Workshop4 min read
Exporting Cut Files That Actually Cut
A cut sheet a person reads and a DXF a machine cuts are not the same file. Here is what a CNC or laser actually needs, and where hand-drawn exports go wrong.
Blog
From the workshop
Guides, updates, and deep dives on subwoofer enclosure design.
Build
Bracing a Subwoofer Enclosure: Where Panel Resonance Comes From
Panel resonance colours your bass and wastes power moving the box instead of the air. Bracing fixes it, but only if you brace the right panels the right way.
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Education
Reading an Impedance Curve: What the Peaks Tell You
The impedance curve is the most information-dense plot in subwoofer design. Learn to read its peaks and you can diagnose tuning, leaks, and driver behaviour at a glance.
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Build
Double Baffle vs Single Baffle: When the Extra MDF Is Worth It
A double baffle stiffens the front panel and deepens the driver mount, but it is not free volume or free strength. Here is when it earns its place and when it is wasted.
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Guide
Aero Port vs Slot Port: Which Should You Use?
Round aero ports and rectangular slot ports both tune a vented box, but they fold, flare, displace volume, and chuff differently. Here is how to pick the right one for your build.
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Guide
How to Wire a Dual Voice Coil Subwoofer (Series vs Parallel)
DVC subs let you choose your final impedance. Here is exactly how series and parallel wiring change the ohm load, how to match it to your amp, and what it does to power.
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Guide
SPL vs SQ: Designing a Subwoofer Box for Loudness or Accuracy
Maximum loudness and accurate bass pull the design in opposite directions. Here is how enclosure type, volume, and tuning trade off - and how to let the optimizer find your balance.
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Guide
10 Common Subwoofer Box Design Mistakes (and How to Avoid Them)
Most disappointing subwoofer builds fail for the same handful of reasons. Here are the ten most common enclosure design mistakes and the fix for each.
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Guide
Why Is My Subwoofer Not Loud? A Systematic Troubleshooting Guide
A built-and-installed subwoofer that sounds weak almost always has one of nine causes. Here is how to diagnose it in order, from wiring to phase to box tuning.
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Education
Subwoofer Phase and Polarity: Stop Your Bass Cancelling Itself
Polarity and phase are different controls that both fix the same problem: a subwoofer cancelling with your front speakers. Here is what each does and how to set them.
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Design Guide
4th Order Bandpass Subwoofer Box: Design Guide
A 4th order bandpass can deliver more SPL in the bass band than any other enclosure type for the same driver. It is also the easiest to design badly.
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Tools
Best Subwoofer Box Calculator Apps in 2026
There are about a dozen subwoofer box calculators online. Some calculate volume correctly. Fewer give port dimensions. Almost none show a frequency response.
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Education
Car Audio Subwoofer Box Basics: What You Need to Know Before You Build
Before you pick up a saw, understand three things: box volume determines frequency response, port tuning determines bass peak, and your driver's T/S parameters determine which designs work.
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Build Guide
How to Build a Subwoofer Box: A Step-by-Step Guide
Complete step-by-step guide to building a subwoofer enclosure, from calculating target volume and generating a cut sheet to assembly sequence, sealing, and post-build verification.
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Build Guide
MDF Thickness for Subwoofer Boxes: Does It Actually Matter?
Most guides say use 3/4 inch MDF. Some say 1 inch. Here is what panel resonance data actually says about when thickness changes anything audible.
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Physics
Port Length Calculator: The Helmholtz Equation Behind the Numbers
Online port length calculators give you a number. This post explains where that number comes from - and why the end correction term matters more than most builders realise.
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How-To
Sealed Subwoofer Box Calculator: How to Get the Volume Right
The sealed enclosure calculation comes down to one formula and two driver parameters. Most builders get it wrong because they calculate gross internal volume when the formula needs net acoustic volume.
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Education
Sealed vs Ported Subwoofer Box: Which Is Right for Your Build?
The sealed vs ported debate never ends. Ported is louder in the bass band. Sealed is more accurate. The right choice depends on your driver, your box volume constraints, and what you are trying to achieve.
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Setup
Subsonic Filter Settings for Subwoofers: The Complete Guide
A subsonic filter is mandatory for any ported subwoofer - but the correct frequency is based on your port tuning, not your driver's Fs. Most setups have it wrong.
