Synthesizers.com Q169 Oscillator++ User manual

Q169 Oscillator++
Oct 25, 2021
The Q169 Oscillator++ module combines
two audio oscillators offering an amazing
array of cross-modulation possibilities, along
with an LFO, envelope generator and sam-
ple-and-hold functions - all gracefully orga-
nized on a triple-wide 5U panel.
Oscillator++ can be used as a dual oscillator
in a traditional synth patch, as a stand-alone
voice, as a pair of FM operators for additive
synthesis, as independent functions, or as a
complex modulation source. Go from tame
to chaos with the turn of a knob.
Both audio oscillators are paired with a VC
amplifier, and each can modulate the others
pitch, pulse width and amplitude at the same
time and in variable amounts. A cross-
modulation extravaganza!
The Q169 is the equivalent of 10 modules
and 20 patch cables arranged in a musically
-useful and understandable way. Configura-
tions you probably wouldn't patch naturally
are easily accessible. Oscillator++ is com-
plexity dignified.
The optional Q168 Aid module provides
patch points for LFO waveforms, the enve-
lope, noise, S&H and a multi-purpose invert-
able attenuator.
Q169 Oscillator++ Specifications
Panel Size: Triple Width 6.375"w x 8.75" (Moog Unit Format)
Input/Output Signals: 10Vpp
Control Voltage Signals: 0-5V unipolar or 10Vpp bipolar
Gate Signals: 5V
Pitch CV Response: 1V/Octave
Pitch Tracking Range: 10+ Octave
VCA Response: Linear
LFO Range: .01hz - 20hz
EG Speed: 10s - 10ms
Power Requirement: +15V@150ma, -15V@150ma, +5V@10ma. Synthesizers.com standard.

Oscillator #1
tuning & range
waveform select,
sync select,
wave inversion
Panel Overview
The Q169 module consists of more than 10 function blocks - two VCOs, each with its own VCA and glide,
an LFO, Envelope Generator, Mixer, Sample & Hold, and more. VCOs offer extensive cross-modulation
of pitch, pulse width and amplitude with easy connection to the LFO, EG and external signals.
Q169 Oscillator++
Individual outputs
and mixed output
LFO and
Envelope
Generator
Gate for triggering
envelopes and syncing
LFO and oscillators
Oscillator #1
modulation
settings
Oscillator #2
tuning and range,
waveform select,
sync select,
Sample & Hold
Oscillator #2
modulation
settings
Oscillator #1
with VCA
Oscillator #2
with VCA
1V/Octave
pitch CV
for one or both
oscillators
1V/Octave
pitch CV
for oscillator #2
Voltage controlled
inverting of oscillator 2

Slew
LED
Triangle
VCO
#1
Wave
Shapers
Envelope
Generator
VCA Out
Attack
Functional Diagram
Q169 Oscillator++
Wave
Selector
Noise
Source
Invert Sw
LFO
EG
VCO2
Pitch modulation
IN
Pitch
Pot
Switch
Jack
LFO
+5V
EG
PWM IN
PWM
Pot
Switch
Jack
LFO
+5V
EG
AMP IN
AMP
Pot
Switch
Jack
AMP IN
Mix
Out
LED
Triangle
VCO
#2
Wave
Shapers
VCA Out
Freq Pot
1V/Oct
Range Sw Wave
Selector
LFO
EG
VCO1
Pitch modulation
IN
Pitch
Pot
LFO
+5V
EG
PWM IN
PWM
Pot
Switch
Jack
LFO
+5V
EG
AMP IN
AMP
Pot
Switch
Jack
AMP IN
Mix
Decay
VCI
LED
LED
S&H
AS/ASR Speed
EG
Gate In
Out Clk
Sample
& Hold
Gate
VCO1
Gate
VCO2
LFO Speed
Range
Sync
Sync
(Normal from 1)
Slew
Freq Pot
1V/Oct
Range Sw

Sustain knob replaces the
Q169's AD/ASR switch and
turns the EG unto a full
ADSR envelope
Q168 Oscillator++ Aid
The optional Q168 module provides additional features to the Q169 by giving access to several of the
Q169's internal signals including the LFO waveforms, envelope generator, noise source, and sample &
hold. A sustain knob replaces the AD/ASR switch providing a complete ADSR envelope. Also included is
an invertable attenuator with offset control that can also be used as a voltage source. A 2 volt output pro-
vides transposing of the oscillators by 2 octaves, and access to oscillator #1's linear pitch signal is provid-
ed.
Q169 Oscillator++
2 volt source to provide
2 octave transposition
of oscillators
Independent signal at-
tenuator with inversion
and offset. Can be used
as a voltage source
Direct access to the
sample & hold output
whose source is oscillator
#1 and clocked by the
LFO
Access to the LFO
sine and square
waveforms
Gate Sync switch controls
whether the LFO is reset
by gate pulses or not.
Without the aid module
it can be jumpered either
way on the circuit board
Linear pitch control for
oscillator 1. Can be
moved to oscillator 2 if
desired
Access to the Q169's
internal noise source
The Q168 Aid module
only works along side
the Q169 Oscillator++
Note: Q168 requires a power connection

