Corsynth C101 MKII User manual

C101 OTA
LOW Pass Filter MKII
USER MANUAL
OTA LOWPASS FILTER MKII
0
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9
10
FREQUENCY
C101
1V / OCT
24dB OUT
6dB OUT
RESONANCE
0
1
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3
45
6
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9
10
-5
-4
-3
-2
-1
0
+1
+2
+3
+4
+5
LEVEL
RES MOD
LEVEL
MIN MAX
INPUT 2
INPUT 1
ENV IN
FM IN
LEVEL
MIN MAX
LEVEL
MIN MAX

C101 OTA LowPass Filter MKII
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The C101 OTA Lowpass lter is a four pole low pass lter
( 24db/octave ) based on four cascade OTA-stages. In this MKII
version a new 6db output has been added expanding the
sonic possibilities of this lter. This OTA lter can be one found
in classic synthesizers like Roland Jupiter 8 , Roland System
100m, Roland SH-1, SH-7, SH-101, Roland System 700 , Jen
SX1000 and many more.
The C101 has been redesigned adding new features and
improving other presents on the original design. The main
changes / improvements are :
- A new rst order output with a 6db / octave response.
With high resonance this output will sound almost like a
bandpass lter.
- A dedicated modulation input for envelopes. This
input has a 0,66 V/Octave response expanding the modulation
range to 7,5 octaves using the typical 5V envelope. In case you
use10V envelopes the input response can be changed to
1V/Octave with a jumper located on the back of the module.
An inverter switch has been added to easily invert the input
signal.
- A better gain compensation circuit for the 24db
output. Not more volume drop when you turn up the
resonance.
- An attenuverter has been added to the resonance
modulation input.
- Better temperature compensation.
At high resonance settings the lter will start to oscillate and it
can be used as a sine wave oscillator. The tracking is perfect
over 5 octaves.
C101 MKII main characteristics
- Two lter outputs with 6db and 24db response
- Temperature compensated
- Dedicated envelope input with 0.66V / Octave response and
inverter
- Filter self oscillate and can be used as VCO ( 1V/Octave )
- Voltage controlled resonance
- Two audio inputs one with attenuator
OTA LOWPASS FILTER MKII
0
1
2
3
4
5
6
7
8
9
10
FREQUENCY
C101
1V / OCT
24dB OUT
6dB OUT
RESONANCE
0
1
2
3
45
6
7
8
9
10
-5
-4
-3
-2
-1
0
+1
+2
+3
+4
+5
LEVEL
RES MOD
LEVEL
MIN MAX
INPUT 2
INPUT 1
ENV IN
FM IN
LEVEL
MIN MAX
LEVEL
MIN MAX
C101 OTA
LowPass Filter MKII

CORSYNTH C101 - OTA LOWPASS FILTER MkII
2
HTTP://WWW.CORSYNTH.COM
OTA LOWPASS FILTER MKII
0
1
2
3
4
5
6
7
8
9
10
FREQUENCY
C101
1V / OCT
24dB OUT
6dB OUT
RESONANCE
0
1
2
3
45
6
7
8
9
10
-5
-4
-3
-2
-1
0
+1
+2
+3
+4
+5
LEVEL
RES MOD
LEVEL
MIN MAX
INPUT 2
INPUT 1
ENV IN
FM IN
LEVEL
MIN MAX
LEVEL
MIN MAX
Cuto frequency
control Resonance control
Resonance
modulation input
Modulation level
control
Modulation level
control
Audio input 2
level
6db lter ouput
Cuto frequency
modulation input
Modulation level
control
Cuto frequency
modulation input
( envelope )
Audio input 1
Audio input 2
Cuto frequency
1V /OCT input
C101 OTA LowPass Filter MkII
Front Panel Description
Polarity
selector
24db lter ouput

