"Designing Audio Power Amplifiers" 2nd edition by Bob Cordell book review

[@envisionelectronics]

Bob’s a good friend of mine. He worked in Bell Labs Transoceanic Optical Amplification division. He designed amps for Crest, Yorkville and many others. One of my servo amp kits was designed by him. Super nice guy, too!

[@JohnAudioTech]

Thanks for chiming in. I hope this vid sells a few extra copies of his book.

[@bradatherton9369]

Good point to mention LTSpice! I have used it to fully model the power amp of an old Pioneer SX-950. It was failing in so many ways that it was unfixable without Spice Sims. Lots of parts were obsolete and consequently many parts had to be replaced with different ones which caused the need for partial redesign. By redesigning the bias stage and simulating a sweep of the feedback ratio and diff pair potentiometer the THD reduced by a factor of 10. Not a huge deal but it was a helluva experience. Took a year and a half!

[@robust98]

That was extremely helpful! I'd quit my position in the medical field since last September and plunged into building audio amplifiers and woodworking (speaker cabinets) this year. Your videos have helped me a lot. Many Thanks from Taiwan! (Robust Chen)

[@ats89117]

Looks like Snickers is trying to absorb the material in the book via osmosis. I've tried sticking books under my pillow to save the time required to actually read them, but it's never worked for me...

[@joohop]

Remember Earthling We Will Let You Use Our Music Free Of Charge Bless Ya Buddy

[@iblesbosuok]

Watching its structure, it would be a bloody good book. I'll get one. Cheers from Indonesia

[@pliedtka]

If there's more things than in the first edition then I might buy it. The original one when it came out was IMO one of the best, most comprehensive books about amps design. Jan Didden at Linear Audio has a lot info in his paper published here and there. I love LTSpice, even though I'm not really good at it, I can simulate others or commercial designs and learn and see how they behave if I change circuit a bit or components.

[@johnyang799]

I have read both the Bob Cordell first edition and Douglas Self's book. I wish there would be a book talking about current feedback amplifiers throughoutly. Doug touched a bit in the push-pull vas section a bit but he didn't like it. He's kinda not as experienced as I hoped and a bit opinionated. Bob I believed he didn't use all the real world measurements. Spice can only do so much especially at ppm range and at higher frequency. An ultra low distortion opamp controlling a high speed CFA would be the ultimate low distortion circuit for me. Or even two opamp cascade + CFA. Resulting 300dB+ total feedback at output stage.

[@JohnAudioTech]

Some people like the current feedback design. I understand it has less PSRR. Perhaps that would be offset with your high open loop gain design.

[@johnyang799]

@@JohnAudioTech The idea is to use a vfa control a cfa. AKA composite amplifier. Resulting best of both worlds and more. I personally did this in headphone amplifier with an opa1656 or similar + tpa6120a2, having distortion of -130db. Sadly discrete design with high voltage is much harder and would be almost impossible to have 300Mhz bandwidth.

[@blaser80]

Another good book on Audio Power Amplfiers is by Douglas Self, though personally I'm more interested in small signal audio design. Self has books on a number of audio topics

[@elgringoec]

Small signal amplification today = choose the right ic op amp. 😁

[@bradatherton9369]

I have Douglas Self's books too and Bob Cordell. Self does amazing work, as does Cordell. And about that comment of choosing the right op amp...that is unfortunately the attitude today. Problem with most ICs is they operate in push pull or totem pole, leaving lots of opportunity for crossover distortion and overshoot because of the copious amounts of negative feedback. There is some material out there that describes a technique called 'forced class A" intended to circumvent the op amp CD issue. Too bad discrete amp designers are dropping out of existence, combined with the pursuit of lowest cost for highest profit margins. The op amp has probably already won the war.

