MIDISKETCH / POLYRACK
MIDISKETCH GUIDE

PolyRack

Available in the 0.9.10.8 beta

Per-note sound for any synth. PolyRack is MIDISketch's plug-in rack. Load any synth and PolyRack plays it as linked copies, one per note, so every note in a chord can bend, swell and slide on its own, even on synths that were never built for that.

PolyRack canvas with a MIDISketch input card wired into a TAL-NoiseMaker synth card showing x4 copies, all four copy cells lit, wired to the Main output.
A simple rack: MIDISketch's notes and expression go into TAL-NoiseMaker, played as 4 linked copies, and out to Main. The numbers are explained below.
1Set the copies

The − xN + stepper sets how many notes play at once: x4 plays a four-note chord.

2Watch and tweak each copy

One cell per copy, lit while it plays a note. Click a cell to open that copy’s own window and change it: good for per-note variations.

3The master

OPEN … (MASTER) opens the master window. What you change there reaches every copy at once.

What is MPE?

MPE (MIDI Polyphonic Expression) lets every note carry its own pitch bend, pressure and slide. A normal synth receives one pitch bend for the whole instrument: bend one note and the whole chord bends. An MPE synth keeps each note separate.

MIDISketch draws and sends MPE. PolyRack is how you hear it on synths that don’t speak MPE.

The basics

Opening PolyRack

Three ways in, all on the Sound page:

The PolyRack buttonWith a synth loaded, click PolyRack on its title bar. The synth moves in with its sound and settings, and MIDISketch switches its output to MPE if it was on Pitch Wheel.
The synth’s menuChoose Open in PolyRack.
The PolyRack tileIn the built-in instruments strip. Click it again to turn PolyRack off, and the synth plays as itself again.
Title bar of the TAL-NoiseMaker synth frame with buttons Check MPE, Recipes, Extensions and PolyRack; the PolyRack button is outlined.
The PolyRack button on a loaded synth's title bar.

EXIT POLYRACK (top right of the rack) leaves it. The first time PolyRack opens, a short card shows the idea: one card on the rack, linked copies behind it. FULL GUIDE brings you here, GOT IT closes it, and + ADD › PolyRack guide brings it back.

The PolyRack guide card with the synth copies stacked behind one card, marked x3.
The card a moment in: the copies stacked behind one card (x3)…
Card titled POLYRACK, Per-note sound for any synth, showing MIDISketch fanning out to Synth note 1, 2 and 3, then to Main, with FULL GUIDE and GOT IT buttons.
…then fanned out: each note plays on its own copy.

Copies: one note per copy

A synth on the rack is a layer card. Behind it are its copies: identical, linked instances of the same synth. Each note you play goes to a free copy, so each note gets its own bend and pressure. True per-note expression, on any synth.

Close-up of the TAL-NoiseMaker card: a minus / x4 / plus stepper, PITCH: BEND and BEND RANGE plus or minus 2 controls, and four green copy cells numbered 1 to 4.
  1. 1The copies stepper: x4 means four notes at once.
  2. 2One cell per copy, lit while it plays.
Tooltip over copy cell 2: COPY 2, FOLLOWS THE MASTER. Click: this copy's own window. What you change there stays on this copy; the master's knob moves still reach it. Right-click: its menu.
Hover a copy for its hint: a click opens that copy's own window.
How manyThe − xN + stepper. One copy plays one note at a time; x4 plays a four-note chord. A non-MPE synth starts at x1, so press + for chords. Up to 14 copies per layer.
The masterOPEN … (MASTER) opens the master window. Every knob you turn there reaches all the copies.
One copyClick a copy’s cell for its own window. What you change there stays on that copy; right-click it for Match the master again.

Play more notes than there are copies and the new note takes the copy that was released longest ago, so tails ring on. A held note is only taken over when every copy is busy.

Synth windows, the master’s and each copy’s, have an AUTO | PINNED switch: PINNED keeps the window above everything. In a DAW on a Mac they open in front of MIDISketch.

