T's Musical Tools

A collection of esoteric VCV Rack modules.

Many are focused around seedable RNG, and/or routing polyphonic signals in useful ways such as shuffling, sorting, joining, or selecting subsets of them.

Spellbook is a sequencer which uses a plaintext, "tracker like" notation, specifically created for a modular environment, and designed to be easily written, edited, and copy & pasted.

Mostly these modules are useful for routing signals and/or working with control voltages, as opposed to generating audio, but most do have the option to run at audio rate if they normally don't (for mad science purposes).

Where to Get It:

• Download from the VCV Rack Library plugin page (recommended)
• Or, check Releases to install the latest release or to install the latest preview

The Modules

The modules might look a little intimidating, because there no knobs in these modules, only jacks. Everything is controlled via CV inputs. But don't worry, they're all very small, focused modules that will make sense once you use them.

• Calendar - Output LFO-like signals, synced to the local time and day based on your computer's clock. Creates rising sawtooths synced with seconds, minutes, hours, days, through to years. Loosely inspired by Aria Salvatrice's "Arcane" module (try sampling Calendar as your RNG seed source!)
• Sight - A scope where time slows down over the width of the scope, letting you see a signal over different time scales simultaneously.
• Seed - Get 16 random numbers, with an option to provide an RNG seed.
• Ouroboros - Step through the channels of a polyphonic signal as a sequence.
• Shuffle - Randomly re-order the channels of a polyphonic signal, with an option to provide an RNG seed.
• Sort - Sort and select channels from a polyphonic cable using other polyphonic CV inputs, inspired by the spreadsheet functions RANK() and FILTER().
• Stats - Get statistical measures like mean, median, mode, product, etc. of the channels of a polyphonic signal, inspired by the spreadsheet functions AVERAGE(), MEDIAN(), MODE(), GEOMEAN(), PRODUCT(), SUM(), and UNIQUE().
• Append - Combine the channels of up to 16 mono or polyphonic cables (i.e. append the multiple lists together into one big list; up to a total internal buffer of 256 channels), then output a 1 to 16 channel subset of them, with CV controls for width and starting point.
• Spine - A few useful, static, CV operations for offsets, inverse, and reverse.
• Spellbook - Plain text "musical markup" sequencing of CVs/pitches, with a broad variety of accepted formats for however you want to write your sequences; such as pitch names, MIDI note numbers, semitones, Hertz, etc. Write out sequences in rows and columns like a spreadsheet!

Getting Started

Mostly these fall into four big camps, with lots of overlap:

• creating or getting "interesting" control voltages
• routing polyphonic signals and control voltages through your patch in complex ways
• seedable randomization
• Spellbook

Whenever RNG is used, there's always an input for the RNG seed for repeatabilty, which is often musically useful.

None of them generate audio, unless you use them wrong like a modular synth player. (Try Indexing Spellbook with an oscillator instead of a phasor!)

You'll want to jump into these with a good understanding of how polyphonic cables work in VCV Rack, especially the built-in Merge and Split modules, and have ready your prefered methods of generating and/or sampling & holding specific voltages.

This plugin pairs well with computerscare modules (which also play a lot of polyphony and random generation), SIM modules (the Coerce module lets you quantize to a polyphonic signal, which opens up a lot of fun ways to dynamically generate what you're quantizing to), and HetrickCV's Phasors (Spellbook's Index feature works well with phasor inputs), and in general any modules which like to handle polyphonic cables and/or have CV controlled parameters. Check out stoermelder for modules which let you control anything in VCV Rack with CV, even when there's not a CV input jack implemented.

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Calendar

Calendar generates a set of very slow LFO-like signals representing the progress through various time/calendar units. The current time and date is based on your system clock and local timezone, or you can toggle to the UTC timezone. The module outputs voltages ranging from 0 to 10v, where each voltage corresponds to the current "progress" through the respective time unit, a "stepped" or "stochastic" version of the ramps where they are rounded to the nearest subdivision, as well as some triggers and gates.

• Ramps, triggers, and gates for seconds, minutes, hours, days, weeks, months, seasons, and years
• Voltages range from 0 to 10v
• Alt Mode: Use UTC time instead of Local time.

Loosely inspired by Aria Salvatrice's "Arcane" module, which gave a new random set of pitches and rhythms each day, and gave everyone everywhere the same set each day, so you could all share this same source of RNG and inspiration in many diverse patches. Making patches with Arcane made me imagine patches which sync up to the days and seasons, which led to Calendar, which was both my first module made for this plugin and my first ever C++ project.

Inputs

• No CV inputs, but in the background it reads the system time.
• The yellow glyph at the top of the module can be clicked to switch to alt mode, which gets the system UTC time instead of local time.

Outputs

Each time unit has a row of five outputs:

1. Linear Ramp: A smooth, continuous voltage ranging from 0 to 10v, representing the progress through the time unit.
2. Stepped Ramp: A stepped version of the smooth output, dividing the progress into equal intervals based on how that time unit is traditionally subdivided:
   • Second: 4 steps
   • Minute: 60 steps (seconds)
   • Hour: 60 steps (minutes)
   • Day: 24 steps (hours)
   • Week: 7 steps (days)
   • Month: 4 steps (weeks)
   • Season: 3 steps (months)
   • Year: 12 steps (months)
3. Trigger: Sends a 10v trigger signal for 1ms at the beginning of each time unit cycle.
4. Gate: Outputs 10v for the first half of the time unit cycle and 0v for the second half.
5. Inverse Gate: The opposite of the Gate output, 0v for the first half and 10v for the second half of the cycle.

