The Audio Pages

Articles Index

Index Last Updated - September 2024

Finding the Acoustic Centre of Loudspeakers The Secret Lives of Phone Plugs and Sockets (Jacks) ESD Protection For Electronic Circuits A short history of the development of opamps over the years Switch contact de-bouncing techniques for toggle switches and pushbuttons Lock-In Amplifiers - How to measure tiny signals swamped by noise Crossover Distortion - Why feedback can't eliminate it. Notch Filters - These useful circuits are described in detail Relays, Part III - Never as simple as people assume. Thermistor Selection For Inrush Current Mitigation

	Quick Links		Overview of Contents ...
	Feature Articles		Lamps & Energy Index, Biamping, Counterfeit Parts, PA Systems, Cinema Sound.
	Amplification		Characteristics of Amplifiers, Operating Classes, Clipping, Distortion & Feedback, Dissipation, Protection, Valves.
	Cables		Coaxial Cables, Impedance, Cable Myths.
	Test & Measurement		Meters, Multipliers, Shunts, Weighting Filters, ABX Tests, Squarewave Testing, High Impedance Circuits.
	Components & Uses		555 Timer, Buffers, Capacitors, Comparators, Fuses, Heatsinks, Relays, Transistors, FETs, Transformers & DC, Variac
	Non-Audio		Information about things that have no direct connection to audio.  Relays, Motors, Morse code, Servos, LC oscillators.
	Microphones etc.		Microphones, Mic Calibration, Audio Transformers, Reverb Tanks, Guitar Measurements.
	General Information		AM Radio, Compression, Equalisation, CD Vs SACD, Importing Gear, Morse Code, Sound, Patents, Phono Cartridges.
	Electrical Safety		Making sure that your working conditions and projects are safe is priority #1.  Please read this section.  Your life may depend on it!
	Beginners' Luck		Basics - Electronics, Amplifiers, Bridging, Opamps, Frequency, Amplitude, dB, Pots, Tools, Voltage Dividers.
	Design Guidelines		Active Filters, Amplifiers, Current Sources, Heatsinks, MOSFET Relays, Noise, Opamps, JFETs, Variable Impedance, VCAs, Balanced Circuits, Bootstrap Circuits.
	Power Supply Design		Bucking Transformers, Inrush Current, Inverters, Mains Quality, Small PSUs, Transformers, Regulators, Isolation Transformers, Mains Wiring, etc.
	Active Crossovers & Filters		Active Vs Passive, Baffle Step, Subtractive Filters, Digital Signal Processing, NTM Crossover, Phase Correction.
	Passive Crossover Design		Data to help you to provide driver impedance correction, and passive crossover design guides.
	Loudspeaker Design		Compliance Scaling, Doppler Distortion, Impedance, Failure Modes, Time Alignment, Subwoofers.
