Filter Blender Manual

1. Welcome & Overview

A filter sweep is the oldest move in the book, and the best part of a filter is the moment you move it: the sweep opens, the loop starts to breathe, and you lean in. Pick a ladder and you get the ladder, all the way through. Filter Blender is built for the moments when you want more than one character: the squelch of a diode filter on the attack, the silk of a state-variable filter in the tail, and everything in between.

Filter Blender puts three analog-style filters on the corners of a triangle and lets you play the space between them. Drag one dot and the sound moves from a warm transistor ladder to a screaming 2-pole to a lo-fi CMOS band, or sits anywhere in between. Each corner has its own cutoff, resonance and drive, so a blend is never just a crossfade: it is three filters, three slopes and three characters working on the same sound at once.

Around the triangle you get 12 filter models, a motion recorder that loops the gestures you draw on the triangle, four effects (Comb Delay, Ring Mod, Phaser, Vowel) that you can place before or after the filter, and a modulation system with nine modulator types. A LOWS crossover keeps the bass out of the whole chain when you want the resonance without losing the foundation.

Formats: AU, VST3, CLAP and AAX on macOS. VST3, CLAP and AAX on Windows. VST3 and CLAP on Linux.
Platforms: macOS 10.13 or later (Apple Silicon and Intel; versions before macOS 11 are not tested), Windows 64-bit, Linux 64-bit.

2. Quick Start: First Great Sound in 60 Seconds

3. Typical Use Cases

4. Interface Overview

The window reads top to bottom, left to right. The left column is where you shape each filter. The right column is where you blend them.

Preset Bar (top)

Undo and redo, an A/B comparison, the preset browser, help mode, the About panel and the window size.

Response Curve

The frequency response you are hearing: one faint curve per corner and the blended result in teal, drawn from the same maths as the audio. Drag a handle left and right for cutoff, up and down for resonance.

Macros and Filter Rows

Three macros act on all three filters at once. Below them, one row per corner of the triangle (A on top, B bottom-left, C bottom-right) holds that filter's model, type and knobs.

Chain Strip and Triangle (right)

The strip at the top opens the modulation panel (MOD) and the effects panel (FX), and shows the processing order as five pills you can click and drag. The triangle below is the blend: the closer the dot to a corner, the more you hear that filter.

Motion Transport

Records the path you draw on the triangle and plays it back as motion. See The Motion Recorder.

Bottom Bar

Global settings, left to right: bypass, stereo topology, cutoff link, bass crossover and oversampling, then the output stage (mix, loudness match, input and output gain, limiter and the self-oscillation gate).

Modulation and FX Panels

MOD opens the modulation panel across the bottom of the window. FX swaps the left column for the effects panel (the button then reads MAIN, click it to come back). Loading a preset opens the modulation panel when the preset has modulators and closes it when it has none.

5. Controls Reference

Top Bar

Response Curve

Macros

Three bipolar controls between the curve and the filter rows. They act on all three filters at once, and every modulator you route to a knob works on top of them.

Filter Rows

One row per corner of the triangle: A on top, B bottom-left, C bottom-right. The knobs take the colour of the row's model.

The Triangle

Bottom Bar

6. The 12 Filter Models

Every model has its own slope, its own resonance and its own way of saturating. The names are ours, and each one is inspired by a classic circuit.

"Sings" means the model can self-oscillate, with DRIVE up and RESONANCE near the top, and turns into a tone generator tuned by its CUTOFF.

7. The Motion Recorder

Draw a path on the triangle once, and Filter Blender plays it back as motion: the blend travels between the three filters on its own, at the speed you choose, in or out of time with the song.

8. The FX Chain

Four effects share a chain with the filter: Comb Delay, Ring Mod, Phaser and Vowel. The filter does not have to come first. Put the ring modulator in front of it and the triangle carves the sidebands, instead of the sidebands being sprayed on top of a filtered sound.

The Chain Strip

The five pills above the triangle show the order the signal goes through, left to right. The default order is FILTER, COMB, RING, PHASER, VOWEL.

• Click a pill to switch that effect on or off. It is coloured when on, grey when off. FILTER is always on.
• Drag a pill to a new position: it is inserted there and the others shift along.

