# Fold a horn into a cabinet

> How the Fold tile packs a front-loaded, back-loaded, tapped or offset-driver horn into a cabinet you can build: patterns, locks, checks, cut list and exports.

Source: https://simulator.00aud.io/docs/horns/folding

A horn that works on the graph still has to fit in a box. The **Fold** tile packs the horn path into a cabinet you can build and sits beside your graphs, where every frequency graph draws the folded horn as a dashed line. You see whether the fold can be built and what it does to the sound at the same time.

_Figure: Side section of the tapped horn example folded into a cabinet 1,130 mm high and 940 mm deep: the boards, the air passage, the dead space and the path from throat to mouth._

The [tapped horn example](https://simulator.00aud.io/app?template=tapped-horn), folded when this page was built: a serpentine fold with 5 runs in a cabinet 530 mm wide.

| | Folded | Your design |
| --- | --- | --- |
| Path length | 2,500 mm (+0.0 %) | 2,500 mm |
| Modelled air volume | 363 L | 409 L |

Cabinet outside: 530 mm wide, 1,130 mm high and 940 mm deep, with 18 mm walls.

## Which horns fold

Folding works on [front-loaded](https://simulator.00aud.io/docs/horns/front-loaded-horn), [back-loaded](https://simulator.00aud.io/docs/horns/back-loaded-horn), [tapped](https://simulator.00aud.io/docs/horns/tapped-horn) and [offset-driver](https://simulator.00aud.io/docs/horns/offset-driver-horn) horns, which each have one path. Stubbed, compound, multiple-entry and Paraflex horns need junction, branch or entry layouts the fold does not handle yet. For those, the **Fold into cabinet** button is disabled and the **Fold** tile says so.

## Open it

Choose **Fold into cabinet** in the **Horn Editor** tile’s title bar, where it reads **Fold** on narrow screens. The first time, it saves a suggested fold, a three-lane serpentine, fits a box to it and adds the **Fold** tile beside your graphs. You can also add the **Fold** tile from the graph picker and choose **Fold this horn**. From then on every change is saved with the enclosure, and undo takes it back.

## Choose the fold

**Auto** folds the path in a pattern you pick. Choose it from **Fold pattern** and set its count; the fit tries every variant of that pattern, with the throat on a wall or sliding and the mouth on the floor or the lid, and never switches pattern by itself.

- **Serpentine:** Lanes that double back on themselves, 2 to 6 lanes.
- **Spiral:** Turns the same way at every bend, 3 to 6 laps.
- **Wrapped serpentine:** A serpentine whose last turns carry on around the cabinet, 3 to 5 rows.
- **Columns:** A serpentine of upright columns, 2 to 5 columns.
- **Straight:** One run, no folds.

**Draw** lets you lay the path yourself. Tap cells from the closed end to the front column, or use the arrow keys and Backspace. Tapping one step past the edge grows the grid, tapping a path cell cuts the path back there, and dragging a bend flips it to the other corner. The fold solves as soon as the path reaches the front.

## Set the cabinet

The cabinet popover holds the outside **Height**, **Depth** and **Width** and the **Material**. Typing a dimension locks it: that is the one your room decides. The unlocked dimensions are solved for the smallest box that passes every check, and **Fit box** runs that fit again. When no box inside the locks passes, the fit returns the buildable fold closest to your horn.

In the drawing you can drag the driver along its board, and its taps follow. Drag a board across itself to hold it there. Shift keeps it level or plumb, and a double-click lets it follow the horn again.

## Read the checks

The tile shows one chip per check. A passing chip shows a tick, a warning keeps its number, and an error names what is wrong. Open a chip for its details and the fixes that apply, such as changing one dimension, re-centring the driver or moving your front tap to the smallest distance a board allows. Nothing blocks saving or simulating.

| Chip | What it checks |
| --- | --- |
| **Length** | The folded path against your design. It warns beyond 0.5 % and fails beyond 3 %. |
| **Front tap**, **Rear tap** or **Driver entry** | Where the driver actually sits on the folded path, against the positions you set. |
| **Driver** | Whether the driver fits where the fold puts it, clears the boards and the shell, leaves the cone room to move, and how much its motor blocks the passage. |
| **Chamber** | The throat or rear chamber the fold leaves, against the volume you set. |
| **Shape** | How far the runs give way from your areas, the narrowest passage, and boards pinned against a wall. |
| **Mouth** | The folded mouth area against your design. It warns beyond 15 %. |
| **Can't build** | Geometry that cannot be made: overlapping passages, boards ending in open space, the mouth off the front panel. The passage is drawn red. |

Boards you hold show a **Held** chip, which also releases them.

## The folded line on your graphs

Every frequency graph, apart from the horn diagnostic graphs, draws the horn this fold builds as a dashed line in the enclosure’s colour: the folded spans, with the taps where the driver really sits. Its pill in the legend and in the tile hides it. It is left out when the fold cannot be built, when the horn already matches the fold, and when the horn is stuffed or damped, because stuffing cannot be carried onto the folded passage yet.

**Use this fold** writes the folded spans and taps into your horn, so the simulation follows the fold. It locks the box and holds every board, and the pill then reads **Matches horn**. **Let the fold follow the horn** on the **Held** chip releases it, and one undo puts everything back.

## Full screen

**Full screen** opens the whole editor: the inputs on the left, the side section or a 3D cutaway in the middle, and **Profile**, **Cut list**, **Hornresp** and **Response** tabs on the right.

- **Profile** plots area against distance from the throat for your design, the folded passage and the simulator’s equivalent of it.
- **Cut list** lists the boards. **Hornresp** gives the folded passage in Hornresp’s terms, with **Copy Hornresp values**. [Hornresp export](https://simulator.00aud.io/docs/horns/hornresp).
- **Fork as enclosure** adds a copy of the enclosure that simulates the fold beside your design. It uses the taps the fold achieves when it places the driver, and your target taps otherwise, and says which in the copy’s name. It needs a fold without errors and a horn without damping.
- **Export** saves the whole geometry as JSON. It is not a fabrication drawing.
- **Boundary Lab** downloads a mesh and project for a coupled FEM and BEM solve in [Boundary Lab](https://github.com/JWSound/boundary-lab), once the fold has no geometry errors.

- **Path length:** Measured through the arc of each bend rather than into its corner, which matches measured horns more closely than the plain centreline.
- **The driver:** An editable estimate sized from the driver you chose. The B&C 18DS115, which has a measured model, uses its real frame, cutout, depth and magnet and is drawn as itself.
- **What it reports:** Tapped and offset-driver horns report the taps the fold achieves. Front-loaded horns report their throat and rear chambers, and back-loaded horns their throat chamber.
- **Dead space:** Every cell the path does not use, with its volume. Front- and back-loaded horns open the throat into it as a chamber.

## Limits

- Folds are side sections: boards span the full internal width, with no folding out of that plane.
- Bends are not modelled as losses or scattering, and driver obstruction is reported but not simulated.
- Chamber volumes and tap positions are geometric results. Check the folded line or a forked copy before you build.

## Ask your AI

**Ask your AI**

Your assistant folds your own horn the way the Fold tile does, through the 00 Simulator connector.

> Using 00 Simulator, fold my tapped horn into a cabinet no more than 600 mm deep and 900 mm high. Compare the alternative folds it finds, simulate the best one beside my design, and tell me what folding costs in response before I save anything.