	Main Index		ESP Home Page

Feature Articles	Flag	Update
Amplifier Troubleshooting and Repair Guide  If it's broken, you may be able to fix it.  This article is designed for those new to repairs		Apr 2003
Amp Troubleshooting and Repair Guide - Part 2  Preamps, crossovers and other opamp circuits can cause grief too		Jan 2007
Lamps & Energy - All material under this heading now has a new home with a separate index		May 2015
Benefits of Bi-Amplification - Not quite magic, but close (Part I)		May 2005
Benefits of Bi-Amplification - Crossovers, tri-amping, etc.  (Part II)		May 2005
Cinema Sound ... Why Isn't It Excellent? - The cinema X-Curve (ISO Bulletin 2969) is used everywhere, but is it right?		Mar 2012
Counterfeit (Fake!) Semiconductors - Don't you be caught with fake, below spec transistors when you build a project!		Feb 2011
Distortion - What It Is And How It's Measured.  A thorough look at the techniques used to measure distortion.		Oct 2022
Education - Customised projects for schools, technical colleges and universities		Apr 2003
Power Amp Development - Power amps have changed a lot since the late 1940s, and this article covers a multitude of designs since then.		Aug 2021
Public Address Systems for Music Applications - Something of an exposé on the pitfalls of PA systems.		Oct 2009
State of Manufacturing - This article should be a mandatory read for all businessmen and politicians, a real wake-up call !  (Nothing has really changed since this was first written.)		May 2010
The Right To Repair, Projects, DIY & Sustainability - A look at many of the issues that face owners of modern equipment that can't be repaired!		April 2020
Amplification	Flag	Update
Amplifier Sound - What causes the perceived differences between amps?  Is it real or imaginary?		Apr 2000
Amplifier Classes - What is the difference between Class-A, Class-B and all the others? The characteristics of each are discussed		Nov 2017
Amplifier Power - How Much Do You Need?  Probably a lot less than you think.		Sep 2019
Capacitor Coupled Power Amplifiers - a close examination of just how capacitor coupling works in a power amplifier		Jan 2022
Class-A - a discussion of the benefits of Class-A amplifiers		Apr 2005
Class-G - One of the lesser known amp classes.  An explanation of how they work		Jan 2009
DC Servos - Tips, Traps & Applications.		Jun 2019
Class-D (PWM) Amplifiers - Theory and design concepts behind these 'new' amplifiers		Jun 2005
Class-D Amplifiers - Part II - Example circuits and some test results on various ICs		Jun 2022
Clipping Behaviour - One of the lesser known effects of amplifier clipping, and the damage it can do.		Oct 2004
Commercial Sound - 70V & 100V 'constant voltage' line public address systems.  Learn the pitfalls before you get caught.		Jun 2012
Crossover distortion is fairly well understood, but this article explains why it cannot be 'cured' with feedback.		Nov 2023
Current Drive - Current Drive Power Amplifiers & Effects on Loudspeaker Drivers.		Apr 2019
Distortion & Negative Feedback - A detailed look at the way negative feedback reduces distortion		Oct 2006
Guitar Amplifiers - Often there is little point repairing, and a replacement power amp should be considered.  This explains why.		Feb 2011
Guitar Speakers - A detailed examination of the things that go towards 'the sound' of guitar speakers.		Sep 2018
IC Power Amplifiers - Getting more power by adding booster transistors.		Jan 2019
Intermodulation Distortion - Interesting finding, symmetrical Vs. asymmetrical.  Where did the difference frequency go?		Sep 2012
Intermodulation Distortion - How it's measured, and what it does to the sound.  A description of the common IMD tests and how it's created.		Feb 2019
Musical Instrument Amplifiers - Guitar, Bass and Keyboard		Feb 2001
Single-Supply Amplifiers.  In the early days, this was the only choice for transistor amp.  It's now uncommon, but the technique should not be considered 'dead'		Jul 2023
Short Circuit Protection - Testing amplifiers to the limits ‡		Aug 2000
Soft Clipping - Is adding a soft-clip circuit worth the effort?		Apr 2006
The Need For Speed - Very high speed opamps from Texas Instruments		Aug 2001
