CG Products XR22 VCO User manual

Modular
XR22 VCO
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 Mode
–Available ith banana or 3,5mm phone sockets
–Eurorack Module
–Width: 12 HP
–Dimensions:
128,5 mm x 60,6 mm
Depth: 40mm
–Supply Voltage: +-12V
Po er consumption:
≈ 70mA
eft: 3,5mm phone jack version
Right: Banana jack version
1
Low F
FSKAM in
AM In
FSK in
F1/com CV F2 CV
F1 CV inv.
F1/com CV F2 CV
Octave
-2 0+2 -2 0+2
Octave
F1/com F2
XR22 VCO
F1/com CV
1V/Oct
F2 CV inv.
/
Σcom CV
F2
F1
F2
Bypass
F2 CV 1V/Oct
Octave
7
6
5
43
2
1
AM In /
Octave
1
2
3
4
5
0
6
7
8
1
2
3
4
5
0
6
7
8
1
2
3
45
0
6
7
8
-1
0
-2
+1
+2
ain

Modular
2. AM and FSK
2.1 AM (Amplitude Modulation)
The / output ( ) amplitude varies linearly with the control voltage applied to "AM in" ( ). The
amount of the input signal can be adjusted with .(See chapter 3: "Functions"). Negative CVs will cause
phase inversion of the / waveform .
Examples:
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" .
Switch "FSK" selects the FSK mode: F1, F2 or
self-switching by the VCO's -output.
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.
Examples:
F1 activated. LED green (Switch "FSK" up) F2 activated. LED red (Switch "FSK" mid)
- Mode (F1+F2 activated) (Switch "FSK" low).
The oscillator frequency-shifts itself.
F1 and F2 can be separately adjusted.
With external FSK control signal applied on "FSK
in" (Switch "FSK" middle position).
2
F1/com Poti
F2 Poti
F1 Octave
F2 Octave
F1/com CV ins
F2 CV ins
+
Switch
"com" Frequency
Control
VCO
FSK in
Switch "FSK"
F1
F2
(without
F1 Octave)
Out ut
14
F1
F2
/ Out ut
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain oti in
ccw ositions of "0"
or AM-CVin < 0V
Gain oti in
cw ositions of "0"
or AM-CVin > 0V
Squarewave
Out ut
/ Out ut
/ Out ut
...
/ Out ut
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain oti in
ccw ositions of "0"
or AM-CVin < 0V
Gain oti in
cw ositions of "0"
or AM-CVin > 0V
Squarewave
Out ut
/ Out ut
/ Out ut
...
/Out ut
/Out ut
/ Out ut
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain oti in
ccw ositions of "0"
or AM-CVin < 0V
Gain oti in
cw ositions of "0"
or AM-CVin > 0V
Squarewave
Out ut
/ Out ut
/ Out ut
...
/ Out ut
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain oti in
ccw ositions of "0"
or AM-CVin < 0V
Gain oti in
cw ositions of "0"
or AM-CVin > 0V
Squarewave
Out ut
/ Out ut
/Out ut
...
/ Out ut
/ Out ut
/ Out ut
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain oti in
ccw ositions of "0"
or AM-CVin < 0V
Gain oti in
cw ositions of "0"
or AM-CVin > 0V
Squarewave
Out ut
/ Out ut
/Out ut
...
/ Out ut
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain oti in
ccw ositions of "0"
or AM-CVin < 0V
Gain oti in
cw ositions of "0"
or AM-CVin > 0V
Squarewave
Out ut
/ Out ut
/Out ut
...
/ Out ut
/ Out ut
/ Out ut
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain oti in
ccw ositions of "0"
or AM-CVin < 0V
Gain oti in
cw ositions of "0"
or AM-CVin > 0V
Squarewave
Out ut
/Out ut
/ Out ut
...
/ Out ut
ext. squarewave
signal on "FSK in"
F1 F2 ...
F1 F1F2 F2
Gain oti in
ccw ositions of "0"
or AM-CVin < 0V
Gain oti in
cw ositions of "0"
or AM-CVin > 0V
Squarewave
Out ut
/ Out ut
/ Out ut
...
/ Out ut
/Out ut

Modular
3. Functions
①F1/com Manual control of frequency 1 (F1). If "Com→F2" switch is in lower position, this pot
also affects frequency 2 (F2). See more under , .
②F2 Manual control of frequency 2 (F2).
③F1 octave switch for frequency 1. Left position: - 2 octaves; right position: +2 octaves. This
switch is not affected by switch .
④F2 octave switch
⑤/ Waveform selector switches between (sinewave) or (trianglewave) output on
socket .
⑥Low F switch: In the lower position the VCO produces low frequency waves suitable for tremolo
effects or signal modulation (like a LFO).
3
Introduction
For better understanding it is recommended to read first about
the control elements and :
FSK mode switch (frequency shift keying)
In upper position: Only F1 is active; LED green
In middle position: Only F2 is active, LED red
In lower position (" ") the (square) output of the VCO is
connected to the FSK input and the oscillator automatically
shifts itself between frequencies F1 and F2. In this mode, the
oscillator produces ramp and pulse signals provided on
output (ramp) and (pulse). The rising and falling time of
the ramp waveform (and also the duration of high and low
levels on -output ) can be separatly adjusted with F1 and
F2 (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.
Low F
FSKAM in
AM In
FSK in
F1/com CV F2 CV
F1 CV inv.
F1/com CV F2 CV
Octave
-2 0 +2 -2 0 +2
Octave
F1/com F2
XR22 VCO
F1/com CV
1V/Oct
F2 CV inv.
/
Σcom CVF2
F1
F2
Bypass
F2 CV 1V/Oct
Octave
7
6
5
4
3
2
1
AM In /
Octave
1
2
3
4
5
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
ain
4
14
24

