Stages segment generator is called the Modulation Construction Set. It is a brilliant design in the true spirit of modular synthesis. There is no preconception of how it should be used. Rather, it provides ways to assemble control voltages of several kinds, including familiar envelopes, LFOs, sequencers, and switches. It works by providing three different types of segment, ramp, step, and hold, and a way to group a series of segments that execute one after the other, based on simple rules. Segments can be single, or can be grouped into a series. A group is defined by the position of a patch cord into a Gate input. All stages to the right of one with a patch cord inserted into Gate that do not have a Gate patched are in the group. There can be groups of one to six segments. (Multiple modules can be chained for even longer groups.)
A Stage
The panel for each stage consists of a Gate input, a CV input, a slider, a button, a mode LED, a small pot, an output and a bipolar output LED. The voltage of the slider and CV input are added together. The button selects the segment type, as well as cycling. The function of the slider/CV and the pot depend on the segment type.
A stage defines a period of time and the manner in which the output voltage will move over that period of time. A stage can be thought of as the way it can move and what ends it.
The Segment Types
I’ve tried to make these definitions more precise than in the manual, which is worded along the lines of generating envelopes. Envelopes are only a part of what Stages can do!
Ramp segment
The output smoothly ramps from one voltage to another, and then the next segment is activated. The ramping time is controlled by the slider and the CV input. The shape of the curve is controlled by the pot. Key idea: The ramp segment ends when the ramp reaches the next voltage, which depends on next segment, and thus is dependent on both the ramp speed and the next segment.
Step segment
The output follows a target voltage until a trigger is received, and then the next segment is activated. The target voltage is controlled by the slider and the CV input. The slew rate is set by the pot. The shape of the curve is decelerating.
Hold segment
The output rapidly follows a target voltage for an adjustable duration, and then the next segment is activated. The target voltage is controlled by the slider and the CV input. The duration of the segment is set by the pot.
There are two differences between a Step and a Hold segment. Step can slew; Hold cannot. Step ends on receipt of a trigger; Hold ends after a specified length of time. Other than that, they are both voltage followers. Step means ‘step to next segment on a trigger.’ Hold means ‘hold this segment until a timeout.’ The target voltage can be moving, such as an LFO. It does not have to be fixed. It can go into negative voltages. Step does not have to mean steps in the output voltage and hold does not have to mean holding a fixed voltage.
Grouping/Triggering/Cycling
A group can be comprised of any number of segments of any type. This means that there are logically 729 different types of sequences six segments long. (((((3 * 3) * 3) * 3) * 3) * 3) Each segment can be cycling by itself, or any subgroup of contiguous segments can be cycling. (Some combinations don’t make logical sense, and Stages prevents these.) That is just the 6-segment sequences! So it’s easy to see why the manual defines the behavior of single segments and then gives some common examples.
If not cycling, a group is kicked off by detection of a positive transition on the Gate input that crosses the 1 volt boundary. This is called a trigger. Pulses are typically used. Once started, a group runs to completion, subject to the rules. However, the length of time the gate stays high, as well as the occurrence of subsequent triggers before the sequence finishes, impact the result.
The Investigation
To get a handle on the possibilities I set myself the task to look at all of the two-segment groups, nine in all. And for each of these, look at the behavior without cycling, with the first segment cycling, the second cycling, and the group cycling. The main output of a group comes from the first segment output jack. I observed the second segment output, too, but haven’t mentioned it very much.
Ramp-Ramp
Not cycling
AD generator with CV up and down times and separately adjustable up and down slopes. Decay begins when output reaches 8 volts. A new trigger received at any point before the end of decay restarts the attack from point the voltage is at. Gate held high is ignored.
Segment 1 cycling
The attack repeats from 0 volts while gate is high, then decay begins. Decay starts down from whatever level the output is at when the gate falls.
Segment 2 cycling
Attack is the same as without cycling. Decay begins when output reaches 8 volts. But if decay completes before receipt of another trigger, the decay segment cycles with fast attacks. On receipt of the next trigger, the attack phase starts again from the point the voltage is at.
Group cycling
Cycles 0 to 8 volts, through attack and decay, while gate is held low. A trigger received at any point restarts the attack from the point the voltage is at.
Ramp-Step
Ramp-Step needs a moving CV input, such as an LFO, on the Step segment to be useful.
Not cycling
The output follows the CV on the step segment (with manual slew). When triggered, the output imparts an inverted envelope, like a VCA, using the time and shape settings of the ramp segment.
Segment 1 cycling
Every other trigger switches between the slewed CV and the slewed CV enveloped inversely by the ramp. The second segment output is the gate divided by two.
Segment 2 cycling
Acts like a single step segment, i.e. a slewed sample & hold, but taken from the group out.
Group cycling
Similar to Segment 1 cycling here, except that starts the enveloped CV on every trigger.
