Maths ....???

[Bluto]

57 years old - 1964 9th Grade General Math 1 & 2 educated. I simply found Math a drag, had my 2 credits needed, no need to pursue this I said. Avoided it in College too.

I'm at this over a year. I'd like to know ....

From Theil & Small, Linkwitz - Riley, Nelson Pass, MLK and all others respected ...... what are we actually dealing with here regards all the formulas? A little bit of Algebra, primarily Geometry, Trigonometry, Calculus, all mentioned and then some?

My kids are in their early 30's, I have no idea what the Public School Systems teach kids these days - how long have Schools been teaching Math's applicable to Audio Theory to at least make most of it understandable? Is at least some of this College level or are kids actually learning this stuff in High Schools?

Can't recall which member quotes Einstein - " Any fool can know - it's to Understand"

Not a statement, not a joke, I'd really like to know.

Bluto .. AKA 'Fool'

 

[MJK]

...... what are we actually dealing with here regards all the formulas? A little bit of Algebra, primarily Geometry, Trigonometry, Calculus, all mentioned and then some?

All of the above and a little more applied physics.

My kids are in their early 30's, I have no idea what the Public School Systems teach kids these days - how long have Schools been teaching Math's applicable to Audio Theory to at least make most of it understandable? Is at least some of this College level or are kids actually learning this stuff in High Schools?

My oldest is in his second year of high school. I have him tracked, and will have the younger two tracked, to get Calculus and Physics in high school. That will help if they decide to pursue a technical career. But audio theory and the physics and math behind it are college level courses if you really want to derive, understand, and manipulate the equations.

That is not saying you need to take it in college to have a chance with more in depth speaker theory. I am completely self taught about speakers but I had the required engineering/physics/math courses in college 30 years ago. Now if I could only remember the courses a little better it would really help.

 

[Dryseals]

I agree with MJK, it takes a little bit of all.

Then way the schools teach math is a drag, I had calc in high school and then never went beyound. But once I joined the Navy and started doing electronics I learned the why's of why I needed a good background. The eye opener was when I was in a industrial programming class and the instructor showed me how I reduce ten lines of program to one, all math related, those little brackets and goofy lines I always thought looked silly.

I took the kid next door, failing in all subjects, but a good kid. He wanted to build a system for his Blazer. So we built a sub woofer box using the math to calc speaker parameters to the box and tuning it on and off for effects.

He graduated in his upper class, found a use for all that garbage they were trying to teach.............

 

[Ron E]

Do you want to know how much education it takes to derive the formulas, or use them? To use the formulas in the Loudspeaker Design Cookbook, I would think high school level math and physics would be enough.

To derive Thiele/Small, that is really graduate level stuff, but a sophomore in (engineering) college should easily be able to muddle through and use their results. The analysis of boxes and crossovers is rather multidisciplinary. You have math, physics, and engineering disciplines like circuits, acoustics.

Then you get into actual construction, that requires skill at making things and an aesthetic sense if you want them to look nice. That's not all book knowledge...

 

[Bluto]

Ron E , et al --

'High School Physics and Math'?

Guys .... in 1965 the highest you could take in High School was Geometry!

This is why I asked. I'm amazed at your answers that Calculus and Physics is being taught in High Schools. If such is the case why can't anyone under 35 make change for a buck in retail establishments? Why can't young people solve simple equations I do in my head without grabbing a calculator? Is it the same reason I can't understand the formulas? Did a way to visualize whats happening in the middle get totally lost?

Loudspeaker Design Cookbook is sitting here gathering dust. Near to none of this book is any good for a beginner despite it often being recommended. I can easily understand Dryseals statement . Way back then some instructor trying to convince us to go further in Math showed an Algebraic problem layed out in General Math .... it took near to 4 paragraphs to show the same thing.

I'm having a hard time even finding what each individual symbol means and each individual symbol represents an entire process and that process combined with the next symbol can cause a number of variations to the next and so on. I likely just made what is easy for most of you to understand sound very difficult.

I 'm about to throw in the towel.

