Sorry if this is the wrong forum,
I am interested in designing my own multi way speakers, but would like to do some technical research on the topic.
I am a recently graduated mechanical engineer, and I have some training in vibrations, measurement systems, circuits, etc. i want to understand the theory of why 2 speakers that have the same frequency response, efficiency, resonance, etc can sound so different.
Any good technical book suggestions on the topic would be appreciated
I am interested in designing my own multi way speakers, but would like to do some technical research on the topic.
I am a recently graduated mechanical engineer, and I have some training in vibrations, measurement systems, circuits, etc. i want to understand the theory of why 2 speakers that have the same frequency response, efficiency, resonance, etc can sound so different.
Any good technical book suggestions on the topic would be appreciated
Where to Look
Obviously the metrics you are looking at for this hypothetical will not reveal the differences you are observing. The culprit is most likely diaphragm geometry and material. These will lead to differences in the breakup modes that occur when wavelength becomes comparable or smaller than diaphragm dimensions.
For a reading source, an associate membership in AES with unlimited library access, would be my recommendation for anyone with a serious interest in acoustics. Cost ($99 + $145)/yr.
Membership Types & Prices
Regards,
WHG
Obviously the metrics you are looking at for this hypothetical will not reveal the differences you are observing. The culprit is most likely diaphragm geometry and material. These will lead to differences in the breakup modes that occur when wavelength becomes comparable or smaller than diaphragm dimensions.
For a reading source, an associate membership in AES with unlimited library access, would be my recommendation for anyone with a serious interest in acoustics. Cost ($99 + $145)/yr.
Membership Types & Prices
Regards,
WHG
In distilling down my collection I would use as primers:
Testing Loudspeakers by Joseph D'Appolito
Loudspeaker Design Cookbook by Dickason
In depth:
High Performance Loudspeakers by Colluoms
Time Delay Spectrometry by Heyser
Additions with tons of math and technical references and application:
Sound System Engineering by Davis-Patronis
the Handbook for Sound System Engineers by Ballou
For fun:
If Bad Sound Were Fatal by Don and Corolyn Davis
Audio's pull on engineering types is surprisingly strong. Understanding it well requires understanding of no less than five disciplines only one of which is mechanical. Your education will certainly help you grasp the others.
Welcome and enjoy.
Testing Loudspeakers by Joseph D'Appolito
Loudspeaker Design Cookbook by Dickason
In depth:
High Performance Loudspeakers by Colluoms
Time Delay Spectrometry by Heyser
Additions with tons of math and technical references and application:
Sound System Engineering by Davis-Patronis
the Handbook for Sound System Engineers by Ballou
For fun:
If Bad Sound Were Fatal by Don and Corolyn Davis
Audio's pull on engineering types is surprisingly strong. Understanding it well requires understanding of no less than five disciplines only one of which is mechanical. Your education will certainly help you grasp the others.
Welcome and enjoy.
100 more votes on D'Appolito. Number one. If you don't understand measurement, you cant test your design.
Bullock on boxes was the first significant design book addressing T/S parameters for mere mortals. (Theil's and Small's papers were not for the casual reader) .
Dickason seems to be a standard, though I have never read it.
For FREE:
Read the True Audio WEB
Read the Linkwitz WEB
Read the owners manual for SoundEasy, TrueRTA, Edge, Arta, Holm and whatever software you can find.
Search on DIY room treatments and bass traps. You may get a lot on your particular interest from that.
I need to polish up my "Cheapskates Guide to speaker measurement for design" and get it posted one of these days. Kind of a quick-start using free or really cheap software.
Floyd Toole is another significant work.
No idea if you could find them, but I have the four volumes on speaker design from AES. Even if you join AES, I suspect they are not cheap. The history can teach you a lot. I also have the first 10 years or so of SpeakerBuilder.
I got very little out of Colluoms, and Sound System Engineering was obsolete when it was published. Useless for a beginning speaker builder. If you ever were in Maryland, you could have them for a beer or so.
I also have a pile of books on acoustical architecture, and psycho-acoustics as understanding why we interpret what we hear the way we do, and why two people will hear the same things differently is one of my interests. Unfortunately, the academic books on this have 300 pages of test description and citations with two paragraphs that say they did not learn anything.
The gentleman who got me started in speaker building was a physicist specializing in vibration. He designed things like missile silo covers. After a career stooping things from vibrating, he decided to make some vibrate. Built and sold speakers. He was one of the first to read Small and produce speakers using his information.
Bullock on boxes was the first significant design book addressing T/S parameters for mere mortals. (Theil's and Small's papers were not for the casual reader) .
