miniAtmegatron Manual V1-0

miniAtmegatron Manual V1-0
INSTRUCTION MANUAL
1
Contents
Contents ......................................................................................................................................................................................................... 0
Functions ....................................................................................................................................................................................................... 2
Waveform Select ............................................................................................................................................................................................................................. 2
Filter Type ........................................................................................................................................................................................................................................... 2
Filter/Pitch Envelope ..................................................................................................................................................................................................................... 2
Amplitude Envelope ...................................................................................................................................................................................................................... 3
LFO (Low Frequency Oscillator) Waveform Select........................................................................................................................................................ 3
LFO (Low Frequency Oscillator) Rate ................................................................................................................................................................................... 3
Wave Crusher / Portamento ..................................................................................................................................................................................................... 3
.................................................................................................................................................................................................................................... 4
Pattern Tempo .................................................................................................................................................................................................................................. 4
Save Patch .......................................................................................................................................................................................................................................... 4
Digital Controls........................................................................................................................................................................................... 5
Filter Cutoff ......................................................................................................................................................................................................................................... 5
Filter Envelope ................................................................................................................................................................................................................................. 5
Filter LFO............................................................................................................................................................................................................................................. 5
Amplitude LFO .................................................................................................................................................................................................................................. 5
Distortion Level ................................................................................................................................................................................................................................ 5
Volume .................................................................................................................................................................................................................................................. 5
Filter Resonance ............................................................................................................................................................................................................................. 6
Pitch Envelope .................................................................................................................................................................................................................................. 6
Pitch LFO ............................................................................................................................................................................................................................................. 6
Pulse Width LFO .............................................................................................................................................................................................................................. 6
Phase LFO........................................................................................................................................................................................................................................... 7
Pitch ....................................................................................................................................................................................................................................................... 7
Audio Waveforms...................................................................................................................................................................................... 8
Filter Types .................................................................................................................................................................................................. 9
LFO Waveforms ....................................................................................................................................................................................... 10
Clock Division Rates ............................................................................................................................................................................... 11
Envelope Presets .................................................................................................................................................................................... 12
Arpeggiator Patterns ............................................................................................................................................................................ 13
Wave Crusher / Portamento Presets ........................................................................................................................................... 14
MIDI Implementation Chart ............................................................................................................................................................... 15
2
Functions
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There are 16 waveforms to choose from. The full list of waveforms can be found on page 8.
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There are 15 filter types to choose from. Setting the value to 0 will turn off the filter. By shaping the
harmonic content of the sound, it can make the sound brighter or duller. The full list of filters can be
found on page 9.
!is theThecaseFilterwithResonance
control doesn’t affect the sound with some filter types. This
filter types 12 to 15. This is because the algorithms for Butterworth
and Bessel filters do not require a resonance parameter.
!the Atmegatron
If you are used to using analogue synthesizers you will notice that the filters on
sound a bit different, particularly at low cutoff values. This is partly to
do with the sound being calculated in 8-bit and partly to do with the way the waveform
is updated.
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This envelope is used to shape the sound, by controlling the cutoff frequency of the filter and/or the
pitch. The amount of shaping is controlled by the controls: Filter Envelope and Pitch Envelope (see
page 5).
There are four parameters (or stages) to the envelope. These are represented in the diagram above.
The Filter/Pitch Envelope uses just one control to set the decay and release time.
The miniAtmegatron has 16 preset envelope shapes, which consist of a variety of combinations of
Attach, Decay, Sustain and Release parameters. The preset envelope shapes are shown on page 12.
3
!shapeIt isofworth
noting that the Attack, Decay/Release and Sustain values only affect the
the envelope. They don’t affect how much the envelope affects the filter and
pitch. Use the Filter Envelope and Pitch Envelope digital controls for this purpose.
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The amplitude (volume) of the sound can be shaped using the amplitude envelope. See the Filter/Pitch
Envelope section for information on how envelopes work.
The amplitude envelope uses the same preset shapes as the Filter/Pitch Envelope.
