AnalogFX SER-2020 User manual

USER MANUAL
SER-2020
REV2.1

SER-2020 V2.1
1
THANK YOU FOR CHOOSING THE SER-2020.
Congratulations on your acquisition of the AnalogFX SER-2020 analog synthesizer with a
formant filter, one of the most exciting and versatile instruments used in electronic music.
Based on the legendary Synton Syrinx1, which was utilized by artists such as Aphex Twin, Air,
Depeche Mode, and many more, the SER-2020 allows you to connect directly to any MIDI
controller, providing immediate access to a world of powerful analog sound. Alternatively, you
can hook it up to an MPE device to explore even deeper layers of sound creation. The SER-
2020 is designed to bring you many hours of joyful and creative sonic enjoyment. We
understand that you are eager to start playing, so please refer to the 'Installation' guide to get
started
Thank you.
Manual Applicable for;
PN: 200 002 000 V2.1
Manual Revision: A

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INDEX
IMPORTANT SAFETY INSTRUCTION ............................................................................................ 4
DANGER .................................................................................................................................. 5
CAUTION ................................................................................................................................. 5
LEGAL DISCLAIMER ................................................................................................................. 5
1 INTRODUCTION .................................................................................................................. 6
2 INSTALLATION .................................................................................................................... 7
2.1 SET UP .......................................................................................................................... 7
2.2 CONNECT TO POWER & MIDI ...................................................................................... 7
2.3 POWER UP ................................................................................................................... 8
2.4 WARM-UP AND GENERAL TUNING ............................................................................. 8
2.5 CONNECT TO AMPLIFIER ............................................................................................. 8
2.6 START PLAYING ............................................................................................................ 8
3 GENERAL DESCRIPTION ...................................................................................................... 9
3.1 LFO AND BENDPAD SECTION ....................................................................................... 9
3.1.1 CONTROLS ............................................................................................................ 9
3.1.2 INPUT AND OUTPUTS ......................................................................................... 11
3.2 CONTROL & MODULATION ........................................................................................ 12
3.2.1 CONTROLS .......................................................................................................... 12
3.2.2 INPUTS AND OUTPUTS ....................................................................................... 13
3.3 VCO SECTION ............................................................................................................. 14
3.3.1 VCO CONTROLS .................................................................................................. 14
3.3.2 VCO INPUT AND OUTPUTS ................................................................................. 15
3.4 MIXER AND ROUTING SECTION ................................................................................. 16
3.4.1 MIXER CONTROLS ............................................................................................... 16
3.4.2 MIXER INPUTS .................................................................................................... 16
3.5 VCF SECTION .............................................................................................................. 17
3.5.1 VCF CONTROLS ................................................................................................... 17
3.5.2 VCF INPUTS AND OUTPUTS ................................................................................ 19
3.6 ADSR SECTION ........................................................................................................... 20
3.6.1 ADSR CONTROLS................................................................................................. 20
3.6.2 ADSR INPUTS AND OUTPUTS ............................................................................. 20
3.7 SAMPLE AND HOLD SECTION .................................................................................... 21
3.8 SPEECH MODE ........................................................................................................... 22
3.8.1 ENABLE SPEECH MODE AND ALLIGN THE PEAK FILTERS .................................... 22
3.8.2 PROGRAM SPEECH MODE .................................................................................. 22
3.9 INPUTS & OUTPUTS ................................................................................................... 23
3.10 KEYBOARD CONTROL ............................................................................................. 23
3.11 VCO AUTO TUNE .................................................................................................... 24
3.12 MIDI CONTROL ....................................................................................................... 25
3.12.1 MME (MPE) ........................................................................................................ 25
3.12.2 DYNAMIC MODE ................................................................................................. 25
3.12.3 VCA CONTROL .................................................................................................... 26
3.13 ARP / SEQUENCER .................................................................................................. 27
3.13.1 MODE ................................................................................................................. 27
3.13.2 PATTERN ............................................................................................................. 27

