CG XR22 VCO FT User manual

Modular
XR22 VCO FT
VCO with AM Input and FSK (Frequency Shift Keying)
1. Features
–AM (Amplitude Modulation) Input
•Ring modulation
•CV controllable sine/triangle volume
•Advanced waveform generation through feedback
–FSK (Frequency Shift Keying)
•Pulse and ramp generation
•Switching between two different frequency CVs
•Advanced waveform generation
– LFO/Ba /High Frequency Mode
–Available with banana or 3,5mm phone ocket
–Eurorack Module
–Width: 12 HP
–Dimen ion :
128,5 mm x 60,6 mm
Depth: 40mm
–Supply Voltage: ±12V
–Current con umption:
≈ 70mA
inijack Version Banana Version Drawing
1
FSK
AM in
AM In
FSK in
F1 CV inv.
F1/com CV F2 CV
F1/com F2
XR22 VCO
F1/com CV
1V/Oct
F2 CV inv.
/
F2
F1
Σcom CV
F2
F2 CV 1V/Oct
Gain
Lo Mid Hi
F1 CV F2 CV
1
2
3
45
0
6
7
8
1
2
3
4
5
0
6
7
8
1
2
3
4
5
0
6
7
8
-1
0
-2
+1
+2
Bypa
AM In /
+1-1 +1-1
Fine Fine

Modular
2. AM and FSK
2.1 AM (Amplitude Modulation)
The / output ( ) amplitude varies linearly with the control voltage applied to "AM in" ( ).
The modulation amount can be adjusted with knob 'A In' (See chapter 3: "Functions"). Negative
CVs will cause phase inversion of the / waveform.
Example :
Ring modulation with external
triangle signal VCO volume control with
external envelope generator
AM in patched with
/ output
(Feedback)
2.2 FSK (Frequency Shift Keying)
The frequency of the XR22 VCO is controlled by two
independent frequency control sections F1 and F2 with
independent manual frequency controls and CV ins;
either one or the other of these routes can be activated
by an external logic signal applied on socket "FSKin" ,
and/or by switch "FSK"
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.
Switch "FSK"
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selects the FSK mode: F1, F2 or self-
switching by the VCO's -output.
In self-keying mode the rising and falling edges of the
triangle waveform (and the hi/lo times of the square-
wave) can be separately adjusted.
Switch "com" is adding the F1-CVs to F2; this is to ensure 1V/oct. tracking if both routes are used
e.g. in the self-frequency shifting - mode.
Example :
F1 activated. LED= green (Switch "FSK"
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up) F2 activated. LED= red (Switch "FSK"
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mid)
- ode (F1+F2 activated) (Switch "FSK"
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low).
The oscillator frequency-shifts itself.
F1 and F2 (≙ falling and rising edges of the
triangle waveform) can be separately adjusted.
With external FSK control signal applied on "FSK
in" (Switch "FSK"
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middle position).
The oscillator switches between F1 and F2,
depending on the logic control signal applied to
FSK in
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.
2
/ Output
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain poti in
ccw positions of " "
or AM-CVin < V
Gain poti in
cw positions of " "
or AM-CVin > V
Squarewave
Output
/Output
/ Output
...
Frequency 1:
"FSK in" = high
Frequency 2:
"FSK in" = low
/
- Output
/
- Output
/ Output
Ext. squarewave
signal applied
on "FSK in"
...
F1 F2
/
- Output
Gain pot in
ccw positions of " "
or AM-CVin < V
Gain pot in
cw positions of " "
or AM-CVin > V
/
- output
...
F1 F1F2 F2
"FSK in" connected to - output:
-output
/ Output
Output/
F1 F1F2 F2
Gain poti in
ccw positions of " "
or AM-CVin < V
Gain poti in
cw positions of " "
or AM-CVin > V
Squarewave
Output
/ Output
/ Output
...
/ Output
ext. squarewave
signal on "FSK in"
F1 F2 ...
/Output
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain poti in
ccw positions of " "
or AM-CVin < V
Gain poti in
cw positions of " "
or AM-CVin > V
Squarewave
Output
/ Output
/Output
...
Frequency 1:
"FSK in" = high
Frequency 2:
"FSK in" = low
/
- Output
/
- Output
/ Output
Ext. squarewave
signal applied
on "FSK in"
...