Set BEND RANGE on the card to match the synth’s own pitch-bend range, so bends land on the right pitch.

MPE synths: one instance

Synths that already speak MPE, like Vital, Serum 2 and Surge XT, don’t need copies. PolyRack plays them as one instance that receives MIDISketch’s MPE directly: the card says ONE INSTANCE · ITS OWN MPE, and the bend range shows AS SENT. Synths on MIDISketch’s verified MPE list open this way; everything else opens as copies.

Mix both in one rack, up to 8 synth layers. Every layer plays every note unless you filter them.

MIDISketch input wired to two synth cards: TAL-NoiseMaker with x4 copies and Vital marked one instance, its own MPE, both wired to the Main output.
Two layers on every note: TAL-NoiseMaker as 4 copies, Vital as one MPE instance.
  1. 1The NOTES port.
  2. 2The EXPRESSION port.
  3. 3The AUDIO port.
  4. 4Vital: one instance, its own MPE.

Building a rack

The canvas: cards and wires

Everything on the canvas is a card, and cards connect with wires. Drag from an output port (right side of a card) to a matching input (left side). Grab a wire by its input end to move it or pull it off, or drop one on empty canvas for a menu of what to put there.

NotesWhich notes play: note on and off, velocity. Drawn in your theme’s note colours.
ExpressionThe per-note movement: bend, pressure, slide, pan, plus velocity and key as values. A white cable that fans out into one coloured line per kind when split. Dashed lines carry one value per note.
AudioSound, from synths and effects to an output. Drawn in your theme’s accent colour.

On the MIDISketch card, ONE WIRE / PER CHANNEL splits the notes by MIDI channel, and ONE WIRE / PER LINE splits expression into its separate lines. A split synth input shows where each line lands: AFTERTOUCH (pressure), CC 74 (slide), CC 10 (pan) and PITCH BEND. You can re-wire any line to any input.

MIDISketch card in PER LINE mode with velocity, pressure, slide, pan, bend and key outputs; coloured wires run into the matching inputs on TAL-NoiseMaker and Vital.
Expression split per line: pressure, slide, pan and bend each get their own coloured wire into the synth's AFTERTOUCH, CC 74, CC 10 and PITCH BEND.

The toolbar

Bottom left+ ADD, zoom − / % / +, and FIT, which frames everything.
Bottom rightTIDY lays every card out fresh. BACKGROUND: dots, grid or horizon. BRIGHTNESS makes the canvas lighter or darker (double-click resets). FLOW turns the animated wire activity on or off.

Zoom with the mouse wheel, one even step per click, or scroll and pinch on a trackpad.

Adding things: + ADD and the quick wheel

+ ADD opens the add menu. Only the new card gets placed: the cards already on the canvas stay where they are, until you TIDY.

SoundAnother synth layer: a new synth, the same sound again, the same sound split at middle C, or an octave up. MIDISketch’s SoundFont player and Kit as layers (the Kit card shows its pads). On a Mac, CLAP synths and effects and older 2.4 plug-ins too (Windows later).
RoutingOutputs (a separate output pair for your DAW, each copy its own output, MIDI out), audio utility, effects, a mix and an FX return.
Notes and controlNotes nodes, inputs, a controller and a lane from the roll.
Watching and moreA monitor, a MIDI log, your saved modules, and the PolyRack guide card.

Middle C follows your Middle C setting: it is MIDI note 60, which MIDISketch calls C4 or C5 depending on that setting.

Right-click anything for its options. Hold the right mouse button instead for the quick wheel: drag toward a section, then release on an item.

Circular menu with sections Synth, Notes, Expression, Audio, MIDI and Watch around an ADD centre; Notes is highlighted and lists Note filter and Transpose.
Hold right-click on empty canvas: the ADD wheel, NOTES section open.
Circular menu over the Vital card with sections Open, Swap, Effect, Copies, Sound and Expression; Copies is highlighted and lists Duplicate and Duplicate + mappings.
Hold right-click on a synth card: its own wheel, COPIES section open.