CORSYNTH C101 - OTA LOWPASS FILTER MKII
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1
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9
10
FREQUENCY
0
1
2
3
4
5
6
7
8
9
10
RESONANCE
1V / OCT
-5
-4
-3
-2
-1
0
+1
+2
+3
+4
+5
LEVEL
RES MOD
CONTROL DESCRIPTION
FREQUENCY
This control sets the cuto frequency of the lter. The frequencies
above cuto frequency are attenuated at a rate of 24dB / 6db per
octave.When the control is set to 10 position the lter is totally
open so it doesn’t have eect over the audio frequency.
RESONANCE
This control sets the resonance level. Above 9 position the lter
will self-oscillate with a frequency dened by the frequency con-
trol. The generated waveform is a very pure sine wave that can be
used as sound source.
1V / OCT
Exponential control voltage for cuto frequency. When the lter is
set to auto-oscillation this input allow the lter to be used as a
VCO. The tracking will be perfect in more or less 5 octaves.
RES MOD
Resonance modulation input. The LEVEL potentiometer set the
amount of modulation ( normal or inverted ). The input allow posi-
tive and negative signals which together with the value set by the
RESONANCE control give the nal value of the resonance.

CORSYNTH C101 - OTA LOWPASS FILTER mk II
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FM IN
LEVEL
MIN MAX
ENV IN
LEVEL
MIN MAX
INPUT 1
LEVEL
MIN MAX
INPUT 2
FM IN
Frequency modulation input. The LEVEL potentiometer set the
amount of modulation. The input allow positive and negative
signals which together with the value set by the FREQUENCY con-
trol, the ENV IN and the 1V / OCT inputs sets the nal value of the
cuto frequency.
ENV IN
Frequency modulation input dedicated to envelopes ( but can be
used with other signals ). This input has 0.66V / Octave response
getting this way a 7,5 octaves modulation range using a 5V envelo-
pe. The response can be changed with a jumper located on the
back of the module to the typical 1V / Octave The LEVEL potentio-
meter set the amount of modulation. The polarity switch allows to
invert the modulation signal. The input allow positive and negati-
ve signals which together with the value set by the FREQUENCY
control, the FM IN and the 1V / OCT inputs sets the nal value of
the cuto frequency.
INPUT 1
Audio input 1.
INPUT 2
Audio input 2. The LEVEL potentiometer allows to attenuate the
input level. This signal is mixed with the one at INPUT 1 and the
result is the signal to be ltered.

CORSYNTH C101 - OTA LOWPASS FILTER mk II
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6dB OUT
6db OUT
Filter output with 6db / octave response.
24dB OUT
24db OUT
Filter output with 24db / octave response.

CORSYNTH C101 - OTA LOWPASS FILTER mk II
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BLOCK DIAGRAM
∑
LEVEL
INPUT 2
INPUT 1
LEVEL
LEVEL
FM IN
ENV 1
FREQUENCY
1V / OCT
∑
6db OUT
LEVEL
RES MOD
RESONANCE ∑
OTA
LOwPASS FILTER
IN
6 db
RESONANCE
CUTOFF FREQUENCY
24 db 24 db OUT
Audio signal
Control signal

CORSYNTH C101 - OTA LOWPASS FILTER mk II
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Synthesizers.com
power connector
MOTM
power connector
Trimmers, power connectors and jumpers
Module Format : 5U, MU format ( Synthesizers.com, Moog )
Module Width : 2 MU ( Moog unit )
Module Depth :52 mm ( 2,05 inches )
Power : +15V@35mA , -15V@33mA
Power connectors : Synthesizers.com , MOTM ( 4 pin )
Signal level : Envelope 5Vpp ( 0V / +5V ) , Bipolar 10Vpp ( +/- 5V )
TECHNICAL DATA
+15V+5V-15VN/C GND
Synthesizers.com
GND +15V-15V GND
MOTM
IMPORTANT !!!!
This module has two power connec-
tors (Synthesizers.com and MOTM).
Only one is needed to power the
module. (Synthesizers.com or MOTM).
Never connect both at the
same time.
1V / OCT Trimmer
Frequency Range
Trimmer
Env In response
jumper
0.66V / Octv
1V / Octv

CORSYNTH C101 - OTA LOWPASS FILTER mk II
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MODULAR LEVEL
MIN MAX
MODULAR SYNTHS