F1 F2
/
- Output
Gain pot in
ccw positions of " "
or AM-CVin < V
Gain pot in
cw positions of " "
or AM-CVin > V
/
- output
...
F1 F1F2 F2
"FSK in" connected to - output:
-output
/ Output
Output/
F1 F1F2 F2
Gain poti in
ccw positions of " "
or AM-CVin < V
Gain poti in
cw positions of " "
or AM-CVin > V
Squarewave
Output
/ Output
/ Output
...
/ Output
ext. squarewave
signal on "FSK in"
F1 F2 ...
/ Output
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain poti in
ccw positions of " "
or AM-CVin < V
Gain poti in
cw positions of " "
or AM-CVin > V
Squarewave
Output
/ Output
/Output
...
Frequency 1:
"FSK in" = high
Frequency 2:
"FSK in" = low
/
- Output
/
- Output
/Output
Ext. squarewave
signal applied
on "FSK in"
...
F1 F2
/
- Output
Gain pot in
ccw positions of " "
or AM-CVin < V
Gain pot in
cw positions of " "
or AM-CVin > V
/
- output
...
F1 F1F2 F2
"FSK in" connected to - output:
-output
/Output
Output/
F1 F1F2 F2
Gain poti in
ccw positions of " "
or AM-CVin < V
Gain poti in
cw positions of " "
or AM-CVin > V
Squarewave
Output
/ Output
/ Output
...
/ Output
ext. squarewave
signal on "FSK in"
F1 F2 ...
/Output
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain poti in
ccw positions of " "
or AM-CVin < V
Gain poti in
cw positions of " "
or AM-CVin > V
Squarewave
Output
/ Output
/Output
...
Frequency 1:
"FSK in" = high
Frequency 2:
"FSK in" = low
/
- Output
/
- Output
/ Output
Ext. squarewave
signal applied
on "FSK in"
...
F1 F2
/
- Output
Gain pot in
ccw positions of " "
or AM-CVin < V
Gain pot in
cw positions of " "
or AM-CVin > V
/
- output
...
F1 F1F2 F2
"FSK in" connected to - output:
-output
/ Output
Output/
F1 F1F2 F2
Gain poti in
ccw positions of " "
or AM-CVin < V
Gain poti in
cw positions of " "
or AM-CVin > V
Squarewave
Output
/ Output
/ Output
...
/Output
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1/com
F2
F1 Fine Tune
F2 Fine Tune
F1/com CV ins
F2 CV ins
+
Switch
"com"
Frequency
Control
VCO
FSK in
Switch "FSK"
F1
F2
Output
6
F1
F2
16
LO MID HI
4

Modular
3. Functions
F1/com Coarse manual control of frequenc F1. Range is ≈ 8 octaves. If switch "Com→F2" is
in lower position, this knob also affects frequenc F2. See more under ,
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.
F2 Coarse manual control of frequenc F2. Range is ≈ 8 octaves.
F1 fine tuning for frequenc F1. Range is ≈ two half notes.
Frequenc range selector The value of the oscillator's timing capacitor, which is working for
both FSK frequencies, can be changed b this switch. 3 different ranges are provided:
1. Lo (switch in left position) for LFO applications and/or tremolo-like sounds
2. Mid (switch in middle position) for bass or sub-bass sounds
3. Hi (switch in right position) for mid-range and high audio frequencies
Because the frequenc CV-ins of the internal VCO chip are not linear over the entire audio
range, it is recommended to use the 'Mid' position for bass sounds and the 'Hi' mode for higher
frequencies (although it is possible to produce low frequencies in the 'Hi' mode too). This
ensures better 1V/oct. tracking in the lower frequenc regions.
F2 fine tuning for frequenc F2. Range is ≈ two half notes.
3
FSK
AM in
AM In
FSK in
F1 CV inv.
F1/com CV F2 CV
F1/com F2
XR22 VCO FT
F1/com CV
1V/Oct
F2 CV inv.