[@tenmillionvolts]

I have "High power audio amplifier construction manual" by G. Randy Slone. Very informative. Many different designs and he debunks audio myths as he goes. I'll have to check out Bob Cordell's book too. Looks great

[@nowt1002]

Will have to try and get hold of this. The first edition is great. Have you read Doug Self's work? I would say him and Cordell are the best on audio electronics. Both very readable as well as having great information. Regarding the spice simulation stuff, that section is really good and got me going with using ltspice to simulate amplifiers. He has even made some spice models of various transistors that are commonly used in amplifiers such as bc550/560 and some of the common output transistors that are supposed to be more accurate representations than many of the commonly available models.

[@JohnAudioTech]

I got hold of Self's book through an inter library loan. It is always good to see another opinion. I like how he puts audio myths to bed right out of the gate. He adds a touch of humor too. Remember the crack on Radio Shack? Self is a bit biased too. For one, he don't consider MOSFETs in power amps. I mentioned Bob's custom models in the video, but it hit the cutting room floor as I wanted the video to stay under 10 min. It was 15 min initially.

[@nowt1002]

@@JohnAudioTech Yes Doug Self is quite opinionated on certain subjects but he is funny. Have you come across his power amplifier design using lots of NE5532s in parallel. I've often thought about giving that a try.

[@JohnAudioTech]

@@nowt1002 I've seen that one in the DIY audio forums. I haven't thought of trying it though. Self seems to be into preamplification these days. I'd like to check out his preamp book.

[@natecontarino1748]

I'd like to get his preamp book too. I have his small signal amplifiers book and I learned a lot about noise that I didn't know.

[@PeterMilanovski]

Some of the books by Self are available as PDF free downloads as well as others...

[@johnsenchakinternetsecurit8935]

We need a book about Snickers !

[@DAVIDGREGORYKERR]

What about a HIFI amp based around the amp that drove the color guns in a NTSC CRT Television which should have a nice frequency response.

[@audiotechlabs4650]

It's been a busy summer for me, so it's been awhile since I viewed your channel, this one caught my eye. John you always have great content in your videos, this one, for me, was exceptionally interesting. I need to expand my amp designing and building. I saw the price of this book on Amazon and found it is a bit out of my price range, at least for now. I do have your wonderful, informative videos to reference. Is there a tube amp book you could suggest that would help newbies get started in tube amp design and build? Yes, tube amps have extremely high D C and A C voltages and caution must be used when exposing yourself to them. I am sorry, but for guitar amps, there is no finer tone than tube amps! I know there will be people who will argue that point, but I am 70 years old and have been plating guitar since I was 12 and have played ever kind of amp, tube amps just sound fuller, louder and more pleasing to my ear. Clean or overdriven, give me a tube amp. Any good books on that subject? I trust your opinion, from watching your videos I have determined you possess a vast knowledge of electronics, my kind of guy! Thanxz

[@JohnAudioTech]

No argument from me. Guitar tube amps are where its at because of the way they distort. The DIYaudio forum is a good place for more tube material. Tube components are expensive especially when power and sound quality are involved (eg. high grade output transformers) so it is something I don't get involved in much.

[@elgringoec]

When I was in Jr high school my orthodontist gave me a Heathkit AA-100. I did a lot of stuff with that amp starting with his cold solder joints and later on converting the outputs to 6L6s. But one day I'm trying to track down a signal loss with the finger on probe signal injector when I hastily counted wrong on an output tube. I'm holding the amp on its side bottom toward me with one hand while probing with the other, and when I hit the plate instead of the grid... Involuntarily I leaped rearward and quite fortunately my bed was close enough behind me that I landed on it and avoided any known injury. Of course I never mentioned this to my parents... Tubes def have their charm with guitar. I've got tons of tube stuff but it's all audio reproduction and sound reinforcement based, nothing guitar specific. I have books but it's been ages since I've read from them; I can scan my shelves for potential goodies if you're interested. But design/troubleshooting/repair is easy once you get a grasp of the valve. Basically you set a quiescent current by plate and grid voltage and cathode resistor, then keep your audio signal within 0-2x that value. The gain to first order is the plate to cathode resistor values. A/B output stages have two tubes, one for the negative going and the other for the positive going signals. Plate current goes through a transformer winding, the center tap of which is fed by a power supply. Cheers!