Dickason seems to be a standard, though I have never read it.
For FREE:
Read the True Audio WEB
Read the Linkwitz WEB
Read the owners manual for SoundEasy, TrueRTA, Edge, Arta, Holm and whatever software you can find.
Search on DIY room treatments and bass traps. You may get a lot on your particular interest from that.
I need to polish up my "Cheapskates Guide to speaker measurement for design" and get it posted one of these days. Kind of a quick-start using free or really cheap software.
Floyd Toole is another significant work.
No idea if you could find them, but I have the four volumes on speaker design from AES. Even if you join AES, I suspect they are not cheap. The history can teach you a lot. I also have the first 10 years or so of SpeakerBuilder.
I got very little out of Colluoms, and Sound System Engineering was obsolete when it was published. Useless for a beginning speaker builder. If you ever were in Maryland, you could have them for a beer or so.
I also have a pile of books on acoustical architecture, and psycho-acoustics as understanding why we interpret what we hear the way we do, and why two people will hear the same things differently is one of my interests. Unfortunately, the academic books on this have 300 pages of test description and citations with two paragraphs that say they did not learn anything.
The gentleman who got me started in speaker building was a physicist specializing in vibration. He designed things like missile silo covers. After a career stooping things from vibrating, he decided to make some vibrate. Built and sold speakers. He was one of the first to read Small and produce speakers using his information.
Someone on this forum has hosted Thiele and Small's papers - a read through those will help with enclosures. If you can find JE Benson's "Theory and Design of Loudspeaker Enclosures" for a decent price (wouldn't pay more than $50 for a paperback) it is _really_ excellent, although nearly solid math. It might be easier to find the original three magazine articles from Australia, though...
DB Keele has put some of his own JAES papers on his website.
If you have a large library near you, it would be easy to find JAES journals that you can peruse.
The Loudspeaker Design Cookbook is an OK tutorial for mildly technical folks. I checked it out from the library pre-internet. I never felt the need to buy it. Now that we have personal computers there is software to do most things he has simplified formulas and tables for. It is cheap enough, though, and gives you some essential education on terminology. Don't get hung up on alignments, though. Alignments are interesting mathematically, but not a terribly useful concept for most purposes.
High performance loudspeakers is a book I wouldn't recommend buying. Way too expensive and not that much information.
Any of David Weems' books are very basic and not worth more than $10, IMO.
I think Ray Alden took over for Weems writing stuff for Radio Shack, I've never seen his books so I don't have an opinion, although I suspect they are similar in scope. Good for beginners and non-technical folk. May be good for learning the vocabulary.
If I were recommending a course for people starting from scratch with your background, I'd say this:
Play around with the equation sets you find at The Subwoofer DIY Page - that will give you a feel for enclosure design. For any given set of parameters, try a typical box, a box that is very large and a box that is very small. For vented boxes try this and various tuning frequencies as well.
Use holmimpulse for measuring speakers acoustically and import the measurements into Speaker Workshop. Speaker workshop does impedance measurements well, but I have had mixed results with the acoustic measurements. I have written my own crossover spreadsheets and used various purchased and free solutions, but I much prefer Speaker Workshop to any I have tried for simulating crossovers. Once you understand the user interface, it is simpler and faster.
Some may recommend Bagby's PCD, an excel sheet for crossover simulation and if you have excel and it works for you, great. I have excel 97 but I won't upgrade again
That and ask a lot of questions is my recommendation
DB Keele has put some of his own JAES papers on his website.
If you have a large library near you, it would be easy to find JAES journals that you can peruse.
The Loudspeaker Design Cookbook is an OK tutorial for mildly technical folks. I checked it out from the library pre-internet. I never felt the need to buy it. Now that we have personal computers there is software to do most things he has simplified formulas and tables for. It is cheap enough, though, and gives you some essential education on terminology. Don't get hung up on alignments, though. Alignments are interesting mathematically, but not a terribly useful concept for most purposes.
High performance loudspeakers is a book I wouldn't recommend buying. Way too expensive and not that much information.
Any of David Weems' books are very basic and not worth more than $10, IMO.
I think Ray Alden took over for Weems writing stuff for Radio Shack, I've never seen his books so I don't have an opinion, although I suspect they are similar in scope. Good for beginners and non-technical folk. May be good for learning the vocabulary.
If I were recommending a course for people starting from scratch with your background, I'd say this:
Play around with the equation sets you find at The Subwoofer DIY Page - that will give you a feel for enclosure design. For any given set of parameters, try a typical box, a box that is very large and a box that is very small. For vented boxes try this and various tuning frequencies as well.