/
F2
F1
Σcom CV
F2
F2 CV 1V/Oct
Gain
Lo Mid Hi
F1/com CV F2 CV
1
2
35
0
6
7
8
1
2
35
0
6
7
8
1
2
35
0
6
7
8
-1
-2
+1
+2
Bypa
AM In /
+1-1
+1-1
Fine1 Fine2
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Introduction
For better understanding it is recommended to read first
about the control elements
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and :
FSK mode switch (frequenc shift ke ing)
In upper position: Onl F1 is active; LED= green
In middle position: Onl F2 is active, LED= red
In lower position (" ") the (square) output of the VCO is
internall connected to the FSK input and the oscillator
automaticall shifts itself between frequencies F1 and F2. In
this mode, the oscillator produces ramp and pulse signals
provided on output (ramp) and
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(pulse). The rising and
falling time of the ramp edges (and also the duration of high
and low levels on -output
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) can be separatl adjusted with
the frequenc knobs for F1 and F2 (and CVin's 1 and CVin's 2).
(Also see chapter 2.2 about FSK and )
LED FSK mode.
Green = F1, F1 CV ins (left half on the module panel).
Red = F2, F2 CV ins (right half on module panel).
When "Com Mode" is active ( in lower pos.), knob "F1/Fcom"
and "com CVin's" work for both green and red leds.
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Modular
FSK mode switch see above ("Introduction")
/ Waveform selector F2 octave switch switches between (sinewave) or (trianglewave)
output on socket .
Common → F2 switch changes the routing between the frequencies F1 and F2. In the upper
position, both frequencies F1 and F2 work independentl and can be controlled separatel b
their respective frequenc knobs and/or CV inputs.
In the lower position, knob "F1/com" and sockets "F1/com CV" "F1/com CV 1V/Oct"
affect both F1 and F2. This coupling ensures that the ratio between F1 und F2 remains the same,
and tracks 1V/oct. using both frequencies within the FSK option. The ratio can onl be changed
b the "F2" knob or the F2 CV inputs , .
Note that in this mode the frequenc range is expanded and that for F2 four independent CV
inputs are now available.
B pass Ratio between the "AM in" signal input and the oscillator / output. The mixed
signal is provided at socket .
AM in level Controls the input level from for amplitude modulation of / .
Gain adjustment Primaril to suppress the oscillator frequenc in ring modulation. The denter
in middle position "0" ma be used as orientation.
This knob regulates an internal offset voltage between ca. ±2V which is added to the AM-input
signal, adjusted b knob . In counterclockwise positions of the potentiometer the / -
phase will be inverted (See also "Examples" in chapter 2.2 "FSK").
In some applications the "Gain" knob ma be used to alter the waveshape (b adding more or
less voltage to our input signal); e.g. if ou feedback the / output to the AM-Input
and adjust and carefull , the oscillator generates ver overtone-rich waveforms.
FSK mode LED: see above ("Introduction")
/ (sine/triangle) output or ramp waveforms output when switch "FSK mode"
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is in
lowest position (" ").
The controller "B pass" adjusts the AM-Input/ / -oscillator output ratio. Full clockwise:
The / -oscillator output is 100%. Full counterclockwise: The / -oscillator output is 0%,
AM-input ( ) is 100%. This is to mix the original to the "effect" signal (≙ "dr /wet") when the
oscillator is used as a ringmodulator.
output voltage: 4Vpp without AM; max. 10Vpp with AM.
output voltage: 8Vpp without AM; max. 14Vpp with AM.
In the banana version of the XR22 VCO FT the red sockets signalize low impedance outputs.
These outputs ma not be grounded or patched together! This ma damage the module.
4
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Modular
AM input Amplitude modulation input for the / section of the VCO. The input amount can
be adjusted with . Also, the input signal can be mixed to the waveform output with B pass
controller .
(also see chapter 2.1 about amplitude modulation)
Ground This socket onl exists in the banana version of the XR22 VCO FT. The ground
connection is required if the module is connected to external equipment, e.g. a mixer. Within the
modular s stem the module is grounded through the power suppl .
FSK in is a logic input. When the "FSK"
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switch is in the middle position ("F2") and a voltage
greater than ≈+2V is applied to the FSK input (e.g. gate signal, squarewave), the internal switch
will be switched from F2 to F1 (F2/ F2 CV (Led → red) to F1/F1 CV (Led → green) .
Note: If switch "Com" is active, the "F1/com" knob and the inputs "F1/comCV" and
"F1/comCV 1V/Oct" affect both frequenc channels F1 and F2.
