User Guide

A complete reference for using the Enclosure Simulator. This guide assumes familiarity with Thiele-Small parameters and enclosure design concepts.

1. Click "Add Enclosure" in the left sidebar
2. Select enclosure type (sealed, vented, or passive radiator)
3. Set box volume and tuning parameters
4. Choose a driver from the database or add a custom driver
5. Review graphs and simulation results
6. Adjust parameters and compare configurations

The simulator updates in real-time as you change parameters. All data is stored locally in your browser.

The interface is divided into three main areas:

Left sidebar: Enclosure list

Shows all enclosures in your project. Each enclosure can contain multiple driver configurations for comparison.

• Enclosure controls: Name, type, volume, tuning (vented), passive radiator selection
• Configuration list: Each configuration represents one driver in the enclosure
• Visibility toggles: Show/hide individual configurations on graphs
• Context menu: Duplicate, delete, or manage enclosures and configurations

Click an enclosure or configuration to select it. The right sidebar updates to show details for the selected item.

Center: Graphs

Displays simulation results for all visible configurations. Available graphs:

• SPL: Frequency response at 1 meter
• Impedance: Electrical impedance magnitude and phase
• Excursion: Cone excursion with Xmax limit
• Max SPL: Thermal and mechanical SPL limits
• Port Velocity: Air velocity in port (vented only)
• PR Excursion: Passive radiator excursion (PR only)
• Group Delay: Phase-derived group delay

Use the graph selector dropdown to choose which graphs to display. Hover over graphs to see values at specific frequencies. Click to lock the cursor at a frequency.

Each graph has a settings icon for customizing axis ranges (auto or manual scaling).

Right sidebar: Configuration details

Shows details and controls for the selected configuration:

• Driver selection: Choose from database or add custom driver
• Driver count: Number of identical drivers (1-50)
• Driver specifications: T/S parameters for selected driver
• EQ/Filters: Add high-pass, low-pass, or parametric EQ
• Environment: Radiation space settings
• Results: F3, F10, sensitivity, max SPL, excursion summary

Bottom bar: Global settings

Controls that affect all simulations:

• Input power: Power level for SPL and excursion calculations (default 1W)
• Advanced: Series resistance (cable/amp output impedance), calculated driver voltage

Sealed

Parameters:

• Volume (0.01 L to 100,000 L)
• Effective volume adjustments (driver displacement, bracing)

Results:

• System Qtc is displayed in results panel
• Typical target: Qtc = 0.5-0.7 for maximally flat response
• Lower Qtc = flatter response but earlier roll-off
• Higher Qtc = extended response with slight peak before roll-off

Vented (ported/bass reflex)

Parameters:

• Volume (0.01 L to 100,000 L)
• Tuning frequency (Fb): Target resonance frequency of port and box
• Port shape: Circular or rectangular
• Port diameter/width (1 mm to 10,000 mm)
• Port height (rectangular only, 1 mm to 10,000 mm)
• Number of ports (1-20)
• End corrections: Inside (default 0.85) and outside (default 0.6)

The simulator calculates required port length automatically based on tuning frequency. Port length is shown in the results panel.

Alignment guidelines:

• QB3 (quasi-Butterworth): Tune to 0.8 × Fs, flattest response
• BB4 (Butterworth): Tune to Fs, slight extension, gentle peak
• C4 (Chebyshev): Tune above Fs, maximum extension, larger peak

These are starting points. Use the graphs to evaluate the actual response.

Passive radiator

Parameters:

• Volume (0.01 L to 100,000 L)
• Passive radiator selection (from PR database)
• Number of PRs (1-50)
• Added mass: Additional mass added to PR for tuning (0-10 kg)

Passive radiator designs work similarly to vented boxes but replace the port with a driven radiator (unpowered cone). Tuning is controlled by adjusting the added mass on the PR.

The PR excursion graph shows how far the passive radiator moves. Make sure it stays within the PR's Xmax limit.

Using the driver database

The simulator includes 100+ drivers with measured T/S parameters. Use the search box to filter by brand or model.