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3.13.3 RANGE ................................................................................................................ 27
3.13.4 GATE LENGTH ..................................................................................................... 28
3.13.5 SWING ................................................................................................................ 28
3.13.6 RATE ................................................................................................................... 28
3.13.7 CLOCK DIVISION ................................................................................................. 28
3.13.8 MIDI CONFIGURATION ....................................................................................... 29
3.13.9 MPE CONFIGURATION MESSAGE ....................................................................... 31
3.13.10 CONTROL PARAMETERS ..................................................................................... 32
3.13.11 MIDI IMPLEMENTATION CHART ......................................................................... 35
4 SPECIFICATION ................................................................................................................. 36
5 SERVICE AND SUPPORT INFORMATION ........................................................................... 38
5.1 LIMITED WARRANTY .................................................................................................. 38
5.2 RETURNING YOUR PRODUCT TO ANALOGFX ............................................................ 38
5.3 CARING FOR THE SER-2020 ....................................................................................... 38
6 LEGAL NOTES .................................................................................................................... 39
6.1 NO LIABILITY FOR CONSEQUENTIAL DAMAGES ........................................................ 39
6.2 ELECTROMAGNETIC COMPATIBILITY (EMC) .............................................................. 39
6.3 EUROPE ...................................................................................................................... 39
APPENDIX A - CALIBRATION ..................................................................................................... 40
BEND PAD OFFSET ................................................................................................................ 40
HIGH FREQUENCY LINEARITY ............................................................................................... 40
PULSE WIDTH ....................................................................................................................... 40
LFO SYMMETRY .................................................................................................................... 40

SER-2020 V2.1
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IMPORTANT SAFETY INSTRUCTION
This symbol wherever it appears, alerts you to the presence of uninsulated
dangerous voltage inside the enclosure – voltage that may be sufficient to
constitute
This symbol, wherever it appears, alerts you to important operating and
maintenance instructions in the accompanying literature. Please read the manual
1. Read this instruction and keep these instructions.
2. Heed all warnings and follow all instructions.
3. Do not use this apparatus near water, rain or moisture.
4. Do not place naked flame sources, such as lighted candles, on the apparatus.
5. Do not clean with solvent based or abrasive cleaners. Clean only with dry cloth.
6. Do not block any ventilation openings. Install in accordance with the manufacturer’s
instructions.
7. Do not install near any heat sources such as radiators, heat registers, stoves, or other
apparatus that produce heat.
8. Do not install in a confined space, such as a book case or similar units.
9. Do not over-tighten the screws, nuts and stand-offs provided.
10. Do not over-turn the control knobs (they are analogue potentiometers, which have end stops)
or over-push the toggle switches.
11. The PCB of individual not assembled Euro-rack modules may contain sharp edges and sharp
points. Keep away from young children.
12. Do not reverse the power connector. And only use the provided power supply or power cord.
13. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has
two blades with one wider than the other. A grounding-type plug has two blades and a third
grounding prong. The wide blade or the third prong are provided for your safety. If the
provided plug does not fit into your outlet, consult an electrician for replacement of the
obsolete outlet.
14. Protect the power cord from being walked on or pinched particularly at plugs, convenience
receptacles, and the point where they exit from the apparatus.
15. Use only attachments or accessories specified by the manufacturer.
16. Use only with the cart, stand, tripod, bracket, or table specified by the
manufacturer, or sold with the apparatus. When a cart is used, use
caution when moving the card or apparatus combination to avoid injury
from tip-over.
17. Unplug this apparatus during lightning storms or when the apparatus is
unused.
18. Refer all servicing to qualified service personnel. Servicing is required
when:
a. Liquid has been spilled or objects have fallen into/onto the apparatus.
b. The power supply cord or plug is damaged.
c. The apparatus has been exposed to rain or moisture.
d. The apparatus does not operate normally or exhibits a marked change in performance.
e. The apparatus has been dropped or the enclosure is damaged.
19. The apparatus shall be connected to a Mains socket outlet with a protective earthing
connection.