Phase Angle Vs. Transistor Dissipation - A simplified approach to understanding Safe Operating Area		Mar 2005
Sound Impairment Monitor - Is This The Answer? - A new method to monitor distortion in real time		Sep 2000
Transistor Safe Operating Area - What is SOA, and how does it affect amplifier designs		Aug 2003
Valves & Amplifiers - A separate section that includes information about valves, myths, etc.		Jan 2010
Cables	Flag	Update
Audio Interconnect Comparisons - Using a null test methodology, this demonstrates the (virtually non-existent) differences between cables.		Oct 2003
Coaxial Cables - An introduction to coaxial (coax) cables, and where (and why) they are used		Jul 2016
Cable Impedance - Characteristic impedance, high capacitance designs and amp stability		Oct 2003
The Truth About Cables, Interconnects and Audio in General - A 'must read' article		Sep 2002
More Truth About Cables - A white paper discussing speaker cables and interconnects *‡		Jul 2001
Test & Measurement	Flag	Update
A-B Switch Box for Amplifier Comparisons - Something to offend everyone, or a great tool? ‡		Aug 2000
ABX Comparator - A true ABX system that does not need a PC or microcontroller ‡		Aug 2002
Attenuators - How to design meter (and oscilloscope) attenuators.  Definitely an article for 'hard-core' enthusiasts		Dec 2021
A-Weighting And Sound Measurements ... How the indiscriminate use of A-weighting causes grief		Sep 2012
Current Detection and Measurement - A look at the various techniques used for current monitoring (measurement) and detection.		Mar 2022
Distortion - What It Is And How It's Measured.  A thorough look at the techniques used to measure distortion.		Oct 2022
High Impedance Circuits - a collection of circuits for piezo sensors, test & measurement applications		Mar 2020
Lock-In Amplifiers - How to measure very small signal levels in the presence of high noise levels.  The techniques are usually only seen in laboratories, but you can have one too.		Jan 2024
Inrush Testing - Testing for worst-case inrush current isn't easy, but this mains switching unit allows repeatable results for transformer and electronic loads.		May 2022
Meters, Multipliers & Shunts - How to use analogue and digital panel meters		May 2006
Multimeters.  Analogue Vs. Digital with a discussion of the advantages/ disadvantages of each.  Includes insulation testers, VTVMs, FET meters, etc.		Feb 2022
Notch filters are used for distortion measurement, but they can be used for so much more.		Nov 2023
Oscilloscopes ... How They Work And Their Usage		Mar 2017
Squarewave Testing - How to interpret the changes made to a squarewave by amplifiers, tone controls and filters		Feb 2015
Components & Uses	Flag	Update
The 555 Timer - How to use it, and some example circuits		May 2015
BJT Parameters - An examination of fundamental bipolar transistor parameters and function.  (Now includes switching.)		Feb 2020
Buying Parts - A general look at the parts you need for electronics hobby work.		Oct 2007
Capacitors - What are the influences that determine the so-called 'sound' of capacitors.  Covers dielectrics, dissipation factor, etc.		Oct 2005
Comparators - The unsung heroes of electronics.  An examination of their performance and usage in circuitry.		Aug 2016
Compound vs. Darlington - An explanation of the differences between Compound (Sziklai) and Darlington pairs.		Jan 2011
DC Offset and Transformers - Many people have found that toroidal transformers growl at times.  This explains why, & how to fix it.		Mar 2008
ESR in Capacitors.  Learn what it is, how it's measured, and alternative measurement techniques.		Aug 2024
FETs (& MOSFETs) - Applications, Advantages and Disadvantages		Sep 2017
Fusing - Circuit protection, how to select the right circuit protection device to prevent serious damage ‡		Sep 2009
Follow The Leader - Voltage Followers & Buffers, the techniques and different topologies are discussed, with the advantages and disadvantages of each explained		Jul 2016
Heatsink - Build Your Own? - Yes, it can be done.  If you have the tools, you can make a heatsink as big as you'll ever want.		Feb 2006
LM358 and LM324 performance improvements - How to (almost) eliminate distortion with these versatile, low-cost opamps.		Sep 2021