100'S of hours on the net trying to find a design for this n that is no longer fun. Wanting to build a speaker of your own design but not being able to understand if it's workable on your own and 'actually' understand so is frustrating. Being in a position you must build others designs is twice as frustrating and even more so when you can't understand the tweeks that may need to be done and even more so the whys? I've always needed to know why. What satisfaction is there when you merely follow commands but don't understand how it all functions? Many I guess are simply happy to own a set of speakers they built. Asking what appear to be
dumb' questions over and over when truth is you're just coming from a place of pure ignorance is humiliating when the ability to begin to comprehend is truthfully beyond you. Why waste others time if you can't make the journey?

Comes a time to be honest with yourself. I had hoped to make this a full time Hobby, perhaps I just build a couple of sets of speaks and take a new perspective on this.

Thanks Guys - I needed to know for myself where I stood.

Bluto

 

[planet10]

Re: Re: Maths ....???

Now if I could only remember the courses a little better it would really help.

Oh yes... 30 years of not using the advanced stuff has evaporated all but the generalities of all the stuff i learned getting an honours BSc in math.

I'm amazed at your answers that Calculus and Physics is being taught in High Schools.

I took both of those in high school in the late 60s, early 70s. (missed a perfect score on the calculus final because of a dumb algebra mistake )

dave

 

[Andy G]

Re: Re: Re: Maths ....???

Oh yes... 30 years of not using the advanced stuff has evaporated all but the generalities of all the stuff i learned getting an honours BSc in math.

I took both of those in high school in the late 60s, early 70s. (missed a perfect score on the calculus final because of a dumb algebra mistake )

dave

oh yeah, 30 years , you loose it for sure.

I did a Pure maths degree, finished in 1978. When I took on this Civil Eng degree a few years ago, it was sooooo darn hard to remember half the stuff, and I had been teaching high school maths for most of the time !!!




So... my advice is not to sweat the maths too much, just learn to use the programs written by those have learnt and retained and used the stuff !!

 

[Ron E]

Loudspeaker Design Cookbook is sitting here gathering dust. Near to none of this book is any good for a beginner despite it often being recommended.

I'm having a hard time even finding what each individual symbol means and each individual symbol represents an entire process and that process combined with the next symbol can cause a number of variations to the next and so on.

I 'm about to throw in the towel.

Take a deep breath and relax. Maybe you are trying to learn too much at once. Sometimes you need to focus on how rather than why for a while before the why starts to sink in.

There is nothing in the LDC (that I recall) that extends beyond algebra, at least not that I recall. That's all just "plug and chug" stuff. Most people don't achieve a comfort level with "plug and chug" until they have taken at least a little bit of physics.

Sounds like you need some face time with someone who really knows what they are talking about. Got any local audio clubs?

Failing that, ask questions. We are all here to help. What do you want to know?

 

[john k...]

Ron E , et al --

'High School Physics and Math'?

Guys .... in 1965 the highest you could take in High School was Geometry!

Bluto

I guess it really depended on what high school you went to. I'm class of '65 and had college level calculus in my senior year, as well as college level physics. Not everyone got it. It depended on the aptitude test results. But it was available for those who were deemed capable.

MJK hit it right on the head though. The background needed depends on what you want to do with it. But I do think to design a speaker with the software out there today can be accomplished by a high school student and a little patience. It's more about understanding the design process/sequence and what does what than how it does it. In other words try to gain an understanding of the concepts rather than the mathematical details. You can get the software to handle the math behind the concepts.

 

[MJK]

The background needed depends on what you want to do with it. But I do think to design a speaker with the software out there today can be accomplished by a high school student and a little patience. It's more about understanding the design process/sequence and what does what than how it does it. In other words try to gain an understanding of the concepts rather than the mathematical details. You can get the software to handle the math behind the concepts.

Exactly right.

If you stay within the capabilities and assumptions of the program you are using then it can be done without any great math education.

However, if you want to stray off the well traveled path and wander into something different it helps to have the math and physics background or you end up having to using trial and error construction. It can be done both ways, some people have an incredible intuitive feel without the mathematical understanding.