Effects and Mix

Effects go in three places:

On a layerAn effect on that synth’s mix: the blue EFFECT card right after the synth, with a DRY / WET fader.
Per noteOne effect instance per copy, so every note gets its own. Good for per-note filters or distortion.
FreeAn effect any layer can feed. Wire several layers in; a second source can go into its SIDECHAIN input.

A Mix card sums whatever you wire into it, with a level knob per input; wire it on to an effect or an output. There’s also an FX return for send effects (each layer gets a send) and Effect on Main output.

TAL-NoiseMaker into a Surge XT Effects card; that and Vital wire into a Mix card with two level knobs, then into a second Surge XT Effects card marked any layer with a sidechain input, then into Main.
  1. 1An effect on TAL-NoiseMaker’s mix.
  2. 2A Mix card summing both layers.
  3. 3A free effect after the mix, with a sidechain input.

Notes nodes

Notes nodes sit between MIDISketch’s NOTES and your synths, and change which notes get through:

Scale lockMoves notes into the sketch’s scale. Turn the scale on in MIDISketch first; the card says which scale it uses.
Note filterLets a key range through (lowest and highest), and can pick white or black keys. Velocity and channel filtering are in its menu.
TransposeShifts notes by semitones.
Velocity curveSofter, louder, or one fixed velocity.

Chain them, and send different chains to different layers: a pad that only plays from middle C up, and a bass an octave down.

MIDISketch's notes wire into a Note filter card set to C4 to G9, then into TAL-NoiseMaker; and into a Scale lock card (into C major) and a Transpose card set to +12, then into Vital.
  1. 1A note filter (C4 and up) in front of TAL-NoiseMaker.
  2. 2Scale lock, in front of Vital.
  3. 3Transpose +12, also in front of Vital.

Shaping expression: CURVE and MATH

Any expression line can drive any synth parameter or MIDI CC. + ADD INPUT on a synth card adds a target: a synth parameter (search by name, or Learn and turn a knob in the synth’s window), a CC, aftertouch or pitch bend. Then drag a line (pressure, slide, velocity…) into it. In between you can put:

CURVEDraw how the input maps to the output. EDIT opens the curve editor: click to add points, right-click to delete, presets Linear, Invert, S-Curve and Steps, and an output range.
MATHCombine two lines, for example A × B: slide scaled by velocity.

Both work per note: each copy gets its own result.

A CURVE card titled Shape between MIDISketch's expression and TAL-NoiseMaker's FILTER CUTOFF input, and a MATH card A x B fed by slide (A) and velocity (B, dashed) into FILTER RESONANCE.
  1. 1Pressure through a CURVE into Filter Cutoff.
  2. 2Slide × Velocity through MATH into Filter Resonance.
  3. 3The two inputs added on the synth card.
Curve editor window titled Pressure to Filter Cutoff with a straight line graph, Output Range 0 to 1, and Linear, Invert, S-Curve, Steps, Apply and Cancel buttons.
The curve editor: Pressure to Filter Cutoff.

Input cards and controllers

By default MIDISketch’s card carries everything: what you drew, your computer keys and your MIDI controllers. Give an input its own card (+ ADD › Add an input: any open MIDI port, Computer keys, or the Trackpad) and it starts out still wired into MIDISketch’s card. Drag its wire to a synth instead and that controller gets its own sound.

Input cards for a MIDI port and Computer keys under the MIDISketch card; the port card is wired to Surge XT, the computer keys card to MIDISketch's INPUTS port; a CC1 Modulation Wheel controller card above.
  1. 1A MIDI port on its own card, playing Surge XT.
  2. 2Computer keys, still feeding MIDISketch’s card.
  3. 3A controller card (CC 1).
  4. 4MIDISketch’s INPUTS port, where the computer keys arrive.

Tools

Watching the signal: Monitor and MIDI log

Drag any wire into a Monitor to see it: notes light a keyboard, expression draws its lines, audio shows a level. A MIDI log lists every message on a wire (time, channel, note, velocity and the raw bytes), handy when a synth doesn’t react the way you expect. Right-click the log to show, pause, clear or copy it.