Phone plugs and jacks (the secret lives thereof).  Common phone plugs and plugs, from 2.5mm to 6.35mm (¼"), with tip-sleeve tip-ring-sleeve, tip-ring-ring-sleeve types discussed.		Aug 2024
Transformers ... The Variac - One of the most useful but misunderstood pieces of workshop equipment.		Feb 2009
Non-Audio Information	Flag	Update
Contact Arc Mitigation & Prevention.  How to extend the contact life of relays and contactors		Sep 2020
Hybrid Relays - Hybrid Relays using MOSFETs, TRIACs and SCRs.  Improved performance & reliability for difficult loads		Aug 2020
Inductor/ Capacitor (LC) Oscillators.  These began the era of radio ('wireless') as we know it.  These are not directly related to audio, but are important building-blocks.		Feb 2022
Morse Code - The birth of electronic messaging, and there's more to it than you might think.		Nov 2016
Electric Motors - Types, Uses And Powering.  All common motor types are covered, but this is intended as a 'starter guide'		Jul 2020
Mathematical Functions In Electronics - Using Analogue Circuits.  Analogue computing is far from 'dead', and this article explains the principles.		Apr 2023
Relays (Part 1) - What they are, what they do, and how to get the best results from them		Dec 2014
Relays (Part 2) - Getting the best results from relay contacts & minimising arcing		Jan 2015
Relays (Part 3) - Additional information, discussing some hybrid options etc.		Oct 2023
Servos, remote control, electronic speed controls and tachometers.  Includes sample schematics and photos of typical equipment.		Jan 2018
Solid State Relays, Types & Usage.  MOSFET, IGBT, TRIAC & SCR types, with schematics and explanations of typical designs.		Nov 2020
Techniques for de-bouncing switch and/ or relay contacts, essential for interfacing with microcontrollers or logic circuits.		Feb 2024
Convert 50Hz to 60Hz, 60Hz to 50Hz, or either to 400Hz (used in aircraft).  This is an odd one, but seriously interesting.		Sep 2023
Microphones & Audio Transformers	Flag	Update
Acoustic Feedback In PA Systems, With Special Reference To Frequency Shifting		Feb 2017
Electret Microphones - Powering & Uses		Feb 2017
Guitar Voltages - How much level should you expect from electric guitar pickups?		Mar 2021
Microphones - An introduction to the different types, polar response and behaviour of microphones		Jan 2006
Microphones Part 2 - Measurement microphones, sound level meters and calibrators		Nov 2016
Microphone Splitters - How to send the output from a single mic to multiple destinations		Dec 2016
PA Transformers - 70V & 100V 'constant voltage' line public address systems.  Learn the pitfalls before you get caught.  These apply whenever any amp is connected to a transformer!		Jun 2012
Phantom Power - What It Is And How It Works.  P48 isn't really as simple as it seems at first.  This article is an in-depth look at the schemes used and how it fits together.		Oct 2021
Reverberation - The care and feeding of spring reverb tanks		Sep 2009
Transformers for 'Line Level' Audio - Extremely versatile and with many features unobtainable with active circuits, but there are traps!		Sep 2014
General Information	Flag	Update
AM Radio - Approaches to high fidelity AM broadcast band reception ‡		Feb 2006
Amplitude Modulation - How to generate AM waveforms in a simulator to test detector performance.		Aug 2016
Analogue vs Digital - Does 'Digital' Really Exist? The question isn't as silly as it sounds at first!		Apr 2017
CD, SACD and DVD-A - A Comparison of the formats in a discussion between Niklas Ladberg and Ing. Ohman (very interesting) ‡		Aug 2002
Compression In Audio - Ever wondered why some music sounds flat and lifeless, even though it's loud?		Dec 2001
Earthing Your Hi-Fi - Tricks and Techniques - How to eliminate hum without affecting safety		Dec 1999
Electrocution - How to avoid being electrocuted, what to do if the worst happens		Apr 2007
Equalisation - Equalisers, The Various Types And How They Work.  From 'Tone Controls' to Parametric EQ		Feb 2021
ESD Protection For Electronic Circuits - This isn't as simple as many circuits might imply		Jul 2024