Use holmimpulse for measuring speakers acoustically and import the measurements into Speaker Workshop. Speaker workshop does impedance measurements well, but I have had mixed results with the acoustic measurements. I have written my own crossover spreadsheets and used various purchased and free solutions, but I much prefer Speaker Workshop to any I have tried for simulating crossovers. Once you understand the user interface, it is simpler and faster.
Some may recommend Bagby's PCD, an excel sheet for crossover simulation and if you have excel and it works for you, great. I have excel 97 but I won't upgrade again
That and ask a lot of questions is my recommendation
I find impedance measurements from Woofer Tester hard to beat. HOLM for acoustic, ARTA for CSD. I still use TrueRTA for some room measurements. I too have my own spreadsheets, but also use Edge, WinIDS, and PSDLite for design. If ARTA was not so hard to pay for, I would license Atra and Limp. (hint folks, accept PayPal) That is my cheap set. I also have Sound Easy. It is anything but easy and is not cheap. It has immense capabilities.
I would HOPE a good engineering library has all the AES papers. Our public library has only a few best sellers and VHS tapes. Useless. UofM library is too hard for me to get to.
I would HOPE a good engineering library has all the AES papers. Our public library has only a few best sellers and VHS tapes. Useless. UofM library is too hard for me to get to.
I got Beranek's "Acoustics" from the Acoustical Society of America, Acoustical Society Bookstore
Most Acoustics textbooks have heavy-duty partial differential equations and the like, but Beranek is a little more accessible. It is a good reference for those who want to dig deeper, but its methods are not as straightforward as Small's or Benson's. The only thing I have by olson is his "Dynamic Analogies" which can be found for free online. It is a good book, but greatly hindered by the use of the cgs system instead of SI.
For Basics
... recommend Marshall Leach's Book
INTRODUCTION TO ELECTROACOUSTICS AND AUDIO AMPLIFIER DESIGN: Jr. W. Marshall Leach: 9780757503757: Amazon.com: Books
Regards,
WHG
P.S. The pricing at Amazon is absurd! Will find a seller elswhere or provide a free copy if you want it.
... recommend Marshall Leach's Book
INTRODUCTION TO ELECTROACOUSTICS AND AUDIO AMPLIFIER DESIGN: Jr. W. Marshall Leach: 9780757503757: Amazon.com: Books
Regards,
WHG
P.S. The pricing at Amazon is absurd! Will find a seller elswhere or provide a free copy if you want it.
Last edited:
This is not really a technical book but it clarifies many ideas about what we can expect from music reproduction by loudspeakers (which is the prior question, isn't ?). It is easy to read :
Loudspeakers: For Music Recording and Reproduction - Philip Richard Newell, K. R. Holland - Google Livres
Loudspeakers: For Music Recording and Reproduction - Philip Richard Newell, K. R. Holland - Google Livres
Nonsense!
Only the LAST of twelve chapters is devoted to the "amplifier".
Obviously, you have not read the book, yet you pass judgment on the recommendations of those that have.
I have provided the table of contents below, so that no doubt remains about Leach's comprehensive treatment of the subject of electro-acoustics.
WHG
Title: Introduction to Electroacoustics and Audio Amplifier Design, Third Edition.
Author: W. Marshall Leach, Jr.