The chain order is saved with presets. It is not a parameter, so it cannot be automated.

The FX Panel

Click FX to swap the left column for the four effect cells (click MAIN to come back). Each cell has, from left to right in its title bar: its position in the chain, its name, a move handle, a zoom button and a power button.

• Power (or a click on the name) switches the effect on or off, like its pill.
• Zoom enlarges one cell to the whole panel. Click it again to return to the grid.
• Move handle: drag a cell onto another one to swap their places in the chain.

The effects run at the host's sample rate. Only the filters are oversampled.

Comb Delay

Ring Mod

Phaser

Vowel

9. The Modulation System

Filter Blender has nine modulator types, up to 16 at once, and modulators can modulate each other. Click MOD above the triangle to open the panel.

The Nine Modulator Types

Routing a Modulator

1. Click + ADD MODULATOR at the end of the panel and choose a type.
2. Set the modulator up in its card.
3. Click ARM in the card header. It lights up and every control that can be modulated gets a blue outline. Macro, MIDI and XY Pad have no header ARM: each of their outputs has its own ARM button.
4. Drag up or down on a control (a knob, a macro, an effect knob, the triangle's Position field): up for a positive amount, down for a negative one. A click without a drag creates the route at +50 %, so you hear it straight away; a route that already exists keeps its amount. While the modulator is armed, a ring around the knob shows the amount it moves.
5. Click ARM again when you are done.

To remove a route, right-click the modulated knob and pick it from the list (Remove all modulations appears when there are several), or click × next to it in Mod Routes. Fields such as STAGES, Curve, the macros and Position show their modulation as a thin coloured bar along the top edge instead of a ring.

What Each Destination Does

At full amount (100 %, up or down):

The LFO Card

Seven waveforms: Sine, Triangle, Saw Up, Saw Down, Square, S&H and Noise. Rate runs from 0.01 to 20 Hz, or switch to tempo sync and pick a division from 8 bars down to 1/64, with dotted and triplet modes. Curve bends the shape: on Square it sets the pulse width, and it is greyed out on S&H and Noise. Phase offsets the start of the cycle. The ± switch chooses symmetrical modulation around the current value or one-sided motion.

The MSEG Card

A draw-anything envelope. Up to 128 points, five curve types per segment (Linear, Smooth, S-Curve, Step, Hold), three play directions (forward, backward, ping-pong), free rate or tempo sync. PRESETS loads a stored shape, the dice draws a random one.

The editor offers seven drawing tools (Pointer, Pencil, Square, Pulse, Ramp Up, Ramp Down, Triangle). With the Pointer, click an empty spot to add a point, double-click a point to delete it, drag the middle of a segment to bend it, and right-click a segment to choose its curve type. The dice draws a random shape as dense as the horizontal snap grid. SAVE stores your shape, PRESETS opens the shape browser.

The Step Sequencer Card

1 to 64 steps, synced to the host tempo. Each step has a value, a shape (Flat, Ramp Up, Ramp Down, Triangle, Sine) and a curve. Drag vertically on a step to set its value. Right-click a step to choose its shape, or apply one shape to all steps. On a shaped step, drag its small handle up or down to bend the curve. Smooth glides between steps, the direction buttons play forward, backward, ping-pong or random. The dice randomises values, shapes and curves, the bin resets the steps.

The Audio Oscillator Card

Unlike the LFO, it runs at audible frequencies: Rate goes from 20 Hz to 20 kHz (default 220 Hz). Routed to a cutoff, it gives FM-style sidebands and growl. Five waveforms: Sine, Triangle, Saw, Square and S&H. The Shape field changes job with the waveform, and its label follows: Drive, Symmetry, Bright, Duty (the pulse width of the Square) and Smooth. Anti-aliasing is always on.

The Envelope Generator Card

An AHDSR envelope with two ways to fire it, chosen with the AUDIO / MIDI button in the card's header:

• AUDIO (the default): your audio plays it. Each time the input rises above the threshold, the envelope runs its Attack, Hold and Decay, stays at Sustain while the sound stays loud, and falls through Release when it drops away. No MIDI needed. Set the threshold by dragging on the meter at the left of the card (-60 to 0 dB, default -20 dB).
• MIDI: your keyboard plays it. Every note-on restarts the attack, even with the previous key still down, and the envelope stays at Sustain until the last key comes up. Use it on a legato line, where the audio never drops far enough between notes to fire the envelope again. The meter becomes a light that shows the gate open.

