Note Generators


This is the second area for investigation. As noted in the log, the atonal muck I aspire to is just the thing for the purposeful randomness1 I will be seeking from these machines. I will include small sequencers on this page in a separate table, starting with the Doepfer. Future Sound Systems plan a small and inexpensive sequencerfor summer 2009.

Source and model Price

Width HP

Power ma Notes
DoepferA-149-1 Source of Uncertainty 92 12 40 see also A-149-2 46, 4HP, 40ma
Cyndustries Universal Event Generator $440      
Elby Designs Panther ED108 - ChaQuO $240 20    
Harvestman Zorlon Canon $295 11    
Livewire Dual Cyclotron $275 28 60  
Makenoise WoggleBug $270 14 50  
Plan B The Model 24 Heisenberg Generator $275 14 90  



Doepfer A-149-1 Source of Uncertainty

Module A-149-1 is the first module of the A-149-x range. In this group we present by popular request several functions of Don Buchla's "Source of Uncertainty 265/266" (SOU) modules that cannot be realized with existing A-100 modules. Many functions of Buchla's 265 and 266 SOU can be realized with existing A-100 modules. For details please refer to A-100 patch examples.

Module A-149-1 has available four different analog random control voltages that are generated in different ways.

The "Quantized Random Voltages" section has available 2 CV outputs: "N+1 states" and "2N states". N is an integer number in the range 1...6 that can be adjusted with the manual control (Man N) and an external control voltage CVN with attenuator. Whenever the rising edge of the input clock signal (Clk In) appears a new random voltage is generated at the N+1 resp. 2N output. The N+1 output is capable to generate N+1 different voltage levels (or states), the 2N output up to 2N different states. If for example N is set to 4 the N+1 output generates up to 5, the 2N output 16 different states. The voltage steps of the 2N output are adjusted to 1/12 V in the factory. Consequently exact semitones can be obtained in combination with a VCO. The voltage steps of the n+1 output are adjusted to 1.0 V in the factory corresponding to octave intervals in combination with a VCO. For each output a trimming potentiometer is available on the pc board that enables the user to select other voltage steps for the output in question.

Even the "Stored Random Voltages" section has 2 stepped CV outputs available: one with even voltage distribution of the max. 256 output states and second one with adjustable voltage distribution probability. The distribution probability is adjusted by a manual control (Man D) and an external control voltage CVD with attenuator. With the control set fully counterclockwise most of the random voltages will be low magnitude but even medium and high magnitude voltages may appear but with smaller probability. As the control is turned to the right (or a positive control voltage appears at the CVD input) the distribution moves through medium to high magnitude voltage probability. The symbol at the lower jack socket shows this coherence graphically. The voltage range is 0...+5V for both outputs of the "Stored Random Voltages" section. For each output a trimming potentiometer is available on the pc board that enables the user to select another voltage range for the output in question.

The A-149-1 can be extended by 8 random digital voltages with the A-149-2 Digital Random Voltages module.

Cyndustries Universal Event Generator

Note: The image is not the EuroRack format module

The UEG can be used as an LFO, envelope generator, and step sequencer!

Eight stages are provided with adjustable time and level settings for each stage, and include LEDs which indicate the relative DC voltage output for each position.

Major Modes of the UEG include:
LOOP-ONLY or LFO mode between two loop points.
ONE-SHOT if you absolutuely positively have to have a full event!
GATE mode which has several different reaction modes including:
STEP (as a sequencer),

The START and END switches control the length of each loop. The output
waveform can have one of three slopes: linear, log, and step. These are shown graphically on the front panel and this finger tip control is extremely handy!

Of course the UEG also has a trigger button for triggering the UEG manually as well, and a TIME jack allowing an input voltage to control the overall time constant of an entire Universal event.

The OUTPUT jack is of course the main output waveform. It is a 0 to 5 volt analog voltage that corresponds to the front panel settings.

The TRIG END jack fires off a short pulse at each stage juncture and the conclusion of the final stage. This can in turn start other mischief elsewhere in your system...