Contents:
1 Basic Principles of Sound 1
1.1 Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Sources of Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Velocity of Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Frequency of Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.5 Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.6 Human Speech . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.7 Frequency Bands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.8 Audio Sub Bands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.9 Sound Pressure Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.10 Equal Loudness Contours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.11 Loudness Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.12 Audio Test Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.13 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Fundamentals of Acoustics 15
2.1 Basic Equations of Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2 The AcousticWave Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3 The PlaneWave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4 Specific Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.5 Acoustic Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.6 Acoustic Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.7 Wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.8 Particle Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.9 The Omni-Directional Spherical Wave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.10 Volume Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.11 The Simple Spherical Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.12 Acoustic Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.13 The Plane Circular Piston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.14 The Pattern Beamwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.15 Fresnel Diffraction Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.16 Acoustic Reflections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.17 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3 Analogous Circuits of Acoustical Systems 33
3.1 Acoustic Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.2 Acoustic Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.3 The PlaneWave Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.4 Acoustic Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.5 Acoustic Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.6 AcousticMass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.7 Acoustic Impedance on a Piston in a Baffle . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.8 Acoustic Impedance on a Piston in a Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.9 Radiation Impedance on a Piston in Free Air . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.10 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4 Analogous Circuits of Mechanical Systems 49
4.1 Mechanical Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.2 Mass, Compliance, and Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.3 Mechanical Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.4 Moving-Coil Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.5 Crystal Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.6 Condenser Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.7 Mechano-Acoustic Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.8 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5 Microphones 63
5.1 Classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.2 Modeling Diaphragm Reflections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.3 DiaphragmBack Acoustical Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.4 DiaphragmMechanical Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.5 CondenserMicrophone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.6 CondenserMicrophone SPICE Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.7 Condenser Microphone Buffer Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.8 DynamicMicrophone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.9 RibbonMicrophone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.10 Proximity Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.11 CombinationMicrophone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.12 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6 Moving-Coil Loudspeakers 85
6.1 Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.2 Analogous Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
6.3 Combination Analogous Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.4 Infinite Baffle Analogous Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.5 Low-Frequency Solution for UD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.6 Low-Frequency Bode Plots for UD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.7 Small-Signal Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.8 High-Frequency Solution for UD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.9 On-Axis Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
6.10 Pressure Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.11 Bode Plots ofOn-Axis Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.12 Filter Theory Description of G (s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.13 Cutoff Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.14 Effect of Non-Zero Generator Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.15 Frequency of Peak Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
6.16 Voice-Coil Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
6.17 The Lossy Voice-Coil Inductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6.18 On-Axis Pressure Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6.19 Acoustic Power Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6.20 Reference Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
6.21 DiaphragmDisplacement Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
CONTENTS v
6.22 Voice-Coil Electrical Power Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
6.23 Displacement Limited Power Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.24 SPICEModels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.25 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7 Closed-Box Loudspeaker Systems 113
7.1 Modeling the Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
7.2 The Analogous Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
7.3 The Volume Velocity Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
7.4 The On-Axis Pressure Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
7.5 Effect of the Box on the SystemResponse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
7.6 Sensitivity of the Lower Cutoff Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.7 SystemDesign with a Given Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
7.8 System Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
7.9 System Design From Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
7.10 A SPICE Simulation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7.11 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
8 Vented-Box Loudspeaker Systems 127
8.1 Modeling the Enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
8.2 Effect of the Vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
8.3 The On-Axis Pressure Transfer Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
8.4 Voice-Coil Impedance Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
8.5 TheMagnitude-Squared Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
8.6 The B4 Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
8.7 The QB3 Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
8.8 The Chebyshev Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
8.9 Example Pressure Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.10 Design with a Given Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.11 System Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
8.12 Design from Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
8.13 Vented-Box SPICE Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
8.14 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
9 AcousticHorns 147
9.1 TheWebster Horn Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
9.2 Salmon’s Family of Horns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
9.3 Finite Length Horn Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.4 AHorn Analogous Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.5 SPICE Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
9.6 Horn Driving Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
9.7 Mid-Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
9.8 Condition for Maximum PAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
9.9 The Horn Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
9.10 The Low-Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
9.11 The High-Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
9.12 Low-Frequency SystemDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
9.12.1 Design with aGiven Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
9.12.2 System Design from Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
9.13 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
10 Crossover Networks 163