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The LFO is used to shape the sound. Unlike the envelope, it continually shapes the sound using a
waveform. This is just like the waveform that is used as the source of the sound, except it oscillates at
a much lower frequency (several Hertz as opposed to many hundred Hertz).
The LFO can control the filter cutoff, amplitude (volume), pitch and waveform pulse width. Use the
Filter LFO, Amplitude LFO, Pitch LFO and Pulse Width LFO analogue controls to control the amount
that the LFO affects these respective parameters.
There are 16 LFO waveforms to choose from. These are listed on page 10.
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The rate (or frequency) of the LFO waveform is set by a division of the internal metronome of the
Atmegatron. This runs at 120bpm by default. See Pattern Tempo for information. See page 11 for a
list of these divisions.
This can be overridden by an external MIDI clock source plugged into the USB MIDI input, which can
run at any tempo. This can come from a MIDI sequencer such as Logic or Ableton, or another MIDI
instrument such as a drum machine. Refer to your software or instrument instruction manual to see if
it can transmit MIDI clock.
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The Wave Crusher allows the resolution of the waveform to be reduced. It can do this in two ways:
reducing the bit depth of the waveform and reducing the sample rate of the waveform. If the waveform
were plotted on a graph or viewed on an oscilloscope, changing the bit depth would alter the
resolution vertically. Changing the sample rate would alter the resolution horizontally. The symbol for
the Wave Crusher demonstrates this process on a sine wave.
There are 7 useful combinations of bit depth and sample rate reduction in the miniAtmegatron. See
page 14 for a list of them. When the value knob is at 0, the Wave Crusher is off.
It is worth noting that the Wave Crusher works differently to a Bit Crusher plugin commonly used in
audio software. The Wave Crusher only affects the waveform and not the overall output of the
4
synthesizer (as would happen with a plugin). This means that the decrease in resolution of sample
rate isn’t fixed, but is a division of the current frequency (or note) being played.
Portamento (or glide) is the time it takes for the pitch to change from the last note to the new note,
when a key is pressed (on a MIDI controller keyboard). The portamento values range from 0 = 0 secs
(i.e. portamento off) to 15 = 6.5 secs.
The miniAtmegatron has an inbuilt sequencer with 15 preset patterns. The root not of the pattern is
selected using the Pitch control or via the USB MIDI Input. The patterns can be found on page 13.
Pattern 0 turns the sequencer off, allowing notes to be play via the Play button or USB MIDI Input.
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The internal tempo can be adjusted by holding down the Func + button and pressing the Value + and –
buttons. The tempo ranges from 60 to 220bpm and each press increments by 10bpm.
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The miniAtmegatron can save the current sound to a patch. The patch is automatically loaded when
the miniAtmegatron is powered up. Press and hold the Func – button. When the Func LED flashes, the
patch is saved.
5
Controls
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This sets the frequency at which the filter acts. For example if the Filter Type is set to 1 (low pass
filter), frequencies above the Cutoff are attenuated.
The Filter Cutoff is inactive when the Filter Type is set to 0 (bypassed).
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This sets the amount that the envelope affects the filter cutoff frequency.
The A, D/R and S values of the Filter/Pitch Envelope set the shape of the envelope. See the Filter/Pitch
Envelope section for more information.
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This sets the amount that the LFO (low frequency oscillator) affects the filter cutoff frequency.
See LFO for information on how to set the LFO’s parameters.
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This sets the amount that the LFO (low frequency oscillator) affects the amplitude of the sound. This is
commonly called a ‘tremolo’ effect.
See LFO for information on how to set the LFO’s parameters.
!minimum
If the LFO waveform is set to 15 (DC offset) and the Amplitude LFO is set to
(fully anti-clockwise), the output of Atmegatron will be silent. This is
intentional, as the DC waveform is useful for assigning a fixed level to the Pulse Width
and Phaser parameters.
