# Front-loaded horn

> How to model a front-loaded horn in 00 Simulator: throat and rear chambers, a sealed or ported rear chamber, the Horn Editor, diagnostics, folding and Hornresp export.

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

The driver sits at the throat and its front face drives the horn. Its rear face loads a rear chamber, which you can leave sealed or port like a bass-reflex box. This is the classic horn: high efficiency over the band the horn loads, in return for size.

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

The default horn path the simulator starts a new horn with, with a B&C 10PS26. Rear chamber volume: 15 L. Drawn by the simulator when this page was built.

## How it connects

The front of the cone feeds the throat, usually through a small throat chamber. The throat chamber and the throat act as an acoustic low-pass filter, so they set how the top of the band rolls off.

The back of the cone faces the rear chamber. Like a sealed box, the rear chamber adds stiffness, which shapes how the driver is loaded at the bottom of the band.

Choose **Port** for the rear chamber and it becomes a vented chamber: the port radiates beside the mouth and adds output around its tuning.

## When to use it

### Good for

- Midbass and upper-bass horns where efficiency and output matter more than size.
- Comparing a horn against a vented or sealed box for the same driver in one workspace.

### Watch for

- The horn only loads the driver where the mouth is big enough and the path is long enough. Below that band, output falls quickly.
- A small rear chamber lifts the upper bass but costs the lowest octave. Check the **SPL** and **Excursion** graphs together when you change it.
- With a ported rear chamber, check the **Port Velocity** graph and the port resonance readouts, as you would for a vented box.

## What you set

Set the enclosure type to **Horn**, then choose **Front-loaded** 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 |
| --- | --- |
| **Throat chamber** | **Volume** only. 0 L connects the driver directly to the horn. |
| **Rear chamber** | **Loading**: **Sealed** or **Port**, and **Volume**. At 0 L the chamber adds no stiffness. Choosing **Port** on an empty chamber starts from 50 L with one round 100 mm port tuned to 40 Hz. |
| **Port** (**Port** loading only) | **Tuning**, **Port length**, **Shape**, **Number of ports** and the port size, as for a vented box. |

### 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 |
| --- | --- |
| **Main horn** | The area at the throat, then up to eight spans, each with a **Flare**, a **Length** and the **Area** where it ends. |

The driver marker is fixed at the throat. Drag the arrows and the dividers between spans to reshape the path, or click a value to type it. [How the Horn Editor works](https://simulator.00aud.io/docs/horns/editor).

## What the rear chamber volume does

Only the rear chamber changes between the lines. The smallest chamber gives the steepest low-frequency roll-off and a flatter upper bass; the largest keeps the most output below about 60 Hz. Above about 200 Hz the three lines are nearly the same, because the rear chamber hardly matters there.

_Figure: Simulated SPL of the front-loaded horn for 3 values of rear chamber volume: 5 L, 15 L, 40 L._

The default horn path the simulator starts a new horn with. Only the rear chamber volume changes between the lines. Simulated when this page was built.

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

| Rear chamber volume | −3 dB |
| --- | --- |
| 5 L | 90 Hz |
| 15 L (the design drawn above) | 99 Hz |
| 40 L | 100 Hz |

## Diagnostics and stuffing

Locations run along the Main path, named by span and end, such as Main H1 throat. **Horn Radiating Outputs** shows the Main mouth, plus the Rear port when the rear chamber is ported. [Reading the horn diagnostics](https://simulator.00aud.io/docs/horns/diagnostics).

Any span of the main horn can be stuffed. [How stuffing works](https://simulator.00aud.io/docs/horns/stuffing).

## Folding and Hornresp

- **Folding:** Available. The **Fold** tile opens the throat into the dead space behind the throat cap. Its **Chamber** chip compares the throat and rear chambers the fold leaves with your targets, and a rear port’s tube volume comes out of the rear chamber.
- **Hornresp export · Nd:** Up to four spans export as a native record. A ported rear chamber is written as Hornresp’s Rear Vented chamber, a mapping that has not yet been checked against a native Hornresp capture. With no rear chamber, the export warns that Hornresp adds an exposed rear radiator.
- **Checked against Hornresp:** 26 native Hornresp cases of this type are re-simulated in the regression tests. 20 of 20 agreement checks meet their tolerances, and 6 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 **Front-loaded** 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 front-loaded horn to my open workspace for the driver I am using now. Compare a 15 L sealed rear chamber with a ported one tuned to 45 Hz, simulate both at 50 W, and show me SPL and excursion.