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20. Where the Mains plug or an appliance coupler is used as the disconnect device, the disconnect
device shall remain readily operable.
21. Correct disposal of this product: This symbol indicates that this product
must not be disposed of with household waste, according to the WEEE
Directive (2012/19/EU) and your national law. This product should be taken
to a collection center licensed for the recycling of waste electrical and
electronic equipment (EEE). The mishandling of this type of waste could
have a possible negative impact on the environment and human health due
to potentially hazardous substances that are generally associated with EEE.
At the same time, your cooperation in the correct disposal of this product
will contribute to the efficient use of natural resources. For more information about where
you can take your waste equipment for recycling, please contact your local city office, or your
household waste collection service.
22. This apparatus, in combination with an amplifier and headphones or speakers, may be capable
of producing sound levels that could cause permanent hearing loss. Do not operate for a long
period of time at a high volume level or at a level that is uncomfortable.
23. Please keep the environmental aspects of battery disposal in mind. Batteries must be
disposed-of at a battery collection point.
24. Use this apparatus in moderate climates. Operate at between 0 °C to +40 °C, <95% Relative
humidity (non-condensing).
DANGER
INSTRUCTIONS PERTAINING TO RISK OF FIRE, ELECTRICSHOCK, OR INJURY TO
PERSONS: Do not open the chassis. There are no user serviceable parts inside. Refer
all servicing to qualified personnel only.
CAUTION
To reduce the risk of fire or electric shock, do not expose this appliance to rain and
moisture. The apparatus shall not be exposed to dripping or splashing liquids and
no objects filled with liquids, such as vases, shall be placed on the apparatus.
LEGAL DISCLAIMER
AnalogFX accepts no liability for any loss which may be suffered by any person who relies
either wholly or in part upon any description, photograph, or statement contained herein.
Technical specification, appearance and other information are subject to change without
notice. All trademarks are property of their respective owners.
©AnalogFX 2021 All rights reserved.

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1 INTRODUCTION
The SER-2020 is a monophonic semi-modular analog synthesizer featuring a formant filter
section, designed for standalone use or in conjunction with Eurorack modules. Drawing
inspiration from the renowned classic Synton Syrinx1 synthesizer, we've enhanced it with the
flexibility of a patch panel and ensured compatibility with Eurorack CVs. The filter section
comprises a 24dB/octave VC Low Pass Filter and two independent Resonant VC Peak Filters,
allowing for dynamic sound shaping. From solid bass tones to articulated formant effects, the
SER-2020 offers a wide sonic range.
We've also integrated MPE (MIDI Polyphonic Expression) capabilities, transforming the SER-
2020 into a dynamic instrument that responds intuitively to its player. With the patch panel's
flexible routing, this synthesizer becomes a versatile tool for creating a variety of sound
effects. Simply connect your MPE controller and dive into the world of sonic exploration
Key Specifications:
 Semi Modular Setup - CV inputs and outputs
 2 VCO's (3340 IC based)
 1 Sub-Oscillator
 Ring Modulator
 Noise Generator
 Audio Mixer
 Multi-Mode Sync & Sync D-Tune
 3 VCF's (3350 IC based)
 Speech Mode, for easy formants programming.
 VCA (3360 IC based)
 2 ADSR's
 2 LFO's with Reset & Shaper Modes
 Auto-Glide
 Multiple Triggering
 Touch 'N Bend Pad, with bend Assign
 Auto Bend Pad nulling
 Sample and Hold
 Auto tune of VCO’s
 Signal and Headphone output
 ARP / SEQUENCER, controllable by MIDI
 MIDI interface
 USB MIDI interface
 MPE compatible - Sensitive for: Strike (note-on velocity), Press (aftertouch), Glide
(pitch bend), Slide (brightness) and Lift (note-of velocity).
1Synton Syrinx is used to associate the sound of this module and is not correlated with AnalogFX.