10.1 Role of Crossover Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
10.2 Passive Crossover Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
10.3 L-Pad Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
10.4 Effect of the Voice-Coil Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
10.5 Effect of the Driver Phase Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
10.6 Constant-Voltage and All-Pass Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
10.7 Active Crossover Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
10.8 A SPICEModeling Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
10.9 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
11 A Loudspeaker Potpourri 187
11.1 The Isobaric Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
11.1.1 The Acoustical Analogous Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
11.1.2 The Small-Signal Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.1.3 SPICE Simulation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.2 4th-Order Bandpass Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
11.2.1 System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
11.2.2 Output Volume Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
11.2.3 On-Axis Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
11.2.4 Fourth-Order Band-Pass Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
11.2.5 System Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
11.2.6 Design with aGivenDriver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.3 6th-Order Bandpass Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.3.1 System Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.3.2 System Alignment Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.3.3 System Design from Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
11.3.4 Example SystemDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
11.4 Passive Radiator Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
11.4.1 System Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
11.4.2 Example SystemDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
11.5 Assisted Vented-Box Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
11.5.1 System Transfer Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
11.5.2 5th-Order Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
11.5.3 6th-Order Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
11.5.4 The Vented-Box SystemParameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
11.5.5 Example Design from Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
11.6 A Closed-Box System Equalizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.6.1 Equalizer Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.6.2 Equalizer Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
11.6.3 Example Realization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
11.7 Driver ParameterMeasurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
11.7.1 Basic Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
11.7.2 TheMeasurement Test Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
11.7.3 Measuring RE , fS , QMS , QES, and QT S . . . . . . . . . . . . . . . . . . . . . . . . . 210
11.7.4 Measuring VAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
11.7.5 Conversion to Infinite-Baffle Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 212
11.7.6 Measuring the Voice-Coil Inductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
11.8 ParameterMeasurement Summary Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
12 Audio Power Amplifiers 217
12.1 Power Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
12.2 Effects of Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
12.2.1 Feedback Amplifier Gain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
12.2.2 Effect of Feedback on Distortion and Noise . . . . . . . . . . . . . . . . . . . . . . . . 220
12.2.3 Effect of Feedback on Output Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . 220
12.3 AmplifierModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
12.3.1 Open-Loop Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
12.3.2 Gain Bandwidth Product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
12.3.3 Slew Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
12.3.4 Relations between SlewRate and Gain-Bandwidth Product . . . . . . . . . . . . . . . 224
12.3.5 Closed-Loop Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
12.3.6 Transient Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
12.3.7 Input Stage Overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
12.3.8 Full Power Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
12.3.9 Effect of an Input Low-Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
12.3.10 JFET Diff Amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
12.3.11 Diff Amp with Current-Mirror Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
12.4 Signal Tracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
12.5 The Stability Criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
12.5.1 The Bode Stability Theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
12.5.2 Single-Pole Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
12.5.3 Two-Pole Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
12.5.4 An Alternate Stability Criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
12.6 Techniques for Compensating Feedback Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . 242
12.6.1 Gain Constant Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
12.6.2 First Pole Lag Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
12.6.3 Second Pole Lead Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
12.6.4 Feedforward Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
12.7 Output Stage Topologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
12.7.1 Common-Collector Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
12.7.2 Common-Emitter Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
12.7.3 Quasi-ComplementaryOutput Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
12.7.4 MOSFET Output Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
12.8 Voltage Gain Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
12.9 Input Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
12.10 Completed Amplifier Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
12.11 Protection Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
12.11.1 BJT Protection Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
12.11.2 MOSFET Protection Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
12.12 Power Supply Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
12.13 Decoupling and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
12.14 Power Dissipation and Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
12.15 The Class-D Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
12.16 AmplifierMeasurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
12.17 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
Only the LAST of twelve chapters is devoted to the "amplifier".
Obviously, you have not read the book, yet you pass judgment on the recommendations of those that have.
I have provided the table of contents below, so that no doubt remains about Leach's comprehensive treatment of the subject of electro-acoustics.
WHG
Title: Introduction to Electroacoustics and Audio Amplifier Design, Third Edition.
Author: W. Marshall Leach, Jr.
Contents:
1 Basic Principles of Sound 1
1.1 Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Sources of Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Velocity of Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Frequency of Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.5 Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.6 Human Speech . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.7 Frequency Bands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.8 Audio Sub Bands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.9 Sound Pressure Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.10 Equal Loudness Contours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.11 Loudness Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.12 Audio Test Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.13 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Fundamentals of Acoustics 15
2.1 Basic Equations of Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2 The AcousticWave Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3 The PlaneWave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4 Specific Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.5 Acoustic Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.6 Acoustic Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.7 Wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.8 Particle Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.9 The Omni-Directional Spherical Wave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.10 Volume Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.11 The Simple Spherical Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.12 Acoustic Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.13 The Plane Circular Piston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.14 The Pattern Beamwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.15 Fresnel Diffraction Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.16 Acoustic Reflections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.17 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3 Analogous Circuits of Acoustical Systems 33
