Hello All.
This is my first post here but I have been lurking for quite a while. A little background to introduce myself and then a request if you would please.
I am a quite experienced electrical engineer (background is electromagnetics and RF circuit design). I have done a few years of electrical audio design along the way.
I have never built a speaker before in my life but it is something that I have wanted to do since I was a kid.
But I am interested. I have access to some rather incredible test facilities at work (an anechoic chamber for example) and the best electronic test equipment that my company's money can buy.
Call it a job perk.
I want to build some loudspeakers. Some incredible loudspeakers. To do that, I think it is important to understand the physics behind the acoustics and understand them well.
I am presently studying TS parameters now.
Can anyone here point me to sites/books/papers that they would recommend and they think would help me in understanding the physics, the mechanics and acoustics that is, of loudspeakers, particularly Bass Reflex designs?
Most of the best loudspeakers that I personally have heard utilize this design type and hence this is the one that most piques my interest.
Thanks.
This is my first post here but I have been lurking for quite a while. A little background to introduce myself and then a request if you would please.
I am a quite experienced electrical engineer (background is electromagnetics and RF circuit design). I have done a few years of electrical audio design along the way.
I have never built a speaker before in my life but it is something that I have wanted to do since I was a kid.
But I am interested. I have access to some rather incredible test facilities at work (an anechoic chamber for example) and the best electronic test equipment that my company's money can buy.
Call it a job perk. I want to build some loudspeakers. Some incredible loudspeakers. To do that, I think it is important to understand the physics behind the acoustics and understand them well.
I am presently studying TS parameters now.
Can anyone here point me to sites/books/papers that they would recommend and they think would help me in understanding the physics, the mechanics and acoustics that is, of loudspeakers, particularly Bass Reflex designs?
Most of the best loudspeakers that I personally have heard utilize this design type and hence this is the one that most piques my interest.
Thanks.
First of all, understand that acoustics are thermodynamic, and electrical analogues, while useful (the math is way simpler!), have their limits. Any time you get stuck, "follow the heat".
Join the AES. I think they still have bound volumes of the speaker stuff available; follow it up into the '80s, at least. Thiele's idea was a great paradigm shift, but it oversimplified things, and the later work of Small and especially Keele is important. (From my own path, I think finding the work of Novak and working through the math will give a better perspective on the Thiele/Small stuff and keep you focused, but it's not likely the quickest path.)
You probably should have a broad reference such as "Sound System Engineering" by Davis and Davis, or whatever the fellows building studios and stages are using now.
For lighter reading, Parts Express has a good library. Dickason's "Loudspeaker Design and Theory" is pretty comprehensive (though you won't learn much if you read all the AES papers first), and Joe D'Appolito's Testing Loudspeakers is a must-have. Mostly, though, most of the published stuff is fairly lightweight and at best a popularization of the AES papers, at worst a regurgitation of earlier, misinformed works.
For a starter, try this site:
The Official website of D.B.(Don) Keele, Jr.
Join the AES. I think they still have bound volumes of the speaker stuff available; follow it up into the '80s, at least. Thiele's idea was a great paradigm shift, but it oversimplified things, and the later work of Small and especially Keele is important. (From my own path, I think finding the work of Novak and working through the math will give a better perspective on the Thiele/Small stuff and keep you focused, but it's not likely the quickest path.)
You probably should have a broad reference such as "Sound System Engineering" by Davis and Davis, or whatever the fellows building studios and stages are using now.
For lighter reading, Parts Express has a good library. Dickason's "Loudspeaker Design and Theory" is pretty comprehensive (though you won't learn much if you read all the AES papers first
), and Joe D'Appolito's Testing Loudspeakers is a must-have. Mostly, though, most of the published stuff is fairly lightweight and at best a popularization of the AES papers, at worst a regurgitation of earlier, misinformed works.For a starter, try this site:
The Official website of D.B.(Don) Keele, Jr.
Relatively light ready, get Dickason's Loudspeaker Design Cookbook. For heavier, theory based stuff, a must read is the AES Loudspeaker audio Anthology 1953-1977. It's a compilation of all the loudspeaker related AES papers written over that time period, and it includes the landmark T/S parameter papers by Thiele and Small. It can be had here.