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2 INSTALLATION
For those of you who can’t wait to play your new SER-2020, the following should get you set up and
running quickly.
NOTE: Please read the entire manual to learn more about the instrument and gain a better
understanding of what you can do with the SER-2020.
Check the contents in the shipping carton
The SER-2020 is shipped with the following items:
1. The SER-2020 Synthesizer.
2. A 12VDC Power Adaptor.
3. User’s Manual.
4. USB cable to connect the SER-2020 to a host computer, for USB MIDI.
What you will need
In addition you will need:
1. A sturdy surface to support the SER-2020
2. A MIDI keyboard, MIDI controller or MPE controller.
3. A MIDI cable.
4. A 6.35 mm (1/4'') instrument cable and amplifier, or a pair of headphones.
2.1 SET UP
Ensure you have an appropriate setup location for your SER-2020. Avoid exposing it to dripping or
splashing, and refrain from placing objects filled with liquids, such as vases, on top of it. Exercise
caution when unpacking the SER-2020, and be sure to retain the carton and all packing materials in
case you need to ship the SER-2020 for any reason.
Here is an overview of the SER-2020 synthesizer’s connectors on the back side:
 Audio : Outputs 6.35 mm (1/4'') mono jack.
 Headphone : Outputs 6.35 mm (1/4'') stereo jack.
 USB : Standard USB type B.
 MIDI Input &Thru : Standard MIDI DIN-5.
 Power DC Input : Internal 2.1 mm, external 5.5 mm. (Ring negative, tip positive.)
2.2 CONNECT TO POWER & MIDI
Connect the Power Adapter to a properly-wired wall outlet and plug the 12VDC power jack into the
back of the unit. The universal power supply can operate with a power source ranging from 100 to 230
Volts AC, 50/60Hz.
For MIDI connectivity, utilize a standard MIDI cable to link the MIDI OUT of your MIDI controller to the
MIDI IN on the SER-2020. The factory default MIDI setting is in standard MIDI mode, allowing the SER-
2020 to receive messages on MIDI Channels 1 to 16. By default, the MIDI channel is set to channel 1
from the factory.

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If you're using USB MIDI with a Windows or Macintosh computer, connect the USB cable from the back
panel of the SER-2020 to a USB port on your computer. The SER-2020 USB is automatically installed as
an HID driver, and it will appear as 'SER-2020' in the MIDI device selection of your MIDI software.
2.3 POWER UP
Turn on the power switch located on the back of the SER-2020. The power (PWR) LED on the front
panel will illuminate, and the LEDs of the LFOs will start blinking. The SER-2020 is now operational and
ready for use.
If auto nulling is enabled, the synth calibrates the bend-pad at startup. This is indicated by the blinking
power LED during startup. Avoid touching the bend-pad at the calibration process otherwise, the
calibration may go wrong, resulting in an offset for the bend-pad
2.4 WARM-UP AND GENERAL TUNING
As with all other analog synthesizers, the SER-2020 requires a warm-up period after being powered
on. Despite having temperature-compensated Voltage Controlled Oscillators (VCOs), it is
recommended to allow approximately 10 minutes for the synthesizer to warm up before use. This
ensures the synthesizer reaches a stable operating temperature, guaranteeing accurate oscillator
pitch. If the synthesizer has been stored outside the recommended operating temperature range, the
warm-up period may need to be extended.
After the synthesizer has reached its operating temperature, tune it to pitch. You can use the internal
440Hz tone or an external tuner to check the instrument’s tuning. If necessary, use the MASTER TUNE
– FINE knob to adjust the SER-2020 to the desired pitch.
The SER-2020 has been designed for operation in ambient temperatures between 20°C and 35°C.
While the SER-2020 can operate over a broader temperature range, extreme external temperatures
or fluctuations may result in longer stabilization times, and the Voltage Controlled Oscillators (VCOs)
may not remain in tune. It is advisable to avoid exposing the unit's case to direct sunlight during
operation, as this can potentially affect the tuning of the VCOs.
2.5 CONNECT TO AMPLIFIER
Always power off all audio gear before making any connections, as failure to do so may damage your
speakers, the SER-2020 synthesizer, or other audio equipment. Set the SER-2020 volume control
levels to 0 before connecting to an amplifier or headphones. Power on the various devices, with the
audio amplifier or monitoring system being the last to power on. Slowly bring up the SER-2020
volume to achieve a comfortable listening level.
2.6 START PLAYING
The SER-2020 operates in the normal note range (MIDI notes 24 - 120). This implies that the SER-
2020 will respond to your playing from 'C8' downward to 'C1'. Using the octave switch, the range can
be transposed to one octave lower or a maximum of two octaves up. Play some notes, tweak the
knobs, and have fun!