Elby Designs Panther ED108 - ChaQuO

The main function of this module is a versatile chaotic signal generator (CG). Chaotic signals are signals that have varying degrees of interesting irregularity without actually becoming random. This CG is an analog electronic simulation of the classical driven double potential-well problem, with the addition of extra gain in the circuit loop, and an extra cross-coupling path to extend the range of chaotic patterns available.
The double-well system is a "second-order" system and therefore requires an external driving signal. This is provided by the second part of the module, a sinusoidal quadrature oscillator (QO). The two parts of the module may be used together or separately. The CG may be driven by any output of the built-in QO or by any external oscillator. The QO may drive the CG or be used independently as a four phase oscillator for the usual spatial modulation and other applications. Both parts of the module are manually controlled, to provide a compact, cost-effective unit. The QO has a frequency span of ~0.03 Hz to ~3 kHz in two overlapping ranges.

Harvestman Zorlon Canon

Voltage-controlled pseudorandom pulse and pitched noise generator.
Zorlon Cannon is two modules in one: Pseudorandom gate generator and "pitched noise" generator (like Atari 2600, 5200, etc.)
The lower section generates four flavors of pitched noise with tap configurations similar to classic Atari sound devices. Each output has an alternate mode switch for a total of 8 possible sounds.
The upper section of the Zorlon cannon operates upon the same principles, at a much lower rate. Each of the outputs here generates a 12 volt gate signal at a pseudorandom interval, with each output offering a different sequence length. In addition to voltage control of the update period, you may adjust the tap configuration for a different repeating sequence of gates.
Try mixing the gate signals together to make a complex control voltage! This capability will be added as an expander module sometime in 2008.


Livewire Dual Cyclotron

A pair of non-concentric, asymmetrical low frequency semi-periodic resonators (or cyclotrons) controlling a subordinate pseudorandom voltage generator. The output voltage which is produced can be used to modulate VCOs, VCFs, VCAs, or any other devices that is voltage controllable. The Dual Cyclotron can be adjusted for extremely long cycles producing slowly changing soundscapes evolving over long periods of time, or ultrahigh cycle rates for totally sick sideband oscillation.

Every Dual Cyclotron is assembled under sterile laboratory conditions and undergoes thorough radiation decontamination prior to shipping.

Makenoise WoggleBug

The "WoggleBug" is a random voltage generator, originally designed by Grant Richter of Wiard Synthesizers. The Wogglebug's sole purpose is to overtake the control voltages produceded by your keyboard during performance, and to give voice to your synthesizer's ID. It is your synthesizer's ID MONSTER.
A continuation of the "smooth" and "stepped" fluctuating random voltage sources pioneered by Don Buchla, the core of the circuit is based on the Buchla Model 265 "Source of Uncertainty" module, which many consider to be the most musical of all random voltage generators. Like the 256, the Wogglebug utilizes a vactrol based low frequency smoothing filter, VCO and Sample & Hold to produce Stepped and Smooth (or lagged, slewed) control voltages in the range of 0 to 10 volts. Grant's Wogglebug design expands on this system to include the other-worldly Woggle CVs (stepped voltages with decaying sinusoids at the edges), which must be heard in action to be truly appreciated.
In a moment of considerable noise, Richter decided to tap into the sound sources at the uncertainly beating heart of the Wogglebug, and bring them forth to the instrument's panel. He then figured a clever way to "ring modulate" these sounds, and that output now graces the panel of all Wogglebugs.
Thus, the Wogglebug is a complete system, no external modules are necessary... however, all voltage controlled systems long to be tickled, bitten, plagued and eventually destroyed by the Wogglebug.
Until now, the Wogglebug has only been available as the Wiard Wogglebug #5 for the 300 series or as the Wogglebug #3 DIY project, popularized by the folks at electro-music. The Make Noise Wogglebug is neither #3 nor #5. In the truest spirit of Wiard Synthesizers, the Make Noise Wogglebug is not a clone, but instead it is a tribute to all that Woggles, a continuation of the Wogglebug.
Like the #3, the Make Noise Wogglebug is a single Wogglebug system. However, the Make Noise Wogglebug improves upon the #3 by offering further functionality:
-External IN for the ringmod circuit
-the Ability to directly inject a signal to the heart of the Wogglebug via the Control IN
-the Random Gate Burst function
All of which have never appeared within any Wogglebug. Finally, Make Noise has redesigned the Cluster circuit, and thus it has been renamed as CHAOS BALANCE to reflect it's further purposes. This control now allows for new functionality that has again, never appeared within any Wogglebug to our knowledge.