Squarewave output Level between ≈ 0V (GND) and +5V. In FSK mode " " (Switch "FSK"
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lower position) pulse waveform output.
F1/com CV Manual control adjusts the input level of F1/com CV in .
F1/com CV inversion switch Inverts the polarit of the signal on socket F1/com CV in .
F2 CV Manual control adjusts the input level of F2 CV in .
F2 CV inversion switch Inverts the polarit of the incoming signal on socket F2 CV in .
F1/com CV in Frequenc control voltage input for F1/com. Level can be adjusted b and the
polarit inverted b switch . See also ,
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.
F1/com CV 1V/Oct in 1V/Octave input for F1/com. See also ,
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. (It ma be necessar to
readjust the tracking. See chapter 4 "Adjustment")
F2 CV in Frequenc control voltage input for F2. Level can be adjusted b and the polarit
inverted b switch
F2 1V/Oct in 1V/Octave input for F2 (It ma be necessar to readjust the tracking. See chapter
4 "Adjustment").
5
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Modular
4. Adjustment
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1V/Octave Adjustment
The VCO is alread carefull adjusted to 1V/Oct. If ou
realize that the XR22 VCO FT isn't in tune with our
other analog s nthesizer equipment, it ma be
necessar to adjust it.
Procedure (Suggestion):
1. Switch on our equipment and the XR22 VCO
FT and wait 1/4 hour until the oscillator have
the right temperature.
2. Put range switch in right position 'Mid'.
Adjust F1 & F2 knobs & to ≈ middle
position (≈ 3 - 5 on scale)
3. Connect a CV from a ke board (or a similar CV
source) both to our favorite VCO's 1V/oct.
input and to the XR22 VCO F1/com 1V/oct.
input . Put switch "com" and switch "FSK"
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in upper position ("F1").
4. Pla a note on our ke board in the middle
range, e.g. "c", or "c1". The note should be
nearb to the tone ou have adjusted on the XR22.
5. Adjust pot "F1" and fine tuning until the pitch of the XR22 is the same like that of the 2nd
VCO.
6. Pla a note ≈ 2 - 3 octaves higher. Adjust trimmer "F1 1V/oct" (see above) until the XR22 VCO is
tracking to the 2nd VCO.
7. Go back to step "4" and repeat all other steps until both oscillators are in tune.
8. Repeat the same procedure with "F2" (with "FSK"
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in middle position and F2 1V/Oct. Input ).
Alternativel , ou can use the 1V/Oct input F1/com for F2, too. Put switch 'com' in lower
position and the 1V/Oct input F1/com is now working for both FSK frequencies. Put FSK
switch
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in middle position 'F2'. Adjust coarse poti F2 and fine tuning until both
frequencies are in tune.
9. Compare F1 and F2 b switching the FSK switch
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from one frequenc to the other; repeat the
tuning and adjustment steps 1.- 8. until both frequencies are perfectl matching and in tune
with the external ke board/VCO.
Bus CV
•Jumper "JP1" in "on" position (on PCB): The Bus CV is controlling the XR22 VCO's frequencies.
•Jumper "JP1" in "off" position (on PCB): The Bus CV is not connected.
6
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F1 1V/oct.
Adjustment
F2 1V/oct.
Adjustment
Potentiometer
'Gain'
-point
Bus CV on/off
Output
Offset
/

Modular
Potentiometer 'Gain' 0-point adjustment
1. Turn knob 'Gain' in middle position (denter locked)
2. Adjust trimmer Tr7
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4
for minimum output amplitude on / output (with no AM-Input
signal applied on ) .
/ - Output DC-Offset
No DC offset voltage should overla the oscillator's / - Output (with the knob 'Gain' in
middle position, the knob 'AM-In Level' turned full left and knob 'B pass' turned full
right). Appl the / - Output to a frequenc CV-input of a 2nd oscillator or to the AM-input
of a 2nd XR22 VCO. There must occur no change of the 2nd oscillator's frequenc or the 2nd XR22
VCO's loudness.
5.Contact Support
cg-products.de/module/xr22-vco-ft/
cg-products.de
Christian Günther
Forster Str. 50
10999 Berlin
[email protected]
Phone: ++49 30 61286299
Mobile ++49 178 7699267
This is Rev.4
© Christian Günther November 2017
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