New EE graduate looking for infomation

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JohnRoberts

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jacomart said:
this is correct, as we say in Italy: "Before running you have to learn to walk"

Cheers
JM
And before you walk you must crawl... and learn to not be discouraged by the noise.

Just do it

JR
 

Newmarket

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sahib said:
I do not need  luck. I have already been designing audio for a long time without control theory.

You obviously have no idea what control theory is or designing audio.

"Control Theory" is a rather loose term so probably no mileage in discussing that as we may be talking about different things. Although note that I mentioned stability criteria etc rather the "Control Theory".
As for "Designing Audio" - literally and historically untrue.
 

sahib

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Dualflip said:
What I usually use (and believe most of us do) is the Gain/Phase margin analysis of the loop gain, which seems to me to be much more intuitive than a root locus, Routh-Hurwitz stability criterion or Nyquist plot

Its an inverting integrator  ;)

Weldone.  ;D

That is my point.

Does it tell anything about the amplifer that the integration takes place around? No.

It is a generic description of input output relationship.

It does not teach you how to design an amplifier.

Just to remind again that please do not go into lands of stability criterion, appreciation of feedback and so on. Just concentrate on designing an amplifier.

It does not teach you how to design an amplifier. As long as you know how to design the building blocks of an amplifier and put them together, and know Ohm's and Kirchhoff's laws, you are set for life. Your design and simulation package will take care of the rest. You do not need to know anything about control theory. If you do (which I know a bit) yes it helps you understand the theory better.

I bought a book, probably about 15 years ago, if not more. It is about a mathematical modelling of Fender Bassman amp. So, clearly a very clever guy with rock solid maths sat down and did it. Do you think Leo Fender used control theory to design it? I don't think he even knew what a control theory was or cared about it. he had the topological knowledge which what makes you design an amplifier. But then this clever gentleman explained the theory of that particular design.

A better example is our JR. I did not hear him saying how he used control theory to design the amplifiers he designed.



 

JohnRoberts

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sahib said:
A better example is our JR. I did not hear him saying how he used control theory to design the amplifiers he designed.
I might if I knew what that is. :-(

Being self-taught, I do not always use the precise academic nomenclature, even though the laws of physics must be obeyed.

JR

PS: Try not to scare the OP with oblique arguments. 
 

Dualflip

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sahib said:
It does not teach you how to design an amplifier. As long as you know how to design the building blocks of an amplifier and put them together, and know Ohm's and Kirchhoff's laws, you are set for life. Your design and simulation package will take care of the rest. You do not need to know anything about control theory. If you do (which I know a bit) yes it helps you understand the theory better.

I guess it depends how far down the rabbit hole you want to go, if you want to create lower distortion amplifiers, there are several different compensation methods, the main purpose is to widen the open loop gain bandwith while still keeping a 6dB/oct slope when crossing the unity gain line. These compensation schemes can lower distortion a lot, specially at high frequencies, in order to do that a good understanding of feedback theory is required.

Also, one of the greatest books on OPAMPs is the one by Roberge, and it is extremely heavy on Control Theory. I think of it like this, you can be an extremely good car mechanic without knowing physics, but if you want to be a great car designer, you will probably have to know the laws and use them..

Stability is extremely important, I gave a lengthy explanation on RF/MW amps in my previous post, stability is the #1 priority before doing anything else, its the first step when designing an amp, and software is not of much use if you don't know what you are doing or the theory behind it. Stability is a very important issue, I wouldn't discard it as something just to relegate to software.

There is an old proverb between amp designers:

"If you want to build an oscillator, design an amplifier...."

 

Dualflip

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To the OP, I agree with the other guys, you wont learn pro audio in college, I am in the later stages of a PhD in EE, everything about audio I learned it by my self.

It is true that they teach you analog electronics in college but nothing compared to the amount of subjects in digital electronics (FPGAs, PLCs, Microcontrollers, etc...).

I teach analog electronics at college for EE undergrad students, most of them are great at digital electronics and coding but have a very weak foundation on subjects like electric circuits, I guess that most of them look at analog electronics as a dead topic or as subjects they need to 'pass' in order to get their degree.