Importing Equipment From Overseas ... Effects of Voltage & Frequency on Electronic Equipment (50/60Hz can make a big difference !)		Feb 2010
Is Sound an Illusion - An interesting discussion about our perception of sound ‡		Sep 2009
Impedance - What does it really mean?  A general discussion on impedance, damping, etc.		Jan 2005
Muting Circuits - Looking at the various options available for muting an audio signal		Oct 2015
Myths in Audio - A Look at some of the more entrenched myths, as well as some that are just too silly for words.		Jul 2012
Opamp History - a look at the development of opamps over the years.  Internal circuits are included.		May 2024
Patents - A look at the patent system, and how (or if) it affects the DIY fraternity.  ‡		May 2010
Phono Cartridge Loading - A detailed examination of the phono cartridge, and how loading affects response		Jan 2012
Why Do Tweeters Blow? - The real reason that tweeters (and other drivers) are destroyed by distortion		Jun 2012
What is Hi-Fi - A contributed article on some of the subtle aspects of Hi-Fi ‡		May 2001
What is Hi-Fi (Part II) - Continuation of 'What is Hi-Fi' explaining the idea of accuracy (amongst other things)		Mar 2004
Yellow Glue - The Enemy Of Electronics - This is a problem mainly seen by service technicians, but it may still affect products you buy		Nov 2019
Electrical Safety - Make sure that you and your loved ones are protected from harm.	Flag	Update
Dangerous Power Supplies - Plug-Pack ('Wall-Wart') power supplies are common and low cost, but don't get caught by un-certified products, some of which are seriously dangerous.		Apr 2022
Isolation Transformers - is an isolating transformer on the test bench a good safety measure or a death trap?		Dec 2016
Mains Safety - Wiring Standards, Insulation, Class I, Class II and Important Information.  Wiring of mains is poorly understood by many, and applicable standards vary worldwide.	Important!	Jun 2023
Power Supply Wiring - There are a lot of considerations for the wiring of a PSU - read about it here		Jun 2003
Beginners' Luck - The beginners' Guide to ...	Flag	Update
Electronics Basics - The Lenard Audio site has an education section that is recommended for those just starting out
Electronics - Part 1   If you are a beginner, read these two articles first.  Covers passive components - resistors, capacitors and inductors		Mar 2001
Electronics - Part 2  The resistor 'E' series (e.g. E12, E24, etc), Zener Diodes		Mar 2004
Amplifier Basics - (Introduction) How Amps Work - How amplifiers do what they do, six part series		Apr 2005
Amplifier Efficiency - Power Loss, DC voltages and current explained		Jan 2000
Bridging - How the 'Trimode' bridging system works in car power amplifiers		Oct 2002
Bulletin Boards - A guide to etiquette when posting at your favourite forum ‡		Apr 2001
Designing With Opamps I - What they are, what they do, and how they do it		May 2000
Designing With Opamps II - Audio applications, filters, crossovers, etc.		May 2000
Designing With Opamps III - More Filters, Specifications, Comparators, etc.		May 2006
Frequency, Amplitude and dB - An explanation of the terms, what they mean, and how they are applied		Dec 2006
Logic - The general principles of basic logic.  Logic families, gates, flip flops and counters.		Jan 2020
Mixing - Active Vs. Passive - The basic principles of mixing two or more signals, as used in simple applications through to multi-channel mixers.		Oct 2010
Potentiometers - what they are and how to use them in practical circuits.		Jan 2003
Power - An explanation of the derivation of PMPO in amplifiers.  Light reading, really		Jun 2000
Tools - The basics of the mechanical aspects of your hobby ‡		Mar 2001
Voltage Dividers & Attenuators - A short article describing how to design these essential circuits		Dec 2002
Design Guidelines	Flag	Update
Active Filters - Active filter design guide ... topologies, component selection, slope (dB/octave), transient response, etc.		Jan 2014
Active Filters, State-Variable - The state-variable active filter is one of the most versatile designs known.  Find out what they can do.		Dec 2012
Active Filters Using Gyrators - Some of the simplest and most complex filters used are based on gyrators.  The range is huge, but good results can be obtained with simple designs		Aug 2021
