Transistor for Powerful Class A Amplifier

[Doodski]

You may find it useful to study the design of an op-amp, because these tend to have many of the common elements in them and there are excellent detailed studies about them which break down their functions and explain what they are doing.

The textbook I referred him to called Semi-Conductor Fundamentals by Floyd covers all the transistor layouts plus has a fully comprehensive OP amp section. The book is maybe 1300 pages if memory serves me correct.

 

[MaxwellsEq]

The textbook I referred him to called Semi-Conductor Fundamentals by Floyd covers all the transistor layouts plus has a fully comprehensive OP amp section. The book is maybe 1300 pages if memory serves me correct.

Hi @Doodski , I've had a dig into this (I like textbooks and was thinking of buying it). There seem to be two versions - "electron flow" and "conventional current". You mentioned the electron flow version, did you prefer it? I've never had a textbook which takes the electron flow view. Pretty much all I've owned or read are conventional current (after the first chapter). Presumably all the diagrams have the arrows reversed, but are there other differences?

 

[Doodski]

Hi @Doodski , I've had a dig into this (I like textbooks and was thinking of buying it). There seem to be two versions - "electron flow" and "conventional current". You mentioned the electron flow version, did you prefer it? I've never had a textbook which takes the electron flow view. Pretty much all I've owned or read are conventional current (after the first chapter). Presumably all the diagrams have the arrows reversed, but are there other differences?

I asked the instruction staff and they said other than using electron flow and the arrow directions they said everything is the same. I've never used a conventional flow version. Electron flow is all I know. My understanding is physicists use electron flow and others use conventional flow. It's important to get the right one because after this it will be ingrained in one's mind the flow directions and to mix might be cumbersome for some that are beginning. For a seasoned expert like you I think getting what you are accustomed to is the better choice.

 

[MaxwellsEq]

I asked the instruction staff and they said other than using electron flow and the arrow directions they said everything is the same. I've never used a conventional flow version. Electron flow is all I know. My understanding is physicists use electron flow and others use conventional flow. It's important to get the right one because after this it will be ingrained in one's mind the flow directions and to mix might be cumbersome for some that are beginning. For a seasoned expert like you I think getting what you are accustomed to is the better choice.

I had a professor who frequently got his intrinsic and extrinsic semiconductors mixed up and swapped between electron and current flow. It made me feel better when I got it wrong.

I self taught myself conventional current direction before I went to university (EE) and that's what was taught there. However, for semiconductor and thermionic behaviour, electron flow is easier to mentally visualise how it works. I think I just did that and then mentally flipped the arrows back for current flow.

 

[GXAlan]

Maybe quiet new laws (thinking CA, EU, US) prohibiting the selling stuff not "x" efficient or in category "x" which consumes more than "x" power. I have a feeling with how over the top they are about things, you couldn't sell, a class A amp over 40WPC commercially in North America in 2025. Probably not since at least 2013.

Unlike those halogen lamps which were a fire hazard (top heavy, concentrated heat without thermal management, etc.) Class A amps are perfectly safe. They are inefficient, but so are Ferrari’s and Lamborghini’s.

Accuphase Laboratory, Inc.　A-300

www.accuphase.com

Xs300 - Pass Labs

The Xs 300 is the kind of amplifier that makes “state of the art” feel like a real thing. It delivers startling realism at any level—micro-detail, dynamics, tonal density, and scale—without ever sounding forced. This is reference Class A power … Continue reading →

www.passlabs.com

Economies of scale and the rising price of summit-fi have made Class A amplifiers luxury statement items where MSRP reflects a lot more than bill-of-materials…

 

[kmanusa]

OK!

Do you know what ended up happening to Kinergetics?

Sorry for hitting this older thread but I just noticed it. According to Stereophile, Kinergetics went bankrupt in August of 2000, see here: https://www.stereophile.com/content/wadias-assets-sold-kinergetics-research-folds

"...In a telephone interview, company president and former owner Tony DiChiro said that sales had been falling for a long time before KR's financial backers decided to pull the plug. DiChiro attributed the company's shutdown to "a shrinking market for high-quality two-channel audio," exemplified by the difficulties of other specialty audio companies such as Wadia and the demise of publications like Fi and Audio. Declining demand for two-channel products led KR to develop products for home theater and multichannel applications, a segment of the market that sustained the company during its last couple of years in business..."

I have the Kinergetics SW-800 subwoofers that were designed to complement the Martin Logan CLS electrostatic speaker. I have never seen any schematics or service manuals for the Kinergetics gear online so repairing the crossover or subwoofers might be difficult in the event of a failure. I suspect this applies to their other products as well.

 

[Cbdb2]

A great book that concentrates on audio power amps and how to minimize there noise and distortion.

The Audio Power Amplifier Design Handbook

The Douglas Self Site, audio amplifiers, The Audio Power Amplifier Design Handbook

douglas-self.com