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3 GENERAL DESCRIPTION
3.1 LFO AND BENDPAD SECTION
3.1.1 CONTROLS
LFO 1 RATE: The LFO 1 offers a frequency range typically from 0.05Hz to 20Hz. The LFOs can be reset
on every 'note on' by using the TRIG switch, ensuring that modulation always starts at the same point.
Additionally, the LFO can be reset by the MIDI clock if desired.
LFO 2 RATE: The LFO 2 offers a frequency range typically from 0.05Hz to 20Hz. When LFO 2 is in the
'ONE SHOT' mode, it functions as an Attack/Release Generator. The LFOs can be reset on every 'note
on' by using the TRIG switch, ensuring that modulation always starts at the same point. Additionally,
the LFO can be reset by the MIDI clock if desired.
SHAPE: The control for the shape of LFO 2 allows adjustment of the triangle wave, ranging from a
ramping up to a ramping down sawtooth. Simultaneously, it provides pulse outputs with a duty cycle
variation between 5% and 95%.

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A440: Switches the noise source between white noise or a clean 440Hz tone for tuning purpose. The
audio level of this signal can be adjusted using the noise control knob on the audio mixer.
TOUCH ‘N BEND: The bend pad is used for controlling the VCO, VCF, or
VCA through the bend assign controls (refer to section 3.2). Additionally,
the speed of LFO 2 can be controlled using the bend pad. The bend pad
output also responds to MIDI modulation, MIDI aftertouch, and MIDI
brightness (CC#74) messages (see Table 1 for settings).
RATE CNTRL: The LFO 2 rate control switch enables the Pad to control the
speed of LFO 2. The UP position activates it, while the DOWN position
deactivates it.
OUT: Volume control of the line output.
PORTAMENTO: Portamento (glide) control, the gliding effect occurs when
the keys are played legato. When the keys are played with only a few
milliseconds between notes, the glide effect is off, this is called auto
portamento. Glide time over 1 octave between 5 milliseconds and 1
second.
AUTO: The portamento mode is enabled by toggling the switch UP,
activating auto portamento (glide). Switching it DOWN disables
portamento (glide).
TRIG: The multi-triggering switch generates a new trigger pulse, resetting
the LFOs and ADSRs each time a key is hit, regardless of whether a higher
key is still depressed. UP position activates it, while the DOWN position
deactivates it. Additionally, both LFOs can be reset by the MIDI clock if
desired.
1 SHOT: The switch enables the 'ONE SHOT' mode, causing LFO 2 to restart each time a key is
depressed. In this mode, LFO acts as an Attack/Release generator. Switch UP activates the 'ONE SHOT'
mode, while switch DOWN disables it.