Plan B The Model 24 Heisenberg Generator

Fully voltage controllable random events with independent Stepped and Smooth functions
Computer-generated random source replicates MM5837 noise chip at 16bit
Accepts external sampling voltage and clocks -or- generates it's own
Multifunctional: Smooth/Stepped Random, Noise Source, Slew Limiter, S+H

The Model 24 Heisenberg Generator is the first computer-based module in the Plan B line. Taking it's name from Werner Heisenberg (the father of the Uncertainty Principle), the Model 24's primary function is a dual wide-band random voltage generator producing simultaneous and fully independent stepped and smooth arbitrary voltages. Along with these random events, it can also be used as a Sample and Hold, a VC Lag Processor, a VC Trigger Generator, a Gate to Trigger Converter or a Digital Noise Source. The Model 24 also provides VC inputs for all of its tactile controls. While totally self contained - producing its own pacing triggers and random states - its also open ended, and will accept external triggers and voltages independently.

section compiled 15th April 2009


With the larger sequencers, I guess it is legitimate to include formats other than Eurorack as these can live outside the box.

Source and model Price

Width HP

Power ma Notes
DoepferA-155 Dual 8 Step Sequencer

            A-154 Sequence Controller







Analogue Solutions SQ8 99 18    
Future Sound Systems mini sequencer        


Doepfer A-155 Analogue/Trigger Sequencer

The A-155 is a dual 8 step analogue sequencer with 4 trigger/gate tracks in 2 rows. The sequencer has 8 CV controls with octave range switching (1V/2V/4V), adjustable glide time (portamento slew limiter), S&H control. There are pre and post glide/S&H outputs. There are 8 external inputs for the 8 steps for control signals or audio, the controls of the lower row then act as attenuators. The trigger rows have 3 position toggle switches which can be used to send a trigger/gate to the track above, below or none. The 3 trigger rows supply a short pulse for each step set, the pulse width corresponds to the pulse width of the clock/step input signal, whilst the fourth row is for gate.

 A-154 Sequence Controller

The A-154 is a supplement to the A-155 sequencer and offers many new features that are not available in the A-155. Two A-155s can be used in parallel (8 steps) or serial (16 step), both modes work with CV controlled step addressing too. For serial operation an additional VC switch (A-150) is required to switch between the CV/trigger/gates of the two A-155. In this case the VC switch is controlled by the 9-16/A4 output of the A-154. The A-154 has voltage controlled running modes forward/backwards/pendulum and random. (Loop or one shot). An internal voltage controlled clock generator with manual and CV control with attenuator is available.

These are the features of the A-154:
Several running modes: forward, backward, pendulum, random, CV controlled step adressing. All modes are available as loop or one-shot.
LED display of the 5 different current modes and one LED for loop/one-shot display
Manual and voltage controlled selection (with attenuator) of the running mode. If no external control voltage is applied one of the 10 modes (5 modes x 2 loop/one-shot) is simply selected with a rotary knob. The CV input with attenuator is used to modulate the running mode with an external control voltage (digital high/low CV to switch between two modes or continuous analog CV to sweep through different modes). With the combination of manual control and CV with attenuator it is possible e.g. to use only two neighbouring modes (e.g. forward/backward) or sweep through all possible running modes
Manual and voltage controlled selection (with attenuator) of first and last step of the sequence. The range is step 1...8 in 8 step mode resp. 1...16 in 16 step mode
If the running mode "CV Controlled Step Address" is selected the First Step section is used to determine the active sequencer step. Consequently manual and voltage controlled selection (with attenuator) of the active step is possible: the active step can be set by hand with the first step manual control and then modulated by an external control voltage (e.g. LFO, Random, S&H, Theremin, Light CV source, Joy Stick) at the first step CV input (with attenuator).

