Your whole rig, on your computer.

Cathode is a guitar processor in the spirit of the Axe-Fx III. Plug into your audio interface and build a rig from circuit-modelled amps, cabinets, drives and effects on a grid, with scenes, channels and modifiers for playing live.

Download Cathode View the source

For macOS, Windows and Linux, and a headless rig for a Raspberry Pi 5. GPL-3.0, no account, no paid tier.

Cathode — Grid

The main window: a preset on the grid, with the selected block open in the drawer below it.

public/screenshots/grid.png

amp models from schematics: 86
block types: 49
cells on the grid: 6 × 14
scenes per preset, channels per block: 8 + 4

Amps built from their schematics

Each of the 86 models is the circuit, stage by stage: the preamp, the tone stack, the power amp, the output transformer and the load of the speaker. The front panel is the amp's own, so the knobs do what they did.

Amp

An amp block's front panel: the amp's own controls, with the expert pages behind them.

public/screenshots/amp.png

Behind the front panel

The expert pages open up what the circuit is made of, for when the panel is not enough.

Tube types, bias and bias excursion
Supply sag and screen supply
Output transformer and speaker load
Boost, saturation and input dynamics
Bias tremolo and output compression

Neural captures too

Load NAM (.nam) and AIDA-X models in the Amp NAM block, and keep them in the Library beside your presets.

American clean

Tweed, brownface and blackface: chime, sparkle and spring reverb, with the vibrato as it was built.

Based on

Deluxe Reverb AB763
Twin Reverb
Bassman 5F6-A
Princeton Reverb
Tweed Deluxe 5E3

British

From the JTM45 and the Plexi to the JCM800 and Jubilee: the crunch that the rest of rock was built on.

Based on

Plexi 1959 Super Lead
JTM45
JCM800 2203
Silver Jubilee 2555
Hiwatt DR103

Class A and boutique

Cathode-biased power amps that compress as you dig in, and the hand-wired amps that followed them.

Based on

AC30 Top Boost
AC15
Matchless DC-30
Dumble Overdrive Special
Trainwreck Express

High gain

Cascaded preamps, tight low end and the saturated leads of the eighties to now.

Based on

Soldano SLO-100
Mark IIC+
5150
Dual Rectifier
Friedman BE-100

Bass and solid state

The bass rigs and transistor amps, for the parts of a song that are not a tube guitar amp.

Based on

Ampeg SVT
B-15-N Portaflex
Roland JC-120
Valvestate 8100

Move the mic, not the cab

The Cab block builds the response from a speaker, a microphone and a cabinet, and where you put the mic. Or load the impulse responses you already have.

Cab

The Cab block: speaker, microphone and cabinet, with the mic position over the speaker.

public/screenshots/cab.png

10
speakers: 11
microphones: 7
cabinets

Place the microphone

Position across the cone, distance up to 3.4 m with auto-align, and angle: the response is built from the three.

Bring your own IRs

Load impulse responses as .wav or .cabgrid, mix two of them, trim and smooth them, export what you made.

Capture your cab

Play a sine sweep through your own speaker and microphone and keep the impulse response it measures.

Every effect after the amp, and before it

49 block types, each with four channels and its own pages of controls, and a Block Library of factory presets to start from.

Drive

Drive, Dynamic distortion, Enhancer

27 overdrive, distortion and fuzz circuits, with every clip type

Delay

Delay, Multitap delay, Ten-tap delay, Plex delay, Megatap

Digital, analogue, tape, ping-pong, reverse and sweep; up to 16 seconds

Reverb

Room, hall, plate, chamber, cathedral and spring, with one to six springs

Modulation

Chorus, Flanger, Phaser, Vibe, Rotary, Tremolo and panner, Ring modulator

Thru-zero flanging, barberpole phasing, a rotary with brake

Pitch and synth

Pitch, Synth, Vocoder, Resonator, Formant

Whammy, harmonies in key, detune, a 16-step arpeggiator

Dynamics

Compressor, Multiband compressor, Gate and expander

Optical, JFET, tube and studio compressors, sidechains

EQ and filter

Parametric EQ, Graphic EQ, Filter, Wah, Crossover, Tone match

Ten graphic layouts, ten wah voicings, matching a reference tone

Routing and tools

Looper, Tuner, Mixer, Multiplexer, Volume and pan, Send and return, FX loop, IR player

Plus an analyser, and an FX loop with its latency compensated

Block picker

Adding a block: every block type, grouped, with a search field.

public/screenshots/effects.png

A grid like the hardware's

Six rows of fourteen cells. Put a block in any of them and wire it to its neighbours: one chain, or a dozen paths that split and meet again.

