave 9
semitones and 23 cents while self oscillating at 24dB/octave. Offset is
displayed in Octave/Semitone/Cent quantities.
Slope
Output selection of 24dB/octave high pass, 12dB/octave low pass, or
24dB/octave low pass.
Amplifier
Level
Exponential response, expressed as a percentage over its range.
State Zero
21
State Zero
22
Comparator
Level
Threshold for comparison, output is positive full scale for input > threshold and
negative full scale for input < threshold.
Sample and Hold
Synchronization
The input value is captured on a positive going edge through zero.
State Zero
23
State Zero
24
Slew Rate Limiter
Up
Exponential response, expressed in nominal units from 0 (infinite hold) to full
scale per sample.
Down
Exponential response, expressed in nominal units from 0 (infinite hold) to full
scale per sample.
Curve and Quantize
Curve
Variable transfer function from soft clipping, through logarithmic, linear, and
exponential, to crossover distortion. Expressed as a percentage of full range
from linear.
Quantize
Step size of quantization from zero to full scale, expressed as a percentage.
State Zero
25
State Zero
26
Mixer
Level
Amplitude of input expressed as a percentage.
Note, the sum of the 4 channels is saturated to full scale.
State Zero
27
State Zero
28
Sources
Pitch
Master pitch source.
Gate
Square wave of key press.
Accent
Velocity of key press.
Pitch bender
Value of pitch bend wheel.
Modulation
Value of modulation wheel.
Noise
Uniformly distributed white noise source.
State Zero
29
State Zero
30
Tempo
Note Length
Tempo clock period selection of quarter, eigth, or sixteenth note length.
Clock
Square wave clock with 0.5 duty cycle at the selected rate.
Rate
Tempo rate independent of clock period selection.
Audio
Audio Input
Source supplied from audio inputs.
Audio Output
Destination for audio outputs.
State Zero
31
State Zero
32
Memory
Save
Holding down this button while sending a program change message will store
the current voice to that location. Alternatively press and hold the save button
then select the save location using the increment/decrement keys while they
are in program mode, the voice will be stored on release of the save button.
Pressing the save button without changing the program number or sending a
program change command will load the voice from the current program
number. To load a specific voice select its program number with the
increment/decrement keys in program mode then press and release the save
button.
Voice
Polyphony
Selection of monophonic unison, monophonic, or polyphonic note assignment.
State Zero
33
State Zero
34
Synthesis Techniques
State Zero
35
Normalling
On powering up the synthesiser the voice stored in memory location 0 is
loaded, allowing a set of normalled connections to be automatically setup with
common patches and parameter values. Equally, additional normalled
schemes could be stored in other memory locations.
These settings will remain until modified by creating a patch to an input or
adjusting a knob. Removing a patch will not return the normalled state but
rather then connect that input to zero.
If you are using extensive normalling to save time it is highly recommended to
mark these connections in coloured pen on the front panel. Historically
modular synthesisers offered a ring around each knob so that settings could
be recorded by marking the desired position of the pointer, and the choice of a
white face plate for State Zero is no coincidence. STAEDTLER Lumocolor
non-permanent pens in the medium or broad size are perfect for this
application.
Portamento
No dedicated portamento function is provided, instead giving the user a choice
of methods.
Portamento (exponential)
Passing the pitch signal through a low pass filter provides exponential
portamento with a constant time for the pitch to arrive at the new note.
Glide (linear)
Passing the pitch signal through a slew rate limiter provides linear portamento
with a constant rate at which the pitch changes to the new note.
State Zero
36
Legato
Playing overlapping notes in one of the monophonic modes will provide a new
trigger for each key press. To achieve legato voicing where the amplitude (if
not other) envelopes do not retrigger for overlapped notes, pass the gate
signal through a slew rate limiter.
With the limiters down rate set slow enough, notes played close together will
not cause the gate signal to cross zero and the envelope will remain held from
the previous note. The up rate should be as fast as possible to maintain
accurate triggering of note on events.
Fingered Portamento
Similar to legato voicing, fingered portamento only slides between notes that
are played overlapping. Again the simplest way to achieve the discrimination
between notes that are overlapped or not is to pass the gate signal through a
slew rate limiter or low pass filter.
Setting both the up and down rates to the correct speed will keep the output
signal negative for notes played without overlap and positive for those played
overlapped. This signal can then be used to control the portamento rate, such
that as notes are played further apart the portamento time will reduce to zero.
This provides a smooth transition from portamento to none, unlike traditional
synthesiser fingered portamento modes where it is either on or off. To achieve
that effect, the output of the slew rate generator would be passed through a
comparator before being used to control the portamento rate.
State Zero
37
Filter Resonance
The filter modules of State Zero do not have a built in resonance control,
instead resonance can be added by mixing the output of the filter back to its
input. Positive feedback gains will be unstable and negative gains too large
will self oscillate uncontrollably.
Self oscillation at the rolloff frequency can be stabilized in several ways, the
simplest using the curve and quantize module in the feedback path to reduce
gain for larger signals. This will greatly increase the gain for small signals and
the feedback gain will need to be adjusted accordingly.
Due to the delay in the feedback loop high frequency oscillations can occur
above the rolloff frequency of the filter when the feedback gain is set very
high. As these oscillations only occur at higher frequencies it is possible to
eliminate them by having the feedback gain negatively modulated by the filter
modulation.
Envelope Curves
The envelopes are linear in operation, but feeding back the output to modulate
the rate of a section allows it to take on a logarithmic or exponential shapes.
State Zero
38
Envelope Variations
The 4 stage point-to-point envelopes provide numerous variations on the
traditional ADSR envelope shapes. Some examples include:
ADSR
With the 3rd stage rate set to zero it is disabled, combined with the 1st and final
stages levels set to 100% and 0% respectively a conventional ADSR envelope
is formed.
AHDSR
Particularly effective for bass voices an almost flat top between the attack and
decay sections can be achieved with a very low rate setting for the 2nd stage,
and its level close in value to that of the 1st stage.
Staccato
Setting the 1st stage to a level of 0 and a very fast rate and using the 2nd stage
as the attack component, the envelope will always rise from 0 for well defined
staccato voicing.
Envelope Hold
Envelopes will always retrigger on a positive going edge through zero at their
synchronization input. If a true hold time is required during which a retrigger
cannot occur, the envelope will need to be triggered by an AD envelope,
which is triggered by the gate pulse. The AD envelope should have an attack
rate as fast as possible and the decay time adjusted to that it reaches 0 at the
desired hold time.
Loading...