New EE graduate looking for infomation

[PRyHyM]

Hi all,

I will be graduating with a EE degree in 2 weeks. Ive always been very interested in audio circuits a discrete amplifier circuits. not to long ago i went to one my professors and asked him what it would take for me to design and build my own preamp. He said in order to design an amp i need to look at amp schematics and understand what each component in that circuit is doing in the amp. While that sounds like a wonderful idea i dont know where to begin to look for that info. i have read several books on amps and there fine but none have went over ever component in a class a circuit. how should i go about getting this info. i would love for someone to show me exactly what everything does in a amp but i have no one willing or able to perform such task. any advice i could get would be of great help. in the end would love to design and build both a preamp and eq from scratch with my own designs..

 

[12afael]

I had a similar problem when I was studying. I started my own forum of guitar pedals and tube amps. it is a good thing to share problems and experiences with other people.
From building clones, we started to modify stuff changing filters, adding stages, etc.
There is a lot you can learn form that. there is a point where more complex stuff is required, circuit synthesis go from a impedance matrix and translate that to a working circuit. I suppose that some universities might teach that.

The books from Douglas Self are very good you should take a look at those circuits and try to recognize them on other schematics. That will give you an idea of why they are there and how the designer thought the circuit.

 

[abbey road d enfer]

Hi all,

I will be graduating with a EE degree in 2 weeks. Ive always been very interested in audio circuits a discrete amplifier circuits. not to long ago i went to one my professors and asked him what it would take for me to design and build my own preamp. He said in order to design an amp i need to look at amp schematics and understand what each component in that circuit is doing in the amp. While that sounds like a wonderful idea i dont know where to begin to look for that info. i have read several books on amps and there fine but none have went over ever component in a class a circuit. how should i go about getting this info. i would love for someone to show me exactly what everything does in a amp but i have no one willing or able to perform such task. any advice i could get would be of great help. in the end would love to design and build both a preamp and eq from scratch with my own designs..

You must start with a single stage, determine how to bias a one-transistor stage, evaluate the performance aspects (frequency response, maximum output vs. load, gain vs. load, distortion mechanisms, noise), then you can start combining more stages to increase gain and take advantage of the various topologies (common emitter, common-base, emitter-follower).
Then you evaluate how using Negative FeedBack (NFB) can improve some aspects of performance (distortion, gain  and operating point stability).
Once you have understood that, you're ready to transpose it to FET's, tubes, opamps, whatever...
But I would have thought a lot of this to be covered in EE course.
Audio is just a (very) particular case of global electronics.

 

[JohnRoberts]

Hi all,

I will be graduating with a EE degree in 2 weeks. Ive always been very interested in audio circuits a discrete amplifier circuits. not to long ago i went to one my professors and asked him what it would take for me to design and build my own preamp. He said in order to design an amp i need to look at amp schematics and understand what each component in that circuit is doing in the amp. While that sounds like a wonderful idea i dont know where to begin to look for that info. i have read several books on amps and there fine but none have went over ever component in a class a circuit. how should i go about getting this info. i would love for someone to show me exactly what everything does in a amp but i have no one willing or able to perform such task. any advice i could get would be of great help. in the end would love to design and build both a preamp and eq from scratch with my own designs..

Your professor gave you good advice. You didn't say what kind of preamp but there are canned solutions involving ICs for mic preamps with application notes from the chip manufacturer. I consider preamps a mature technology so there is not much room to improve upon the current state of the art.

In high performance audio design everything matters. There are subtle and not so subtle differences between  components. It would be pedantic and boring to most readers to explore every single component selection in a complex design, but the design engineer did think about each one.

You can learn a lot by looking at classic designs and figuring out why certain components were used where, even including the values.

JR

 

[PRyHyM]

Your professor gave you good advice. You didn't say what kind of preamp but there are canned solutions involving ICs for mic preamps with application notes from the chip manufacturer. I consider preamps a mature technology so there is not much room to improve upon the current state of the art.

In high performance audio design everything matters. There are subtle and not so subtle differences between  components. It would be pedantic and boring to most readers to explore every single component selection in a complex design, but the design engineer did think about each one.

You can learn a lot by looking at classic designs and figuring out why certain components were used where, even including the values.

JR

What’s the best way to go about doing that? I understand the core components of a class a discrete preamp but when I look at say a neve pre schematic there are tons of things I don’t understand. How do people learn the purpose of those components without someone explaining each component to them. It’s hard for me to believe a scope would explain all this...

 

[sahib]

But I would have thought a lot of this to be covered in EE course.

Sadly not.

I am also about to complete my EEE honours degree (at the age of 60). Only two exams away. Analogue  takes up a very small part of the curriculum and is very very and very basic. All digital and programming as this is where the vast majority of jobs are.  I did not have to do anything to pass the exams (with good marks). However I can not complain as my embedded design skills improved considerably. I learned reasonably good Verilog (also taught myself VHDL) and have better C chops now.