Guide

Calendar offers a unique way to sync your patches with real-world time. It's like having LFOs that align with the passage of time on your computer's clock. Here's how to use it:

1. Connect any of the outputs to CV inputs on other modules. For example, you could use the Day Linear Ramp to slowly modulate a filter over the course of a day.

2. Use the Trigger or Gate outputs to affect or trigger events at the start of each time unit. Maybe a new section starts every minute?

3. Click the toggle switch at the top of the module to switch between local time (default) and UTC. This can be useful for synchronizing patches across different time zones.

Calendar updates in real-time based on your computer's clock, so it's perfect for long-running, evolving patches or installations that change over extended periods.

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Sight

Sight is a logarithmic oscilloscope for visualizing voltage signals in VCV Rack. Unlike traditional scopes, Sight displays time non-linearly across its horizontal axis, allowing you to observe both rapid changes and slower movements simultaneously.

• Non-linear time display: The rightmost edge shows the most recent sample, with time stretching logarithmically towards the left.
• Voltage range: Displays signals from -10v to +10v vertically.
• Variable update rate: Toggle between a default 1kHz refresh rate and full audio rate processing.

Inputs

• Voltage Input: Connect any voltage source to this input to display its waveform on the scope.
• The yellow glyph at the top of the module can be clicked to switch to alt mode. By default, Sight updates at 1kHz. Toggle this to process at audio rate (CPU intensive).

Outputs

• No CV outputs; visual only.

Behavior

1. The scope continuously samples the input voltage, storing 8192 samples in a circular buffer.

2. The display maps these samples across the width of the scope:

   • The rightmost pixel represents the most recent sample.
   • Each pixel to the left represents an exponentially increasing time span.
   • The leftmost pixel shows the oldest sample.

3. They aren't placed uniformly; the logarithmic time scale means the horizontal axis is warped:

   • Recent changes appear more spread out on the right side.
   • Older signal history is compressed towards the left side.
   • It's sort of like the zoom level is different at each point along the timeline, so you see all zoom levels simultaneously.

• Faster patterns in the signal will be easier to see on the right.
• Slower changes or overall trends become apparent towards the left.

Guide

1. Connect any voltage source to the input.

2. Observe the unique perspective on your signal:

   • Instantaneous changes
   • Short-term patterns
   • Long-term voltage trends

3. Toggle the "Alt Mode" switch for audio-rate processing if needed, but be aware this is more CPU intensive.

Sight is particularly useful for visualizing complex modulation sources, envelopes with long release times, or signals with both fast and slow components. It provides a unique view of your patch's voltage behavior over multiple time scales simultaneously.

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Seed

Seed is a static random voltage generator with 16 individual outputs and a polyphonic output. It generates the values based on the input voltage, which is used as a seed for the random number generator, so you can return to the same seed/pattern if desired, or you can supply a randomly generated voltage for a totally random pattern.

• 16 individual random voltage outputs
• Polyphonic output with 16 channels
• Seed-based random voltage generation
• Alt Mode: Snap outputs to 0v or 10v (useful for generating gate patterns)

Inputs

• Seed Input: Voltage used as the seed for random number generation. If no input is connected, a random seed is used.

Outputs

• Poly Out: Polyphonic output with 16 channels containing the generated random voltages.
• Out 1 - Out 16: Individual outputs for each of the 16 random voltages generated.
• The yellow glyph at the top of the module can be clicked to switch to alt mode. By default, outputs are uniformly random between 0v to 10v, in alt mode they are snapped to either 0v or 10v.

Behavior

1. The module reads the voltage from the Seed input (or uses a random value if unconnected).
2. It uses this seed to initialize a random number generator.
3. The generator produces 16 random voltages between 0v and 10v.
4. These voltages are output individually and as a polyphonic signal.

Guide

Seed is designed for creating reproducible randomness in your patches:

1. Basic Usage: Leave the Seed input unconnected, and it boots up with a randomly generated seed, giving you 16 static random voltages, each between 0 to 10.
2. Controlled Randomness: Connect a stable voltage to the Seed input to get a consistent set of random voltages. Connecting or changing this voltage will produce a new set of random values. Going back to the same voltage, generates the same values.
3. Evolving Patterns: Use an LFO or sequencer to modulate the Seed input for evolving random patterns.
4. Gate Generation: Enable Alt Mode to turn Seed into a random gate generator, outputting only 0v or 10v.
5. Sequence the Seed: If you send a sequence of seed values, you'll get a series of "random patterns" that loops back around and does the same random patterns again, making it a breeze to incorporate random but intentional-feeling modulations to your patches.
6. Correlate Modulations: Connect a Seed to an existing CV somewhere in your patch, and you get 16 new CVs that change along with that CV, in surprising but consistent ways. For example, maybe your effects all get modulated differently for each note in your melody, but it's always the same for the same note.

Click the toggle switch at the top of the module to activate Alt Mode. In this mode, instead of outputting voltages across the full 0-10v range, Seed will round each output to 0v or 10v, effectively turning it into a random gate generator.

Seed is perfect for adding controlled randomness to your patches. Use it to generate random pitches, modulation sources, or even random rhythmic patterns when in Alt Mode. The ability to control randomness via the seed input allows for repeatable "random" sequences, which can be crucial for composing with randomness or creating generative patches that can be recreated. I like AS Triggers MkI for a quick way to set a specific voltage that gets saved with the patch when it closes, and which can be randomized with Ctrl+R.