Personally, I like to wander off into the weeds way out in left field and see what I can learn before I get completely lost. But that is just my way, doing the math and writing the code is half the fun. I had a manager when I was a young engineer who once told me that unless you can write a working Fortran program to solve a problem you don't fully understand the solution yet. I have updated that concept to use MathCad over Fortran.

 

[HiFiNutNut]

I got a 4 year BSc pure maths as my first Uni degree 23 years ago. My advanced maths are all gone but only the basic stuff. I agree with John K that we don't really need advanced maths to do what is required in speaker design because of the availability of computer software.

The good news is that we can now leave the maths to MJK, John K, and others to do...

Regards,
Bill

 

[jupiterjune]

Bluto-

I don't know if you've tried Ray Alden's book, "Loudspeakers 101" (first edition -- there is a new edition, but I haven't seen it), but it is pretty good for what you want to learn. He goes through step by step doing the calculations for speaker and crossover design.

You don't need to be able to derive the formulas, and most of the algebra is of the simplest type ie V=IR, change to I=V/R, etc. Also, you need to know how to use a calculator to make it give the right answer; ie 2-(2-1)-(-2)=______ --I believe he goes through that as well.

If you are patient and repeat what you don't get the first time through, you will get it.

Some of the formulas Mr. Alden goes through in his book are really, really, long. But then, trying to design a speaker doing hand calculations would be nuts. The book was great to help develop an understanding of the symbols and terms. To actually design speakers, I use Crossover Pro from Harristech.


JJ

 

[MJK]

I don't know if you've tried Ray Alden's book, "Loudspeakers 101" (first edition -- there is a new edition, but I haven't seen it), but it is pretty good for what you want to learn. He goes through step by step doing the calculations for speaker and crossover design.

That is a great recommendation. I have both editions and for me I thought the first was much better at providing a physical feel for how a speaker works and how to design a classic sealed or ported box system. The second edition was not as good in my opinion.

 

[Andy G]

I got a 4 year BSc pure maths as my first Uni degree 23 years ago. My advanced maths are all gone but only the basic stuff. I agree with John K that we don't really need advanced maths to do what is required in speaker design because of the availability of computer software.

The good news is that we can now leave the maths to MJK, John K, and others to do...

Regards,
Bill

Seems there is quite a few ex-"good at maths" guys floating around. But doesn't it disappear fast !!! 20 years of high school maths teaching, but I left 10 years ago, and I am already having forgettory issues with some of the stuff I don't use in Civil Engineering.

Yesm, leave it to the guys who use the heavy stuff on a regular basis. ;-))

 

[Looneytunes]

Regardless of Bluto’s AKA, I don’t think him a fool at all. I feel like I’m in the same boat. I want to understand this stuff too, but using someone else’s plug & chug formulas will never lead you to more that a simple understanding of what’s going on. For example, if I wanted to understand why Lynn Olsen’s Ariel speaker cabinet starts out as something that looks like a transmission line and ends in a labyrinth (?) and what advantages or disadvantages that might bring to the table, I’m not going to learn that in Speaker Building 201.

I got farther in math than Bluto (1 yr college calculus, 1 yr calculus based physics, yada, yada) but between what I’ve forgotten and what I’ve never learned, getting started on the path to understanding this stuff can be intimidating. I think Bluto can learn this if he has the time and interest and a road map to follow.

Maybe you guys can help us out by suggesting a curriculum for a BS in speaker building with a minor in audio electronics. I was thinking about combining some of the basics (algebra, calculus, physics, etc) with some practical stuff like how-to books while making a few published designs along the way to learn the practical side.

Any takers?


My input to Bluto would be that the Loudspeaker Design Cookbook is probably a great second book. I would start with something a little more basic like the Speaker Building 201.

Looney

Btw, if anyone can answer the Ariel question…

 

[Conrad Hoffman]

I have no natural abilities with math, but I can slog my way through reasonably complicated stuff. As long as I get it into a spreadsheet or dedicated program right then and there, I'm ok. An hour or so later, I've forgotten everything! IMO, the usual T-S based loudspeaker calculations are pretty easy if they're presented well. There was a series way back in Speaker Builder that did an excellent job. My old Loudspeaker Design Handbook did a good job, but I haven't updated in a long time.

