# Transfer Function Magnitude > How to read the Transfer Function Magnitude tile in 00 Simulator: each design’s response shape against its own reference, with power taken out. Source: https://simulator.00aud.io/docs/reference/tiles/transfer-function Each design’s response as dB above or below its own reference level. Power and listening distance drop out, so this is the tile to compare the shape of different boxes on, whatever their sensitivity. - **Shows:** Each design’s response in dB against its own reference level, so power and listening distance drop out and only the shape is left. - **Healthy when:** The curve holds near 0 dB through the band you want and rolls off smoothly below it, with no peak you did not plan. - **If it is not:** Change the box, tuning or EQ for the shape, then read the level on the SPL tile. ## The tile _Figure: The Transfer Function Magnitude tile for the vented example, with the dashed 0 dB reference line._ 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. | Curve | Reference | At 30 Hz | | --- | --- | --- | | Vented example | 88.1 dB SPL at 1 W | −3.2 dB | Here the vented example’s 0 dB is 88.1 dB at 1 W, and at 30 Hz it is −3.2 dB. At 200 W the SPL is higher but this curve is the same: the largest difference is 0.0 dB. - [Open this example](https://simulator.00aud.io/app?template=vented) in the simulator and add the tile, then hover the curve for the level at a frequency. - Each visible enclosure draws its own curve in its colour, each against its own reference. The dashed line is 0 dB. - For most enclosures, 0 dB is the average level over the top end of the simulated range: its highest 12 % of frequencies, on the chart’s log scale. - For a bandpass box, which falls away at both ends, 0 dB is its peak. ## How to read it - Below 0 dB is how far the bass has fallen compared with the top of the range. Above 0 dB is a hump. - Boxes with different drivers or power line up near 0 dB, so the tile shows which one keeps its level deeper, not which is louder. - It is the same curve as [SPL (dB)](https://simulator.00aud.io/docs/reference/tiles/spl) moved up or down, EQ and all. Read the level there, and the limits on [Excursion](https://simulator.00aud.io/docs/reference/tiles/excursion) and [Max SPL (dB)](https://simulator.00aud.io/docs/reference/tiles/max-spl). - The F3 markers on the SPL tile measure from the loudest octave, not from this 0 dB, so the two can differ a little on a curve that is not flat at the top. ## Three shapes The sealed, vented and bandpass examples: three drivers and three powers, on one scale. _Figure: The sealed, vented and bandpass examples on the Transfer Function Magnitude tile._ The sealed example (Dayton Audio DCS205-4, 15 L), the vented example (Ciare 12.00SW, 55 L at 32 Hz) and the bandpass example (B&C 18SW115), half space, 1 m. Simulated when this page was built. | Curve | At 30 Hz | At 60 Hz | 0 dB is | | --- | --- | --- | --- | | Sealed example | −11.8 dB | −3.2 dB | the top of the range | | Vented example | −3.2 dB | −2.0 dB | the top of the range | | Bandpass example | −8.8 dB | 0.0 dB | its peak | - The sealed box rolls off early and gently: −11.8 dB at 30 Hz. - The vented box holds its level down to its 32 Hz tuning and then falls fast: −3.2 dB at 30 Hz. - The bandpass box peaks at 0 dB and falls away on both sides: −8.8 dB at 30 Hz. > **Horns read high** A horn uses the same top-of-range reference as a sealed or vented box. Most horns are well down by the top of the range, so the passband sits above 0 dB, often above the top of the axis. In the tapped horn example, simulated to 500 Hz for this page, it reaches +15.2 dB. **Upper frequency** in **Settings › Display…** sets how far the solver runs, so it moves this reference too. Read a horn’s level on [SPL (dB)](https://simulator.00aud.io/docs/reference/tiles/spl). ## What moves it | Change | Effect | Why | | --- | --- | --- | | Power, 1 W to 200 W | None (0.0 dB) | The SPL and its reference rise together. | | Listening distance | None | It moves every frequency by the same amount. | | Radiation space | None for a box | A box moves by the same amount at every frequency. A horn’s shape changes, because the walls and floor change how its mouth radiates. | | A 25 Hz high-pass, 24 dB/oct | −10.1 dB → −13.2 dB at 25 Hz | EQ is in the curve, as on the SPL tile. | | Box size, tuning or enclosure type | The shape | This is what the tile is for. | | **Upper frequency** | Can shift the whole curve | The reference is the top of the simulated range. | ## Settings and controls | Control | Where | What it does | | --- | --- | --- | | **EQ** | Tile header | Edits the selected enclosure’s filters on the chart. **Exit** leaves. | | **Y-axis settings** | Tile header | Shows −30 to +5 dB in 5 dB steps, in **Auto** and **Manual** alike. For more room, type a **Min** (down to −80 dB) and **Max** in **Manual**. | | **Add filter**, **Add note** | Right-click the chart | A filter, or a note, at the frequency you clicked. | ## What to try | Try | What it changes | | --- | --- | | [Compare shapes, not levels](https://simulator.00aud.io/docs/guides/compare) | A quiet design and a loud one both sit near 0 dB here, so you see only how each box rolls off. | | [Try a high-pass](https://simulator.00aud.io/docs/guides/eq-and-filters) | Filters show here as they do on **SPL (dB)**: click **EQ** in the tile header, or right-click the chart and choose **Add filter**. | | [Read horns on SPL](https://simulator.00aud.io/docs/reference/tiles/spl) | A horn’s passband can sit well above 0 dB on this tile. **SPL (dB)** shows its real level. | ## Ask your AI **Ask your AI** Your assistant runs the same solver on your own designs through the 00 Simulator connector. > Using 00 Simulator, simulate my open workspace and compare the response shape of each enclosure regardless of its level: how many dB each is below its own passband at 25, 35 and 50 Hz. Then put the Transfer Function Magnitude tile on screen.