[@paulmilligan3007]

GeoMac Granddad I miss the thrill of getting electrocuted and living to tell the story and the blue flashes when your test probe slips.

[@johnyang799]

Is there anywhere I can buy for PDF version?

[@JohnAudioTech]

I'd check with the publisher, Routledge, to see what they offer.

[@johnyang799]

@@JohnAudioTech Thanks, John!

[@elgringoec]

Nice! I feel like I used to read articles by him back when I got audio magazines. The layout of the book looks great; it woulda been nice to see how deep and mathy he gets. I don't know how far you can go before showing content becomes copyright infringement. I guess you could write/call Bob for a level of permission?

[@JohnAudioTech]

Bob states in the preface that he keeps the math to a minimum but when you look through the book there are equations throughout. It is difficult to describe circuits without some math. He gets pretty deep but without calculus an other advanced math. He uses a lot of graphs, basic formulas and good explanation on how the circuit functions.

[@elgringoec]

@@JohnAudioTech Thanks.

[@SunitaSharma-eo6ud]

What books we have to read first to understand this book ? Please tell.

[@JohnAudioTech]

"The Art of Electronics" is a respected book.

[@SunitaSharma-eo6ud]

@@JohnAudioTech thanku sir

[@linorocha6319]

Now you can do discrete audio amplifiers using MOSFET, that would be a neat thing to do. What do you think?

[@johnyang799]

@@ralfstocker7742 No. For high power audio 300W+ or 1000W+ it's more than suitable. Also for class d it's like the only option. With enough open loop gain, the distortion will be low anyway.

[@Mr_Meowingtons]

@@ralfstocker7742 ROFL WHAT?

[@JohnAudioTech]

Read this book! It shows otherwise with good design.

[@aljivenalejo3904]

me my book is from le old author called pagarigan amplifier thats kind off make me idea to make power amps

[@rrangana11]

Routledge has better pricing than Amazon.

[@JohnAudioTech]

I never got the appeal of Amazon. Everything I bought, I could find cheaper elsewhere.

[@alunroberts1439]

I have the 1st edition in a PDF you like it let me know

[@iblesbosuok]

I like it

[@carlfranz6805]

Still doesn't explain why the Sansui 881 is the best $$@% receiver ever. 🤣

[@elgringoec]

😂 I know, right?

[@a-job7276]

well... i will have 700 pages for learn inglish... omg!! holy bible. Mucha papa canaria

[@elgringoec]

How do you eat a whale? (Para comer una Ballena?) One bite at a time! (Una mordida por una!) Que Dios lo acompañe.

[@carlfranz6805]

Hot damn!!

[@CalebePriester]

it's like the bible lol

[@NielsCG]

first!!

[@thesquarerootofnegativei6225]

Your mom must be so proud.

[@adamsmith5913]

First da worst

[@NielsCG]

@@thesquarerootofnegativei6225 yeah She is, thank you, your mom is also proud of me Son...

[@thesquarerootofnegativei6225]

@@NielsCG The apple clearly doesn't fall far from the tree.

[@isoguy.]

Penultimate, drat, two more comments have been added. Doh!

[@shyamkumarsuman7417]

Class A B amplifier book repair ho sakta

[@nicoras8803]

I would argue that most electronic engineers are familiar with most of these concepts. Unless you have limited knowledge on the subject, why buy a book.

[@JohnAudioTech]

EEs may know a lot about the building blocks but may not, for example, have a full grasp on the distortion mechanisms in an audio circuit. I've worked around professional engineers and professors. Each of them has racks full of reference material.

[@johnyang799]

Unless you have read the book. EE only gives you the tool to get start and do all the work being done in the book. When you read the book you necessarily getting the outcome without doing all yourself. It's very similar to reading papers.

[@rrangana11]

EEs including my self familiar with these concepts still have or would like to have bunch of books for reference. Why do you say that ?