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Ouroboros

Ouroboros steps through the channels of a polyphonic signal, essentially turning it into a monophonic sequence. It's designed to work seamlessly with other modules in the plugin and VCV Rack's polyphonic cables. That does let you use it like an arpeggiator, however it's generalized for use with any polyphonic signal, like control voltages, or you could even step through audio channels.

Ouroboros shines in complex patches where you need to create sequences from static polyphonic sources or cycle through multiple modulation options. It's especially powerful when combined with other modules in the TMT collection, allowing for creative sequencing and routing strategies.

• Converts a polyphonic input into a stepped monophonic sequence
• CV-controlled sequence length
• Reset and Clock inputs, behaves pretty much like any normal sequencer
• Alt Mode: Outputs the average of current and next step voltages

Inputs

• Poly Sequence Input: The main polyphonic input to be sequenced.
• Trigger Input: Advances to the next step on each rising edge.
• Reset Input: Resets the sequence to the first step. Uses Grids-style logic: if Clock is low, it arms the Reset for the next Clock; if Clock is high, it resets immediately.
• Length Input: Controls the active sequence length (0v: one step, 10v: all steps).

Outputs

• Mono Sequence Output: The resulting monophonic sequence output.
• The yellow glyph at the top of the module can be clicked to switch to alt mode.

Behavior

1. Ouroboros reads the voltages from each channel of the polyphonic input.
2. On each trigger pulse, it advances to the next channel.
3. The current channel's voltage (or rolling average, in Alt Mode) is sent to the output.
4. When it reaches the end (determined by the Length input), it loops back to the beginning.

Click the toggle switch at the top of the module to activate Alt Mode. In this mode, instead of outputting just the current step's voltage, Ouroboros outputs the average of the current and next step voltages. (Note: this is not a "slew" or "glide", rather the output is a static blend of two consecutive channels).

• The Length input scales from 1 to the number of connected input channels: 10v roughly means "include all", 5v means "include half", 0v means "include 1".
• In Alt Mode, the output is the mean of two consecutive channels (current and next).
  • The mean of two audio signals essentially mixes them.
  • The mean of two control voltages gives you a control voltage halfway between them.

Guide

Ouroboros is versatile for creating sequences from polyphonic sources:

1. Basic Sequencing: Connect a polyphonic chord or set of CVs to turn them into a stepped sequence.
2. Random Patterns: Use with Seed and Shuffle to generate evolving random sequences.
3. Chord Arpeggiation: Input a polyphonic chord to create arpeggios.
4. CV Sequencing: Cycle through multiple modulation sources.

Ouroboros adapts to changes in your patch. If you add or remove channels from the polyphonic input, or adjust the Length input, Ouroboros will automatically adjust its sequence length.

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Shuffle

Shuffle is a module that reorders the channels of an incoming polyphonic signal, outputting a newly arranged polyphonic signal. It offers control over the number of output channels and provides a trigger input to initiate the shuffle process.

• Polyphonic input and output (up to 16 channels)
• Deterministic shuffling of the channels based on a seed input
• CV control over the number of output channels
• Trigger input to initiate shuffle
• Continuous passthrough of the input channels while maintaining the current shuffle order
• Alt Mode: Allows for potential multiple selections of input channels in the output

Inputs

• Trigger Input: Initiates a new shuffle of the polyphonic voltages when a rising edge is detected.
• Polyphonic Input: The main input for the signals to be shuffled. Accepts up to 16 channels. If no cable is connected, a default one-octave chromatic scale is used.
• Seed Input: Provides a random seed for the shuffle. The same seed always produces the same shuffle order. If unconnected, a new random seed is generated for each trigger.
• Output Channels Input: Controls the number of active output channels. 0v outputs one channel, 5V outputs half the input channels, and 10v outputs all input channels. If unconnected, all input channels are used.
• The yellow glyph at the top of the module can be clicked to switch to alt mode.

Outputs

• Polyphonic Output: The reordered channels based on the current shuffle.

Behavior

1. On receiving a trigger, Shuffle reorders its internal list representing the channel order.
2. If a seed input is connected, it uses this voltage to seed its random number generator, ensuring reproducible results for the same seed.
3. In default mode, it performs a true "shuffle" - each input channel appears exactly once in the output.
4. In Alt Mode (activated by the toggle switch), each output channel is independently randomized, allowing for potential duplicates or omissions of input channels.
5. The number of output channels is determined by the Output Channels input, or defaults to the number of input channels if not connected. Like Ouroboros, the Channels input scales from 1 to the number of connected input channels: 10v means "include all", 5v roughly means "include half", 0v means "include 1".
6. Between triggers, the module continuously passes through input voltages in the current shuffled order, allowing for dynamic input changes while maintaining the shuffle pattern, allowing routing of audio signals.

Guide

Shuffle is versatile for adding controlled randomness to your patches:

1. Basic Usage: Connect a polyphonic signal to shuffle its channels. Trigger a new shuffle as needed.
2. Controlled Randomness: Use a stable voltage at the seed input for repeatable randomization. Change this voltage for new, but still deterministic, patterns.
3. Variable Output: Modulate the Output Channels input to dynamically change the number of active outputs.
4. Random Routing: Shuffle CV or audio signals to randomly route them. or you could randomly pick one by sending 0v to 'Output Channels' to just get one channel at random.
5. Alt Mode Experimentation: Enable Alt Mode for more chaotic results, potentially duplicating or omitting input channels in the output.
6. Generate Scales: Because the default input is a chromatic scale, if you send 5v to 'Output Channels' you'll pick half (7) of them, creating a random scale. Select half of those with another Shuffle to generate chords!

