Every signal reaches an IR loader missing something different. Find yours, and what puts it back.
If your sound already went through a power amp (a full amp-sim plugin, a modeller's complete amp block, your amp's line out, a load box or attenuator output), leave the tubes off and use Iron on its own; adding a power stage a second time stacks compression that is already in the signal. It is off by default, and ReactIR stays a plain IR loader until you switch it on.
A resistive load, a clean solid-state power amp, or a guitar straight into an interface. The response comes out flat for the same reason, and the same fix applies.
IRs captured through a load box. Through a resistive load the amp-speaker conversation never happened at all, so Reactance is the piece that puts it back. Through a reactive load some of it is already there, and Reactance adds a further layer of it, under your control.
A rig that already has the interaction. Add Reactance on top and you push it further than the real thing, on purpose, for more presence and depth. If you did not want that, turn it down.
A guitar-friendly EQ for post-production. Put it on any finished guitar track as a shaping tool; its curve moves with what you play, which a static EQ cannot do.
The valve power stage
TUBES + IRON builds the whole power stage, valves and transformer, for a signal that has none. IRON ONLY adds output-transformer character to a signal that already went through a power amp.
Each voicing is inspired by a legendary amplifier architecture, and described here by how it plays.
EL34
Forward in the mids and tight underneath. It holds its shape when you hit it hard, so chords stay readable instead of smearing.
6L6
Stays clean and scooped a long way up, then softens rather than breaking up. The flattest of the five under a pedal.
6V6
Sags under the pick and swells after it, and it breaks up early. Notes bloom instead of sitting still — the most alive and the least tidy of the five.
EL84
Lets the speaker's own character through more than the others, so the top end rings and the feel changes with the cab you load. Springy rather than solid.
KT88
Does not sag and does not blur, however hard it is hit. The biggest and firmest of the five — the low end stays put under the heaviest playing.
It does not claim to be any named amplifier. It is a model, not a measurement of a particular amp.
Iron
Iron is a tool in its own right, not only a repair. Used on a sound that already has one, it is sophisticated transient shaping, compression, saturation and EQ in a single stage, tuned for guitar, and it reacts to your playing: hit hard and low notes compress and bloom, play softly and the stage stays out of the way. It is the kind of weight and control a tone gets when it is recorded through good iron, and you can add it to a track that was not.
Lighter and simpler, with the top end easing off earlier.
Hi-spec and open, with the top end left wide.
The push-pull American blackface sound.
Single-ended: warmer and more coloured, and it gives way unevenly.
A big transformer. The low end thins out when you play quietly and fills back in as you dig in.
Built for bass. It holds the bottom down to 30 Hz and stays steady with level, then gives way sharply rather than gradually when pushed.
A small studio transformer run past what it was built for: top end wide open even at low level, then a wall early instead of easing into it.
Reactance
A real amp and a real speaker push and pull on each other as you play, and that conversation is a big part of what makes a rig feel three-dimensional. Reactance puts it back.
It started out as the solution to a problem, and it became a creative tool for any situation. ReactIR lifts almost every guitar sound you put through it, even a fully miked vintage amp.
Use it as your IR loader. Put it after your digital guitar processor or your amp plugins. Use it as a post-production stage on any guitar track.
ReactIR does not model any named amplifier, and nothing here is a measurement of one.
I cannot say which loader is best for you, but here is what ReactIR does. It is the first IR loader that's alive: it models real-world analog behaviour (Temporal Dynamics), so the sound is never flat and sterile. It also does what a plain loader does not. It loads several IRs at once, each with its own level, trim, delay, polarity and pan, and it levels every IR between 200 Hz and 5 kHz as it loads, so swapping IRs changes the sound, not the volume. On top of that it models what an impulse response cannot hold: the speaker's impedance interaction, the output transformer and, optionally, a valve power stage. You can switch all of that off and use it as a loader only. ReactIR Lite is free if you only want the loader.
An impulse response is a linear measurement of one moment, so everything in a real rig that is not linear, or that changes with how hard you play, is missing: the output transformer, the way the speaker's impedance pushes back against the amp, and the power stage. ReactIR models each of those separately: Iron for the transformer, Reactance for the speaker interaction and a valve power stage for signals that have none.
A resistive load box replaces the speaker with a resistor, which is a flat load, so the interaction between the amp and a speaker's changing impedance never happened in that recording. Reactance models that interaction from real driver and enclosure data and puts it back, which is why it is a must with a resistive load. A reactive load box gets part of the way there, and Reactance adds a further layer on top, under your control. If the IR was captured through a clean solid-state power amp or straight into an interface, the same reasoning applies.
