Cookbook

Cookbook · Vented

Vented 12-inch subwoofer

Use the Ciare 12.00SW in the 55 L vented example to explore three linked decisions: tuning, port area and low-frequency protection. A deeper response is only useful if the port fits and the cone stays within its limits.
Starting box
55 L net, tuned to 32 Hz
Starting port
One 10 cm round port, 35.6 cm long
Comparison conditions
100 W, half space at 1 m

Start with the example#

  1. 1

    Open the starting design

    Open the vented example, at 100 W. Keep its driver and volume fixed for this comparison.
  2. 2

    Read the response and its costs

    Compare SPL (dB), Excursion and Port Velocity. The cone moves least near tuning, while the port moves much of the air. Below tuning, output falls and cone travel rises.
  3. 3

    Keep a reference

    Use Duplicate to keep the original before changing the copy. Match input power and environment when comparing.

Tune and size the port together#

Start from the vented exampleA 55 L box tuned to 32 Hz through one 10 cm port, at 100 W. The grey line is an unchanged copy. Around the tuning, the air in the port passes the dashed 17 m/s warning line.
Schematic
Simulating…
SPL (dB)
Simulating…
Port Velocity
Simulating…

The app’s controls lower Tuning to 28 Hz, then change Number of ports to two. The original response stays visible for comparison.

DesignF3Each port’s lengthPeak port speedPeak cone travel
32 Hz, one port30.3 Hz35.6 cm20.1 m/s at 30.1 Hz15.0 mm
28 Hz, one port29.6 Hz48.3 cm18.6 m/s at 26.1 Hz15.2 mm
28 Hz, two ports29.6 Hz102.6 cm9.3 m/s at 26.1 Hz15.2 mm
All at 100 W over 10–400 Hz. The port warning is 17 m/s; the driver’s Xmax is 13.5 mm.

A lower tuning changes the response shape and needs a longer port. Increasing the total port area reduces air speed, but adds still more length at the same tuning. Check Port length and Gross volume before deciding the change is practical.

Protect the cone below tuning#

Now double the drive to 200 W on the 28 Hz design with two ports. Compare it with a 28 Hz fourth-order Butterworth high-pass. The filter reduces low-frequency output as well as travel.

Excursion with and without a high-pass filter

mm

  • No filter21.5 mm at 10 Hz
  • 28 Hz high-pass5.6 mm at 40 Hz
Ciare 12.00SW, 55 L tuned to 28 Hz, two 10 cm ports, 200 W, half space at 1 m. Simulated when this page was built.

Across 10–400 Hz, peak travel changes from 21.5 mm at 10.0 Hz to 5.6 mm at 40.2 Hz. Compare that with 13.5 mm Xmax, then inspect the filtered SPL and port speed too. This is a filter comparison, not a certified operating limit.

Add the intended High-pass in the enclosure’s filter controls and check Max SPL (dB) and Headroom. A filter does not remove the need to check the thermal limit and amplifier load. EQ and filters explains the controls.

Before you cut wood#

  • Allow for the air volume, ducts, driver displacement and bracing inside the walls.
  • Use end corrections that match the physical port ends. Keep enough clearance around the openings and check the duct’s first resonance against the operating band.
  • Save the final driver, port, filters and power together, then measure the finished tuning and response.
  • If the required ports cannot fit, compare a larger box or a passive radiator design instead of accepting a noisy port.

Ask your AI

Using 00 Simulator, compare my selected vented enclosure with two ports and a lower tuning without saving. At its current power, report the SPL changes, port lengths, peak port air speed and peak cone excursion. Then compare a high-pass filter and explain the output it gives up.
or open it inClaudeChatGPT

Connect your assistant so it can open your designs.

VentedPorts and end correctionFix a noisy portHeadroom