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Distortion is an effect on the output that clips the waveform. It does this by multiplying each sample by
a value. If the result is greater than the maximum amplitude, it sets the sample to the maximum
amplitude. There are in fact only 8 discrete values for the distortion level. They range from a multiplier
of 1 when the knob is fully anti-clockwise (i.e. no distortion) and a multiplier of 128 when the knob is
fully clockwise.
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This sets the volume of the audio. It controls the volume of the sound digitally. The volume should be
set to maximum when using the headphone jack as a line output.
6
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Resonance (also known as emphasis or Q) is the magnitude of the peak of the filter at the cutoff
frequency. The resonance ranges from 0.5 when the knob is fully anti-clockwise to 20 when the knob
is fully clockwise.
Resonance adds a sharp characteristic to the sound. It can be very useful for sound effects.
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This sets the amount that the envelope affects the pitch (or frequency) of the sound.
The A, D/R and S values of the Filter/Pitch Envelope set the shape of the envelope. See Filter/Pitch
Envelope for more information.
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This sets the amount that the LFO (low frequency oscillator) affects the pitch (or frequency) of the
sound. This is commonly called ‘vibrato’.
See LFO for information on how to set the LFO’s parameters.
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Many classic analogue synthesizers have a pulse width parameter. Traditionally this controls the
mark/space ratio of a square wave. The Atmegatron’s pulse width parameter works in a similar way
and is the ratio of sound to silence within the waveform. The LFO (low frequency oscillator) affects the
pulse width value over time.
The Pulse Width LFO control sets the amount that the LFO affects the pulse width. For example with
the LFO control set to half, the pulse width will be 50% at the peak of the LFO waveform.
!offset)To and
hold the pulse width at a fixed value, set the LFO Waveform Select to 15 (DC
use the Pulse Width LFO control to set the pulse width.
7
mÜ~ëÉ=icl=
This sets the amount of ‘phaser’ effect. It is created by adding a delayed copy of the wavetable to the
output sound. The LFO controls the delay time of the waveform.
When the Phase LFO control is fully anti-clockwise, the effect is off. When it is fully clockwise, the
maximum delay is equal to the length of 1 waveform cycle.
To prevent distortion, the amplitude of the main waveform and delayed waveform are halved. If the
Phase LFO control is fully anti-clockwise, the effect is off and the output waveform is unaffected.
With certain waveforms, the delayed waveform can actually cancel out the main waveform. This is only
momentary, as the LFO continually adjusts the delay.
To use a fixed delay, set the LFO Waveform Select to 15.
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The Pitch control sets the pitch of the Play button and also the root note of the Pattern Sequencer. The
Pitch value can also be set via the USB MIDI Input.
8
Audio Waveforms
0
Pure Square
1
Pure Saw
2
Pure Sine
3
Octave Square
(Juno 60)
4
Square Fifths
5
Pulse Wave
(RP2A07)
6
Warped Sine
7
Bass
(Multivox)
8
Metal 1
9
Metal 2
10
Vocal 1
11
Brass
(Multivox)
12
Reed Organ
(PPG)
13
Bell
(PPG)
14
Chord
15
Continuously
Generated Noise
9
Filter Types
0
Filter Bypassed
1
Low Pass Filter
2
High Pass Filter
3
Band Pass Filter
4
Notch Filter
5
Parametric EQ
(10dB gain)
6
Parametric EQ
(30dB gain)
7
Parametric EQ
(100dB gain)
8
Low Shelf
(10 dB gain)
9
Low Shelf
(30dB gain)
10
High Shelf
(10dB gain)
11
High Shelf
(30dB gain)
12
Butterworth Low Pass Filter
13
Butterworth High Pass Filter
14
Bessel Low Pass Filter
15
Bessel High Pass Filter
Cutoff and Resonance controls
inactive
Resonance control inactive
Resonance control inactive
Resonance control inactive
Resonance control inactive
10
LFO Waveforms
0
Sine
1
Triangle
2
Ramp Down
3
Exponential Ramp
Up
4
Sine + 3rd
Harmonic
5
5% Pulse
6
25% Pulse
7
50% Pulse
8
75% Pulse
9
95% Pulse
10
Ramp Up and Hold
11
Hold and Ramp
Down
12
Duh Dugga
13
Dugga Duh
14
Noise-like
15
DC (static) offset
11
Clock Division Rates
0
4 beats
1
2 beats
2
1 beat
3
3/4 beat
4
2/3 beat
5
1/2 beat
6
3/8 beat
7
1/3 beat
8
1/4 beat
9
3/16 beat
10
1/8 beat
11
3/32 beat
12
1/16 beat
13
3/64 beat
14
1/32 beat
15
1/64 beat
12
Envelope Presets
0
0,0,15 (Attack time, Decay time,
Sustain level)
1
0,3,0
2
0,5,0
3
0,5,15
4
0,7,0
5
0,7,7
6
0,11,0
7
0,11,15
8
3,0,0
9
3,5,0
10
5,7,0
11
7,0,0
12
7,3,0
13
7,7,7
14
11,7,7
15
15,15,0
13
Sequencer Patterns
0
1
Sequencer off. miniAtmegatron can be played by Play button
1
or via MIDI.