The foundation of the Oscillator++ module are two precision triangle-core VCOs (Voltage Controlled Os-
cillator) - #1 on the left side, #2 on the right side. Triangle cores don't have a reset glitch like sawtooth
cores and produce smoother Sine and Triangle waves.
Both oscillators track a standard 1V/Octave keyboard pitch voltage accurately over a wide range of tem-
peratures. The VCOs can be used independently or together. They can track together and modulate
each other.
The main frequency knobs are large and easy to tune with a range of +/- 1/2 octave either side of center.
At 0 pitch voltage, the center position is approximately C.
The range switches are wired so the oscillators can be 0, 1, 2 or 3 octaves apart.
A 6-position waveform switch selects sine, triangle, pulse, sawtooth, anti-sine and random. The pulse
waveform is variable from 0 to 100% . The sawtooth wave is double frequency. The anti-sine wave is
like subtracting a sine wave from a triangle wave and produces interesting harmonics.
The next section is the modulation matrix. This arrangement gives you easy access to amazingly com-
plex cross-modulation between the two oscillators - pitch, pulse width, and amplitude.
The PITCH jacks at the bottom are 1V/Octave scaling to track a standard keyboard. VCO #1's jack is
automatically connected to VCO #2's jack unless a plug is inserted into VCO #2. This makes dual-
oscillator patching easy.
Just above that, each VCO has a PITCH jack wired to a variable
glide circuit, aka slew-limiter, aka portamento. The jack for VCO
#1 is also automatically connected to VCO #2's jack unless a plug
is inserted into VCO #2 as indicated by the panel graphics.
VCO #2
Oscillator #1 and #2
Q169 Oscillator++
VCO #1
At the bottom of the panel in the center are the output jacks. The
oscillators can be operated completely independently or together.
Each oscillator has its own dedicated output jack that can be used
any way you wish in a system patch.
In the center is a mixed output which provides a combination of
the two oscillators.
Outputs

Both oscillators offer multiple ways to control the most important aspect
of their sound - pitch.
Manual Control
The large knob at the top of each oscillator provides fine tuning of the pitch - plus or minus 1/2 octave
from center. At the center position and control voltages summing to zero the pitch is C. There is no
standard for what pitch an absolute control voltage produces, but the scaling of 1 volt per octave is stand-
ard. Our keyboard controllers produce integer volts (0V, 1V, 2V, etc) at their C keys which matches our
oscillators.
Range Switch
Next to the manual pitch control is the 3-position range toggle switch. The
center position set the pitch to C1 for 0 volts. This is about 32hz and corre-
sponds to 16' organ pipes.
The upper and lower switch positions changes octaves above or below that
according to the numbers shown, each side is different. This arrangement
allows for unison between the oscillators as well as separation by 1, 2 or 3
octaves.
Pitch Jack
At the very bottom is a Pitch jack which is scaled at 1V per octave - stand-
ard scaling for modular synthesizers. VCO #1's pitch input is normalized to
VCO #2's pitch input as indicated by the panel graphics. This connection
is broken when a plug is inserted into VCO #2's jack. A typical use for this
jack is a pitch bend wheel.
Pitch with Glide
Second from the bottom pitch jack is also 1V per octave scaling. A knob
controls glide time for the control voltage signal. This feature can also be
referred to as portamento or slew limiting. VCO #1's pitch input is normal-
ized to VCO #2's pitch input and broken in the same way as the pitch jack
on the bottom. A typical use for this jack is a keyboard controller.
Pitch Modulation
Third from the bottom is a pitch jack with variable scaling via a knob. This
is part of the modulation section where signals from the other VCO, the EG
and the LFO provide modulation.
When there is a plug inserted into the jack, the incoming signal is attenuat-
ed through the pot from 0 to 1V per octave. In this case the toggle switch
is ignored.
Without a plug inserted into the jack, the toggle switch determines the pitch
control voltage source - LFO, envelope generator, or the output of the other
VCO (cross modulation). For all 3 of these sources the knob controls the
amount. In the center position, make sure the other oscillator has its AMP
turned on or there will be no effect. Set the knob to zero if you do not want any of these modulations -
this is a common source of unexpected results, sometimes unwanted, sometimes wonderful.
Pitch Control
Q169 Oscillator++
Pitch, note, frequency all
describe the same thing.