Here's a secret for electronics math. Shop used book stores for intro Electrical Engineering textbooks from the '40s to the '60s. Things from authors like Timbe & Bush, Terman, and the electrical measurement books by Stout, Harris, and Farmer. They were designed for people who actually had to build things, and the explanations and math are far better presented, than the modern texts designed for math prodigies. For a horrible example in mechanics, look at an old book on vibration, vs a modern one. From clear and simple, to completely unfathomable. IMO, it's no wonder that freshly minted engineers need so much training before they can do anything. For modern books, find a used copy of Barnsted's (sp?) Circuit Analysis- that goes into depth, but is pretty clear. Some people like the ARRL handbook, but I find the index and organization dreadful.

 

[Ron E]

Btw, if anyone can answer the Ariel question…

WRT Ariels: There is a certain point where Audio extends into the realm of uncertainty, flooby dust, and creative writing. I haven't read the Ariel papers in 10 years, but I had the distinct impression I was being ever so gently "sold" on the design... People swear by them, and I've never heard them, so take my fuzzy memory of the write ups with a grain of salt. I think DIY has come a long way since then.

As to curriculum, the class that really began to open things up for me was "Analysis of Dynamic Systems" Basically this was an applied differential equations class that involved solving mechanical translational/rotational, electrical, hydraulic and thermal systems the hard way before they taught us the shortcuts. Some call this a "Spring-mass-damper" class. The prerequisite for that is Differential and integral calculus and a class on differential equations (most importantly laplace transforms), as well as a year of physics and engineering statics and dynamics.

After that a formal introduction to circuit analysis, control theory and a course on engineering acoustics should lead you well on your way to having the tools to learn anything you want. During that, to get Audio specifics, you spend a lot of time reading old Journal articles. This is not to say that all of that is "required" to make great sounding speakers. It is only required to understand the process - in the connotation I have for the word understand in this particular situation.

My first book on this stuff was by Weems - I looked at the equations he gave, and by comparing them to his design writeups it became apparent that none of his "designs" were done after the sort of cookbook equations that he gave in his books. Vance Dickason's LDC made me hunger for whatever was behind the alignment tables - then I learned that the whole alignment - QL thing he recommends as a design process is really rather excessively particular about adhering to alignments - and crossovers can't realistically be designed without measurement and modeling software and/or a lot of trial and error.

One can always get a copy of Speaker Workshop, work through the long unofficial "manual" - really a tutorial written by Jay B. - and I really think there is a lot more useful content in that guide than there is in the LDC.

 

[jamikl]

I guess I am just a tad more comfortable with the maths than Bluto but still know nothing. There is a symbol which I can't recall that is often used in calcs put up by MJK and others. I believe that it represents the square root of -1. I try to understand this, look it up and am told that it is an imaginary number. If I could see how this is used in an actual equation with a result it might make sense to me but at present such things are beyond what used to be called gibberish or double dutch. No offence meant to anybody.

Sometimes just seeing something worked through can help a lot. a big problem is that a lot of teachers, and mine was like this, cannot really explain or work through a sample. They are so capable that they leave steps out which they have done mentally so what you see on the board does not help understanding.

jamikl

 

[Ron E]

There is a symbol which I can't recall that is often used in calcs put up by MJK and others. I believe that it represents the square root of -1. I try to understand this, look it up and am told that it is an imaginary number. If I could see how this is used in an actual equation with a result it might make sense to me but at present such things are beyond what used to be called gibberish or double dutch. No offence meant to anybody.

The symbol is "i" in mathematics, but usually "j" is used in engineering to avoid confusion with current, which often called "i".

An imaginary (aka complex) number is really a number that is used to describe magnitude and phase. The complex number 3+4i has magnitude=sqrt(3^2+4^2)=5 and phase=arctan(4/3). Aside from the mechanics of working with them, that is enough to get you by....

 

[Conrad Hoffman]

I curse the chowderhead that called that number "imaginary". That description messed me up for years. For the way we use it, there's nothing imaginary about it. Complex is just fine, thank you very much. There has to be a better way to teach math, but "the new math" wasn't it.