Analogue Solutions SQ8 CV / Gate Sequencer

Analogue sequencers allow you to programme a set of voltages and Trigger events (8 in this case), and allow you to step through them by using a clock signal or LFO square wave. With each step, then next voltage as set by the contol is present at the CV output. This way repeating melodic lines can be produces. The sequencer need not control pitch, it could be used to change the filter cut-off, volume, or LFO speed.

The advantage analogue sequencers have over hardware sequencers is firstly their immediacy. Having all the controls, switches and sockets in front of you allows quicker programming. Secondly, as the output is an analogue control voltage and not a digital MIDI signal, the output of analogue sequencers can easly be mixed with other voltages, or processed in some way. The SQ8 is a single channel sequencer with 8 steps. As it is single channel, larger sequencing systems can be built up by doubling up on sequencers. As they are all separate, you can clock them at different speeds or clock divide ratios. When used with our master clock module MC01 all sequencers can be reset globally from the Master Clock and they will be reset to THE LAST STEP. With just about all other sequencers, especially when using MIDI as the master clock, the sequencer must manually be stepped to the last step, otherwise when the clock is started, step 2 is in fact the first step triggered. Our automatically go to the last step eliminating this problem (see note in MC01 section for more explanation).

Clock In The SQ8 requires a +5V clock signal. Each clock signal will advance the sequencer 1 step. When the last step is reached, it resets back to the first step. Take the clock signal from a square wave LFO, Clock module or MIDI to Clock converter.
Clock Thru The clock signal appearing at the CLOCK IN socket is buffered and transferred to the CLOCK THRU socket, so it can be daisy chained to another sequencer.
Reset In A 5V signal in here will reset the sequencer to step 1.
Step 1 Out Each time step one is played, the step 1 gate socket will go high (output +5V). This socket can be used to trigger other devices, such as a cymbal sound at the start of each bar, or to trigger another sequencer. It can also be used to allow the FS01 fill in module to count bars. The step 1 out will give a clock signal that is the main clock in divided by out.
CV Out This socket will output a control voltage set by the pot for the current step. It can be changed in real time.
Gate Out This socket will output a 5V gate signal at each step where the CV control is not at the zero position (i.e. Gate on).
Step Button This allows the sequencer to be manually stepped by one step at a time whilst the clock is not running. It can also be used to reset the sequence. As with most analogue sequencers, step it to the last step (8 or whatever is patched) so that when you start the clock, the sequencer starts on position 1. Note: The step button will only work when any clock input signal is at a low state (0V). So it will note work when the clock input is high. This situation will note arise in normal use, as one would only normally use the step button when the master clock is stopped (making the clock signal low). If the sequencer is being clocked by a clock divider, even when the clock is stopped, it is possible that the clock signal may still be high until reseted.
CV / Gate pots / Range switch The CV and Gate functions are built into a single combined pot/switch. Turning the pot fully left will turn the Gate off. You will fell the switch click off.
There are 8 CV pots, 1 for each step. When the range switch is HI the range is approximately 0 to 10V, when LO the range is approximately 0-5V. LO is best for use when controlling a VCO as this gives better abillity to fine tune each step. The CV pots have a built in Gate switch. Pull the knob out to turn off the gate, push it in to turn it on.
LED Indicators There are 8 LEDs. These will light in turn to show step position.

Future Sound Systems mini sequencer

The Future Sound Systems Mini-Seq is a small, basic eight-step sequencer designed for systems which only need simple sequencing capabilities. The module is therefore physically very small (1U in MOTM/DotCom), taking up minimal space in a modular system. The module only has a clock input and two CV outputs as well as the necessary eight step controls. The sequencer also features a digital engine for clear clocking and CV output.


1  I thought I might have coined a phrase there but, of course, no. Google found 25,800 references as at 8th April 2009.