Amplifier Design - ESP's contribution to the everlasting debate		Jun 2001
Amplifier Design With HEXFETs - Getting good performance from vertical MOSFETs is possible (Updated)		Mar 2014
Balanced Driver (Part 1) - with Floating Output.  An in depth discussion of the design process ‡		Apr 2002
Balanced Interfaces (Part 2) - Essential reading for anyone designing equipment using balanced interconnects ‡		Jan 2010
Balanced Interfaces (Part 3) - Inputs & Outputs (The things no-one tells you)		Sep 2017
Balanced Interfaces (Part 4) - The Confounding Case Of The Differential Amplifier Balanced Input Stage (It's much better than some people claim)		Sep 2021
Bootstrap Circuits - There are several ways that bootstrapping can be applied.  Boost input impedance, increase gain & linearity, or create a boosted voltage power supply		Mar 2023
Current Feedback Vs. Voltage Feedback - The two are very different, and it's worthwhile knowing how CFB amps and opamps work, and why you may need CFB rather than VFB.		Aug 2021
Current Sources, Sinks & Mirrors - A discussion on these much misunderstood circuits.		Apr 2007
DC Offset On AC Mains and Transformers - Many people have found that toroidal transformers growl at times.  This explains why, & how to fix it.		Mar 2008
Designing circuits with JFETs (junction field-effect transistors) can be challenging - Most of the JFETs you can get have a wide parameter spread, making them difficult to work with.		Apr 2021
Heatsinks - An article on heatsink selection, transistor mounting and thermal transfer principles		Feb 2021
How much heatsink do I need for my amplifier? How long is a piece of string? - A discussion on sizing the heatsink for your amplifier		May 2015
INAs (Instrumentation Amplifiers) vs Opamps.  A look at some common INAs, how they work, and how to use them.  Comparisons between INAs and common opamp circuits are shown.		Aug 2017
MOSFET Relays - Very different, but extremely useful for high power amps that will destroy any normal relay.		Dec 2019
Negative Impedance - What It Is, What It Does, And How It Can Be Useful		May 2017
Noise in Audio Amplifiers - An explanation of noise figures, and how circuit noise is calculated		Jan 2000
Opamp Alternatives - A sample of the circuits that were in common use before opamps 'took over'		Apr 2014
Opamp Bandwidth Vs. Gain And Slew Rate - Three important parameters of opamps are all linked, and this article explains how and why.		Jan 2023
Power Supply Design - How to design linear power supplies - transformers, rectifiers and filters		Dec 2007
Sinewave Oscillators/ Generators - An examination of different sinewave generation techniques.		Apr 2010
Transistor Matching Tests - Matching Bipolar or MOSFET transistors for critical amplifier applications		Dec 2001
Variable Impedance Amplifiers - How you can control the output impedance of a power amp		Apr 2000
Voltage controlled Amplifiers/ Attenuators - An investigation into VCA techniques, including JFETs, LED/LDR modules and 'true' VCAs		Dec 2012
Power Supply Design	Flag	Update
Bench Power Supplies - Buy Or Build?  One of the most challenging DIY builds is a good, reliable bench power supply (includes examples, but is not a construction article!)		Nov 2019
Bleeder Resistors, and using Active bleeders to discharge PSU capacitors when power is removed.		Oct 2020
Bucking Transformers - Here is a bit more info than you'll find elsewhere - how to do it properly		May 2010
Capacitance Multiplier Power Supplies - The name is wrong, but they are still useful.  The design process, and a close look at the filter network.		May 2022
Convert 50Hz to 60Hz, 60Hz to 50Hz, or either to 400Hz (used in aircraft).  This is an odd one, but seriously interesting.		Sep 2023
DC Offset On AC Mains and Transformers - Many people have found that toroidal transformers growl at times.  This explains why, & how to fix it.		Mar 2008
Discrete Voltage Regulators - Used when you cannot use an IC regulator because the voltage or current is too high		Dec 2021
Electronic Fuses - A collection of useful ideas with example circuits.  These aren't always as hard as you might think		Feb 2020
