# Phase

> How to read the Phase tile in 00 Simulator: the acoustic phase of each design in degrees, including EQ and filters, and why the line jumps at ±180°.

Source: https://simulator.00aud.io/docs/reference/tiles/phase

Where each frequency’s sound sits in its cycle, in degrees, with EQ and filters included. It shows how much a box and its filters turn the sound, which matters where two sources play the same notes.

- **Shows:** The phase of each design’s sound in degrees at each frequency, including EQ and filters, wrapped to the range −180° to +180°.
- **Healthy when:** It turns smoothly. A jump from −180° to +180° is the wrap, not a fault.
- **If it is not:** A fast twist comes from a resonance or a steep filter. Check the same frequency on the SPL tile, and try a gentler filter slope.

## The tile

_Figure: The Phase tile for the vented example, with the phase wrapping from −180° to +180° near the box tuning._

Ciare 12.00SW in the 55 L vented example tuned to 32 Hz, at any power, half space, 1 m. Simulated when this page was built.

| Frequency | Phase |
| --- | --- |
| 20 Hz | −100° |
| 30 Hz | −167° |
| 40 Hz | 120° |
| 60 Hz | 79° |
| 100 Hz | 45° |
| 200 Hz | −2° |
| 400 Hz | −40° |

Reading left to right, the vented example’s phase falls steadily. Near 31.2 Hz, close to its 32 Hz tuning, it passes −180° and carries on from +180°. That jump is the wrap, not a change in the sound.

- [Open this example](https://simulator.00aud.io/app?template=vented) in the simulator and add the tile, then hover the curve for the phase at a frequency.
- Each visible enclosure draws its own line in its colour.
- It is the phase of the sound each design makes, not of its impedance. The [Impedance](https://simulator.00aud.io/docs/reference/tiles/impedance) tile shows magnitude only.

## How to read it

- A whole cycle is 360°. The tile folds every angle into −180° to +180°, so a vertical jump from one edge to the other is the same angle, one turn on.
- The phase turns fastest where the level changes fastest: around a tuning, a resonance and a filter’s corner. How fast it turns is the delay on [Group Delay](https://simulator.00aud.io/docs/reference/tiles/group-delay).
- The steeper the roll-off, the further it turns. Below its tuning a vented box turns about twice as far as a sealed box does below its resonance.
- Phase counts where two sources play the same frequencies, such as a subwoofer and the main speakers around the crossover. The tile shows each design on its own; it does not add two together.
- The time sound takes to reach you is left out: **Listening distance** does not change this tile.

## Filters turn it too

A high-pass filter turns the phase well above its corner. The same vented box with a 25 Hz high-pass:

_Figure: The vented example’s phase with and without a 25 Hz Butterworth 24 dB/oct high-pass._

Ciare 12.00SW in the 55 L vented example tuned to 32 Hz, at any power, half space, 1 m. Simulated when this page was built.

| Frequency | No filter | 25 Hz high-pass |
| --- | --- | --- |
| 40 Hz | 120° | −140° |
| 60 Hz | 79° | 142° |
| 100 Hz | 45° | 82° |
| 200 Hz | −2° | 16° |

Added to the vented example’s phase, simulated when this page was built. The steeper filters turn it further, and the turn is still 38° at 100 Hz, 4 times the corner frequency, for the 24 dB/oct Butterworth.

| 25 Hz high-pass | Turn at 40 Hz | Turn at 100 Hz |
| --- | --- | --- |
| Bessel, 12 dB/oct | 48° | 19° |
| Butterworth, 12 dB/oct | 55° | 21° |
| Butterworth, 24 dB/oct | 100° | 38° |
| Linkwitz-Riley, 24 dB/oct | 110° | 41° |

A gentler slope turns it less: the 12 dB/oct Butterworth adds 21° at 100 Hz. The Phase tile has no **EQ** button; edit filters on [SPL (dB)](https://simulator.00aud.io/docs/reference/tiles/spl#eq-on-the-tile), on the [EQ Editor](https://simulator.00aud.io/docs/reference/tiles/eq-editor) tile or in **EQ / filters** in the Driver panel, and this tile follows.

## What moves it

| Change | Effect | Why |
| --- | --- | --- |
| Power, 1 W to 200 W | None (0°) | Turning the level up does not change the timing. |
| **Listening distance** | None | The time the sound takes to travel is left out. |
| **Radiation space** | None for a box | A box only gets louder. A horn’s phase changes, because the walls and floor change how its mouth radiates. |
| A high-pass or low-pass filter | Turns it, most near the corner | Every filter that is switched on is in the phase. |
| Box type and tuning | Where and how far it turns | A higher-order box turns further below its tuning. |
| **Non-horn upper response** | None | It only changes the level; phase always uses the physical model. |

## Settings and controls

| Control | Where | What it does |
| --- | --- | --- |
| **Y-axis settings** | Tile header | Shows −180° to 180° with a line every 45°, in **Auto** and **Manual** alike. **Manual** takes other limits as a **Min** and **Max**. |
| **Add note** | Right-click the chart | A note at the frequency you clicked. |

## What to try

| Try | What it changes |
| --- | --- |
| [Read the delay](https://simulator.00aud.io/docs/reference/tiles/group-delay) | The faster the phase turns, the later that frequency arrives. **Group Delay** shows it in milliseconds. |
| [Try a gentler slope](https://simulator.00aud.io/docs/guides/eq-and-filters#slopes) | A 12 dB/oct high-pass turns the phase less than a 24 dB/oct one at the same frequency. |
| [Compare two designs](https://simulator.00aud.io/docs/guides/compare) | Each visible enclosure draws its own line in its colour, so you can see where their phase parts company. |

## Ask your AI

**Ask your AI**

Your assistant runs the same solver on your own designs through the 00 Simulator connector.

> Using 00 Simulator, try a 25 Hz Butterworth 24 dB/oct high-pass on each enclosure in my open workspace without saving, and tell me how much it turns the phase at 40, 80 and 120 Hz. Then put the Phase tile on screen.