Drivers are organized by brand (Dayton Audio, B&C, Faital, etc.). Parameters are taken from manufacturer datasheets.

Finding drivers in the wild

Need to find specifications for a driver not in the built-in database?

Loudspeaker Database (.wdr files):

loudspeakerdatabase.com is the primary source for professional driver specifications. It contains thousands of drivers with complete T/S parameters in .wdr (Woofer Data Record) format.

• Search for your driver model
• Download the .wdr file
• Import into the simulator or manually enter the T/S parameters

Manufacturer Datasheets:

• Check the driver manufacturer's website for specification sheets
• Look for Thiele-Small parameters section
• Enter parameters manually when adding a custom driver

Adding custom drivers

To add a driver not in the database:

1. Click "Add new driver" in the driver selector
2. Enter brand and model name
3. Fill in T/S parameters from the driver's datasheet
4. Click "Create Driver"

Required parameters: Fs, Qts, Qes, Qms, Vas, Re, Le, Bl, Mms, Cms, Rms, Sd, Xmax, Pe. The tool will calculate derived parameters automatically where possible.

Custom drivers are stored locally and appear in your driver list with a "Custom" tag.

Editing driver parameters

Click the edit icon next to a driver's specifications to modify its parameters. You can:

• Save as new: Creates a new custom driver with your changes
• Overwrite: Updates the existing driver (only available for custom drivers)

This is useful for tweaking parameters to match measured values or creating variants (e.g., testing sensitivity to parameter variation).

Multiple drivers

Set driver count to simulate multiple identical drivers in one enclosure. The simulator accounts for:

• Combined Sd (total radiating area)
• Reduced electrical impedance (parallel connection)
• Reduced excursion per driver (shared load)
• Increased SPL output (+6dB per doubling)

Driver count applies to acoustic coupling (same enclosure). It does not model separate enclosures or different drivers.

Each configuration can have filters applied to shape the frequency response. Filters affect SPL, excursion, and port velocity calculations.

Filter types

High-pass filter

• Attenuates frequencies below the cutoff
• Slopes: Butterworth 2nd/4th order, Linkwitz-Riley 2nd/4th order
• Use to protect the driver from over-excursion at low frequencies
• Typically set slightly below F3 to extend safe operating range

Low-pass filter

• Attenuates frequencies above the cutoff
• Same slope options as high-pass
• Use for crossovers in multi-way systems

Parametric EQ

• Boost or cut at a specific frequency
• Parameters: Center frequency, gain (-15 to +15 dB), Q (0.1 to 16)
• Use to flatten response peaks or compensate for room modes

Adding filters

1. Select a configuration
2. Expand the "EQ / Filters" section in the right sidebar
3. Click "Add Filter"
4. Choose filter type and set parameters

Filters can be enabled/disabled individually with the checkbox. Drag the filter rows to reorder (order matters for cascaded filters).

Filter considerations

• High-pass filters reduce excursion dramatically but also reduce output below the cutoff
• Steeper slopes (4th order) provide more protection but affect phase response
• Linkwitz-Riley filters are designed for crossovers (summed response is flat)
• Parametric EQ can't fix enclosure design problems, only fine-tune response

SPL graph

Shows on-axis frequency response at 1 meter for the specified input power.

• Y-axis: dB SPL (sound pressure level)
• X-axis: Frequency (Hz, logarithmic scale)
• Smooth response in passband is desirable
• Roll-off rate depends on enclosure type and alignment

Sealed boxes roll off at 12 dB/octave below F3. Vented boxes are flatter near tuning but roll off at 24 dB/octave below Fb.

Max SPL graph

Shows maximum SPL before reaching thermal (power handling) or mechanical (Xmax) limits.

• Red line: Mechanical limit (Xmax exceeded)
• Blue line: Thermal limit (Pe exceeded)
• The lower of the two limits defines max SPL at each frequency

Typically, mechanical limits dominate at low frequencies (high excursion), while thermal limits dominate at higher frequencies.

Impedance and phase

Shows the electrical impedance magnitude (primary line) and phase (secondary line).