Each oscillator provides control over the polarity of its waveform.
Oscillator #1 provides manual control using the INV switch located next to the waveform
selector. This can be useful when using the oscillator as a modulator while being sync'd to
the GATE input.
Oscillator #2 provides voltage control of its waveform polarity using the VC INV jack at the
bottom of the panel. Audio speed VC inverting offers some very nice metallic effects. To
use this, patch Oscillator #1's output to the VC INV jack while listening to Oscillator #2 or a
mix of the two. Changing waveforms on both oscillators offers many different results.
Inverting Waveforms
Q169 Oscillator++
Each oscillator offers a sync (synchronize) input which allows a signal, usually from another
oscillator to restart the waveform at some point within its cycle. This is a classic effect found
on many synthesizers sometimes referred to as Hard Sync.
A toggle switch near the waveform knob controls sync for each oscillator. The center position
is off - no sync. The upper position syncs the oscillator to the other oscillator. Typically a
slower oscillator will sync the faster oscillator for the best effects. Oscillator #1 is typically
used as the slower oscillator.
The bottom position causes the waveform to sync to the GATE IN jack. This is useful when
using an oscillator as a modulator where each press of a key produces the same waveform
progression.
Sync
Oscillator #2 can be controlled by the internal Sample & Hold circuit. The switch can be found
next to the waveform knob. This circuit captures the waveform from Oscillator #1 and feeds it to
Oscillator #2's pitch. The speed of the capture is clocked by the LFO.
Normally when using the Sample & Hold feature, Oscillator #1 is run at a fixed speed, and Oscil-
lator #2 is listened to. Oscillator #2 can be controlled by a keyboard during this process or free
running.
The amount of waveform feeding the Sample & Hold is adjusted from Oscillator #1's AMP control
(Amplitude).
Use Oscillator #1's sine, anti-sign or Triangle wave for up and down sequences. Use the sawtooth wave
for descending sequences, or flip the INV switch for ascending. Use the random waveform setting for
random pitches.
Sync Oscillator #1 to a keyboard using the GATE IN for sequences that act the same way each time a
key is pressed.
Sample & Hold

The magic of the Q169 module is the modulation possibilities and their easy access. Modulation is just a
fancy word for having one signal change something about another signal. For each oscillator, three
things can be modulated - Pulse width, waveform amplitude, and pitch. These three things can be modu-
lated by the LFO, by the Envelope Generator, by the other oscillator, by an external signal into the jack, or
manually controlled by the knob. The possibilities are amazing, and most don't require patch cables.
Pulse Width (PWM)
The width of the pulse waveform is controllable and has a nice effect on the sound, like phase shifting.
The oscillator's pitch stays the same but the waveform appears to our ears as moving. PWM only applies
to the pulse waveform.
The toggle switch determines the source of the modulation. Options are
LFO or EG (Envelope Generator). When LFO or EG is selected, the knob
provides control over the attenuation (strength of the effect).
The center toggle switch position is off and then the knob gives you man-
ual control over the pulse width from 0 to 50%. Since an inverted wave-
form sounds the same to our ears, 50% to 100% sounds the same. If you
need an inverted form of the pulse for modulation purposes, use the IN-
VERT switch.
A jack is provided for an external signal to control the pulse width. When
a plug is inserted, the toggle switch sources are bypassed and the knob
provides attenuation. The external signal can come from another module
or perhaps the S&H output on the Q168 Aid module, or possibly noise or
another waveform from the other oscillator.
Amplitude
Each oscillator on the Q169 has a built-in VCA (amplifier) to provide con-
trol over the waveform amplitude. This provides many possibilities not found on other oscillators such as
using the module as a stand-alone voice with the VCAs controlled by the internal EG, or by creating FM-
style operator synthesis where pitch and amplitude modulation provides amazing new sounds. All of this
is easy with Oscillator++.
The toggle switch determines the source of modulation. When LFO or EG is selected, the knob provides
attenuation. When the toggle switch is in the center, the knob provides manual control of the amplitude -
this is basically a volume control.
A jack is provided for an external signal to control amplitude. This signal is added to the other sources as
indicated by the panel graphics. Use the jack to modulate from the other VCO.
Pitch
The toggle switch provides the source of pitch modulation - LFO, EG, or the other VCO. The knob pro-
vides attenuation in each position. When an external signal is plugged into the jack, the toggle switch
source is bypassed and the knob becomes the attenuator for it.
The result of pitch modulation is dramatic, especially when having both oscillators modulate each other.
Experimentation is the only way to fully appreciate this.
When selecting position [2] on the toggle switch, make sure oscillator #2 has its AMP turned on.
Modulation Section
Q169 Oscillator++