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Vehicle Guide
Toyota Hilux Subwoofer Box: Enclosures for Every Cab
The Hilux rear cabin space varies significantly between single, extra, and double cab configurations - and the right enclosure type for each is different.
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Education
Thiele-Small Parameters Explained: What the Numbers Mean
Fs, Qts, Qes, Qms, Vas, Xmax, Re, Le - every driver spec sheet lists these. Here is what each one means and which ones actually determine how your enclosure should be designed.
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Tools
WinISD vs RokketBox: Which Subwoofer Simulator Should You Use?
WinISD is still the most-cited free subwoofer simulation tool. It is also Windows-only, last updated in 2016, and requires driver library setup before your first simulation runs.
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Education
Why Your Subwoofer Box Peaks Above the Tuning Frequency
You tuned your ported box to 32 Hz but the SPL peaks at 40 Hz. Here’s why that’s normal - and what tuning frequency actually controls.
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Guide
How to Calculate Subwoofer Box Volume
The math behind subwoofer enclosure volume - from Thiele-Small parameters to optimal litres, and why online "recommended volume" charts miss the point.
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Education
Port Velocity: What Happens When It’s Too High
Port velocity above 17 m/s causes turbulence, chuffing noise, and group delay anomalies. Here’s what’s happening and how to fix it.
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Guide
Sealed vs Vented vs Bandpass: Which Enclosure is Right?
A practical comparison of the three enclosure types supported by RokketBox, and when to choose each.
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Education
Understanding Thiele-Small Parameters
What Fs, Qts, Vas, and the rest actually mean - and why they matter for your box design.
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Announcement
Welcome to RokketBox
Introducing RokketBox - a free, browser-based tool for designing and optimizing subwoofer enclosures.
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Engineering
Port Routing Collision Detection: Fitting Ports in Real Boxes
The math behind routing a port inside an enclosure without it crashing into the driver, bracing, or itself - a problem most tools ignore.
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Engineering
Motor Force (BL) Isn't Constant: What Happens at High Excursion
Your driver's spec sheet gives one BL number. In reality, BL drops as the cone moves — and this changes everything about high-excursion performance.
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Engineering
Latin Hypercube Sampling: Why We Don't Use Brute Force
How quasi-random sampling explores a design space more efficiently than grid search — and why that matters for subwoofer optimization.
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Engineering
The Leach Model: Accurate Voice Coil Inductance Modelling
Most calculators model voice coil inductance as an ideal inductor - or ignore it entirely. The Leach semi-inductance model gets it right.
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Engineering
Inside the RokketBox Simulation Engine
Under the hood of RokketBox's simulation engine: circuit-domain modelling, radiation loading, and why dense frequency sweeps matter.
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Guide
What Size Port for My Subwoofer?
How to calculate the right port cross-sectional area for your subwoofer - and why the answer depends on more than just driver size.
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Education
Voice Coil Heating and Power Compression
Your subwoofer loses output as it heats up. Power compression means 1000W in does not mean 1000W of sound - here is why, and how much you actually lose.
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Guide
Kerf Bending MDF for Subwoofer Ports
How to calculate kerf slot spacing, depth, and layout for bending MDF into curved subwoofer ports - and why kerfed ports can outperform straight tubes.
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Guide
How to Tune a Ported Subwoofer Box
Step-by-step guide to choosing and setting the tuning frequency for a vented subwoofer enclosure - from driver parameters to final verification.
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Education
Cabin Gain: The Free Bass You're Not Accounting For
Your car cabin boosts bass by 10 dB or more in the deep bass below about 30 Hz. If your box design ignores cabin gain, your tuning is wrong for your actual listening environment.
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Guide
Subwoofer Box Dimensions: Getting the Ratio Right
Box shape affects standing waves, panel resonance, and build practicality. Here is how to choose the right length, width, and height ratios.
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Guide
Port Length Calculator: The Math Behind Tuning
How port length, area, and box volume interact to set your tuning frequency - the actual equations, not just a calculator.
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Education
Group Delay Explained: What You Hear vs What You Measure
Group delay numbers look scary on paper but most of it is inaudible. Here is what group delay actually is, what thresholds matter, and when to stop worrying.
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Education
Helmholtz Resonance: The Physics Inside Your Subwoofer Box
The mass-spring system hiding inside every ported enclosure - how a tube of air and a box of air create the resonance that defines your bass.
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