# Compound horn

> How to model a compound horn in 00 Simulator: separate front and rear horn paths, coupling chambers, rear tuning, diagnostics and Hornresp export.

Source: https://simulator.00aud.io/docs/horns/compound-horn

Each face of the diaphragm drives its own horn, so the cabinet has two mouths. The rear horn can extend the bass while the front horn covers the upper band.

_Figure: The compound horn drawn by the simulator's schematic, with its chambers, paths and outputs._

The default front and rear horn paths, with a B&C 10PS26. Rear horn length: 1.5 m. Drawn by the simulator when this page was built.

## How it connects

The front of the cone feeds the front horn and the back of the cone feeds the rear horn, each through an optional coupling chamber.

The two mouths are separate outputs that add with their phase at the listener, like the horn and direct radiator of a back-loaded horn.

When the rear horn is short enough to act as a vent, the horn card shows its **Rear tuning**.

## When to use it

### Good for

- Getting horn loading on both sides of the cone.
- Designs where a short rear path should behave like a port.

### Watch for

- The two mouths can cancel where their outputs overlap. Check **Horn Radiating Outputs**.
- Switching a horn to compound moves both entries to the throat. If you switch back to tapped, set the rear tap again.
- The diagnostics graphs call the front path Main.

## What you set

Set the enclosure type to **Horn**, then choose **Compound** under **Horn type**, in the enclosure panel or in the **Horn Editor**’s path bar.

### In the horn card

The horn card in the enclosure panel lists each path as a row: click one to open that path in the **Horn Editor**. The card also sets:

| Control | What it sets |
| --- | --- |
| **Front coupling chamber** and **Rear coupling chamber** | **Volume** for each, and a **Front cross-section** and **Rear cross-section** under **Advanced**. |
| **Rear tuning** | A readout, shown only when the rear horn is short enough to act as a vent. |

### In the Horn Editor

The path itself is set on the **Horn Editor** tile. Drag it in the drawing, or switch the tile to **Table** to type each value:

| Control | What it sets |
| --- | --- |
| **Front horn** | The area at the throat, then up to eight spans. |
| **Rear horn** | Under the **Rear** chip in the path bar, the same. A new rear horn is one 1.5 m exponential span. |
| Driver marker | On the front horn, where the front of the cone joins it; on the rear horn, where the back of the cone does. Each in cm from that horn’s throat. |

The driver marker can be dragged along either path. Use the **Front** and **Rear** chips in the path bar to switch which horn you are editing. [How the Horn Editor works](https://simulator.00aud.io/docs/horns/editor).

## What the rear horn length does

Only the rear horn length changes. Each longer rear horn carries the output lower, and the ripple through the band changes as the two mouths interact differently.

_Figure: Simulated SPL of the compound horn for 3 values of rear horn length: 0.75 m, 1.5 m, 2.25 m._

The default front and rear horn paths. Only the rear horn length changes between the lines. Simulated when this page was built.

Rear horn length, SPL: B&C 10PS26, Half Space · 1.0 m · 50 W.

| Rear horn length | −3 dB |
| --- | --- |
| 0.75 m | 106 Hz |
| 1.5 m (the design drawn above) | 83 Hz |
| 2.25 m | 62 Hz |

## How the outputs add up

The dashed lines are the front and rear mouths on their own. The total follows whichever is louder, and dips where they are close in level and out of step.

_Figure: Compound horn, rear horn length 1.5 m: the total response and main mouth and rear mouth on their own._

The outputs are pressures, so they add with their phase: where the dashed lines are close in level and opposite in phase, the total drops below both.

Compound horn, rear horn length 1.5 m. Solid: the total. Dashed: Main mouth and Rear mouth on their own.

## Diagnostics and stuffing

**Horn Radiating Outputs** shows the Main mouth and the Rear mouth with their total. Main coupling and Rear coupling appear when their chambers have a cross-section. [Reading the horn diagnostics](https://simulator.00aud.io/docs/horns/diagnostics).

Spans on both horns can be stuffed. [How stuffing works](https://simulator.00aud.io/docs/horns/stuffing).

## Folding and Hornresp

- **Folding:** Not yet. Folding handles one horn path, so the **Fold into cabinet** button is disabled for compound horns and the **Fold** tile says the type does not fold yet.
- **Hornresp export · CH, CH1, CH2 or CH3:** Entries must be at the throat or the first junction. A rear coupling chamber cannot currently be exported, and the export says so. The two faces need opposite polarities.
- **Checked against Hornresp:** 13 native Hornresp cases of this type are re-simulated in the regression tests. 12 of 12 agreement checks meet their tolerances, and 1 more track stuffing-model differences without claiming agreement.

[Folding a horn into a cabinet](https://simulator.00aud.io/docs/horns/folding) · [Exporting to Hornresp](https://simulator.00aud.io/docs/horns/hornresp)

## Try it

_Interactive walkthrough in the page: the simulator's own tiles running a short demo._

There is no example for this type yet. Open the simulator, add an enclosure, set its type to **Horn** and choose **Compound** under **Horn type**. It starts from the default horn path.

- [Open the simulator](https://simulator.00aud.io/app)

## Ask your AI

**Ask your AI**

With 00 Simulator connected to Claude, ChatGPT or another MCP client, your assistant runs this same solver on your own workspaces.

> Using 00 Simulator, add a compound horn to my open workspace for the driver I am using now. Try rear horn lengths of 1, 1.5 and 2 m without saving, simulate each at 50 W and show me SPL. For the best one, use the radiating outputs in the results to tell me where the two mouths work against each other.