Attack runs from 1 ms to 10 s, Hold from 0 to 10 s, Decay and Release from 10 ms to 10 s. You can also drag the handles on the shape.

The Envelope Follower Card

Turns the loudness of your audio into modulation. Attack (0.1 to 100 ms) sets how fast it rises, Release (1 to 1000 ms) how fast it falls. Sensitivity (-12 to +24 dB) sets how much level it takes to reach full modulation: raise it for quiet sources. Detection mode chooses how it listens:

• Peak follows the literal level.
• RMS follows the averaged loudness, smoother and slower.
• Hybrid (the default) grabs the attack like Peak and releases smoothly like RMS.
• Transient ignores the sustained level and fires on each attack: a hit out of silence gives full modulation, a softer re-attack less, and a held note nothing after its onset. Turning the source down does not change it, since it measures how sharp the attack is, not how loud.

The Macro Card

Four outputs, each routed on its own: Knob 1, Knob 2, Button 1 and Button 2. Route one knob to three things at once and a single gesture morphs them all.

The MIDI Card

Four sources at once, each routed to its own destination: Keytrack (where you play on the keyboard, set with a Root note and a Spread in semitones), Velocity (captured at note-on), Aftertouch (channel pressure, and per-note pressure in CLAP hosts that send it) and Mod Wheel (CC1). Keytrack and Velocity each have their own ARM button, Aftertouch arms from AT and Mod Wheel from MW. The MIDI card needs MIDI sent to the plugin (see the FAQ).

Click ADV to shape each source. Velocity, Aftertouch and Mod Wheel each get a Sensitivity, a Tension that bends the response curve (drag the handle on the curve), a Smooth time and a bipolar switch. Keytrack has Root, Spread, Tension and Glide instead. Every curve shows a live trace of what you play.

The XY Pad Card

Two outputs, X and Y, each with its own ARM. Drag the cursor while the track plays for two-parameter moves. Smooth (0 to 500 ms) takes the jitter out of your hand, Return springs the cursor back to the centre when you let go.

Mod Routes

Click ☰ on any modulator card to open Mod Routes. Each modulator gets a column listing every route that leaves it, with its destination and amount (-100 % to +100 %). Drag an amount to fine-tune it, click × to remove the route. + Route adds a route from the full list of destinations, including the fields of the other modulators. The Macro column has a separate + for each of its four outputs.

Intermodulation

Modulators can modulate each other. Arm one, then drag up or down on a field inside another modulator's card. Examples:

• An LFO on another LFO's Rate: the wobble speeds up and slows down on its own. "Cross Mod" does this.
• An Envelope Follower on a Step Sequencer's Smooth: the steps glide when the source plays loud and snap back into place when it goes quiet.
• A Macro knob on the Rate of two LFOs (both in Hz mode): one knob sets the speed of all the motion.

The fields that take modulation are the LFO's Rate (in Hz mode), Amount, Phase and Curve, the Envelope Follower's Attack, Release, Sensitivity and Amount, the Envelope Generator's times, Sustain and Amount, the Step Sequencer's Smooth and Amount, the MSEG's Rate and Amount, the Audio Oscillator's Rate, Shape and Amount, the XY Pad's X, Y, Smooth and Amount, and the Macro's Knob 1 and Knob 2. The Audio Oscillator cannot drive an LFO or MSEG Rate: at audio rate that modulation averages out to nothing.

10. Advanced Tips & Workflows

Gain Staging

Most of the character lives in the saturation, and the saturation depends on how hard you hit it. Use IN to set that: +3 to +6 dB for more grind, -6 dB to clean up a hot source. Turn on LOUDNESS while you compare settings, so you judge the tone and not the volume. Set OUT last.

The limiter sits right after the three filters. An effect placed after the filter (a ring mod, a comb with high feedback) comes after the limiter, so keep an eye on your meters when you push those.