Loudspeakers: An Anthology of Articles on Loudspeakers From the Pages of the Journal of the Audio Engineering Society,Vol. 1-Vol 25 (1953-1977): Audio Engineering Society: Amazon.com: Books
Loudspeakers: An Anthology of Articles on Loudspeakers From the Pages of the Journal of the Audio Engineering Society,Vol. 1-Vol 25 (1953-1977): Audio Engineering Society: Amazon.com: Books
Thanks guys, this is a great start for me. I'm thinking a mix of overview (for the broader picture) and heavy theory (to get a comprehensive understanding) is probably the right path to go down.
The lead engineer of our acoustics department (I work in the high tier portable & mobile radio business... think FBI, marines, state police) has offered me use of a spare license for their acoustics software and training on how to use it (the caveot is, appropriately so, that I will act as a liason, or bridge b/w the electrical and acoustical engineering groups, which is fine with me). The name of the SW eludes my memory, but I do know it's along the lines of $10K US for a license.
The lead engineer of our acoustics department (I work in the high tier portable & mobile radio business... think FBI, marines, state police) has offered me use of a spare license for their acoustics software and training on how to use it (the caveot is, appropriately so, that I will act as a liason, or bridge b/w the electrical and acoustical engineering groups, which is fine with me). The name of the SW eludes my memory, but I do know it's along the lines of $10K US for a license.
Ouch! Just got bit by the half-hour edit rule. I envy all of you who can typo fast. (BTW, what good is the "contact administrator" thingie if you lose everything going to a new page?!?)
Anyway.... something messed up with cut and paste - Speakerdoctor is correct, Dickason's book is the "Loudspeaker Design Cookbook".
And I went on to say I'm not really a fan of the AES.... but I'll spare you the rant. What I really wanted to say was "Welcome!" You'll likely find as much good information here as anywhere else. There's no government funding for speaker research, and with the PC based tools we hobbyists now have, you stand as good a chance as anyone to seriously contribute to the art. So, good luck on your journey.
Or... yeh.... if you have $10K software at your disposal, AND time in an anechoic chamber...
(BTW, what good is the "contact administrator" thingie if you lose everything going to a new page?!?)Anyway.... something messed up with cut and paste - Speakerdoctor is correct, Dickason's book is the "Loudspeaker Design Cookbook".
And I went on to say I'm not really a fan of the AES.... but I'll spare you the rant. What I really wanted to say was "Welcome!" You'll likely find as much good information here as anywhere else. There's no government funding for speaker research, and with the PC based tools we hobbyists now have, you stand as good a chance as anyone to seriously contribute to the art. So, good luck on your journey.
Or... yeh.... if you have $10K software at your disposal, AND time in an anechoic chamber...
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Well, I've been with this company now for 15 years, and I still kick myself for not taking the leap into this endeavor earlier with the embarrassment of riches at my fingertips, such as the anechoic chamber (I'm buddies with all the acoustic engineers) the SW, and the electronic test equipment at my beck and call (I have BOTH a Rohde and Swarz UPL Audio Analyzer AND an Agilent U8903 Audio Analyzer in my office AND a full copy of Labview on my laptop). I can also sign out most any equipment that I need.
So, take all of that into account, and then I find this place, which after reading for quite a while I have concluded is chock full of very knowledgeable and competent speaker builders, and viola!, all the reasons not to do it are gone.
I think I'm gonna like this place. And have a lot of questions.
So, take all of that into account, and then I find this place, which after reading for quite a while I have concluded is chock full of very knowledgeable and competent speaker builders, and viola!, all the reasons not to do it are gone.
I think I'm gonna like this place. And have a lot of questions.
Hi,
The "theory" of small signal TS parameters bass analysis is well known and
built into many simulation programs, e.g. Basta! goes into the the details :
Basta! technical documentation
Large signal analysis is a completely different kettle of fish and Home is
probably the best resource available to learn about the ins and outs of this.
FWIW designing the bass end of speakers hardly ever involves
the use of anechoic chambers, they are inaccurate in the bass.
rgds, sreten.
The "theory" of small signal TS parameters bass analysis is well known and
built into many simulation programs, e.g. Basta! goes into the the details :
Basta! technical documentation
Large signal analysis is a completely different kettle of fish and Home is
probably the best resource available to learn about the ins and outs of this.