Shuffle shines in generative patches, for creating evolving textures, or for adding an element of controlled unpredictability to your modular system. Try using it to reorder chord voicings, reassign signal routings, or create variations in sequenced patterns.

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Append

Append was designed to combine multiple polyphonic cables into a single polyphonic output. Unlike Merge, it accepts polyphonic inputs (each of which might have up to 16 channels), allowing for flexible signal routing and manipulation. This primarily gives you a way to combine two or more polyphonic signals into one, without having to Split and then Merge them, which would have led to having to worry about the number of channels changing.

Append is perfect for complex patches where you need to combine, select, or dynamically route multiple polyphonic signals. It's especially powerful when combined with other modules that create varied and changing polyphonic signals (like Aaron Static's ChordCV), allowing for creative signal manipulation and routing strategies.

This is not a mixer! The channels are "joined", not mixed, as if combined into up to 256 polyphonic channels. Sadly, the output can't actually give you all 256 channels at once (VCV Rack only supports up to 16 channels per cable), so you have some some controls for which subset of channels you get, if needed.

• Combines up to 16 input signals (mono or polyphonic) into an internal buffer of up to 256 channels (16 inputs, up to 16 channels per input)
• Outputs a customizable subset of the internal buffer as a polyphonic cable
• CV control over output "width" (number of channels to output) and "rotation" (which input channel to start counting from)
• Handles dynamic changes in the number of channels in each input, without re-patching cables

Inputs

• Signal 1-16 Inputs: Connect up to 16 mono or polyphonic input signals.
• Width Input: CV input to set the output width (number of channels). 0v = 1 channel, 10v = maximum allowed channels (up to 16).
• Rotation Input: CV input to set the output starting point. 0v = start from the first channel, 10v = start from the last channel.
• The yellow glyph at the top of the module can be clicked to switch to alt mode.

Outputs

• Poly Out: Polyphonic output containing the selected subset of voltages from the input signals.

Behavior

1. Append collects all channels from all connected input signals into a single internal buffer.
2. The Width input determines how many of channels will be included in the output (1 to 16).
3. The Rotation input sets the starting point within the buffer for the output channels.
4. The module outputs the selected subset of voltages as a polyphonic signal.

• Internal buffer can hold up to 256 channels total (up to 16 inputs of 16 channels each).
• If no inputs are connected, the output will provide a number of 0v channels based on the Width input.
• Width and Rotation inputs are clamped between 0v and 10v for predictable behavior.
• The module efficiently handles varying numbers of input channels and dynamically adjusts the output.

Guide

Append is versatile for signal routing and manipulation:

1. Combining Signals: Use it to merge multiple separate signals (mono or poly) into a single polyphonic cable.
2. Dynamic Subset Selection: The Width and Rotation inputs allow you to "window" into different parts of the internal buffer.
3. Polyphonic Sequencing: By modulating the Rotation input, you could create interesting sequences from static input voltages.
4. Flexible Routing: Great for patches where you need to dynamically reroute or recombine signals.

Remember, Append adapts to changes in your patch. If you add or remove input cables, or if the number of channels in polyphonic inputs changes, Append will automatically adjust its internal buffer, skipping empty jacks and adding or removing channels.

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Sort

Sort manipulates and passes through a polyphonic signal from the first input, using a sorting pattern specified by another polyphonic signal in the second input, and selectively includes/excludes (not mutes!) the channels based on a polyphonic gate/boolean pattern in the third input.

Inputs

• Toggle Audio Rate: By default, Sort recalculates every 10ms, which is plenty for most CV needs. Toggle the yellow glyph at the top of the module to run at audio rate, which is pretty CPU heavy, but lets you process audio signals if you want.
• Data Input: Polyphonic signal containing the data to be sorted.
• Sort Input: Polyphonic signal that determines the order of sorting for the Data input.
  • If you hook up the random poly output from Seed to the Sort Key, that's equivalent to the Shuffle module, so you could think of Sort like a generalized, manually-controlled Shuffle.
• Select Input: Polyphonic signal that determines which channels of the Data input are included in the output, based on a threshold voltage (e.g., channels with voltages above 5V are included). This doesn't just mute the channels, it removes them entirely.

Outputs

• Passthru Output: Outputs the Data input as is, without any sorting or selection.
• Sorted Output: Outputs the Data input sorted according to the Sort input.
• Selected Output: Outputs only the channels of the Data input that meet the threshold criteria set by the Select input.
• Sorted and Selected Output: First sorts the Data input as per the Sort input, then applies the selection criteria from the Select input.
• Selected and Sorted Output: First applies the selection criteria from the Select input to the Data input, then sorts the resulting channels as per the Sort input.
• Ascending Output: Outputs the channels of the Data input sorted in ascending order based on their own values.
• Descending Output: Outputs the channels of the Data input sorted in descending order based on their own values.

Guide

This module offers unique ways to manipulate polyphonic cables that go beyond typical VCV Rack operations.

In VCV Rack, polyphonic cables carry multiple voltages at once. Usually, we might combine or separate these voltages, but Sort allows us to reorganize them in ways you might not have considered before.

Sort lets you "sort" (rearrange or reorder) and "select" (choose which voltages to include or exclude) a polyphonic cable, using other polyphonic CVs. This is basically spreadsheet RANK() and FILTER() functions. Or you might prefer to imagine a hypothetical RANKIFS() function- that's this module.