My advice is the following: really really become an expert at analyzing both intuitively and mathematically electric circuits in general, you should be able to take a look at a circuit and intuitevely know more or less how it works and then make use of all the great electric circuit tools, specially ohms law, superposition theorem, node analysis, finding equivalent resistance, mesh analysis is useful but not as useful as the other ones. Learn the basic electronic components by heart: transistor (BJT, JFET and MOSFET), you don't need to know how they work at the quantum level, but you need to know how to bias them, how the basic configurations work (common base, emmiter, etc...), learn the OPAMP inside out, learning about power amps is useful for this because power amps are basically discrete OPAMPs with more muscle in the output stage.

Read all of Douglas Self's books, also the book on power amps by Cordell, then, like your teacher suggested, take a look at real schematics and try to figure out how they work, simulate the circuits in software and mess with them around. Read about noise theory, the book by Motchenbacheris a great one, read application notes from the masters: Jim Williams, Bob Dobkins, Bob Pease, etc.... A lot of people suggest the book 'The Art of Electronics' I think it is a good book, however, in my case I find it a bit light on the theory, I like more equations and math and that book fails to deliver that, but its a great book.

Ask questions here to the experts: JR loves to share his stories, experience and knowledge, abbey knows a lot and is always willing to help, aswell as Jakob, I have not seen PRR since last year but he is also a master. Other members can also help, squarewave is a great guy and is constantly offering help, Brian Roth has a ton of experience, CJ is the transformer guru, pucho is great and always makes me laugh, and so on.... This is a great forum, full of great people, most are extremely friendly and helpful, however it is sad that many of the great gurus have left over time for a variety of reasons.

If you want to get into 'Tube stuff' you will need to start from scratch although in many ways they are very similar to JFETs, there are a lot of good books on tubes, the most prominent is RDH4, I am not a big fan of tubes but many people here are, if you are almost an EE, you probably know quite a bit about solid state stuff and nothing about vacuum tubes, so I would suggest you to continue with what you know rather than starting with tubes.

Anyway, welcome and good luck in this journey!
 

sahib

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Dualflip said:
Also, one of the greatest books on OPAMPs is the one by Roberge, and it is extremely heavy on Control Theory. I think of it like this, you can be an extremely good car mechanic without knowing physics, but if you want to be a great car designer, you will probably have to know the laws and use them..

I have got it in my library. It is a very heavy book. But I have heavier books than that in terms of circuit analysis.

I do not wish this to drag on too long as people are probably getting bored. But you are still making analogies to car design etc and I do not think this will get us anywhere. So, I will agree to disagree and bow out.
 

Dualflip

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sahib said:
I have got it in my library. It is a very heavy book. But I have heavier books than that in terms of circuit analysis.

I do not wish this to drag on too long as people are probably getting bored. But you are still making analogies to car design etc and I do not think this will get us anywhere. So, I will agree to disagree and bow out.

Its the first analogy I made in this thread  ;D but ok... I'm not saying that Roberge's book is the most advanced, if you want heavy books, read books on Network Synthesis, authors like Cauer, Bode, Brune, etc... those are heavy books circuit and math wise..
 

Winston OBoogie

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The books on amplifier design by Doug Self and Bob Cordell will get you a long way.  I would advise to read those, then build a few of the various blocks within and then listen, test, evaluate, rinse, and repeat etc...

Douglas Self's book primarily focuses on one particular topology and, while my experience is that improvements can be had by taking his basic topology beyond the point he arrives at,  it's a decent place to start.

For example: read the paper by Harry Dymond et al. for a somewhat contradictory to Self breakdown of how to implement two pole compensation, then build it and see for yourself. 

Bob Cordell is more accepting of topologies, choices of silicon type used etc., schemes that Self outright dismisses, and these are also well worth exploring IMHO.

As are simpler topologies by John Curl, Nelson Pass etc.  These may not be winning any competitions in the specs race, but elements they use can show how, sometimes, less is more.

I've no idea where I'd begin if my brief was to apply/use "control theory" to build an amplifier. 
Simulation of phase margins etc I'm fine with.  But there's no substitute for a decent 'scope, sine/square generators, and getting your hands dirty.