Modular
⑦Common → F2 switch changes the routing between the frequencies F1 and F2. In the upper
position, both frequencies F1 and F2 work independently and can be controlled separately by
their respective frequency 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 only be changed
by the "F2" knob or the F2 CV inputs , . The octave selectors "F1Octave" and "F2 Octave"
also work indepently.
Note that in this mode the frequency range is expanded and that for F2 four independent CV
inputs are now available.
⑧Bypass Ratio between the "AM in" signal input and the oscillator / output. The mixed
signal is provided at .
⑨AM in level Controls the input level from for amplitude modulation of / .
⑩Gain adjustment Primarily to suppress the oscillator frequency in ring modulation. The denter
in middle position "0" may be used as orientation.
This knob regulates an internal offset voltage between ca. +-2V which is added to the AM-input
signal, adjusted by 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 may be used to alter the waveshape (by adding more or
less voltage to your input signal); e.g. if you feedback the / output to the AM-Input
and adjust and carefully, the oscillator generates very overtone-rich waveforms.
⑪LED see above ("Introduction")
⑫ / (sine/triangle) output or ramp waveforms output when switch "FSK mode" is in
lowest position (" ").
The controller "Bypass" adjusts the AM-Input/ / -oscillator output ratio. Fully clockwise:
The / -oscillator output is 100%. Fully counterclockwise: The / -oscillator output is 0%,
AM-input ( ) is 100%. This is to mix the original to the "effect" signal (≙ "dry/wet") when the
oscillator is used as a ringmodulator.
Sinewave output voltage: 3Vpp without AM; max. 6Vpp with AM.
Trianglewave output voltage: 6Vpp without AM; max. 8Vpp with AM.
In the banana version of the XR22 VCO the red sockets signalize low impedance outputs. These
outputs may not be grounded or patched together! This may damage the module.
⑬AM 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 Bypass
controller .
(also see chapter 2.1 about amplitude modulation)
4

Modular
⑭FSK mode switch see above ("Introduction")
⑮FSK in is a logic input. When the "FSK" 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 that if switch "Com" is active the "F1/com" knob and the inputs "F1/comCV" and
"F1/comCV 1V/Oct" affect both frequency "channels".
⑯ Squarewave output Level between ≈ 0V (GND) and +5V. In FSK mode " " (Switch "FSK"
lower position) pulse waveform output.
⑰Ground This socket only exists in the banana version of the XR22 VCO. The ground connection
is required if the module is connected to external equipment, e.g. a mixer. Within the modular
system the module is grounded through the power supply.
⑱F1/com CV Manual control adjusts the input level of F1/com CV in .
⑲F1/com CV inversion switch Inverts the incoming signal on socket F1/com CV in .
⑳F2 CV Manual control adjusts the input level of F2 CV in .
F2 CV inversion switch Inverts the incoming signal on socket F2 CV in .
F1/com CV in Frequency control voltage input for F1/com. Level can be adjusted by and
inverted by switch . See also , .
F1/com CV 1V/Oct in 1V/Octave input for F1/com. See also , . (It may be necessary to
readjust the tracking. See chapter 4 "Adjustment")
F2 CV in Frequency control voltage input for F2. Level can be adjusted by and inverted by
switch .
F2 1V/Oct in 1V/Octave input for F2 (It may be necessary to readjust the tracking. See chapter
4 "Adjustment").
5