The module has three main inputs:

1. The "Data Input" - your main polyphonic input, carrying the voltages you want to manipulate.
2. The "Sort Key" - another polyphonic input which determines how to reorder the voltages from your Data Input.
3. The "Select Key" - a third polyphonic input that lets you choose which voltages from your Data Input to include or exclude.

Think of your "data" input as being like a "column of signals", the sort key becomes a "rank" for each channel in column 2, the select key becomes a boolean true/false pattern in column 3, and this module gives you spreadsheet style sorting & filtering of that 3-column table.

Sort then provides several outputs, each offering a different way to reorganize or choose from your original voltages:

1. "Passthru" gives you your original voltages, unchanged, unsorted, just for convenience.
2. "Sorted" reorders the voltages based on the Sort Key. The idea is, in the Sort input, you have a matching set of polyphonic channels, and you put the lowest voltage in whichever channel you want to be first, then the second lowest in the channel you want to become second, and so on, and the "data" channels will be sorted in that order. By carefully constructing the sort key, you can re-order the data channels in any desired order, regardless of what's going on with the data signals themselves.
3. "Selected" passes through only specific channels, based on the Select Key. The matching Select Key voltage for each channel in the data has to be 5v or greater, otherwise that channel get excluded. Importantly, the channel is not muted, but rather the entire channel is not even included in the channels of output cable at all.
4. "Sorted and Selected" first reorders, then chooses from your voltages.
5. "Selected and Sorted" first chooses, then reorders your voltages. These are both available because the order of operations often matters to the result.
6. "Ascending" and "Descending" simply order your voltages from lowest to highest or highest to lowest, ignoring the Sort and Select keys. These are just here because it would feel weird for a module named "Sort" to not have them.

Example:

These inputs:

Data	Sort	Select
x	2v	10v
y	3v	0v
z	1v	10v

Would output:

Output
z
x

The rows get sorted by whatever is in the column 2 sort key, and any rows that have a 0v (false) in the select key get removed, and you have your new sorted and filtered data set.

The signal does pass through at audio rate, so you can use this to route audio signals, but by default it will only recalculate the order/selection every 10ms; switch to Alt Mode if you also need audio rate recalculation.

Remember, Sort isn't altering the individual voltages themselves, but rather changing their order and selectively including them. This could route signals like Shuffle, but instead of only random ordering, you can specify any possible order and subset you want. In fact, if you hook up random voltages to the Sort input, Sort is identical to Shuffle.

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Stats

Stats is a statistical function module. It computes and outputs various statistical metrics from the signals of a polyphonic input cable. You might find this surprisingly easy to understand the outputs, because control voltages end up encoding essentially all of the important information about your patch as simple-to-interpret numbers like "pitch" or "cutoff" (i.e. whatever you're using those voltages for), but it might have some applications for audio signals as well.

Inputs

• Toggle Audio Rate: By default, Stats recalculates every 10ms, which is plenty for most CV needs. Toggle this to run at audio rate, which is pretty CPU heavy, but lets you process audio signals if you want.
• Polyphonic Input: Receives the polyphonic signals to analyze.
• The yellow glyph at the top of the module can be clicked to switch to alt mode.

Outputs

• Mean Output: Outputs the average voltage of the input signals.
• Median Output: Outputs the median voltage.
• Mode Output: Outputs the most frequent voltage(s) as a polyphonic signals.
  • If multiple modes are found, it lists all of them as a polyphonic signal.
  • If no modes are found, outputs 0.
• Geometric Mean Output: Outputs the geometric mean of the input voltages.
• Product Output: Outputs the product of all input voltages.
  • ! This can output extremely large, out-of-spec voltages (e.g. quickly rises to millions of volts).
• Count Output: Outputs the number of polyphonic channels in the input as an integer voltage.
  • ! The output range can exceed 10v, because counts can go from 0v to 16v.
• Sum Output: Outputs the sum of all input voltages.
• Ascending Output: Outputs the input voltages sorted in ascending order.
• Distinct Output: Outputs one of each distinct voltage from the input, ignoring very close values (+/- 0.0001v) as not distinct.

! In VCV Rack, many modules might simply ignore voltages outside -10/+10, but there are no guarantees what any given module will do with non-standard voltages.

Guide

Stats takes all the voltages from a polyphonic cable and crunches the numbers, giving you a bunch of different statistical outputs. It's like having a couple spreadsheet formulas in your rack.

First, you've got your basic statistical measures. The Mean output gives you the average of all the voltages. Median gives you the middle value. And Mode is the most common voltage, or voltages (as polyphonic channels) if there are ties.

The Geometric Mean output is like a special kind of average that's great for working with frequencies or exponential changes.

The Product output multiplies all the voltages together - but watch out, this one can get crazy high really fast!

• GeoMean and Product both break if ANY (even one) of the inputs channels are 0, because they involve multiplication, so be wary of that; VCV Rack patches end up having 0v signals all over the place- low gates, middle C, etc.

The Count output tells you how many polyphonic channels are in your input. This is super useful for generative patches where the number of signals in a cable could itself be used as a modulation source.

The Sum output adds up all the voltages.

The Ascending output sorts all the input voltages from lowest to highest. This one is only here because there was space for an extra jack, but it is often something you'll end up wanting from a polyphonic signal anyway.

And if you want to find unique values, the Distinct output has got you covered- duplicate voltages get excluded from the output. This one is actually the reason the module exists- you can use this to remove duplicate pitches from a generated chord, or anywhere else where you need a set of voltages that are all distinct from each other.