Yes: Reactance, in ReactIR. It models the interaction between a valve amp's output stage and a speaker's impedance curve, built from real driver and enclosure data, and it responds to the signal you play. It is not an EQ curve. Amount sets how much of the amp is in the interaction; Presence and Depth are the amp's feedback loop. It is part of the full ReactIR and is not in Lite.
Yes: Iron, in ReactIR. It models output transformer saturation, with three Generic sizes and seven named archetypes fitted to measured transformer data: UK simple-wound, UK interleaved, US blackface, US tweed, US high-power 150 W, US bass 300 W and a hi-fi toroidal 20 W. It is an extremely detailed recreation of a real output transformer, working as a transient shaper, a saturator and an EQ in one, and it responds to how you play. Amount sets how much of the transformer you hear, and zero is a true bypass.
It does not matter. Iron is a tool in its own right: it works as transient shaping, compression, saturation and EQ in one stage, tuned for guitar, and it reacts to your playing. Use it on a sound that already has a transformer for more weight and control, or on one that has none. If you did not want the extra, turn Amount down; at zero it is a true bypass.
Add what a digital amp sim leaves out. Iron adds an output transformer that thickens and blooms as you dig in, and Reactance adds the amp-and-speaker interaction an impulse response cannot hold. Both respond to how hard you play, so the result moves with your playing instead of sitting still. ReactIR goes after your amp sim or digital guitar processor in the chain.
Yes. Both work as guitar-friendly post-production tools on any guitar track, not only inside an amp chain. Their curves respond to what you play, which a static EQ does not do. Use Amount to set how much of either you hear.
ReactIR has a valve power stage with its phase splitter, placed in front of an output transformer model fitted to measured transformer data. Use it when the signal has no power amp in it: a preamp pedal into your interface, your amp's FX send or preamp out, a plugin that models only a preamp, or a bass DI or preamp. Choose TUBES + IRON. It offers five voicings: British 50 (EL34), American Clean (6L6), Tweed (6V6), Chime (EL84) and Clean Stack (KT88). It is a model, not a measurement of a particular amp.
No. It is off by default, and ReactIR stays a plain IR loader until you switch it on. It is part of the full ReactIR and is not in ReactIR Lite.
A saturator adds one fixed kind of colour. Iron is an extremely detailed recreation of a real output transformer, so it works as a transient shaper, saturator and EQ in one and changes with how you play. Its models are fitted to measured transformer data and they differ from each other, for example single-ended against push-pull. ReactIR does not include a tape model, and Iron is not a tape emulation.
Temporal Dynamics is the modelling of real-world analog behaviour. In nature nothing is stationary, and with analog gear the electronics react and change in time while you play, so it is never flat and sterile. Temporal Dynamics brings that to ReactIR, which is why it feels alive and breathes under your hands instead of sitting still, and why no two takes are absolutely identical. We do not publish how it works. It can be switched off, for a job that needs a frozen result, and Presets never touch that switch.
File formats: WAV, AIFF/AIF, FLAC and Ogg Vorbis. On macOS, files the system's own parser can read also work. Maximum IR length: 10 seconds. Maximum sample rate: 384 kHz. Channels: mono or stereo. Maximum file size: 128 MB.
Yes. The stage gives a little under hard playing and recovers, the way a real amp does, and the voicings differ in how much. Tweed sags the most; Clean Stack does not sag at all.
No. It runs strictly offline. Only activation talks to Lemon Squeezy, and it sends your host application's name and a hardware identifier to validate your key. Nothing else leaves your computer. ReactIR Lite makes no network connections at all.
Windows 10 or 11, 64-bit. macOS 12 or later, with Apple silicon and Intel in one installer. The macOS installer is signed with an Apple Developer ID and notarised. The Windows installer is not yet code-signed, so SmartScreen may show a warning; you can verify the download against its SHA-256 checksum.
One key, up to five of your own machines, and it never expires. Every future update of ReactIR accepts the same key. The 14-day trial is the same installer with a 14-day key for one machine, with the full plugin; when it ends, ReactIR passes the signal through dry until you enter a key. Price: $99.
Yes. Stage runs Iron at your session rate with no delay at all, and is the mode for tracking and live use; it is available with the power stage off, so for a zero-delay path use Stage with IRON ONLY. Detail runs Iron at twice your session rate for cleaner harmonics and reports a small added delay to the host, which lines the track back up; the valve power stage always runs in Detail. Separately, the Zero / Buffered latency mode controls how the convolution runs: Zero adds no delay and costs more CPU.