• Sealed: One peak at Fs
• Vented: Two peaks (driver resonance and port resonance), with minimum between them
• Minimum impedance determines amplifier load
• Phase indicates reactive component (capacitive or inductive)

Voice coil inductance (Le) causes impedance to rise at high frequencies.

Excursion

Shows peak cone excursion at the specified power level.

• Red horizontal line: Driver's Xmax (linear excursion limit)
• Excursion peaks at low frequencies and drops off higher up
• Vented boxes have much lower excursion near the tuning frequency
• High-pass filters dramatically reduce excursion below cutoff

If excursion exceeds Xmax, either reduce power, increase box size, add a high-pass filter, or choose a driver with higher Xmax.

Port velocity (vented only)

Shows air velocity in the port. High velocity causes turbulence and audible "chuffing" noise.

• Conservative target: Keep under 17 m/s for minimal noise
• Realistic tolerance: With well-designed, flared round ports, 25-40 m/s is often acceptable
• Port dimension ratio: Aim for length to diameter less than 6:1
• Peaks occur near the tuning frequency
• Reduce by using larger diameter ports, multiple ports, or reducing power

Results summary

The results panel shows key metrics:

• F3: -3dB point (half-power frequency)
• F10: -10dB point
• Sensitivity: SPL at 1W/1m (averaged over passband)
• Max SPL: Peak SPL in passband before hitting limits
• Peak excursion: Maximum excursion in the simulated range
• Qtc (sealed only): System Q factor
• Fb/Port length (vented only): Calculated port dimensions

Radiation space

Speakers radiate into different solid angles depending on their placement. This affects SPL.

• Full space (4π): Free-field, no boundaries (outdoor, anechoic chamber)
• Half space (2π): Against one boundary (on floor, against wall). +6dB.
• Quarter space (π): Two boundaries (floor + wall corner). +12dB.
• Eighth space (π/2): Three boundaries (room corner). +18dB.

Choose the radiation space that matches your intended placement. The default is half space (most common for subwoofers on the floor).

Input power

Sets the power level for SPL and excursion calculations. Default is 1W (reference sensitivity measurement).

Use the slider or input field to set power from 0.1W to 1000W. The graphs update in real-time.

Series resistance (advanced)

Models cable resistance and amplifier output impedance. Default is 0.1Ω.

Higher values reduce damping (effective Qts increases), which can affect response shape. Most users can leave this at default.

You can share your designs with others via a link.

1. Click the share icon in the header
2. Select which enclosures and configurations to include
3. Click "Generate Share Link"
4. Copy the link and send it

The link contains a snapshot of your design (drivers, enclosures, settings). Recipients can view the simulation and import it into their own simulator.

Share links are read-only. Changes made by the recipient don't affect your original design.

Workflow suggestions

• Start with recommended alignments (QB3, BB4, etc.) then fine-tune based on graphs
• Use multiple configurations to compare drivers in the same box
• Create duplicate enclosures to compare different box sizes
• Lock graph cursor at key frequencies (Fb, F3) to compare designs
• Use the Max SPL graph to identify limiting factors (thermal vs mechanical)

Common mistakes

• Ignoring excursion: High SPL doesn't mean usable SPL if you exceed Xmax
• Port velocity: Small ports in high-output designs cause noise
• Box too small: Results in poor response or high distortion
• Wrong alignment: Using high-Qts drivers in vented boxes or vice versa
• Unrealistic power: Testing at 500W when your amp delivers 100W

Simulation accuracy

This simulator uses lumped-parameter modeling, which is accurate at low frequencies (below ~200-300 Hz) in the linear range.

Real-world factors not modeled:

• Cabinet resonances and panel vibration
• Port and enclosure losses (partially modeled with Ql and Qp)
• Room acoustics, boundary reinforcement, standing waves
• Nonlinear behavior at very high power (parameter modulation)
• Cone breakup and off-axis response

Use simulation to narrow down designs and understand trade-offs. Verify with measurements if building.

Further reading

• Thiele-Small Parameters Reference
• Enclosure Types Comparison
• Simulation Limitations
• Glossary
• Technical Approach (EMC Circuit Model)