3.1 Acoustic Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.2 Acoustic Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.3 The PlaneWave Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.4 Acoustic Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.5 Acoustic Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.6 AcousticMass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.7 Acoustic Impedance on a Piston in a Baffle . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.8 Acoustic Impedance on a Piston in a Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.9 Radiation Impedance on a Piston in Free Air . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.10 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4 Analogous Circuits of Mechanical Systems 49
4.1 Mechanical Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.2 Mass, Compliance, and Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.3 Mechanical Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.4 Moving-Coil Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.5 Crystal Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.6 Condenser Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.7 Mechano-Acoustic Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.8 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5 Microphones 63
5.1 Classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.2 Modeling Diaphragm Reflections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.3 DiaphragmBack Acoustical Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.4 DiaphragmMechanical Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.5 CondenserMicrophone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.6 CondenserMicrophone SPICE Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.7 Condenser Microphone Buffer Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.8 DynamicMicrophone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.9 RibbonMicrophone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.10 Proximity Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.11 CombinationMicrophone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.12 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6 Moving-Coil Loudspeakers 85
6.1 Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.2 Analogous Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
6.3 Combination Analogous Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.4 Infinite Baffle Analogous Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.5 Low-Frequency Solution for UD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.6 Low-Frequency Bode Plots for UD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.7 Small-Signal Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.8 High-Frequency Solution for UD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.9 On-Axis Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
6.10 Pressure Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.11 Bode Plots ofOn-Axis Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.12 Filter Theory Description of G (s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.13 Cutoff Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.14 Effect of Non-Zero Generator Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.15 Frequency of Peak Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
6.16 Voice-Coil Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
6.17 The Lossy Voice-Coil Inductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6.18 On-Axis Pressure Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6.19 Acoustic Power Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6.20 Reference Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
6.21 DiaphragmDisplacement Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
CONTENTS v
6.22 Voice-Coil Electrical Power Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
6.23 Displacement Limited Power Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.24 SPICEModels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.25 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7 Closed-Box Loudspeaker Systems 113
7.1 Modeling the Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
7.2 The Analogous Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
7.3 The Volume Velocity Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
7.4 The On-Axis Pressure Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
7.5 Effect of the Box on the SystemResponse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
7.6 Sensitivity of the Lower Cutoff Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.7 SystemDesign with a Given Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
7.8 System Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
7.9 System Design From Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
7.10 A SPICE Simulation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7.11 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
8 Vented-Box Loudspeaker Systems 127
8.1 Modeling the Enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
8.2 Effect of the Vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
8.3 The On-Axis Pressure Transfer Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
8.4 Voice-Coil Impedance Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
8.5 TheMagnitude-Squared Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
8.6 The B4 Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
8.7 The QB3 Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
8.8 The Chebyshev Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
8.9 Example Pressure Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.10 Design with a Given Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.11 System Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
8.12 Design from Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
8.13 Vented-Box SPICE Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
8.14 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
9 AcousticHorns 147
9.1 TheWebster Horn Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
9.2 Salmon’s Family of Horns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
9.3 Finite Length Horn Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.4 AHorn Analogous Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.5 SPICE Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
9.6 Horn Driving Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
9.7 Mid-Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
9.8 Condition for Maximum PAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
9.9 The Horn Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
9.10 The Low-Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
9.11 The High-Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
9.12 Low-Frequency SystemDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
9.12.1 Design with aGiven Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
9.12.2 System Design from Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
9.13 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
10 Crossover Networks 163
10.1 Role of Crossover Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
10.2 Passive Crossover Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
10.3 L-Pad Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
10.4 Effect of the Voice-Coil Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
10.5 Effect of the Driver Phase Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
10.6 Constant-Voltage and All-Pass Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
10.7 Active Crossover Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
10.8 A SPICEModeling Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
10.9 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
11 A Loudspeaker Potpourri 187
11.1 The Isobaric Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
11.1.1 The Acoustical Analogous Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
11.1.2 The Small-Signal Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.1.3 SPICE Simulation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.2 4th-Order Bandpass Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
11.2.1 System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
11.2.2 Output Volume Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
11.2.3 On-Axis Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
11.2.4 Fourth-Order Band-Pass Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
11.2.5 System Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
11.2.6 Design with aGivenDriver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.3 6th-Order Bandpass Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.3.1 System Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.3.2 System Alignment Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.3.3 System Design from Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
11.3.4 Example SystemDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