Inrush Current - What it is, what it can do, and how to prevent it from causing problems		Oct 2010
Inrush Current Tester - Minimising inrush current is easy enough, but it's hard to measure it.  This tester will turn on the mains at zero crossing or the peak of the AC cycle		May 2022
Isolation Transformers - is an isolating transformer on the test bench a good safety measure or a death trap?		Dec 2016
Inverters - Squarewave, modified squarewave, modified sinewave, pure sinewave - What are the differences, and should you really care?		Mar 2014
LDO (Low Dropout) Voltage Regulators - A short primer on these sometimes difficult devices		Mar 2017
Lithium Charging - Lithium Cell Charging & Battery Management.  Not as simple as it seems.		Feb 2017
Mains Power Quality - Does it matter if the mains is distorted, and is an expensive 'regenerator' or other system worth the price?		Aug 2014
Mains Safety - Wiring Standards, Insulation, Class I, Class II and Important Information.  Wiring of mains is poorly understood by many, and applicable standards vary worldwide.		Mar 2019
NTC Thermistor Selection For Inrush Limiting.  Explains how thermistors are specified and how to choose the right one(s)		Sep 2023
Off-Line Flyback Power Supplies.  How they work, waveforms and why I don't recommend that you build your own		Jul 2022
Over- And Under-Voltage Protection Techniques For Sensitive Electronics.  How to protect expensive electronics from damage caused by a failed power supply or other major failure.		Apr 2022
Power Factor - Much of what you'll read is nonsense, so read this to find out how it really works.		Jul 2020
Power Supply Design - How to design linear power supplies - transformers, rectifiers and filters		Dec 2007
Power Supply Design Part II - the design of linear power supplies - transformers, rectifiers and filters and SMPS comparisons		Apr 2022
Power Supply Pre-Regulator Techniques - A look at the various types of bench power supply pre-regulators		Feb 2020
Power Supply Simulations - not quite as simple as they first appear.		Sep 2019
Power Supply Snubbers - Are They Necessary And Why Might I Need One?		Jan 2019
Power Supply Wiring - There are a lot of considerations for the wiring of a PSU - read about it here		Jun 2003
Rectifiers.  Half wave, full wave, bridge, voltage doublers & multipliers and multi-phase rectifiers explained.		Feb 2018
Reverse Polarity Protection.  Using diodes, MOSFETs or bipolar transistors to protect circuitry from damage if the supply polarity is reversed (AN013).		Jan 2017
Small Power Supplies (Part I).  Design of small PSUs - includes information that might save your life!  Also includes 'super' regulators.		May 2008
Small Power Supplies (Part II).  Regulated Power Supplies, Transient Response & Noise		Apr 2018
Small Power Supplies (Part III).  Easy ways to obtain a small supply for ancillary circuitry.  Includes linear and adapting a switchmode supply as an internal supply.		Dec 2023
Soft Start Circuits - a follow-on article to augment the 'Inrush Current' article listed above		Dec 2017
Switchmode Power Supply Primer - A discussion covering the different types of SMPS, and how they work		Oct 2015
Transformerless Power Supplies; How to configure them properly, and when to give up and use a SMPS		Jul 2022
Transformers, Part 1 - The basics of transformers, what they do, and how they do it		May 2001
Transformers, Part 2 - The details of magnetic circuits, windings, core types and losses.  Now includes current transformers		Oct 2012
Transformers, Part 3 - Designing and analysing transformers - not at all for the faint-hearted, but all very useful information		Jan 2006
Transformers, Part 4 - Further information on transformer usage, including captured waveforms and worked examples		Jan 2006
Voltage & Current Regulators - The basics of both voltage and current regulators, and how (and where) to use them		Jul 2013
Active Crossovers, Filters and Signal Processing	Flag	Update
Active Vs. Passive Crossovers - An explanation for the profound audible differences		Jan 2004
Baffle Step Compensation - What it is and why we need to compensate for it		Dec 2001
