Acoustics 101 : Speaker design basics and enclosure design
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Acoustics 101 : Speaker design basics and enclosure design

How to design your own sealed or bass reflex enclosure. Follow the speaker building techniques for a great audio system.
4.5 (16 ratings)
Instead of using a simple lifetime average, Udemy calculates a course's star rating by considering a number of different factors such as the number of ratings, the age of ratings, and the likelihood of fraudulent ratings.
76 students enrolled
Created by Marius Tanasescu
Last updated 6/2017
Price: $45
30-Day Money-Back Guarantee
  • 3 hours on-demand video
  • 1 Supplemental Resource
  • Full lifetime access
  • Access on mobile and TV
  • Certificate of Completion

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What Will I Learn?
  • Design sealed speaker enclosures.
  • Design bass reflex speaker enclosures.
  • Understand how sound waves work and their characteristics.
  • Know how a speaker is producing sound and what are the speaker components.
  • Interpret the data on a speaker specification sheet.
  • Understand the pro's and con's of different enclosure types.
  • Build loudspeaker boxes which produce linear sound with minimal distortion.
View Curriculum
  • You should be passionate about audio and sound quality.
  • You need to have an understanding of mathematics at an intermediate level.
  • You should own and be able to use a PC at a basic level.
  • You need Microsoft Excel installed or other application that can open *.xlsx files.

Design an enclosure to match your preferences

The main purpose of this course is to teach you how to properly design an enclosure for your speaker. There is no such thing as "This enclosure is the best choice for this particular speaker". You have to take into consideration your application and your personal preferences. Do you want it to sound loud? Do you want it to sound deep and don't care about loudness? You want it to be as smooth and linear as possible? These are all just a few examples of questions that needs answering before you get to work. The final result will always be a compromise between the acoustical qualities of an enclosure. Only you can decide which sound qualities are more important to you and you should be the one who "moves the sliders".

Acoustics basics

This course assumes that you have minimal knowledge about acoustics, and therefore starts slowly with some basic information about sound waves, how they are created and what are their characteristics. Then moves on to how the speaker is designed and some other relevant information about acoustics. This is obviously needed for a beginner, but it's also good for an intermediate student, as I'm sure he will also find new information to make matters even more clear.

Enclosure types

Most of the common enclosure types are listed, explaining their working principle, pro's and cons for each one. But, we will focus our attention for the sealed and bass reflex enclosures. These are covered with extensive details regarding their characteristics and how to design them according to the standard alignments, or to complete custom response curves.

Modeling software

To model the response curve of the enclosure and to calculate the dimensions of the box, two methods will be used. You will receive an excel spreadsheet, that has all that you need to model a sealed or a bass reflex enclosure with minimal difficulty. It even has a chart to show you the modeled frequency response. It's basically a complete package for a beginner. The other method is by using a paid application. There are a lot of speaker design software solutions out there but I chose : "Subwoofer design toolbox". The main reasons are : it's cheap, simple, easy to understand and it has all the basic functions. If you are a beginner it's very important to start slow, otherwise you will get overwhelmed by complicated applications with extra features that will only confuse you.

This types of courses are not common and are intended only for a select niche. For this reason they are not included in the discount programs.

Who is the target audience?
  • Audiophiles who want to learn more about sound and speaker systems.
  • DIY-ers who want to build their own speaker enclosure.
  • People who built enclosures by following some speaker plans, but want to understand the design process.
  • People interested in acoustics and electro-acoustics
Compare to Other Acoustics Courses
Curriculum For This Course
37 Lectures
2 Lectures 04:37

Introduction and complete overview of the course.

Preview 01:36

How the course is structured and a quick briefing about each section.

Preview 03:01
Sound waves
5 Lectures 26:04

A visual perspective on how sound waves work.

Visualization of sound waves

How sound is created with emphasis on a speaker.

How sound waves are created

Explanation of the first three (out of 4) sound wave characteristics.

Sound wave characteristics : Amplitude, frequency, wavelength

The last sound wave characteristic : Phase.

Sound wave characteristics : Phase

With the help of a signal generator and an oscilloscope, we will see in real time how amplitude and frequency change, and how it affects the sound.

Real time sound wave analysis
Speaker design
1 Lecture 07:09

Overview on how the speaker each designed. Complete description on each component of the speaker and how they function.

Speaker design
Frequency response
3 Lectures 16:23

How to interpret a frequency response chart. What to look for, and explanation of few common response curves.

Frequency response charts

The F points on a frequency response chart : F0 , F3 and F10.

F points

What is an octave and few examples. Explanation on why the response curve is rolling off and how to interpret the steepness of the roll-off slope.

Octaves and roll-off slopes
Thiele / Small parameters
6 Lectures 16:29

Brief description of the Thiele Small parameters. The resonant frequency (Fs).

Introduction to T/S parameters, Fs

The quality factor : Q.

Qms, Qes and Qts

Compliance (Cms) and Equivalent compliance as a volume (Vas).

Cms and Vas

DC resistance (Re) and Nominal Impedance.

Re and Impedance

Maximum linear excursion (Xmax), Maximum mechanical excursion (Xmech), Effective cone area (Sd).

Xmax, Xmech and Sd

Speaker moving mass (Mmd) and Total moving mass (Mms).