11.4 Passive Radiator Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
11.4.1 System Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
11.4.2 Example SystemDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
11.5 Assisted Vented-Box Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
11.5.1 System Transfer Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
11.5.2 5th-Order Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
11.5.3 6th-Order Alignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
11.5.4 The Vented-Box SystemParameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
11.5.5 Example Design from Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
11.6 A Closed-Box System Equalizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.6.1 Equalizer Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
11.6.2 Equalizer Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
11.6.3 Example Realization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
11.7 Driver ParameterMeasurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
11.7.1 Basic Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
11.7.2 TheMeasurement Test Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
11.7.3 Measuring RE , fS , QMS , QES, and QT S . . . . . . . . . . . . . . . . . . . . . . . . . 210
11.7.4 Measuring VAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
11.7.5 Conversion to Infinite-Baffle Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 212
11.7.6 Measuring the Voice-Coil Inductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
11.8 ParameterMeasurement Summary Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
12 Audio Power Amplifiers 217
12.1 Power Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
12.2 Effects of Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
12.2.1 Feedback Amplifier Gain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
12.2.2 Effect of Feedback on Distortion and Noise . . . . . . . . . . . . . . . . . . . . . . . . 220
12.2.3 Effect of Feedback on Output Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . 220
12.3 AmplifierModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
12.3.1 Open-Loop Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
12.3.2 Gain Bandwidth Product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
12.3.3 Slew Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
12.3.4 Relations between SlewRate and Gain-Bandwidth Product . . . . . . . . . . . . . . . 224
12.3.5 Closed-Loop Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
12.3.6 Transient Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
12.3.7 Input Stage Overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
12.3.8 Full Power Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
12.3.9 Effect of an Input Low-Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
12.3.10 JFET Diff Amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
12.3.11 Diff Amp with Current-Mirror Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
12.4 Signal Tracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
12.5 The Stability Criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
12.5.1 The Bode Stability Theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
12.5.2 Single-Pole Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
12.5.3 Two-Pole Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
12.5.4 An Alternate Stability Criterion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
12.6 Techniques for Compensating Feedback Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . 242
12.6.1 Gain Constant Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
12.6.2 First Pole Lag Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
12.6.3 Second Pole Lead Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
12.6.4 Feedforward Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
12.7 Output Stage Topologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
12.7.1 Common-Collector Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
12.7.2 Common-Emitter Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
12.7.3 Quasi-ComplementaryOutput Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
12.7.4 MOSFET Output Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
12.8 Voltage Gain Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
12.9 Input Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
12.10 Completed Amplifier Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
12.11 Protection Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
12.11.1 BJT Protection Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
12.11.2 MOSFET Protection Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
12.12 Power Supply Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
12.13 Decoupling and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
12.14 Power Dissipation and Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
12.15 The Class-D Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
12.16 AmplifierMeasurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
12.17 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
WHG,
"Not a place to start"
http://www.amazon.com/INTRODUCTION-...qid=1384288202&sr=1-1&keywords=Marshall+Leach
is why I have only skimmed it in a library. $1800
"Not a place to start"
http://www.amazon.com/INTRODUCTION-...qid=1384288202&sr=1-1&keywords=Marshall+Leach
is why I have only skimmed it in a library. $1800
Last edited:
Disinformation
.. will not 'save the day' for you. You parrot an URL link already provided and characterized by me as "absurd". The works of d'Apolito & Toole which I have read and studied as well, are certainly not works for beginners. The work of Leach is succinct and embodies and distills that presented earlier by Olson, Beranek, Thiel & Small as well as others. The only requirement is that the reader have a minimum mathematical skill of a high school student who has passed an advanced algebra course. Bottom line: you have not read the book that you say is “not a place to start”. That dog is not hunting well here for you.
WHG
Here is what Leach has to say about the purpose of this work:
Preface
This book is an outgrowth of a senior level elective course in audio engineering that I have taught to
electrical engineering students at the Georgia Institute of Technology. The first part of the book covers basic
acoustics. The emphasis is on that part of acoustics that pertains to the field of audio engineering. Most
of the remainder of the book concerns the application of the tools of electroacoustics to the analysis and
synthesis of microphones, loudspeakers, crossover networks, and acoustic horns. The book also concludes
with a chapter that covers the basic theory of audio amplifier design.
Electroacoustics is that part of acoustics that pertains to the modeling of acoustical systems with electrical
circuits. Because most acoustical devices have a mechanical part, the modeling of mechanical systems with
electrical circuits is a basic part of electroacoustics. Separate chapters in the book are devoted to analogous
circuits of mechanical systems and to analogous circuits of acoustical systems. The traditional approach in
these circuits has been to use transformers to model the coupling between the electrical, the mechanical, and
the acoustical parts. A major departure in this book is the use of controlled sources to model the coupling.
An advantage of this approach is that it avoids the need for mobility analogs. In addition, I have found that
students have much less difficulty with the approach. Perhaps this is because the controlled-source circuits
are more intuitive than the transformer circuits. The circuits can be easily analyzed with circuit simulation
software such as SPICE.
Electroacoustic models are developed for the more common microphone types and for the moving-coil
loudspeaker driver. Separate chapters cover closed-box and vented-box loudspeaker systems. Although
the emphasis is on basic system theory, practical methods of design are also presented. Because crossover
networks are such an important part of loudspeaker systems, a chapter is devoted to crossover networks.
Acoustic horns are a vital component in public address systems. A chapter is devoted to horn models.
A chapter entitled “A Loudspeaker Potpourri” covers topics such as the isobaric loudspeaker connection,
band-pass systems, passive-radiator systems, equalized systems, and loudspeaker parameter measurements.
In all cases, SPICE simulation examples are presented where appropriate.
One might ask why a chapter on audio amplifiers is included in a book that is primarily concerned with
electroacoustics. Without a power amplifier, a loudspeaker could not make sound. Therefore, one might
say that the role of an amplifier in a system is just as important as the role of a loudspeaker. The chapter
on amplifiers is not intended to be an in-depth chapter on electronic theory. Instead, it addresses the more
important aspects of amplifier design with an emphasis on the basic operation of the circuits. Practical
examples are presented that illustrate how some of the pitfalls of amplifier design can be avoided.
>snip<
An errata and updates can be found at An Introduction to Electroacoustics and Audio Amplifier Design.