Just my humble $0.02









 
 

abbey road d enfer

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@Dualflip & sahib
Who would have thought the OP's innocent question would result in such controversy, as I'm sure both of you are well-meaning.
The apparent result is the OP has deserted...
The road to hell bla-blah...
 

sahib

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Indeed and thank you Abbey,

As it often happens here in this forum, the discussion drifted away from the main issue. I do not mean to blame  but I was merely trying to say that asking somebody, who could not even understand what a capacitor does in a circuit,  to start with control theory was surely not needed.

However, I'll conclude again by saying that those who are interested in designing discrete audio amplifiers should buy that book I suggested. One does not need the control theory or its gruelling maths, but simple algebra. Accompanying books also teach passive circuits, including filters in detail and again using simple algebra. Frequency response, feedback, compensation, poles, zeros the lot explained in a very very simple way without resorting to heavy control theory. They are highly practical books that will make one design literally after a few pages.

I hope this steers the discussion back to its main point.
 

Winston OBoogie

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abbey road d enfer said:
The apparent result is the OP has deserted...
The road to hell bla-blah...

He may simply just have his head in a book.

Which could just as easily indicate a  road to hell...

Interesting viewpoints from all concerned, glad I stopped by and read.

Peace brothers.

 

abbey road d enfer

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sahib said:
As it often happens here in this forum, the discussion drifted away from the main issue.
I have nothing against drifting, on the contrary. Sometimes it is advisable to start a new topic, so the OP doesn't get entangled in sectarian squabbles that make them going to GS for comfort.  ;)
Peace anyway.
 

Matador

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sahib said:
I do not mean to blame  but I was merely trying to say that asking somebody, who could not even understand what a capacitor does in a circuit,  to start with control theory was surely not needed.
Indeed, I will just apologize for mentioning it in the first place and leave it at that.

I deleted my first post, and hopefully there are enough other links / suggestions to get the OP started.
 

Dualflip

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abbey road d enfer said:
@Dualflip & sahib
Who would have thought the OP's innocent question would result in such controversy, as I'm sure both of you are well-meaning.
The apparent result is the OP has deserted...
The road to hell bla-blah...

Abbey, I responded sahib once and also made a lengthy post directly addressing the OP with my recommendations on books, who to address in this forum (you included) etc... I only made 3 posts in this thread, the one to sahib, the one to the OP and the last brief one responding sahib, I don't think that makes it a huge controversy, the controversy started way before sahib and I had a conversation, it was between Newmarket, sahib, and others but I guess I climbed on the bandwagon so I am not denying my participation.

I don't wish to discourage new members, we don't even know if he is periodically reading the thread, perhaps he will chime in later on, after all, he is a new member.

In any case, I apologize
 

abbey road d enfer

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Dualflip said:
I only made 3 posts in this thread,
That's right, but I know too well, having been guilty of it, and not sure I'm vaccinated against it  ;)  that sometimes a single post is enough to inflame a debate.
I'm not putting the blame on anybody, I'm just waving the white flag...  8)
 

sahib

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Matador said:
Indeed, I will just apologize for mentioning it in the first place and leave it at that.

I deleted my first post, and hopefully there are enough other links / suggestions to get the OP started.

I would be happy for my posts to be deleted too if it helps bringing back the topic. 

Perhaps I came across too harsh and I too apologise if I offended anybody.

We are all long time members here and I trust we all know each other well and no offence was intended.
 

PRyHyM

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What Im learning from this thread is that my formal education has ended and my practical education has just begun... I've heard of most of the things discussed in this thread (control theory, etc, etc) but learned them in a very abstract way. I never understood how they expect a person to learn engineering by having  someone stand there and explain it to them. every course should be a lab imo....
 

john12ax7

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There are some schools that incorporate a large hands on component,  but it's not the norm.  Even if you do well in school you still need some years of real world implementation.

Are you planning to get an engineering job? That would be another good resource to learn,  senior engineers are often willing to share their knowledge.  I started out in RF and did audio on the side.  The senior analog guys weren't audio people,  but they had a lot of practical knowledge on getting things to work that could then be applied to audio designs.
 

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