However, anybody who is interested in learning transistor amplifier design MUST have this book

https://www.ebay.co.uk/itm/263925775586?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Do not waste time on anything else.  There are other two books from the same seller. Get them too. These books cost for a burger meal but are worth gold in their weight. Incidentally, the seller is the actual publisher who is retired. A wonderful man.

 

[Bo Deadly]

Analogue  takes up a very small part of the curriculum and is very very and very basic. All digital and programming as this is where the vast majority of jobs are.

I was wondering why an EE would have so little knowledge of basic analog electronics but this actually makes perfect sense. Analog circuit design is really a highly specialized field at this point. It's like working on old cars with carburetors and the like. Young people who are trying to find something interesting, meaningful, satisfying and monetarily rewarding would be far better off designing hardware for GPU computing or whatever the latest thing is.

 

[john12ax7]

Getting some books more geared to practical applications would be a good way to go. Simulation can also be an invaluable tool,  as it allows you to make changes and see the consequences of those changes.

 

[Audio1Man]

Hi PRyHyM
Some time is hard to see forest, unless you study each little thing one at a time. Like the BIG Douglas fir, then the roots then trunk, then first branch, then when you finish start with the Moss, shade, mushrooms, etc. Start One Stage @ a time.

You need to study each type of CAPACITOR, RESISTOR, INDUCTOR, and other component and understand the finite differences of each component.

A single stage Emitter-follower can also be come a Common-base OSCILLATOR if the base is low Z, so we add a small resistor or ferrite bead on the base.

On and on each, item by item. I’m still learning each day. Enjoy the progress, and treasure each day as new treat.
Duke

 

[Brian Roth]

However, anybody who is interested in learning transistor amplifier design MUST have this book

https://www.ebay.co.uk/itm/263925775586?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Do not waste time on anything else.  There are other two books from the same seller. Get them too. These books cost for a burger meal but are worth gold in their weight. Incidentally, the seller is the actual publisher who is retired. A wonderful man.

Looks interesting!  I did some digging and found the other two titles.  Approx. $15 each plus S&H from a USA seller via Ebay.

Bri

 

[JohnRoberts]

What’s the best way to go about doing that? I understand the core components of a class a discrete preamp but when I look at say a neve pre schematic there are tons of things I don’t understand. How do people learn the purpose of those components without someone explaining each component to them. It’s hard for me to believe a scope would explain all this...

Sorry there is no easy short cut for how to acquire decades of design experience overnight. You have to melt lots of solder trying various circuit configurations looking for improvement.

It helps to be mentored by senior engineers to keep you pointed in the right direction. There are many decades of design experience resident in forum members here, and within the archive of old posts answering previous member's questions. 

Be patient, it takes decades to get decades of experience.

If that Neve is too complicated maybe back up to something simpler... Complex circuits are made up from a number of simple building blocks combined together.

JR

PS: A scope will show you voltage waveforms wrt time... This is a basic bench tool, after VOM.

 

[sahib]

What’s the best way to go about doing that? I understand the core components of a class a discrete preamp but when I look at say a neve pre schematic there are tons of things I don’t understand. How do people learn the purpose of those components without someone explaining each component to them. It’s hard for me to believe a scope would explain all this...

I can understand you better because I have been asked the same question by my classmates.

Get your RCL circuit knowledge rock solid. If you do not know what these three components actually do then you will never be able to understand analogue (or also called linear) electronics.

Then as Abbey said, learn the single transistor amplifier configurations. What is a common base, common emitter or common collector?

What you see in a big circuit is all made up of individual circuit blocks. All reduced to a single transistor.

As I mentioned before, get those books. They will teach you how to design discrete amplifiers by practical examples and detailed analysis. But no differentials or integrals here. Simple algebra. If you can add, multiply, subtract and divide, you are good to go. The author Lorne MacDonald should have been given an award for these books.

My experience of higher education proved what once a great guy called PRR, who used to be a regular here, said. You graduate with skills to write beautiful equations but you can not design a thing. 

 

[ruffrecords]

Hi all,

I will be graduating with a EE degree in 2 weeks. Ive always been very interested in audio circuits a discrete amplifier circuits. not to long ago i went to one my professors and asked him what it would take for me to design and build my own preamp. He said in order to design an amp i need to look at amp schematics and understand what each component in that circuit is doing in the amp.

What university is this? I cannot believe that any EE degree course would not teach basic transistor theory and design. And did you not do a final year project as part of your degree course? You could easily have designed and built a preamp for that project.

Cheers

Ian

 

[abbey road d enfer]

I guess part of the problem is that many see electronics as standing in front of a computer and typing like a machine-gun.
It looks like the OP's teach is in about the same state of mind. The lack of direction of his answer is symptomatic.
But there are still many areas of hard-boiled electronics that flourish, like RF, radar and power electronics.
Not so much with analog audio. Everything is pretty much covered, with all aspects of performance being served close to perfection.

 

[merlin]

The books from Douglas Self are very good

+1 Doug Self's books explain every single component in excruciating detail; see Small Signal Analogue Design.
If you want to know about power amps then Bob Cordel's Audio Power Amplifiers is a littler easier to read than Self's.