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3.1.2 INPUT AND OUTPUTS
INPUTS
CV IN : The external CV input can be routed to either the internal pitch CV or Bend Pad
CV, and this can be configured using the MIDI CC message (CC#112), as
detailed in Table 1. The Pitch CV is quantized to 1 semi-tone.
Note: When using this input as pitch CV, MIDI note events take precedence
over the external CV input. If MIDI active sense is employed, this input is
disabled during connection with a MIDI device.
GATE IN : The external gate input can be utilized to trigger the ADSR generators and reset
the LFOs. Note: MIDI note events take priority over the external gate input
OUTPUTS
CV OUT : The internal CV output provides internal pitch CV from the internal MIDI to CV
converter, which is routed to the VCOs and VCF. The sensitivity is 1 Volt per
octave (V/oct), and the range is from 0 to 8 Volts.
GATE OUT : The gate output provides an internal gate from the MIDI to CV converter, with
a level ranging from 0 to 5 Volts. 0 Volts indicate a gate-off state, while 5 Volts
indicate a gate-on state.
BND OUT : The CV output of the Bend Pad has a nominal output of 0 Volts.
LFO1:
TRI OUT : Triangle wave output of LFO 1. Output level between 0 and 5 Volt.
SQR OUT : Square wave output of LFO 1. Output level between 0 and 5 Volt.
LFO2:
TRI OUT : Triangle wave output of LFO 2. Output level between 0 and 5 Volt.
PLS OUT : Pulse wave output of LFO 2. Output level between 0 and 5 Volt.
TRI BND OUT : The triangle wave output of LFO 2 is multiplied by the CV of the Bend Pad. The
level of this output is controlled by the bend pad.

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3.2 CONTROL & MODULATION
3.2.1 CONTROLS
MASTER TUNE:
FINE: Tune control for both VCOs, with fine-tuning over a range of
+/-8 semi-tones.
OCTAVES: Transpose switch for both VCOs, allowing selection
between -1/0/+1/+2. When both 'OCTAVES' and 'OCTAVE'
switches are set to '0', VCO 1 and VCO 2 are in their zero positions,
and the A4 key on the keyboard can be tuned to 440 Hz.
BEND ASSIGN(BND ASN):
VCO: Bend pad control assigned to the VCO. Turning this knob clockwise controls the
VCO frequency with the bend pad or MIDI messages (modulation, aftertouch, or
CC#74). Pitch bending with the pad can be achieved over a 5-octave range. Note that
both VCOs are simultaneously controlled when they are not in sync or in soft sync
mode. In hard sync mode, only one VCO is controlled.
VCF: Bend pad control assigned to the VCF. Turning this knob clockwise controls the
VCF cut-off frequency and the frequency of the bandpass filters with the bend pad or
MIDI messages (modulation, aftertouch, or CC#74). The bend pad can cover a
maximum control range of over 8 octaves up or down when assigned to the VCF
section.
VCA: Bend pad control assigned to the VCA. Turning this knob clockwise controls the
VCA with the bend pad or MIDI messages (modulation, aftertouch, or CC#74). The
VCA pad action ranges from 0% to 100%.

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FREQUENCY MODULATION (FM):
LFO 2 TRIANGLE: Modulation level for both VCOs. The triangle wave can modulate a
maximum of 6 semi-tones.
LFO PULSE: Modulation level for both VCOs. The square/pulse wave can modulate a
maximum of 2 octaves. When the external Frequency Modulation input is used, this
knob sets the amount of external modulation.
VCA:
GAIN/MOD: Initial gain control of the VCA. This control allows for listening to the
synthesizer without any key being depressed, which can be convenient when a routing
or filter setting has to be made.
Note: when Bend Assign VCA is used this knob can be used for tuning the VCA to the
best dynamic performance. When the external VCA Modulation input is used this knob
controls the level of modulation to the VCA.
Positive input signals subtract from the ADSR 2 envelope, while negative signals add to
the ADSR 2 envelope.
3.2.2 INPUTS AND OUTPUTS
INPUTS
VCA MOD : External VCA modulation input. This input is routed to the VCA GAIN/MOD
knob.
Note: Positive input signals will be subtracted from the ADSR 2 envelope and
negative signals will be added to the ADSR 2 envelope.
FM IN VCO 1 & 2 : External VCO frequency modulation input routed to the LFO 2 Square FM knob.
Note: When an external modulation signal is used, the internal square wave to
the VCOs is disabled.