Chain Order Is a Sound

Moving an effect in front of the filter changes what the filter works on:

• Ring Mod before the filter: the triangle carves the sidebands into a new instrument. Try it with a notch, a band-pass and a lowpass on the three corners ("Ring Before").
• Comb before the filter: the metallic tail gets filtered, so the filter's motion plays the comb ("Crush Kit").
• Phaser before the filter: the sweep sounds like movement inside the tone rather than a coat on top ("Organ Grit").

Playing the Blend

There are three ways to move the dot without touching it, and they stack:

• Modulate Level A, B or C with an LFO, an MSEG or a follower. The blend follows the modulator, and the ghost dot shows where it is.
• Record a path with the motion recorder, or pick a Shape.
• Modulate SPREAD or SHIFT while a path plays, so the corners move while the dot travels between them ("Circle Wobble").

Self-Oscillation

On a model that sings, turn DRIVE up and push RESONANCE toward 100 %: CUTOFF becomes a pitch. On MooLadder, LushJup8, MorphPoleX and WildDiode3 it sings on the note shown under the CUTOFF knob. The other four sing off it, so tune them by ear against the track. Keep LIM on BRK to catch the peaks, turn HUSH on so it stops when the music does, and use the blend to decide how much of the tone you hear against the source. Two singing corners at slightly different cutoffs beat against each other ("Siren Call"). A Step Sequencer on a singing cutoff is a bass line ("Acid Scream").

Per-Note Filter Envelopes

For a filter envelope per note, the Envelope Generator in MIDI mode is the most reliable way: every note-on restarts it, legato included. Route it to one or two cutoffs at 30 to 60 %. Without MIDI, a fast Envelope Follower with a short release does a similar job from the audio ("Pluck Tight"), and the MIDI modulator's Keytrack makes the cutoffs follow the melody ("Three Body" tracks them at 60 %).

Stereo

On a full mix or a stereo bus, M/S filters the centre and leaves the sides alone, and each corner's W sets how much side comes back. Stagger W across the corners (80, 100, 130 %) and moving the blend becomes a width sweep. In L/R, the balance field places each corner left or right, so the blend pans as it moves.

CPU

A corner at 0 % is not computed at all. MONO halves the cost of the filters. Leave OS at 1x unless you hear harsh, folded highs on bright, driven settings: the automatic 2x above 8 kHz already covers the most common case. Each effect and each modulator adds a little, so switch off what you do not use.

11. Factory Presets

Filter Blender ships with 30 factory presets in eight categories. Every one of them moves on its own within a few seconds of playing, and each is level-trimmed to sit close to your dry signal. Click the preset name in the top bar to browse them.

Key Presets

All Categories

• Init & Basics (1): Init.
• Drums & Loops (5): Break Glue, Hat Lift, Loop Breather, Step Carve, Crush Kit.
• Bass (3): Acid Line, Growl Wide, Pluck Tight.
• Guitar & Keys (4): Auto Cry, Rhodes Silk, Organ Grit, Wah Pedal.
• Vocals (3): Vowel Talk, Radio Cab, Air Lift.
• Synth & Pads (4): Drift Pad, Three Body, Glass Stack, Fat Unison.
• Sound Design (6): Circle Wobble, Rosette Bloom, Rosette Drift, Ring Before, Cross Mod, Phase Cancel.
• Self-Oscillation (4): Ladder Song, Acid Scream, Siren Call, Hive.

A preset carries every parameter, the modulators and their routes, the chain order, LINK and the motion path. It does not touch IN, LOUDNESS or BYPASS: those are the way you listen, not the sound.

Saving Your Own Presets

Click Save, name the preset, and it appears under User in the menu. Open Presets Folder... shows the files. User presets are .fbpreset files in:

• macOS: ~/Library/UB DSP/Filter Blender/presets
• Windows: %APPDATA%\UB DSP\Filter Blender\presets
• Linux: ~/.config/UB DSP/Filter Blender/presets

Presets in Your DAW's Browser

In CLAP hosts with a preset browser (Bitwig Studio, REAPER), the 30 factory presets show up in the host's own browser, with tags, and load in full, modulation and motion included. Your own presets are only in Filter Blender's menu.