W. Marshall Leach, Jr.
April 2003
.. will not 'save the day' for you. You parrot an URL link already provided and characterized by me as "absurd". The works of d'Apolito & Toole which I have read and studied as well, are certainly not works for beginners. The work of Leach is succinct and embodies and distills that presented earlier by Olson, Beranek, Thiel & Small as well as others. The only requirement is that the reader have a minimum mathematical skill of a high school student who has passed an advanced algebra course. Bottom line: you have not read the book that you say is “not a place to start”. That dog is not hunting well here for you.
WHG
Here is what Leach has to say about the purpose of this work:
Preface
This book is an outgrowth of a senior level elective course in audio engineering that I have taught to
electrical engineering students at the Georgia Institute of Technology. The first part of the book covers basic
acoustics. The emphasis is on that part of acoustics that pertains to the field of audio engineering. Most
of the remainder of the book concerns the application of the tools of electroacoustics to the analysis and
synthesis of microphones, loudspeakers, crossover networks, and acoustic horns. The book also concludes
with a chapter that covers the basic theory of audio amplifier design.
Electroacoustics is that part of acoustics that pertains to the modeling of acoustical systems with electrical
circuits. Because most acoustical devices have a mechanical part, the modeling of mechanical systems with
electrical circuits is a basic part of electroacoustics. Separate chapters in the book are devoted to analogous
circuits of mechanical systems and to analogous circuits of acoustical systems. The traditional approach in
these circuits has been to use transformers to model the coupling between the electrical, the mechanical, and
the acoustical parts. A major departure in this book is the use of controlled sources to model the coupling.
An advantage of this approach is that it avoids the need for mobility analogs. In addition, I have found that
students have much less difficulty with the approach. Perhaps this is because the controlled-source circuits
are more intuitive than the transformer circuits. The circuits can be easily analyzed with circuit simulation
software such as SPICE.
Electroacoustic models are developed for the more common microphone types and for the moving-coil
loudspeaker driver. Separate chapters cover closed-box and vented-box loudspeaker systems. Although
the emphasis is on basic system theory, practical methods of design are also presented. Because crossover
networks are such an important part of loudspeaker systems, a chapter is devoted to crossover networks.
Acoustic horns are a vital component in public address systems. A chapter is devoted to horn models.
A chapter entitled “A Loudspeaker Potpourri” covers topics such as the isobaric loudspeaker connection,
band-pass systems, passive-radiator systems, equalized systems, and loudspeaker parameter measurements.
In all cases, SPICE simulation examples are presented where appropriate.
One might ask why a chapter on audio amplifiers is included in a book that is primarily concerned with
electroacoustics. Without a power amplifier, a loudspeaker could not make sound. Therefore, one might
say that the role of an amplifier in a system is just as important as the role of a loudspeaker. The chapter
on amplifiers is not intended to be an in-depth chapter on electronic theory. Instead, it addresses the more
important aspects of amplifier design with an emphasis on the basic operation of the circuits. Practical
examples are presented that illustrate how some of the pitfalls of amplifier design can be avoided.
>snip<
An errata and updates can be found at An Introduction to Electroacoustics and Audio Amplifier Design.
W. Marshall Leach, Jr.
April 2003
WHG, chill! I am not trying to gore your favorite book, just suggest that starting with the quality online sources is a better place to start, and my experience is that really understanding what you are measuring is very important or you won't be able to put to use everything else you learn.
As the OP is an engineer, he will have no trouble with D'Apolitto, and probably no trouble with Linkwitz or any of the ASE papers as we don't need to explain imaginary numbers to him.
As the OP is an engineer, he will have no trouble with D'Apolitto, and probably no trouble with Linkwitz or any of the ASE papers as we don't need to explain imaginary numbers to him.
Beranek's "Acoustics", Revised
Has anyone here read this book?
If so, comments please.
Regards,
WHG
Title: Acoustics: Sound Fields and Transducers
Author (1): Lep L. Beranek
Author (2): Tim Mellow
Date: October 4, 2012
ISBN-10: 0123914213 |
ISBN-13: 978-0123914217
Edition: 1
Abstract: A thoroughly updated version of Leo Beranek's classic 1954 book that retains and expands on the original's detailed acoustical fundamentals while adding practical formulas and simulation methods.
Has anyone here read this book?
If so, comments please.
Regards,
WHG
Title: Acoustics: Sound Fields and Transducers
Author (1): Lep L. Beranek
Author (2): Tim Mellow
Date: October 4, 2012
ISBN-10: 0123914213 |
ISBN-13: 978-0123914217
Edition: 1
Abstract: A thoroughly updated version of Leo Beranek's classic 1954 book that retains and expands on the original's detailed acoustical fundamentals while adding practical formulas and simulation methods.
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