SPL Graph

How to read the SPL graph, including frequency response, EQ, cutoff annotations, baffle-step markers, and port resonance markers.

Direct answer

The SPL graph shows predicted sound pressure level across frequency for each visible enclosure at the current power, radiation, distance, and EQ settings.

What it measures

• SPL in dB over the simulator frequency range.
• Optional F3, F6, F10, or custom cutoff annotations.
• Optional baffle-step transition markers and port resonance markers where those simulations apply.

Why it matters

• It is the main response-shape view for extension, passband smoothness, and EQ impact.
• It shows how enclosure tuning changes output distribution across frequency.
• It helps compare sensitivity and extension tradeoffs between designs.

How to read it in 00 Simulator

• Look at the whole response shape before focusing on cutoff points.
• Use cutoff annotations as landmarks, especially when comparing sealed and vented alignments.
• Treat deep notches, sharp peaks, or response features near port resonance as prompts to inspect the enclosure setup.

What good, warning, and bad usually look like

Good

The response supports the intended bandwidth without relying on extreme boost.

Warning

A desirable low cutoff is paired with a large ripple, narrow peak, or tuning artifact.

Bad

The response shape only works because EQ or tuning pushes other physical limits too hard.

Common false conclusions

• A flatter simulated curve is not automatically the best in-room or outdoors result.
• A lower F3 is not the only measure of useful bass.
• The SPL graph alone does not show whether the design can survive the required power.

App behavior notes

• The UI graph id is `spl`; the internal graph key is also `spl`.
• SPL supports the EQ overlay in the simulator.
• When baffle step is enabled, the baffle-step frequency marker is shown by default and can be hidden in the SPL F-point settings.