# 15 L sealed subwoofer

> Change the driver and power in a live 15 L sealed box, then compare bass output, system Q and cone excursion.

Source: https://simulator.00aud.io/docs/cookbook/sealed-subwoofer

Start with the Dayton Audio DCS205-4 in a 15 L sealed box. Compare its output at 40 Hz with the travel it needs, then try another driver in the same space.

- **Box:** 15 L sealed, net air volume
- **Starting drive:** 50 W, equivalent to 14.0 V RMS
- **Conditions:** Half space at 1 m, 0.1 Ω series resistance

## Keep the first experiment simple

A sealed box removes port tuning and duct geometry from the experiment. The question becomes whether the driver and available air volume give useful extension and enough output before travel becomes the limit.

At the starting power, this driver has Qtc 0.62, system resonance 54.0 Hz and F3 65.8 Hz. It produces 94.5 dB at 40 Hz under these modelled conditions.

## Try the model

_Figure: Interactive sealed-box example with driver and power controls, SPL and cone-excursion graphs._

The box stays at 15 L. Changing the driver is a comparison, not a recommendation that every driver belongs in this volume.

Driver comparison at 50 W in 15 L, half space at 1 m.

| Driver | Qtc | F3 | SPL at 40 Hz | Peak travel, displayed band | Xmax |
| --- | --- | --- | --- | --- | --- |
| Dayton Audio DCS165-4 | 0.46 | 76.6 Hz | 91.6 dB | 12.8 mm | 6.0 mm |
| Dayton Audio DCS205-4 | 0.62 | 65.8 Hz | 94.5 dB | 7.9 mm | 8.8 mm |
| Dayton Audio DCS255-4 | 0.82 | 69.4 Hz | 94.5 dB | 4.3 mm | 8.3 mm |

## Read both graphs

1. **Increase the power.** Compare 1 W with 100 W. The level at 40 Hz changes from 77.5 to 97.5 dB. F3 stays at 65.8 Hz: more drive changes level, not the alignment.
2. **Watch the travel.** At 50 W the displayed band peaks at 7.9 mm near 10.1 Hz, against this driver’s 8.8 mm Xmax. At 100 W the peak becomes 11.2 mm. Check the whole operating band.
3. **Swap the driver.** The box stays the same, but its system Q, resonance and travel change. Compare the bass level and travel together instead of choosing by nominal cone size alone.

> **Look below the visible graph** The graph starts at 10 Hz; the solver continues to 5 Hz. At the starting power the full simulation peaks at 9.9 mm near 5.0 Hz. Include a suitable high-pass filter in the final design if the source contains unwanted energy that low.

## Before you cut wood

- Build enough internal space for 15 L of air plus the driver, bracing and anything else inside the cabinet.
- Verify the exact driver data and Xmax. A linear-travel rating is not a guarantee about distortion or mechanical noise.
- Use the final filter settings and intended drive in the main simulator. Check **Max SPL (dB)** and **Headroom** as well as the two graphs here.
- Measure impedance and acoustic response on the finished box. Room gain, cabinet vibration and sample variation are outside this example.

- [Open the starting design](https://simulator.00aud.io/app?template=sealed&driver=Dayton%20Audio%20DCS205-4&power=50): Continue with the same driver, volume and power in the simulator.

**Ask your AI**

> Using 00 Simulator, inspect my selected sealed enclosure at its current power. Report system Q, F3, cone excursion and the limiting frequencies. Compare a lower power and a high-pass filter without saving either change.