It's one of those modules that might not seem essential at first glance, but once you start experimenting with it, you'll find all sorts of creative uses.

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Spine

Spine is a utility module that provides a set of common voltage offsets and transformations for an input signal. It's designed to be a quick and easy way to adjust or manipulate voltages in your patch. Or, if you leave the input disconnected so x=0, the outputs are basically just a set of constant voltage sources: 0, 1, -1, 5, -5, 10, and -10. These are useful for a lot of the CV inputs of other modules in this set, and many others.

• Polyphonic processing (up to 16 channels)
• Various voltage offsets and transformations
• Alt Mode: Process at audio rate instead of every 10ms
  • Not a very CPU intense module compared to some of the siller modules in this set, but it's not particularly hyper-optimized either, and sometimes that extra performance helps

Inputs

• X Input: The main input signal to be transformed. If disconnected, X is 0.
• The yellow glyph at the top of the module can be clicked to switch to alt mode.

Outputs

• Zero Output: Passes through the input signal unchanged X + 0v
• Add 1V Output: Adds 1 volt to the input signal X + 1v
• Sub 1V Output: Subtracts 1 volt from the input signal X - 1v
• Add 5V Output: Adds 5 volts to the input signal X + 5v
• Sub 5V Output: Subtracts 5 volts from the input signal X - 5v
• Add 10V Output: Adds 10 volts to the input signal X + 10v
• Sub 10V Output: Subtracts 10 volts from the input signal X - 10v
• Inverse Output: Inverts the polarity of the input signal X * -1
• Reverse Output: Reverses the voltage range 10v - X

Behavior

1. Spine reads the voltage(s) from the X input.
2. It applies the various transformations to each channel of the input signal.
3. The transformed voltages are sent to the corresponding outputs.
4. All outputs maintain the same number of polyphonic channels as the input.

Guide

Spine is versatile for quick voltage adjustments:

1. Offsets: Use the Add and Sub outputs to shift your voltages up or down by common amounts, or use an empty Spine for a few useful constants.
2. Inversion: The Inverse output flips the sign of your voltage, useful for creating inverse modulations.
3. Reversal: The Reverse output can be used to create "backwards" or "upside down" CV ranges, where 0v becomes 10v and vice versa. If you use it with a 0 to 10 input voltage, this would be the same as inverting and adding 10: you still have a 0 to 10 voltage (not 0 to -10), but now it's "upside down" or "backwards" (depending on what you're using it for).

Remember, Spine processes polyphonic signals, so you can transform entire chords or complex CV setups at once.

Click the toggle switch at the top of the module to activate Alt Mode. In this mode, Spine processes at audio rate instead of every 10ms. This allows for audio-rate modulations and can be used for creative sound design, but is more CPU intensive.

Spine is perfect for patches where you frequently need to adjust voltage levels or create variations of a control signal. It's especially useful in complex patches where you need quick access to common voltage transformations without adding multiple utility modules.

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Spellbook

Spellbook is a module for VCV Rack to sequence pitch and control voltage (CV) patterns in a eurorack-style environment using the plain text RhythML syntax. It has 16 outputs, each of which outputs a voltage controlled by the corresponding column in RhythML-formatted text input.

Inputs

• Step Forward: Advances to the next step in the sequence on the rising edge of a trigger.

• Step Backward: Advances to the prior step in the sequence on the rising edge of a trigger.

• Reset Input: Resets the sequence to the first step on the rising edge of the input signal.

• Index Input: Set the current step to a specific index, where 0v is the first step through to 10v for the last step, like a phasor controlling a "play head".

• Index Mode Toggle: Toggle the yellow glyph to switch to "absolute address" mode, where 1v is step one, 2v is step two, etc.

Outputs

• Poly Out: Outputs all columns as channels of a polyphonic cable, for convenience.
• Out 1 thru Out 16: Individual outputs for the first 16 columns specified in the RhythML sequence.
• Relative Index Out: Outputs the current step as 0v = step 1, through to 10v = last step.
• Absolute Index Out: Outputs the current step as a voltage, e.g. step 3 outputs 3.0v.

Guide

If plaintext and spreadsheets make sense to you, you might like Spellbook. Very loosely inspired by oldschool music trackers, where it tries to capture that same sense of fast, keyboard-focused editing, adapted to the the modular eurorack/VCV Rack environment instead of MIDI. It also tries to capture the benefits of working in plaintext, like being able to copy and paste text snippets in Discord, or work with it in any text editor.

If other sequencers don't jive with you, give Spellbook a try, but be warned: it is weird.

Spellbook sequences are described in plain text using the RhythML format, a syntax to define pitch and CV patterns in plain text. Sort of a "tablature" or "markup" vibe, rather than "scripting" or "coding" (there is no conditional branching, or calculations, or loops, or anything like that). Each row in the sequence represents one step, typically triggered sequentially by the "Step Forward" input. Text written in each "column" (defined by the commas) is parsed to determine what voltage to send to the corresponding output jack (one per column) for the current step.

Introduction to Spellbook & RhythML | VCV Rack - YouTube

RhythML Syntax Quick Start

Ultimately, every output is merely a simple voltage, but the syntax allows you to "express" a desired voltage in a variety of ways; whichever works best in context and for your brain. You don't even have to stay consistent from row to row or column to column.