12. Controllers & Automation

Every knob of Filter Blender is a parameter your DAW can automate and a controller can play. The host shows each value the way the interface does: Cutoff A reads “1.00 kHz”, Resonance B “50.0 %”, Filter A “LushJup8”, Limiter Mode “Brickwall”. Type a value into the host (“2.5 kHz”, “LushJup8”) and it lands where it says. The corner parameters are named A, B and C, like the corners: Cutoff A, Resonance B, Phase Flip C.

Remote Control Pages (Bitwig Studio)

In Bitwig Studio (CLAP), Filter Blender puts itself on the eight knobs of any controller, in ten pages:

The Blend page plays the three corner levels, never the X and Y of the dot: a triangle does not play from two knobs. Live and Push do not read these pages (see Other Hosts below).

Level A ±, Level B ±, Level C ±

Buttons You Can Reach

Prev Preset, Next Preset and Motion Play are parameters, so a controller button can press them. They are on the Perform page in Bitwig. In Ableton Live with Push (VST3), they come at the end of the parameter list: use Configure in Live to bring them forward. They work with the plugin window closed, and every press fires, whether the controller button toggles or springs back. Nothing records them: not the session, not undo, not presets.

Other Hosts

Hosts that do not read the remote pages, Live and Push among them, list the parameters in banks of eight, in the plugin's own order. Automation written with an earlier version keeps playing: only the names changed (Cutoff A used to be Cutoff 0).

13. About & Settings

Click About in the top bar. Click outside the panel or OK to close it.

Theme, look-ahead, spectrum and the update check are remembered for every new instance, in ~/Library/UB DSP/Filter Blender/settings.xml on macOS, %APPDATA%\UB DSP\Filter Blender\settings.xml on Windows and ~/.config/UB DSP/Filter Blender/settings.xml on Linux.

14. Installation & Activation

macOS

Run the installer (.pkg). It is signed and notarised. Each format is a separate component, so you can untick the ones you do not use. The plugins go to:

• AU: /Library/Audio/Plug-Ins/Components/Filter Blender.component
• VST3: /Library/Audio/Plug-Ins/VST3/Filter Blender.vst3
• CLAP: /Library/Audio/Plug-Ins/CLAP/Filter Blender.clap
• AAX: /Library/Application Support/Avid/Audio/Plug-Ins/Filter Blender.aaxplugin

To uninstall, delete the bundles listed above.

Windows

Run the installer. You can choose any of the formats, and the plugins go to:

• VST3: C:\Program Files\Common Files\VST3\Filter Blender.vst3
• CLAP: C:\Program Files\Common Files\CLAP\Filter Blender.clap
• AAX: C:\Program Files\Common Files\Avid\Audio\Plug-Ins\Filter Blender.aaxplugin

Linux

Unpack the archive and run install.sh. It installs for your user in ~/.vst3 and ~/.clap, or for every user in /usr/lib/vst3 and /usr/lib/clap with --system.

Restart your DAW after installing, and rescan plugins if it does not pick Filter Blender up.

Trial Mode

Without a licence, Filter Blender is fully functional, with 2 seconds of silence every 40 seconds (with short fades, so it does not click). The window shows TRIAL MODE across it, a DEMO - SILENCE badge during each silence, and an Activate License button.

Activating

1. Download your keyfile (.ubkeyfile) from your account on ubdsp.com or from your purchase email.
2. Click Activate License in the plugin window (or Activate License... in the About panel).
3. Choose the keyfile. The plugin confirms with License Activated and your name.

Activation works completely offline: the keyfile is checked on your computer and the licence never touches the network. It is checked again at every launch. The plugin looks for your keyfile in its default folder (~/Music/Audio/Presets/UB DSP/Filter Blender/ on macOS, Documents\UB DSP\Filter Blender\ on Windows, ~/.config/UB DSP/Filter Blender/ on Linux), next to the plugin, and where you last loaded it from. Keep a copy in the default folder and you will never be asked again.

15. Troubleshooting & FAQ

Filter Blender does not show up in my DAW

Restart the DAW and rescan plugins. Check that the format your DAW uses was installed (see Installation). On macOS, Filter Blender is an Audio Unit music effect because it accepts MIDI for its modulators, so Logic Pro lists it under MIDI-controlled Effects.

How do I send MIDI to Filter Blender?