Four watch cards around a MIDISketch-to-Vital rack: a keyboard with C4, E4, G4 lit; expression traces; an audio level trace; and a MIDI log listing NOTE ON and NOTE OFF rows.
  1. 1A monitor on the notes.
  2. 2A monitor on the expression.
  3. 3A monitor on Vital’s audio.
  4. 4A MIDI log of the notes.

Modules

Select several cards (Cmd-drag a box, or Cmd-click cards) and press Cmd+G (Ctrl+G on Windows) to group them into a module: one tidy card with the same inputs and outputs. OPEN MODULE steps inside; a breadcrumb shows where you are, and Esc steps back out.

Two Surge XT Effects cards with white selection outlines, wired after Vital.
Two effects selected (white outline)…
A single card titled Module, linked copies share it, with IN1, OUT1 and an OPEN MODULE button, between Vital and Main.
…Cmd+G makes them one module card.
Module view with the breadcrumb Inside a module, Esc to go back: Rack, Module and cards In, Surge XT Effects, Surge XT Effects, Out.
Inside the module: its In, the two effects, its Out. The breadcrumb says where you are; Esc goes back.

Copy, paste, duplicate, undo

Two Module cards, the lower one selected and outlined, both wired from Vital's audio into Main.
Cmd+D on a module: the duplicate lands below, already wired between Vital and Main.

Presets and Init

PRESETS (top right) saves the whole rack as a preset, loads saved ones and opens the presets folder. Init returns to the default rack (it asks first). The MULTICORE switch spreads the copies over your CPU cores, and the header shows layers, copies and CPU per block.

Reference

Keyboard shortcuts

ActionMacWindows
Copy cards (no wires)Cmd+CCtrl+C
Paste cardsCmd+VCtrl+V
Duplicate with wiringCmd+DCtrl+D
Group into a moduleCmd+GCtrl+G
Undo / redo rack editsCmd+Z / Cmd+Shift+ZCtrl+Z / Ctrl+Shift+Z
Box-selectCmd-drag on empty canvasCtrl-drag
Add / remove a card from the selectionCmd-clickCtrl-click
Duplicate by draggingShift-drag a cardShift-drag
Leave a moduleEscEsc
Stop all sound (panic)Esc on the rack, outside a moduleEsc
OptionsRight-clickRight-click
Quick wheelHold right-click, drag, releaseThe same

FAQ

Why copies?

Ordinary synths get one pitch bend and one pressure for every note at once. With one copy per note, each note has a synth to itself, so it can bend and swell on its own.

Does it use more CPU?

Yes. Each copy is a full synth instance, so four copies cost roughly four synths while they play. Idle copies can sleep, and MULTICORE spreads copies across CPU cores. Use as many copies as the largest chord you play; MPE-ready synths need just one instance.

Which synths are MPE-ready?

Those on MIDISketch's verified MPE list, for example Vital, Serum 2 and Surge XT. They open as one instance; everything else opens as copies. The synth setup page covers the synths MIDISketch knows.

Will my synth's sound and settings carry over?

Yes. The PolyRack button on a loaded synth keeps its sound and settings, and every copy follows the master window.

A plug-in crashed MIDISketch. What now?

Open your sketch again. If a plug-in closed MIDISketch while the sketch was opening, the next open skips that plug-in once and tells you. It stays in the rack as a card, so the sketch is safe to save.

Does it work in my DAW?

PolyRack is in the MIDISketch 0.9.10.8 beta, built into MIDISketch itself (not the MIDI FX version), and rack audio can go to MIDISketch's main output, to separate outputs for DAW mixer tracks, or out as MIDI. Tested in your DAW? Tell us on Discord.

Is it finished?

Not yet: it is in beta. This page grows as it does.

PolyRack is in the MIDISketch betaSame license, same two activations. New to MIDISketch? Every feature free for 7 days, no card, then $50 once.
Get the beta