FWIW designing the bass end of speakers hardly ever involves
the use of anechoic chambers, they are inaccurate in the bass.
rgds, sreten.
And you need to build some simple, proven designs to get a feel. No book or set of books will teach you everything (and besides there are lots of contradictions -- or better set, a differing viewpoints on which sets of compromises are more important.
As mentioned earlier, T/S are simplistic (for instance, most people still think of them as scalars instead of "curves"). To get a good handle on the physics Berenak's Acoustics (this is n engineering book with all the mtch from 1st principals -- it is not error free). If you could only have 3, Dickason for a basic overview, Harry Olson's Acoustics because everone should have a copy, Leviton, and the AES Loudspeaker Anthologies (some of the best triologies have 6 books in them).
And to fill out a basic library Toole (really should be in the triology above), D'Appolito -- basics of measuring, Colloms, Watkinson.
And i think that no matter which of the 2nd set you get, this book gives a very important alternate viewpoint to the current norm. http://www.diyaudio.com/forums/vendors-bazaar/157787-secret-tube-amplifiers-revealed-much-more.html
dave
Hi,
FWIW great "physics" understanding of speakers is probably more of
a hindrance than help in designing really good speakers. The idea that
you want to design "incredible" speakers presupposes that somehow
you will be better at it than all who have gone before, not very likely.
rgds, sreten.
Most of the physics is very simple, its understanding what physics
is applicable to a speaker design or not that causes problems.
FWIW great "physics" understanding of speakers is probably more of
a hindrance than help in designing really good speakers. The idea that
you want to design "incredible" speakers presupposes that somehow
you will be better at it than all who have gone before, not very likely.
rgds, sreten.
Most of the physics is very simple, its understanding what physics
is applicable to a speaker design or not that causes problems.
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The Boynton Beach facility closed years ago. A lot of those guys came down here to the Ft Lauderdale facility but most of them went into the Mobile Devices section of the facility which is now Google.
Nice deduction on where I work by the way.
I do not know George. At one time there were 9,000 of us between the two plants. Now it's down to about 2,000 or so, especially after the selloff of our mobile phone division to Google.
Dave, I can absolutely see the wisdom in this line of thinking. It's the approach that I take when I mentor other engineers on certain subjects. I tell them to go get an older design, study it, study it some more, then start messing with it and see what happens. Then I challenge them to figure out what went wrong and why.
It's called tacit knowledge and it's the kind of knowledge that cannot be transferred by either spoken word or by text. It's that "feel" or intuition that you get from experience, and 8/10 times that gut feel is spot on.
Thinking along these lines, I am considering building a pair of THOR TL speakers designed by Joe D' Appolito as shown here
The Madisound Speaker Store
Do any of you guys know anything about this specific design?
I figure doing this one would give me a bit of that "insight" that you can't learn in a book.
By the way, one of my hobbies is woodworking. I have a woodshop in my garage.
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It is a good project if you want to know about how things go wrong.
Despite Joe being considered a master speaker design and having literaly written the book on testing, he blew the design of the TL and compounded it by making a stupid measuring mistake.
http://www.diyaudio.com/forums/multi-way/64799-clarity-seas-thor-kit.html
This is a design i would never personally consider, unless it was part of an article to support the thesis of the above thread,
It breaks 2 guidlines that i hold dear: 1/ it puts an XO right where the ear is most sensitive, and 2/ the centre-to-centre distance of the drivers is greater than 1/4 wavelength at the XO point.
It is also a lot of money to spend on a 1st effort.
I'd suggest getting a pair of these: You can learn a lot.
The Madisound Speaker Store (also available with copper cones)
They may well save you of much of the "conventional" wisdom, and even if not, make a 1st class midrange.
dave
That is a good choice.
Someone I know used those as a core for a larger system. The Thor design is in the middle of the cabinet. The lower two drivers are part of a larger transmission line that runs either side of the inner cabinet.
Dr. Mark Carter has the pictures of the build somewhere on his site on the link below. Contact him is you would like at Dr. Mark Says.
THE FINISHED WALBERSWICK STUDIOS - mdcarter's Photos
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