Q169 Oscillator++
The center-top section of the module is an LFO. The output of the LFO is a
sine wave and used for modulation. You'll see the LFO label several places
in the modulation section - for PWM, amplitude (tremolo), and pitch (vibrato).
Speed of the LFO is set by the knob and the range switch selects between
slow, very slow and off.
In the SLOW position, speeds range from .1hz to 20hz. In very slow position
speeds range from .01hz to 2hz.
LFO
The center-middle section of the module is an envelope generator (EG).
You'll see the EG label several places in the modulation section - for PWM,
amplitude, and pitch. This feature may be used or ignored.
Typically a gate signal patched into the gate jack will trigger the envelope,
but the LFO can also trigger the envelope by setting the first toggle switch to
LFO.
The envelope can be either Attack/Decay or Attack/Sustain/Release as set
by the AD/ASR switch. In the AD position, the envelope will trigger at the
beginning of the gate, then when the peak is reached begins decay regard-
less of the gate's status (typically a keypress). In the ASR position, the enve-
lope stays on (sustains) as long as the gate is present (typically a keypress),
then the release phase begins. Decay and release are the same speed.
A speed switch provides short and longer envelopes.
Envelope Generator
OFF
It's not mandatory to use the LFO or
the envelope generator. Don't let
their availability sway your creativity.
SLOW
VERY
SLOW
If the EG is set to trigger from the
LFO and the LFO is set for Gate
Sync on the Aid module then a
strange loop will be created.

Gate from
keyboard
Q169 Oscillator++
The Q169 is super easy to patch, even complex patches that you wouldn't normally do. In this example
Oscillator++ is being used as a complete dual-oscillator voice using the built-in VCAs and envelope gen-
erator. Use the center output jack for a mix of the 2 VCOs. The pitch normalization reduces the need for
multiples and patch cables. Set pitch range however you'd like. Notice the S&H is turned OFF and the
Pitch modulation knobs are 0. Adjust the EG controls to your taste. This patch performs as a complete
synth voice. From this humble beginning you can experiment with PWM from the LFO, pitch modulation
from LFO, EG or the other oscillator, VC inverting, sync'ing and much more.
Dual Oscillator Voice Patch
Audio
Output
Pitch voltage
from keyboard
OFF
SLOW
+1
+2 +3
SLOW

Gate from
keyboard
Q169 Oscillator++
Cross-modulation is having each oscillator's output modulate the pitch of the other while listening to one
or both of them. With the Q169, cross-modulation is easy - set the pitch modulation toggle switch to the
center position where [1] or [2] shows that the source is the other oscillator. Then set the knob to the de-
sired amount. Start with very small amounts. Take audio out from the center output jack and turn the
output mixer to hear one or both of the oscillators. Tune to your liking, experimenting is where the magic
happens. In this patch the amplifiers are turned fully on and you can use an external VCA/EG to control
that.
Dual Oscillator Cross Modulation Patch
Audio
Output
Pitch voltage
from keyboard
OFF
SLOW
+1
+2 +3

Q169 Oscillator++
VCI (Voltage controlled inversion) is an interesting effect where one oscillator's output controls the polarity
of the other oscillator's waveform. In this particular patch, the amplifiers are set to full for use with an ex-
ternal VCA/EG, but you can also use the internal EG to control them for stand-alone operation.
VC Inversion Patch
Audio
Output
Pitch voltage
from keyboard
OFF
SLOW
+1
+2 +3

Q169 Oscillator++
A sample and hold circuit takes an input and freezes it at every clock pulse. This captured signal is its
output until the next clock pulse captures the next input value. The Q169's built-in S&H circuit takes its
input from VCO #1 and is clocked by the internal LFO. The output controls the pitch of VCO #2. Flip the
S&H toggle switch up to turn it on. Set the AMP on VCO #1 to control the amount of the pitch control.
The LFO speed controls how often the S&H is triggered. Normally in this type of patch you want to only
listen to VCO #2.
Sample and Hold Patch
Audio
Output
Pitch from
keyboard
OFF
SLOW
+1
+2 +3