 

[Matt Nolan]

What university is this? I cannot believe that any EE degree course would not teach basic transistor theory and design. And did you not do a final year project as part of your degree course? You could easily have designed and built a preamp for that project.

Cheers

Ian

As another example, I did an IEE approved Bachelors / Masters in Electronic and Communication Engineering from 1992 to 1996.

I learned more about how electrons move inside transistors and ICs than I did about how to design circuits with them. More about impedance matching microstrip at RF and TEM modes in waveguide. More about optimising control loop parameters using Laplace transforms and S-plane diagrams. More about fractals, chaos, and strange attractors. More about asynchronous digital design and plesiochronous communication networks. More about laser LEDs. More about AI and Intelligent Systems Design. More about sub-Nyquist sampling, FFTs, oversampling, ADCs and DACs. More about generating, receiving and demodulating SSB FM...

At least I went through slightly ahead of software taking over almost everything. We learned Fortran 77 FFS! Not even C.

We did a little bit of Analogue circuit analysis in the first year. Kirchoff's and the likes. We did a tiny bit of class C amp design with transistors later on, but more to do with linearising using feedforward and feedback networks than the actual part in the middle there. Actually, now I think about it, there was a little bit of load lines, class A, B and AB for audio, but I think all we really analysed was stuff like power efficiency - not frequency response, stability, SNR, distortion, etc. We learned how to design filters with poles and zeros, specified pass and stop bands, ripple constraints, etc. but it was never really related to analogue components, more the digital side: FIRs and IIRs.

I barely dare think what the syllabi are like now.

 

[ruffrecords]

I think you are right Matt, most of this (basic) stuff is taught in the first year. In went to Nottingham in 1970. The first year course had some common elements that ALL undergraduates took - stuff like thermodynamics, strength of materials and of course lots of maths - don't forget the maths. The rest was course specific but my course was for both electrical and electronic engineers so it included transmission line and generator theory as well as Kirchoff, Thevenin, maximum power transfer, semiconductor physics, magnetics and basic transistor theory, equivents circuits and class A, B and C amplifiers. Everyone was given a little PCB and some components to build a simple 3 transistor calls A amplifier ( basically a dc couple pair with the first transistor replaces with a Darlington pair). We learnt ots about biasing, NFB and input/output impedances playing around with it. Most important of all, it made a great fuzz box.

Cheers

Ian

 

[JohnRoberts]

I turned on, tuned in, and dropped out in the 60's (sophomore year) so I can't expound about college curriculum. And I was planning to major in ME but do recall one hands on electronics lab that was one of the few classes I would wake up for and attend regularly.

FWIW back in the 70s I sold a lot of my hifi audio kits to college students majoring in EE. Apparently it was a popular course requirement to have them alter a design and explain what and why they did. I already provided some design equations in my Popular Electronics kit articles, but momma didn't raise no fool so I started adding even more design equations to my kit instructions.

It was almost cheating for them, but they still had to understand enough to do the actual math even with the design equations dropped in their lap.

I repeat the best way to get decades of experience is spending decades of bench time doing it. Perhaps find a company in the industry you like and start working as a bench tech, or maybe sweeping the floors. I started as an electro-mechanical bench technician working at MIT Instrumentation lab. My original interest was not electronics but life nudged me in that direction with every subsequent job change. Even in the army my MOS was maintaining tank targeting computers but they just awarded me that MOS based on my civilian experience.

JR

 

[Bo Deadly]

As another example, I did an IEE approved Bachelors / Masters in Electronic and Communication Engineering from 1992 to 1996.

I learned more about how electrons move inside transistors and ICs than I did about how to design circuits with them. More about impedance matching microstrip at RF and TEM modes in waveguide. More about optimising control loop parameters using Laplace transforms and S-plane diagrams. More about fractals, chaos, and strange attractors. More about asynchronous digital design and plesiochronous communication networks. More about laser LEDs. More about AI and Intelligent Systems Design. More about sub-Nyquist sampling, FFTs, oversampling, ADCs and DACs. More about generating, receiving and demodulating SSB FM...

Very well said and great points. I think I understand small signal analog, some power and basic digital well enough for DIY projects but clearly I should definitely never claim that I have knowledge of EE in general.

 

[sahib]

I can also understand that electronics as a subject is no longer what it was in say 70s. It is vastly much wider of a subject now, and impossible to cover all of it. So the universities have to focus on the  areas where jobs are. At the end of the day they have to produce employable graduates.

My complaint is/was that we wasted a lot of time on doing modules like integrated engineering. I got an exemption from it in year one but ended up doing it in year 2 and 3 which was an utter waste of time. A total micky-mouse subject. Whereas they could have filled these with, say, even basic power electronics. Equally again in year one we did one module programming Lego using Robot C and another one  literally copying Arduino programs, supposedly to introduce the student to programming. Why not introduce C directly? As a result from year 2 and 3 you can feel that they are cramming a lot of stuff in a very limited time.  By the time you are in year 4 you are sprinting (as one lecturer said).

@ squareave,

The science side even at its basic indeed requires a lot more than understanding diy electronics. Although, nobody designs analogue audio using laplace you have to chew a lot of serious maths.