Modular
4. Adjustment
The VCO is already carefully adjusted to 1V/Oct.
If you realize that the XR22 VCO isn't in tune with your other analog synthesizer equipment, it may be
necessary to adjust it.
Procedure (Suggestion)
1. Switch on your equipment and the XR22 VCO and
wait ½ hour until the oscillators have the right
temperature.
2. Bring octave switches F1 and F2 in middle
position. Adjust F1 & F2 knobs & to ≈ middle
position (≈5-6 on scale)
3. Connect a CV from a keyboard (or similar) both to
your favorite VCO's 1V/oct. input and to the XR22
VCO F1/com 1V/oct. input .
Put switch "com" and switch "FSK" in upper
position ("F1").
4. Play a note on your keyboard in the middle range,
e.g. "C", or "c". The note should be nearby to the
tone you have adjusted on the XR22.
5. Adjust pot "F1" until the pitch of the XR22 is the
same like that of the 2nd VCO.
6. Play 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"
in middle position and F2 1V/Oct. Input ).
9. After this it is necessary to readjust the octave
tuning for switches F1 and F2 , too.
10.Disconnect the CV from your keyboard to the XR22
and bring FSK switch in upper position ("F1").
11.Turn F1 pot in fully counterclockwise and octave
switch in middle position.
12.Tune your 2nd VCO until it pitches with the XR22
VCO.
13.Play a note 2 octaves higher on the 2nd VCO and
bring the octave switch in right position ("+2)
14.Adjust trimmer "+2 Octaves" until it matches.
15.Repeat step 11and the following until the trimmer
no longer needs to be adjusted.
16.Turn F1 pot in fully clockwise and octave switch
in middle position.
17.Tune your 2nd VCO until it pitches with the XR22
VCO.
18.Play a note 2 octaves lower on the 2nd VCO and
bring the octave switch in left position ("-2).
19.Adjust trimmer "-2 Octaves" until it matches.
20.Repeat step 16 and the following until the trimmer
no longer needs to be adjusted.
6
-2 Octaves
+2 Octaves
F1 1V/Octave
F2 1V/Octave
F1 1V/Octave
F2 1V/Octave
+2 Octaves
-2 Octaves
-2 Octaves
+2 Octaves
F1 1V/Octave
F2 1V/Octave
F1 1V/Octave
F2 1V/Octave
+2 Octaves
-2 Octaves

Modular
Older Version:
5. 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.
Note In the older version of the XR22 VCO there is no Bus CV Jumper. The Bus CV is always connected
to the VCO's frequency control.
7
-2 Octaves
+2 Octaves
F1 1V/Octave
F2 1V/Octave
F1 1V/Octave
F2 1V/Octave
+2 Octaves
-2 Octaves
-2 Octaves
+2 Octaves
F1 1V/Octave
F2 1V/Octave
F1 1V/Octave
F2 1V/Octave
+2 Octaves
-2 Octaves
-2 Octaves
+2 Octaves
F1 1V/Octave
F2 1V/Octave
F1 1V/Octave
F2 1V/Octave
+2 Octaves
-2 Octaves

Modular
. Patch Templates
Note your o n patch ideas "
Template Height: 70mm; Width: 33,1mm
7.Contact & Support
Christian Günther
Forster Str. 50
10999 Berlin
[email protected]
Phone: ++49 30 61286299
Mobile ++49 178 7699267
www.cg-products.de
© Christian Günther 03.September2014
8
Low F
FSKAM in
AM In
FSK in
F1/com CV F2 CV
F1 CV inv.
F1/com CV F2 CV
Octave
-2 0+2 -2 0+2
Octave
F1/com F2
XR22 VCO
F1/com CV
1V/Oct
F2 CV inv.
/
Σcom CVF2
F1
F2
Bypass
F2 CV 1V/Oct
Octave
7
6
5
43
2
1
AM In /
Octave
1
2
3
45
0
6
7
8
1
2
3
4
5
0
6
7
8
1
2
3
45
0
6
7
8
-1
0
-2
+1
+2
ain
Low F
FSKAM in
AM In
FSK in
F1/com CV F2 CV
F1 CV inv.
F1/com CV F2 CV
Octave
-2 0+2 -2 0+2
Octave
F1/com F2
XR22 VCO
F1/com CV
1V/Oct
F2 CV inv.
/
Σcom CVF2
F1
F2
Bypass
F2 CV 1V/Oct
Octave
7
6
5
43
2
1
AM In /
Octave
1
2
3
45
0
6
7
8
1
2
3
4
5
0
6
7
8
1
2
3
45
0
6
7
8
-1
0
-2
+1
+2
ain
Low F
FSKAM in
AM In
FSK in
F1/com CV F2 CV
F1 CV inv.
F1/com CV F2 CV
Octave
-2 0+2 -2 0+2
Octave
F1/com F2
XR22 VCO
F1/com CV
1V/Oct
F2 CV inv.
/
Σcom CVF2
F1
F2
Bypass
F2 CV 1V/Oct
Octave
7
6
5
43
2
1
AM In /
Octave
1
2
3
45
0
6
7
8
1
2
3
4
5
0
6
7
8
1
2
3
45
0
6
7
8
-1
0
-2
+1
+2
ain
Low F
FSKAM in
AM In
FSK in
F1/com CV F2 CV
F1 CV inv.
F1/com CV F2 CV
Octave
-2 0+2 -2 0+2
Octave
F1/com F2
XR22 VCO
F1/com CV
1V/Oct
F2 CV inv.
/
Σcom CVF2
F1
F2
Bypass
F2 CV 1V/Oct
Octave
7
6
5
43
2
1
AM In /
Octave
1
2
3
45
0
6
7
8
1
2
3
4
5
0
6
7
8
1
2
3
45
0
6
7
8
-1
0
-2
+1
+2
ain