Proposed documentation for the VCV Fundamental SEQ 3 module

Currently the V2 SEQ 3 documentation shows “coming soon…”. Perhaps the following text can be used for the documentation. Or at least give a head start on creating some official documentation.

VCV Fundamental SEQ 3

SEQ 3 is an 8 step sequencer with a built in clock and 3 channels of CV output, plus gate and trigger outputs.

The TEMPO knob sets the clock rate, from 15 bpm up to 960 bpm. The default is 120 bpm.

The clock rate may be modulated by the TEMPO input and attenuator, using a 1V/Oct scale. Every positive volt of modulation doubles the clock rate, and each negative volt halves the rate. The clock may be modulated to high audio rates, or extremely low LFO rates.

Alternatively an external clock may be used by patching the clock into the CLK input. The internal clock and TEMPO modulation are ignored if the CLK input is patched.

The STEPS knob sets the number of sequence steps to a value between 1 and 8. The number of steps may be modulated via the STEPS input and attenuator. Each positive volt of modulation increments the step count by 1, and each negative volt decrements the count by 1. Partial volts are rounded up at 0.5. So 0.05V increments by 1, and -1.5V decrements by 1. The number of steps cannot be modulated below 1 or above 8. The current effective setting for the step count is output at the STEPS output as 1V per enabled step.

Each clock pulse advances the current step by one. If at the final step of the sequence, then the sequencer loops back to step 1. Each step has a Gate output that is high (10V) when the step is active, and low (0V) when inactive. A yellow LED indicates which step is active. The LED is red if the step is disabled (greater than the current STEPS count).

The run status of the sequencer may be toggled with the RUN button, or by a trigger at the RUN input. The button is white (lit) when the sequencer is running. All clock pulses are ignored if the sequencer is not running, meaning the sequencer will not advance, and there will be no clock or trigger outputs. A 1 msec trigger is generated at the RUN output every time the run status is toggled on or off.

The sequencer may be immediately reset to the first step by pressing the RESET button, or by a trigger at the RESET input. A 1 msec trigger is generated at the RESET output every time the sequencer is reset. Any clock pulse received within ~0.9 msec of a reset is ignored, meaning the sequencer will not advance to the next step.

Note that a reset does not reset the internal clock. This has a profound impact on the first step when starting or resetting - the first step will always be short unless the start or reset happens to coincide with the start of the internal clock cycle. SEQ 3 does not provide any mechanism to synchronize start or reset with the internal clock.

For every clock pulse that advances the sequencer, the LED below the CLK input blinks yellow, and a 1 msec trigger is produced at the CLK output.

Each step has a trigger button that can be enabled (lit or white) or disabled (dark or gray). A 1 msec trigger is generated at the TRIG output each time a step is entered due to a clock advance, and the step has the trigger button enabled. Note that a reset does not produce a trigger at step 1.

Also note that the TRIG output may be cut short if a reset is received after it has begun, and the step 1 trigger button is disabled.

The context menu has a “Clock passthrough” option that significantly changes the CLK and TRIG outputs.

  • The CLK and TRIG produce (pass through) the clock gates rather than 1 msec triggers. Note if using the internal clock that it uses a 50% duty cycle square wave.
  • As long as the sequencer is running, then all pulses are passed through the CLK output, even if the pulse does not advance the sequencer due to a reset.
  • If step 1 has the trigger button enabled, and there is a reset, then the clock pulse for step 1 is still passed through, even it does not trigger an advance.

By default the clock passthrough is disabled.

If driving the sequencer at audio rates >= 1000 Hz, then the clock passthrough option should be used.

There are three independent channels of CV output available that are controlled by three rows of eight knobs - 1 knob per step per channel. The top row of knobs is for channel 1 (CV1), the middle channel 2 (CV2), and the bottom row channel 3 (CV3). The CV1, CV2, and CV3 outputs generate the assigned CV of the current active step. The voltage range is -10V to 10V.

The context menu has “rotate left” and “rotate right” options that shift the CV and trigger button settings one step left or right. When rotating right, step 8 settings are “rotated” to step 1. Likewise when rotating left, step 1 settings are “rotated” to step 8.

There is always exactly one step that is active, even if the sequencer run status is off. There is no gap between any of the gates or CV outputs. So if all the step gate outputs are summed together by a summing mixer, then the result is guaranteed to be a constant 10V.

The CLK, RUN and RESET inputs are all triggered at 2V. The voltage must drop below 0.1V in order to reset and be ready for the next trigger.

If the sequencer is bypassed, then all inputs are ignored and all outputs are 0V.

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These are great, @DaveVenom !

I made some significant edits/corrections concerning CLK and TRIG outputs when Clock Passthrough is enabled.

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Added an important note about how reset does not reset the internal clock, and the impact that has.

This was a new discovery for me, and arose out of this question: I still have misconceptions about the sequencer switch, would you help me fix my flawed logic?

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