Grand Piano
1
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2
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Grand Piano
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3
3
4
Grand Piano
Grand Piano
4
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5
5
6
7
8
9
10
11
12
13
14
15
.
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.
2
Grand Piano
Grand Piano
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F
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Grand Piano
Grand Piano
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F
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F
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F
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F
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. .
12
% \\
. .
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.
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F
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O. .
. .
% \\
14
Grand Piano
Grand Piano
.
.
.
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.
.
.
.
.
.
.
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1
1
.
!!
1
1
1
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1
1
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1
.
O.
O. .
. O. .
10
O
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. O.
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O. . O.
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13
Grand Piano
.
8
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O. . P. . O.
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F
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.
11
Grand Piano
.
.
.
. . . .
. . . .
. . . . .
9
Grand Piano
.
.
. . . . . . . . . . . . . Q. . .
7
Grand Piano
.
.
.
. . . . . . .
6
Grand Piano
.
.
.
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O.
.
.
. . .
. . .
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15
. . . . .
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Q. . . . . . . . .
1
1
1
14
Wave Crusher / Portamento Presets
Bit Depth Reduction
Sample Rate Reduction
Portamento Time
0
Off
Off
Off
1
2 bit
Full
Off
2
4 bit
1/2
Off
3
2 bit
1/2
Off
4
4 bit
1/4
Off
5
2 bit
1/4
Off
6
4 bit
1/8
Off
7
2 bit
1/8
Off
8
Off
Off
5ms
9
Off
Off
27ms
10
Off
Off
77ms
11
Off
Off
195ms
12
Off
Off
477ms
13
Off
Off
1145ms
14
Off
Off
2728ms
15
Off
Off
6484ms
15
MIDI Implementation Chart
Manufacturer: Soulsby Synthesizers Model: Atmegatron
Functions
Basic Channel
Default
Changed
Mode
Default
Messages
Note Number
Transmitted
Velocity
Note ON
Note OFF
After Touch
Key
Channel
Pitch Bender
Control Change
1
16
17
71
74
79
91
92
93
94
95
Program Change
System Exclusive
System Common
Song Position
Song Sel
Tune
System Real Time
Clock
Commands
Aux Messages
Local On/Off
All Notes Off
Active Sense
Reset
Notes
Recognised
Version: 1.0
Date: 21/9/13
Remarks
X
X
1-16
1-16
X
X
X
Mode 2
Mode 2
0-127
X
X
V=1-127
V=0-127
X
X
X
X
X
O
7 bit resolution
X
X
X
X
X
X
X
X
X
X
X
O
O
O
O
O
O
O
O
O
O
O
Pitch LFO
Filter Envelope
Distortion Level
Filter Resonance
Filter Cutoff
LFO Rate
Pulse Width LFO
Amplitude LFO
Filter LFO
Pitch Envelope
Phase LFO
X
X
X
X
X
X
X
X
X
X
X
X
O
X
X
X
X
X
X
X
O
O
There is a limit on maximum
output frequency.
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