Control Voltages

• Decimal Voltages: Type a normal decimal number, with optional decimals or negative sign, and you get that number as a voltage.
• Percentages: Numbers ending in % (e.g. 50% or 12.5%), are normalized to eurorack CV standards so that 0% = 0v and 100% = 10v.
  • This is the range most modules expect for CV inputs, but of course you can scale them to other ranges if needed using the core Rescale module.
  • The values are not clamped to 0v-10v, you can also enter -12.5%, 300%, etc.

Pitch Representations

These formats are all parsed and translated into the equivalent 1v/octave control voltage. Decimals are allowed for all of them, but microtones may not be supported by all things you send those signals to (for example VSTs, DAWs, and MIDI mostly round to the nearest MIDI note, unless you do a little mad science, but most VCV Rack modules will accept microtonal pitches no problem). Case is NOT sensitive. Errors or undefined values become 0v outputs.

• Scientific Pitch Names: Specify pitches by name, accidental(s), and octave (e.g., C4, G#3, Ab4, C#4). C4 and C = 0v.
  • You can stack and combine as many accidentals as you want: C##4 parses to the same voltage as D4, for example.
  • Microtonal accidentals are also available: $ for half-sharp, and d for half-flat (e.g. C$4 for "C half-sharp 4")
• MIDI numbers: Numbers prefixed with m (e.g. m60) are parsed as MIDI note numbers. m60 = 0v.
  • Decimals are allowed, but most MIDI devices will round it back to the nearest MIDI number anyway, so for microtonal MIDI you could send a pitch bend from a second column to get those microtones, and make sure your MIDI instrument handles pitch bending.
• Semitones: Numbers prefixed with s (e.g. s7) are parsed as semitones relative to C4. s0 = 0v.
• Cents: Numbers ending with ct are parsed as cents relative to C4. 0ct = 0v.
• Hertz: Numbers ending with Hz are parsed as frequencies. 261.63Hz = 0v.

Gate and Trigger Commands: These are just shorthand so you don't have to type out a bunch of numbers for things like drum sequences which don't care about pitch or the exact voltage.

• W or | for a full-width gate; this one has no rising edge, so there will be no gap between this step and the prior step. This is identical to simply writing "10" or "100%" in the cell. The basic use case is to hold a gate open from the prior step for multi-step gates.
• T or ^ for a 1ms trigger pulse (this also guarantees a rising edge, so you'll get 0v for 1ms, then 10v for 1ms, then 0v until the next step), so that the output doesn't stay high for the entire step. This is usually what drum or clock-related modules will prefer.
• X or _ for retrigger, a 10v output which guarantees a rising edge when the step begins even if the output was already at 10v, by dropping to 0v for the first 1ms.

Comments: A ? in a cell will begin a "comment"; it and all text for the rest of that cell will be ignored and highlighted in a different color. You can use these for labels, in-line comments and notes, or anything else where seeing a little text might be helpful.

• If there are comments in the first row, Spellbook assumes they are columns labels, and they will be shown in the tooltips for the output jacks.

Refer to RhythML for comprehensive guidelines on the syntax. Check out the manufacturer presets in the module's right click menu for examples and templates of various types of sequences, including some mad science like using Spellbook as a wavetable. If you think of any other number/voltage/pitch formats for which there's a good (mathematical) way to translate them into 1v/oct, let me know and we can add it to RhythML!

Timing with Spellbook

Sequences in Spellbook can be played step by step (e.g. using an incoming clock or other trigger source), or by "index". Importantly, RhythML itself has no concept of "time" or "duration", only "steps in a sequence". It's up to you to decide how to clock or index Spellbook to actually play a RhythML sequence, and what each "step" means- is it going to be clocked on 8th notes? Whole notes? Bars? None of the above because you're doing some modular mad science?

You might step a Spellbook once per bar, for a sequence which controls the chord progression, or you might clock it on 16th notes for a drum loop.

It's often useful to have one Spellbook for each musical part in your patch, so they can be sequenced and timed independantly based on the overall need of the music and the patch, and kept in sync using traditional modular methods such as a master clock and clock dividers. Spellbook makes working with multiple clock speeds really easy because RhythML sequences can be any arbitrary length; just add or remove rows.

Steps

• Step Forward / Step backward: Acts the most like a basic "clock in". Simply advances the sequences to the next or prior row each time they're triggered, wrapping around to the first step at the end. Ignored if anything is connected to the Index input.

Index

• The Index input is in Relative mode by default, where it acts like a phasor input: If you send a smooth rising sawtooth control voltage, Spellbook will set the "currently active step" as the first step when the Index voltage is 0v, and the last step when the Index is 10v, and the proportional step for every voltage in between. If you sync two Spellbooks with different length sequences to the same Phasor for their Index, this is a great way to get easy polyrhythms or polymeters.
• Click the small gold symbol to change Index to Absolute mode. In this mode, Spellbook expects an Index voltage representing exactly which step to be on like an address: 1v sets Spellbook to step one, 2v is step two, 14v is step fourteen, and so on. If you send a higher voltage than you have number of rows, it will wrap around (for the nerds: modulo sequence length). Unlike Relative mode, even if the length of the sequence changes, the same index voltage always takes you to the same row.