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3.3 VCO SECTION
3.3.1 VCO CONTROLS
VCO1
Total frequency range of VCO 1 is from 10Hz to 20KHz.
SYNC: Control for VCO synchronization. VCO 2 can be synchronized to VCO 1 in three
modes: SOFT, HARD-Pulse, and HARD-Sawtooth. In both hard modes, only one VCO is
detuned by the Pad or MIDI command for special coloration effects.
SHAPE: Wave SHAPE selector for Triangle wave, Sawtooth wave, Square wave, and
pulse outputs. Pulse Width Modulation (PWM) can be adjusted in two modes, with
respective trip points at 50% for Square wave and 10% for Pulse wave.
PWM/LFO 2: Independent PWM amount control of LFO 2, routed to the Square wave
or Pulse wave. The pulse width can be varied between approximately 10% and 90%.
Since both VCOs have a separate LFO for PWM, chorus-like effects can be obtained by
controlling both pulses with different LFO speeds.

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VCO2
INTERVAL: Control for the interval of VCO 2, a fifth up or down. When the control
indicates zero, along with the OCTAVE selector, both VCO 1 and 2 are in unison.
OCTAVE: The octave transpose switch; -1/0/+1/+2 octave.
SHAPE: Wave SHAPE selector for Triangle wave, Sawtooth wave, Square wave, and
pulse wave. Pulse Width Modulation (PWM) can be adjusted in two modes, with
respective trip points at 50% for Square wave and 10% for Pulse wave.
PWM/LFO 1: Independent PWM control of LFO 1, routed to the Square wave or Pulse
wave. The pulse width can be varied between approximately 10% and 90%.
.
3.3.2 VCO INPUT AND OUTPUTS
INPUTS
CV IN VCO2 : CV input for VCO 2, to control VCO 2 separately from VCO 1. When using this
input, the internal CV is disconnected from VCO 2.
OUTPUTS
VCO1 : Output of VCO 1 after the Waveform switch.
VCO2 : Output of VCO 2 after the Waveform switch.
NOISE : Direct output of the noise source (White Noise).
SUB : Direct output of Sub-oscillator of VCO1.

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3.4 MIXER AND ROUTING SECTION
3.4.1 MIXER CONTROLS
MIXER:
VCO 1: Audio level of VCO 1.
VCO 2:Audio level of VCO 2.
SUB 1: Audio level of the sub-oscillator, this
generates a frequency one octave below the pitch
of VCO1. The output signal of SUB 1 is a square
wave.
RM: Audio level of the Ring-Modulator or external
filter input. The ring modulator multiplies the
Triangle wave of VCO 1 with the Triangle wave of
VCO 2. When the external filter input is used, this
knob controls the audio level of the external
input, and the ring modulator is disabled.
NOISE: Audio level of the Noise Generator (White Noise). With the A440 switch, this output generates
a clean 440Hz signal for tuning the VCOs.
ROUTING:
VCF RTNG: Filter routing switch that cascades or parallels both filter
sections and provides different routing for the mixer input signals;
- (A) First mode : Both peak filters and the lowpass filter are in series.
- (B) Second mode : Both filter sections parallel.
- (C) Third mode : The signals from VCO 1, VCO 2 and SUB 1 will be processed by the low pass
filter only. The signals of the Ring Modulator (RM) and the Noise Generator
(NSE) will be processed by the peak filter and the low pass filter.
- (D) Fourth mode : The signals of the Ring Modulator (RM) and the Noise Generator (NSE) will be
processed by the peak filters. The signals from VCO 1, VCO 2 and SUB 1 will be
processed by the low pass filter.
3.4.2 MIXER INPUTS
VCF IN : VCF input for external audio signals. This input disables the ring-modulator.