Ramp-Hold
Ramp-Hold seems to work almost identically to Ramp-Step, except that the segment 2 output behaves differently.
Step-Ramp
Not cycling
A very useful Attack-Sustain-Release envelope in two phases, with a CV-able sustain level. The first trigger initiates the step segment, which slews to the target voltage at the rate set by the pot. Output sustains at the target level until the next trigger starts the release, with variable shape and CV time. Patching an LFO to either CV input produces interesting results. Another trigger before target voltage reached caused a rapid spike to 8 volts to begin the release. Another trigger during release starts the Step segment over from the point the voltage is at.
Segment 1 cycling
Like a single step segment, i.e. sample & hold.
Segment 2 cycling
Similar to not cycling, except that if release finishes before the next trigger, the release cycles with fast attacks until a trigger is received.
Group cycling
Follows step target voltage until the next trigger starts the release. At end of release the step segment begins again.
Step-Step
Not cycling
A two step sequence with manual slewing, or a CV switch. On receipt of a trigger moves to/follows next segment target voltage. Easily generalizes to more than two segments.
Segment 1 cycling
Like a single Step segment, i.e. sample & hold.
Segment 2 cycling
Like a single Step segment, i.e. sample & hold, except that the CV sampled from segment 2 comes out of segment 1.
Group cycling
Exactly the same as no cycling.
Step-Hold
Not cycling
Similar to Step-Step, except that the second segment has no slewing. The next trigger ends the segment. The hold time pot has no effect.
Segment 1 cycling
Like a single Step segment, i.e. sample & hold.
Segment 2 cycling
Same as not cycling.
Group cycling
A two step sequence or switch, but in this case the Hold segment respects the value of the time pot. If a trigger is received before the time set by the pot elapses, the Hold segment restarts and never ends.
Hold-Ramp
Not cycling
A Sustain-Release envelope that starts when triggered. The output follows the hold value for the length of time set by the pot and then the release starts down from the point the voltage is at. If a trigger arrives before the hold time is elapsed, the hold time is reset, preventing movement to the release. A trigger arriving during release starts the hold stage over, i.e. the output does not reach zero volts.
Segment 1 cycling
On a gate, first segment follows the hold value, but for as long as the gate is high, not respecting the time pot. The falling gate triggers the release, which starts from the point the voltage is at. If the release has not fallen to zero at the start of the next gate, the hold segment still starts.
Segment 2 cycling
Same as not cycling, except the release cycles with fast attacks until the arrival of the next gate.
Group cycling
With gate held steady (high or low), cycles between hold segment and release segments. Triggers arriving faster than the cycle time cause the cycle to start over, resulting in the output not falling to zero before starting over.
Hold-Step
Not cycling
On a trigger, the output follows the hold value for the length of time set by the pot and then the step stage starts from the point the voltage is at and follows the step voltage until a trigger is received. If a trigger arrives before the hold time is elapsed, the hold time is reset, preventing movement to the step stage.
Segment 1 cycling
On a gate, first segment follows the hold value, but for as long as the gate is high, not respecting the time pot. The falling gate triggers the step stage, which starts from the point the voltage is at. The hold segment starts again on receipt of the next trigger.
Segment 2 cycling
Like a single Step segment, i.e. sample & hold, except that the CV sampled from segment 2 comes out of segment 1. The hold stage is never engaged.
Group cycling
A two-step sequence/switch in which the duration of the first segment is set by the hold time pot and the second segment slews and is ended by the next trigger, starting the cycle over. If a trigger arrives before the hold time is elapsed, the hold time is reset, preventing movement to the step stage.
Hold-Hold
Not cycling
On a gate, the output follows the first segment voltage for the length of time set by the pot and then the second hold stage starts from the point the voltage is at and follows that segment voltage until a trigger is received. The second hold stage time pot is ignored. If a trigger arrives before the first hold time is elapsed, the hold time is reset, preventing movement to the second stage.
Segment 1 cycling
A two-step sequence/switch without slewing, controlled by the width of the gate. On a gate, first segment follows the hold value for as long as the gate is high, not respecting the time pot. When the gate falls, the second segment voltage is followed until the gate rises again, starting the cycle over. Neither time pot has any effect.
Segment 2 cycling
Same as not cycling, except that the second stage output is different.
Group cycling
A two-step sequence/switch without slewing, controlled by time pots. With gate held steady (high or low), the first segment follows the stage voltage for the time set by the pot, then the second segment follows its stage voltage for the time set by its pot. A trigger resets to the start of the first stage.
Conclusion
I’ve gained a detailed understanding through this investigation of how two-segment groups work. This will surely generalize to longer groups. I will look to the Step and Hold segments more generally for use as sequential switches, which is how I see the real power of Stages.
Really interesting method of approach. Enjoyable. Kind regards.