Derived (Subtractive) Crossovers - An examination of these networks, and why they are unsuitable for serious use		Sep 2005
Digital Signal Processing (DSP) - What DSPs can (and cannot) do for your system		Dec 2006
NTM™ Crossovers - This is a topic that has virtually zero technical information on the Net ... until now.		Sep 2005
Passive Line Level Crossovers (PLLXO).  Useful Or Not?		Apr 2020
Phase Correction - Myth or Magic? - Do all-pass filters really work to correct loudspeaker phase anomalies?		May 2007
Using Phase Shift Networks To Achieve Time Delay For Time Alignment.		Nov 2020
Passive Crossover Network Design	Flag	Update
6dB/ Octave Serial Crossover Networks - The simplest of all, but only for low to moderate power		May 2020
Impedance Compensation For Passive Crossovers - How to make any driver appear resistive to the crossover network		May 2020
Passive Crossovers - The Design of High Quality Passive Crossover Networks		Nov 2001
Serial vs. Parallel Crossover Networks - Are there any real differences?		Aug 2003
Passive Crossover Design Tables - Make your life a little easier with this handy guide to crossover design.		May 2020
Loudspeaker L-Pad Calculations.  An online calculator and formulae for calculating the values for L-Pads.		Aug 2018
Loudspeaker Design	Flag	Update
Acoustic Centre of Loudspeakers - How to locate it (several schemes are discussed)		Sep 2024
Compliance Scaling - Fitting just about any driver to just about any alignment		Jun 2005
Current Drive - Current Drive Power Amplifiers & Effects on Loudspeaker Drivers.		Apr 2019
Doppler Distortion in Loudspeakers - Is the effect real or imaginary when applied to loudspeakers?  The results may surprise you		Aug 2004
Enclosure Design Guidelines - Some tips, tricks and techniques to help you design an optimum loudspeaker enclosure.		Sep 2019
Guitar Speakers - A detailed examination of the things that go towards 'the sound' of guitar speakers.		Sep 2018
Impedance - Effects Of Source Impedance on Loudspeaker Drivers		Jul 2001
The Linkwitz Transform Circuit - What it is, what it does and how it does it ‡		Sep 2002
Loudspeaker Failure Modes - Why do loudspeakers fail? What can be done to prevent failures? Not what you expect! ‡		Jun 2012
Loudspeaker Power vs. Efficiency - There's more to this than meets the eye		Dec 2006
Loudspeakers (Part I) - see the production of my latest triamped speaker boxes unfold		Jul 2001
Loudspeakers (Part II) - The electronics that drive the 3-way system are described		Nov 2001
Phase, Time and Distortion in Loudspeakers - Is 'Time Alignment' worth the effort?		Jul 2002
Pikku 9 - Simple Network Lowers f3 - A useful approach for obtaining better bass from a very small loudspeaker ‡		Jul 2006
Satellites & Subwoofers - Description of the little known QB5 loudspeaker alignment.  Maximum SPL from 2-way bookshelf speakers. ‡		Aug 2004
Small Satellite Loudspeaker - Using techniques described in various articles, this project should have wide appeal for home theatre ‡		May 2007
Subwoofer Conundrum - Some tips and hints on subwoofer selection, efficiency and placement		Mar 2004
Thiele Small Parameters - Determining the Thiele/Small parameters for a loudspeaker driver		Jan 2006
Volume Filling a Reflex Box - It is generally thought that vented boxes should not be filled, but this isn't necessarily the case ‡		Feb 2007
Practical DIY Waveguides - Waveguide definition, calculation and construction ‡		Dec 2006

Explanation of Symbols ...

	New article.  Less than 6 months old (typically).
RED	Dates in the update column indicate a new or updated (within six months) article.  Usually accompanied by
	Indicates an article that may include humour - caution is advised
‡	Contributed article (see copyright notice on article page)

Main Index

Although it goes without saying (but I will say it anyway ) the contributed articles and projects from all over the world have added considerably to the overall value and range of topics covered in these pages, and on behalf of all the readers of The Audio Pages, I thank the authors for their efforts.  Writing a clear and descriptive technical article is not an easy task, but your perseverance is acknowledged, and I am grateful that you have taken the time to share your knowledge.