Parallel paths

Split anywhere and run a dry path beside a wet one, or two amps side by side into one cab.

Mixers and multiplexers

Merge rows with their own level and balance, or pick one row of several with a switch.

Feedback loops

Two send and return pairs carry a signal back up the grid, for delays that feed a reverb that feeds the delay.

Built for playing live

A preset is a whole song. Scenes change which blocks are on and which channel each one plays, in one press, without a gap in the sound.

Eight scenes, four channels

Try it

Every block has channels A to D, each with its own settings. A scene picks one for each block and switches blocks on or off.

DRV Channel B
AMP Channel C
DLY Channel A
REV Channel A

Modifiers on any knob

Right-click a control and drive it from a source: a filter that breathes with an LFO, a wah on your picking, a delay mix on an expression pedal.

LFO
Envelope
Sequencer
MIDI controller

Perform

The Perform page: big scene buttons and the controls picked for the song.

public/screenshots/perform.png

Perform page

Big scene buttons and the handful of controls you picked for the song, readable from where you stand.

MIDI and footswitches

Map program changes and CCs, lay out your footswitches, and send MIDI to other gear on every scene change.

Metronome and tap tempo

Delays and modulation follow the tempo; tap it in, or let the preset bring its own.

Every tone in one Library

Presets, the blocks inside them, your captures and your impulse responses, kept together and arranged for the gig in front of you.

Library

The Library: presets in banks and setlists, block presets, NAM amps and IR cabs.

public/screenshots/library.png

What it keeps

Presets, in banks and setlists
Snapshots and templates
Block presets, to reuse a drive or a delay
NAM amps and IR cabs, in the same place
Preset info: a name, an author and tags to find it by

Ins and outs for a real rig

Use every channel your interface has. Cathode measures your round-trip latency with a loopback test, and aims for 64 samples at 48 kHz.

Inputs

Guitar, a second instrument, a microphone for the vocoder, USB channels.

Stereo outputs

Each with its own EQ: one to the front of house, one to your monitor.

FX loop

Put a pedal or a rack unit in the grid, with its round-trip latency taken out.

Out for reamping

Record the dry guitar beside the processed one and dial it in later.

Audio setup

Settings: the audio interface, sample rate and buffer, and the measured latency.

public/screenshots/setup.png

Leave the laptop at home

Run Cathode on a Raspberry Pi 5 or a mini PC in your rig, with your audio interface and no display, and play and edit from a phone, a tablet or any laptop's browser.

Starts with the power

The installer starts Cathode at every boot, and prints the address to open and an access token.

The editor in a browser

The same editor as the desktop app, served to your network. Or connect the desktop app to the rig.

x64 and ARM64

One package for Linux on either, with systemd services for the engine and the server.

Install on the rig

tar xzf cathode-server-<version>-linux-arm64.tar.gz
cd cathode-server-<version>-linux-arm64
sudo ./install.sh

Choosing the interface, updates and logs

Phone

The editor in a phone browser, connected to a headless rig.

public/screenshots/remote.png

Download

Cathode is early: it has no stable release yet, so expect rough edges and changes to the preset format. Every build is on the Releases page, with SHA256SUMS to check it against.

macOS

Plays sound

Apple Silicon · CoreAudio and CoreMIDI

Cathode-<version>-mac-arm64.dmg

Not notarised yet: the first time, right-click the app and choose Open.

Get it from Releases

Linux

Audio in progress

Linux desktops · ALSA and JACK in progress

Cathode-<version>-linux-x86_64.AppImage

Make it executable (chmod +x) and run it.

Get it from Releases

Windows

No audio yet

Windows 10 and 11 · Not yet: ASIO is planned

Cathode-<version>-win-x64.exe

Not signed yet: SmartScreen asks you to confirm. Edits presets, without sound for now.

Get it from Releases

Your first sound

1Connect your audio interface and open Cathode.
2Open Settings, then Audio setup, and choose your interface. 64 samples at 48 kHz is the target; a loopback test measures your real latency.
3Double-click an empty cell on the grid to add a block. An Amp and a Cab between Input and Output make a rig.
4Select a block to edit it in the drawer below the grid. Right-click a knob to add a modifier or put it on the Perform page.
5Save with ⌘S. Press ? to see every keyboard shortcut.

Plug in and play

Free and open source, under the GPL. Bring an audio interface and a guitar; Cathode brings the rest.

Download Cathode Star on GitHub