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3.5 VCF SECTION
3.5.1 VCF CONTROLS
FREQUENCY:
PEAK 1 / PEAK 2: Frequency control for peak filter 1 and for peak filter 2.
LPF: Frequency control for the low-pass filter.
RESONANCE:
PK 1 / PK 2: Resonance control for peak filter 1 and for peak filter 2. The band width for peak 1 and 2
for minimal resonance is greater than 3 octaves, and for maximum resonance less than 1 semi-tone.
LPF: Resonance control for the low-pass filter.
FM PK 1&2:
Since both peak filters are controlled simultaneously, there is only one modulation control section.

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LFO 2 / EXT. MOD: Modulation control for both peak filters by LFO 2. This means that both peak
frequencies will always move in the same direction according to the interval set by the Frequency
control of the peak filter. The maximum LFO control range for PEAK 1 and 2 is 8 octaves up. When the
external modulation input is used, this knob controls the level of external modulation.
ADSR 1: Control from ADSR 1 to both peak filters. In the center position (0), there is no modulation.
Turning the knob clockwise results in positive modulation. The filter frequencies shift up during the
Attack status, then return to the preset frequencies in the Decay and Release modes. Turning the knob
counterclockwise results in negative modulation, shifting the frequency down first and then going up
to return to the preset value. ADSR 1 can control the peak filters over 8 octaves up or down.
KBD TRK PEAK 1 & 2: Control for keyboard tracking. Keyboard tracking can be adjusted between zero
(no tracking) and 2, in this case for every octave on the keyboard the filter is shifted over two octaves.
A common situation is that this control is on 1, which means that the filter frequency will track the
VCO frequencies. This is also convenient when resonant peaks have to track fundamentals.
FM LPF:
LFO 2 / EXT MOD: Modulation control for the low-pass filter. Positive and negative modulation can be
achieved by turning the knob right or left from its center zero position. This feature allows modulation
of the peak filters and the low-pass filter in opposite directions. The maximum LFO control range for
the low-pass filter is 8 octaves up or down. When the external modulation input is used, this knob
controls the level of the external modulation.
ADSR 1: Control from ADSR 1 to the low-pass filters. In the center position (0), there will be no
modulation. Turning the knob clockwise results in 'positive' modulation, shifting the filter frequencies
up during the Attack stage and returning to preset frequencies in the Decay and Release modes.
Turning the knob anti-clockwise results in 'negative' modulation, shifting the frequency down first and
then up, returning to the preset value. The low-pass filter can be controlled over 8 octaves up or down
by ADSR 1.

SER-2020 V2.1
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KBD TRK LPF: Control for keyboard tracking. Keyboard tracking can be adjusted between zero (no
tracking) and 2. In this case, for every octave on the keyboard, the filter is shifted over two octaves. A
common setting is 1, meaning the filter frequency will track the VCO frequencies. This is also
convenient when resonant peaks need to track fundamentals.
3.5.2 VCF INPUTS AND OUTPUTS
INPUTS
PK 1&2 VCF FM IN : Modulation input for voltage controlled bandpass filter 1 and 2.
PK 2 VCF FM IN : Modulation input for voltage controlled bandpass filter 2. This input is directly
wired to the second band-pass filter, attenuation should be applied externally.
When this input is used the ‘PK 1&2 VCF FM’ input controls only the first band-
pass filter.
LPF VCF FM IN : Modulation input for the voltage controlled low pass filter.
OUTPUTS
PEAK 1 VCF OUT : Direct output of voltage controlled bandpass filter one.
PEAK 2 VCF OUT : Direct output of voltage controlled bandpass filter two.
LPF VCF OUT : Direct output of the voltage controlled low pass filter.