Controls and Hotkeys

The Spellbook module offers a variety of hotkeys and controls for managing its interface and functionality effectively. Here is a comprehensive list of controls and hotkeys available for the Spellbook module:

Text Field Behavior:

• Click anywhere inside the text box on Spellbook's panel to enter "editing mode". You'll see a text cursor when focused. The prior sequence will continue playing "in the background", unchanged as you edit, until you "commit" your changes.
• Edit your sequence, making sure to follow the syntax rules for RhythML.
• Click anywhere outside the text box to leave editing mode, or press Ctrl+Enter, to "commit" the text without losing focus (so you can keep editing).
• Spellbook will trim and/or pad cells so that columns align visually, and parse the updated RhythML as a new sequence.
• The parser evaluates each cell to convert it into an appropriate output voltage. Errors default to 0 volts.
• It tries to stay on the same "current step" if it can, but will modulo the current step into the new sequence length if the new sequence is shorter, which should hopefully help live-editing stay in sync without relying on frequent Resets, if you're careful.

Special Keyboard Shortcuts:

• Ctrl+Enter: Commit and parse the current text, but stay in editing mode.
• Ctrl+[ or Ctrl+]: Decreases or increases the text size.

Additional Notes:

• Resizing: You can resize the module by dragging the right edge of the panel, to handle different numbers of columns in your sequences. I place minimized Spellbooks with one-column sequences all over my patches for short simple loops all the time.
• Autoscroll: When not in editing mode, the text field autoscrolls to keep the currently "playing" step centered, so you can see what the sequence is doing as it plays.
• Scrolling: While in editing mode, you can scroll up and down using the mouse wheel, or in any direction by moving the text cursor until it touches the edge of the viewport.

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Appendix

Basics of VCV Rack

VCV Rack is virtual modular synthesizer platform for Windows/Mac/Linux that simulates Eurorack modules, in addition to original modules that go beyond hardware. You place modules on a grid, interact with their knobs, sliders, and buttons with your mouse, and connect their input and output jacks with virtual cables to create synth patches just like a physical eurorack.

Spellbook is a module for VCV Rack, and RhythML was designed with VCV Rack, and modular synthesis in general, in mind.

All signals in VCV Rack are virtual voltages (really just "a number", a fact which many modules in T's Musical Tools play with), but they can roughly classified into:

• Audio signals are audible if played through your speakers. They contain audio-rate frequencies typically between 20Hz to 20kHz.
• CV (control voltage) signals can modulate parameters of other modules. For example, an LFO (low-frequency oscillator) can oscillate the pitch of a VCO (voltage-controlled oscillator) or the volume level of a VCA (voltage-controlled amplifier).
• 1v/oct (1 volt per octave) signals are CV signals that represent a pitch or note. In this standard, an increase of 1V increases the pitch by 1 octave. Since there are 12 semitones in an octave, an increase of 1/12v increases the pitch by 1 semitone.
• Gate signals are treated like an on/off signal. A "low" signal represents "off", and a "high" voltage represents "on".
  • Typically you would send 0v for low, and 5v-10v for high. The standard in VCV Rack is to accept 1v or more as "high", and send 10v by default, which lets you route gates directly into a VCA and treat that VCA as a Voltage Controlled Gate (for example).
  • For example, the core MIDI module outputs a separate pitch signal and gate signal when a key is pressed, which could be sent to the pitch CV of an oscillator, and the trigger/gate of an envelope generator, respectively.
• Trigger signals are very short gates (usually around 1 millisecond), typically used for cases where the "length" of the gate is unimportant, like a drum trigger, or a clock pulse, though many modules freely accept either gates or triggers in many use cases no problem.
• Clock pulses are gates or triggers played at a steady tempo, in order to set musical timing. Anything that sends a steady pulse can become a clock, such as an square wave LFO, or you could use a dedicated clock module with features such as creating multiple related clocks or aligning to traditional time signatures.
• Other: Some patches might intentionally "misuse" signals, or define their own specific uses within parts of the patch, etc.

Signals can be connected from module to module via patch cables. It doesn’t matter what type of signal a cable carries—you can connect any output to any input.

Polyphonic Cables

In VCV Rack, "polyphonic cables" refers to the ability of a single cable to carry multiple voltages simultaneously. This could be multiple pitches, in the traditional sense of "polyphony", but really it can be ANY set of voltages in one cable. This is a powerful feature that allows for complex patches with fewer visible connections.

• A polyphonic cable in VCV Rack can carry up to 16 separate channels of voltage.
• Polyphonic cables appear thicker than monophonic cables in the interface.
• Each channel in a polyphonic cable is its own independent voltage, like a regular (monophonic) cable, and modules might process them in parallel, in sequence, or use them in other ways.
  • If sent to a monophonic module, they usually read only the first channel, but polyphonic modules can do all sorts of things with the extra channels.

Playing with Polyphonic Cables with T's Musical Tools

Many modules in T's Musical Tools are designed to manipulate polyphonic cables in various ways:

1. Shuffle: Reorders the channels within a polyphonic cable, allowing for randomization of chord voicings or CV routing.

2. Ouroboros: Switches through the channels of a polyphonic input sequentially, turning it into a sequence. This can be used to create patterns from static polyphonic sources. Try combining with Shuffle to get randomized variations of the same sequence.

3. Append: Combine multiple mono or polyphonic cables into a single polyphonic cable, allowing for complex signal routing.

4. Stats: Analyzes a polyphonic cable and outputs various statistical measures, treating the polyphonic channels like a dataset.

5. Sort: Provides advanced sorting and selection of channels within a polyphonic signal, controlled by other polyphonic CVs.

6. Spellbook: Using the polyphonic output, Spellbook can sequence any complex polyphonic pattern to be fed into other modules.

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License

T's Musical Tools (TMT) - A collection of esoteric modules for VCV Rack, focused on manipulating RNG and polyphonic signals. Copyright (C) 2024 T

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License or the license.txt file for more details.