The MIDI modulator and the Envelope Generator in MIDI mode need notes sent to the plugin, which works differently in every DAW: in most, you route a MIDI track's output to the plugin. Everything else in Filter Blender works without MIDI.

The filter keeps singing after the music stops

That is self-oscillation: with DRIVE up and RESONANCE high, eight of the twelve models become oscillators. Turn on HUSH and the filter fades out after 400 ms of silence at the input. Or lower RESONANCE below the point where it starts to sing.

The resonance peak is not on the CUTOFF dot

The dot on the response curve marks CUTOFF, the frequency you set. The peak is where the filter resonates. On a resonant low-pass it usually sits below CUTOFF, by a few semitones up to more than an octave depending on the model. Each model resonates in its own place, so with LINK on, the three corners share one CUTOFF but not one peak, and the blend plays with that spread. Push RESONANCE toward the top and most peaks close in on CUTOFF.

Does an update change how my sessions sound?

No. When a new version improves a filter model, a session or a user preset saved before keeps the model it was made with and sounds exactly as it did. New instances and the factory presets get the improved one. In 1.1.0, WildDiode3, LushJup8, FunkyFollowIII, MooLadder and the MorphPoleX Notch changed, and sessions from 1.0.2 keep their sound. In 1.1.1, LushJup8 changed again: it now keeps its bass at the plugin's output, where 1.1.0 only kept it inside the filter. Sessions from 1.1.0 and earlier keep their sound. To hear the new models in an old project, open a new instance and set it up again, or load a factory preset.

It gets too loud when I push the resonance

Keep LIM on BRK: it holds the filter's peaks around -0.2 dBFS. Lower OUT if an effect placed after the filter pushes the level up again, since those come after the limiter. LOUDNESS keeps the overall level close to the dry signal.

The bass disappears

Turn on LOWS and drag its handle on the response curve: everything below it bypasses the filters and the effects. 80 to 120 Hz for a bass, 150 to 250 Hz for a drum bus or a full mix. If you want the resonance to touch the bass, put LushJup8 in LP on a corner: it keeps its low end as RESONANCE rises, where a MooLadder at the same setting loses most of it.

My host's bypass automation stopped working after the update

Before 1.1.1, the VST3 and AAX versions showed two Bypass parameters: Filter Blender's own, and one your host added, which its bypass button worked. There is now only one, Filter Blender's. Automation written on the old host bypass (or, in Pro Tools, on the plugin's Bypass) has to be written again. A VST3 session saved with the host's bypass on reopens with the plugin active.

I added a modulator but nothing moves

A modulator does nothing until it has a route. Click ARM in its card header, then click a control (the route starts at +50 %) or drag up or down on it to set the amount. Check that the card's power button is on, and open Mod Routes (☰) to see the routes and their amounts. The Envelope Follower and the Envelope Generator in AUDIO mode need audio, the MIDI modulator and the Envelope Generator in MIDI mode need MIDI notes. An Envelope Generator whose threshold sits above your signal never fires: drag the threshold down on its meter.

A follower preset stays wide open, or never opens

A follower reacts to the level of your track. Adjust its Sensitivity: down if it stays pinned open, up if it barely moves. The factory presets are set for a normally gain-staged track.

My motion path does not play

Press PLAY in the motion transport. Playback starts from Position. If the rate is set to a long note value (4/1 is four bars), the path moves slowly. The recorder follows the host tempo but does not start with your DAW's transport.

Loading a preset did not change my input gain or loudness setting

That is on purpose. IN, LOUDNESS and BYPASS describe how you listen, not the sound, so presets leave them as they are.

High CPU

Set OS back to 1x, switch off the effects and the modulators you do not use, and park the dot away from corners you do not need (a corner at 0 % costs nothing). On a mono source, MONO halves the cost of the filters.

The sound drops out for 2 seconds every 40 seconds

Filter Blender is in trial mode. See Activating. If you already activated and the silence came back after an update or a move to a new computer, load your keyfile again from the About panel.

Something is wrong and I need help

Open the About panel and click "Plugin not working? Run diagnostic". This opens the Diagnostic Tool page, where you can download a small application that checks your system, lists your installed UB DSP plugins and sends a full report to support. It is the fastest way to get help. You can also write to support@ubdsp.com.