Mmd and Mms
Decibel scale
1 Lecture 07:40

How sound is measured and how to compare different sound levels. Efficiency of speakers and how to interpret the numbers in the specification sheet.

Decibel scale
Enclosure types
7 Lectures 11:18

What is the purpose of an enclosure, and what do they have in common, regardless of their type.


The Infinite baffle enclosure.

Infinite baffle

The Sealed / Closer / Acoustic suspension / Air suspension enclosure.


The Bass reflex / Ported / Vented enclosure.

Bass reflex

The Bandpass enclosure.


The Transmission line or Acoustical labyrinth enclosure.

Transmission line

How an enclosure is actually a compromise between 3 qualities.

Hoffman's Iron Law
Sealed enclosure
4 Lectures 28:50

Complete explanation on how the sealed enclosure works.


Learn how to design a sealed enclosure using the included Excel spreadsheet.

Preview 06:36

Learn how to design a sealed enclosure using the designated paid application.

Design using the paid application

What are the effects of filling the box with sound dampening material.

Bass reflex enclosure
5 Lectures 33:57

Detailed explanation on how the bass reflex enclosure works.


What are box losses (QL), and how they affects the frequency response.

Box losses

Predefined alignments which you can chose when tuning the box.

Bass reflex alignments

Learn how to design a bass reflex enclosure using the included Excel spreadsheet.

Design using the Excel spreadsheet

Learn how to design a bass reflex enclosure using the designated pain application.

Design using the paid application
Box builds examples
3 Lectures 32:55

Tips and tricks on how to build a great enclosure.

Construction tips

Full detailed example and how to design a sealed box, and how to calculate the box components using the Excel spreadsheet.

Sealed enclosure design from start to finish

Full detailed example on how to design a bass reflex box, and how to calculate the box components using the designated paid application.

Bass reflex enclosure design from start to finish
About the Instructor
Marius Tanasescu
4.5 Average rating
16 Reviews
76 Students
1 Course
Owner of

Hi! My name is Marius and I'm from Romania. I majored in economics and computer science, and have a college and masters degree in this field. Regarding the audiophile part of me, I started to intensely study this area since several years ago. It’s difficult to get a college degree in this field, since there are only a few universities around the world which have this specialization (from what I know, In Europe, there is a famous one in Denmark, and another in UK). The closest specialization would be electrical engineering, but I wanted something a bit more specific. So instead of going abroad for studies, I decided to study at home in my free time. The things I find important or interesting I write them down on my blog. Here is a list of books I have read, some of them even twice or three times :

1.       Master Handbook of Acoustics by F. Alton Everest, Ken Pohlmann (McGraw Hill Professional, 2009)

2.       Introduction to Sound System Design and Electro-Acoustics by Peter Swarte (DHvV Interactive Lab, 2014)

3.       Audio Engineering Explained by Douglas Self (Taylor & Francis, 2012)

4.       Electroacoustics by Mendel Kleiner (CRC Press, 2013)

5.       The Audio Expert: Everything You Need to Know About Audio by Ethan Winer (Focal Press, 2012)

6.       Electroacoustic Devices: Microphones and Loudspeakers 1st Edition by Glen Ballou (Focal Press, 2009)

7.       The Complete Guide to High-End Audio 5th Edition by Robert Harley  (Acapella Publishing, 2015)

8.       Introduction to Loudspeaker Design: Second Edition by John L. Murphy (True Audio, 2014)

9.       Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms 1st Edition by Floyd Toole, (Focal Press, 2008)

10.   Basic Electricity (Dover Books on Electrical Engineering) 2nd Edition by Bureau of Naval Personnel (Dover Publications, 1970)

11.   Distortion: The Cause Of Harmonics And The Lie Of THD by Dan P. Bullard (CreateSpace Independent Publishing Platform, 2015)

12.   Audio Engineer's Reference Book 2nd Edition by Michael Talbot-Smith (Focal Press, 2001)

13.   Loudspeaker and Headphone Handbook 3rd Edition by John Borwick (Focal Press, 2001)

14.   Loudspeaker Design Cookbook 7th Edition by Vance Dickason (Audio Amateur Pubns, 2005)

15.   How to Build Speaker Enclosures by Alexis Badmaieff and Don Davis (Howard W. Sams  & Co, 1966)

16.   Making Sense of Sound by Alvis J. Evans (Prompt Publications, 1992)

17.   Designing, Building, and Testing Your Own Speaker System with Projects 4th Edition by David Weems (McGraw-Hill Education TAB, 1996)

18.   Testing Loudspeakers by Joseph D'Appolito (Audio Amateur Pubns,1998)

19.   Speaker Building 201: A Comprehensive Course in Speaker Design by Ray Alden (Audio Amateur Pubns, 2004)

20.   Loudspeaker Recipes: Book 1 : Four Two-Way Systems by Vance Dickason (Audio Amateur Pubns, 1994)

21.   The Sound Reinforcement Handbook 2nd Edition by Gary Davis and Ralph Jones (Yamaha, 1988)

The difficult part Is making sense of all the information from a text book, since there is no mentor to guide you. There is a lot of study to be done, when you have a question that needs answering. Hopefully, the courses I’m about to publish, will save you from this ordeal and give you concentrated and easy to digest information.