Orbit Guitar Cab Builder: free guitar cabinet simulator plugin

Where does the sound come from?

A mathematical (not AI) model of guitar cabinets calculates it. You set the cabinet's configuration and the positions of the mics, and the plugin calculates the IR of that cabinet and plays through it. This is a heavy mathematical operation, so we build an IR that then runs fast: in the plugin itself or in any IR loader.

What goes into the IR calculation?

• the speaker's Thiele/Small parameters (fs, Qts, Vas);
• the speaker's character (MID, BRIGHT, DARK, SCOOP, FLAT, SNAP): each has its own Thiele/Small, its own breakup zone and its own cone modes, its own knee with a steep roll-off past it, its own dips and presence;
• the paper cone (PAPER): after breakup the edge of the cone still moves, smeared in time, so the edge sounds darker and a mic farther away does not get brighter;
• the box: CLOSED, PORTED, or with an OPEN or a half-closed back (HALF, as on the vertical 2x12);
• with an open back: its own column of air behind the cone, the rear sound in reverse polarity, partly blocked by the front panel; the box modes partly go away;
• a closed guitar box is not sealed, so its hump at resonance is lower than a sealed box's; a small open combo rings around the speaker's own resonance, a big open box hardly at all;
• the echo inside a closed box: the rear sound bounces off the walls and comes back out through the cone;
• the box ringing in the mids, quieter in an open one;
• the cabinet's geometry: the size of the front panel, where the speakers sit, the depth of the box;
• each cone as a surface of many patches, each with its own path to the mic; the depth of the cone;
• cone breakup and cone modes, voice coil inductance; after breakup the outer cone lets go first, while the center with the coil and the dust cap keeps moving;
• the dust cap and the coil still sound where the paper has let go: a shelf at the very top;
• the top ringing on: after breakup the top keeps ringing for a short while;
• the speakers in one cabinet differ a little: sensitivity and mode frequencies;
• standing waves inside the box and the modes of its walls;
• all the cones in the cabinet, not just the one nearest the mic;
• diffraction at the edges of the front panel;
• the reflection from the floor;
• WALL: a wall 40 cm behind the cabinet that returns 80% of the rear sound;
• the mic's polar pattern (cardioid, figure-8 for the RIBB ribbon), the proximity effect, the loss of top end off axis, each model's capsule;
• the mic's position, distance and angle;
• the arrival time (ALIGN), polarity (Ø), shift (TIME) and blend of the second mic;
• EQ: HPF, LPF and three bands, baked into the IR itself.

Not taken into account: the room, reverb, the grille, the speaker's distortion and compression, the amp.

Oh, so it’s not a real IR, and it’s worse than the real ones?

No, not worse. A "real" IR is not better than a synthetic one just because it is "real".

Capturing a good IR takes not only a good cabinet, good microphones and a good room, but also a fair amount of experience, an understanding of what to do, and good taste. Yes, masters of this craft exist, but the vast majority of "real" IRs are much worse than the ones we present here. If only because we do not give out IRs with a wrong frequency response, with comb filtering, with a noisy room or with a poor signal-to-noise ratio. We did not capture in our IRs the concrete basement where the cabinet stood, and we did not capture a tube amp with a character that an IR does not need. People often capture cabinets by running a sweep through a tube amp, which colors the cabinet, but not the way a proper simulator of that amp does.

All in all, we believe that in a great many cases, and especially for rock and metal, our IRs are much better than most "real" ones. Enjoy.

What is FRED?

It is the Fredman miking, typical for heavy genres and metal. The name comes from Studio Fredman in Gothenburg, Sweden.

Two SM57s sit on one speaker, capsule to capsule, at the edge of the dust cap, 2 cm from the cone. One points straight at the cone and gives the bite and the presence. The other is turned 45° toward the cap: it sounds darker and rounds off the top, with less fizz. The capsules sit at almost one spot, so the sound reaches both at the same time and the pair adds up without comb filtering. The blend between the two works as a tone control for the top end, no EQ needed.

Here one button does it for the current cabinet and speaker. FRED, under FIND BEST POSITION, puts both mics there, turns ALIGN on, sets TIME to zero and the blend to the middle. The pair goes on the half of the speaker where A was. The cabinet, the speaker, the back and the EQ stay as they were, and from there you can move either mic as usual. Eight of the guitar presets are built the same way: VENOM, SPIKE, SHADOW, HAVOC and FANG in Metal, BLAZE and TOWER in Rock, SQUAT in Punk.

Is it a plugin or an app?

A plugin: in a DAW it sounds like a guitar cabinet on its own. An app comes with it too: in the app you can play live through an audio interface, without a DAW, and save IRs as WAV for a processor, a pedal or any IR loader. And on this page you can try the plugin right in your browser.

Why is it slow while the mic moves?

The recalculation is heavy. Basically, there is a lot to calculate: all the reflections, the sum of the sound from all the speakers, and so on. Download the plugin and it is several times faster: in the browser the same code runs slower and calculates on one core, while the plugin calculates on several, in its own background thread, without getting in the DAW's way.

Will the IR work in a Helix or Quad Cortex?

Yes, both take WAV. If a device expects a particular format, choose it with the arrow next to DOWNLOAD IR.

The pedal won’t take the downloaded IR?

Choose the format with the arrow next to DOWNLOAD IR: many pedals and processors don't convert the sample rate and expect exactly 44.1 kHz, often 16 bit and 1024 or 2048 samples.

Does a NAM capture need a cabinet?

If the capture was made of the amp alone, without a cabinet (amp only), then yes: without a cabinet the distortion hisses and buzzes. If the capture was made of the whole rig, with the cabinet and the mic (full rig), the cabinet is already in it, and a second one is not needed.

Why does an amp without a cabinet buzz?

Distortion makes harmonics all the way up, to 20 kHz. A real guitar speaker plays almost nothing above 5–7 kHz, and that grit never reaches the listener. An amp sim without a cabinet lets all of it through. The cabinet cuts it the same way a real speaker does.

Can I use these IRs anywhere?

Yes, under CC BY 4.0: in music, in software, in devices, in commercial and closed products too. One condition: credit Darwin's Cat, for example "IR: Darwin's Cat, darwinscat.com". This goes both for the IRs you made here yourself and for the ready-made IRs from the archives.

Where can I download ready-made IRs?

Ready-made IRs of the TOP 12 set, all the factory presets and the typical cabinets, by style and by cabinet size, free, under the CC BY 4.0 license: on the guitar cabinet IRs page.

How can I help you? How can I say thanks?

Leave a link to us wherever you can. It helps more people get this cool thing. And feed the cat.