Amplifier Classes

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soundNERD said:
but am not sure if they are riht. Are they? If not, what type of amp falls under each category?

http://www.electronet.5u.com -main site
http://www.electronet.5u.com/audio.htm -audio page

Thanks for the help, Mike


Nope, not right. :xeye:

There have been many sometimes discussions on this board dealing with the classification of amplifiers. The distinction between class A, AB and B has to do with the operating point of the gain devices, not the use or lack of output transformer. Tube amps can be class A and need output tranformers (eg. a SE 300B)

Also your commment about "Mosfets produce little heat" is only partially true. A mosfet amp running class A produces lots of heat. (Think Aleph or worse yet, Zen) Class AB amps are more efficient, but can be made with tubes, bipolars or mosfet output devices. There are other errors on the page, as well.

I'd suggest you do a bit more research before claiming to have the ultimate audio site ;)
 
Sorry to say this, but your understanding of amplifier classes is completely wrong - there are several sites that explain it, but it basically comes down to how frequently the devices are "on".

Class A - Always on, never cut off

Class B - On half the time, switches from one device to another at zero volts output

Class AB - Mostly similar to class B, but with some overlap of the output pairs "on" time, reducing crossover distortion

Class C - On less than half the time, as you said it isn't used for audio because of the very high distortion

Class D - Switches the output on and off rapidly - which "averages out" to the desired signal with some low-pass filtering

These are fairly informal and probably partially wrong definitions, but it should help you to understand the situation.

There are also a few other things I would revise if I were you - some other classifications are wrong (Gainclones are solid state amps, and MOSFETs are transistors - you speak of them as if they were seperate categories, and not sub-categories).

Also - I know of no solid state devices that can get as hot as a light bulb (several thousand degrees), do not confuse heat output and temperature - if there was no difference between the two, we wouldn't need heatsinks.
 
I do applaud your desire to want to put together a simplified informational page about amplifier types, but it appears you've over-simplified to the point of being wrong in most of your statements. ( ex. the "D" in "Class D" does not stand for "digital" )


-Maz
 
And people wonder why you should not believe anything you read on the web.

So many errors, my suggestion would be to can the whole idea. We already have enough people who post similar nonsense here without another source.

Nothing personal.............so don't take it that way.

BTW, I ran across something that did a very good job of not only explaing the different classes, but had good block diagrams of the different types. Too bad I can't find it when I need it.

Jocko
 
Owl

Jocko Homo said:
And people wonder why you should not believe anything you read on the web.

So many errors, my suggestion would be to can the whole idea. We already have enough people who post similar nonsense here without another source.

Nothing personal.............so don't take it that way.

BTW, I ran across something that did a very good job of not only explaing the different classes, but had good block diagrams of the different types. Too bad I can't find it when I need it.

Jocko
Hi Jocko,
Is it my imagination that I believe your owl is looking more angry day by day.
:clown:
Keep up the good work;)
 
sorry SN,

I have to concur with other comments here, you are way out
of your depth, suggest you you give it up before you sink.

Nearly everything you say on your site is not correct.

Unfortunately having a basic knowledge of electronics does
not qualify you to write a basic introduction to electronics.
Introductions to subjects are incredibly difficult to write,
they have to be simple but more importantly not wrong.

You need to learn a lot more before you will be able to do this.

:) sreten.

If you carry on I can't wait for the "Tips and Tricks" section !
 
Nope.....

Sorry, Frank....none of those.

Was either on a manufacturer's site.....someone like TI......or some universtiy maybe. The diagrams had all sorts of G(s)H(s) stuff......with intergrators in the feedback loops.

If I could only just remember........

The story of my life after 50.

Jocko
 
diyAudio Senior Member
Joined 2002
Hi Jocko,

Sorry, Frank....none of those.

I thought as much...Which is why I wrote "In the meantime:"...

The diagrams had all sorts of G(s)H(s) stuff......with intergrators in the feedback loops.

Yeah...exactly what I thought you meant...

If I could only just remember........

Maybe we should both ask JC for advise on vitamin cocktails...;)

Cheers,;)
 
Is it possible the posters after #1 were all subject to an alternate identity playing with us ? I seem to remember a thread started a year ago by "Bose(0)" or someone that basically trolled us all into responding to tell him how wrong he was.

Perhaps this poster was doing the same (?) with his "#1 electronics site on the internet"

*raises a suspicious eyebrow*

-Maz
 
Well, i posted stuff i have read or heard, so don't blame me.

The light bulb heat to semiconductior heat with no heatsink i was told on another forum. the d for digital i also read or was told on the internet. And I didn't consider transistor and mosfet as different classes. the title "Solid State" is in size 4 and the mosfet and transistor is in size 3. i guess I should make a bigger size difference.

The class stuff I mostly guessed on by looking at class a and b amps in the latest issue of nuts and volts. all class a amps were transistor, and all class b had transformers on the output. I know class c because i was told by somebody on this site what it was. class d i was told stood for digital


Also, as i don't know much about vacuum tubes, would somebody be able to give me some info about them for my site? Any other changes that need to be made would also be helpful.

and hey, thats why I asked. because i thought i was wrong. i don't feel the insults neccesary.

Thanks for the help, Mike
 
"The ultimate!"

?????

Someone told me that they saw something to that effect there. Maybe not. (I get so much crazy stuff in my inbox.....I can't keep it all straight.)

But anyway, you did make the site, so we do blame you.

Seriously, if you have to ask the gang here if the information is right..............then that should be your first clue that it may not be. Just because you read it on the web does not make it the truth. Anyone can say anything on the web, and you are proof of that.

Unless you are dead sure, by having done this for years, you may want to leave out your assumption of facts, and stick to stuff that you are interested in that you have enough faith in to back up.

Without having to get your big brother to stand behind you in case of a fight.

Good luck with your endeavor.

Jocko
 
soundNERD said:
The light bulb heat to semiconductior heat with no heatsink i was told on another forum.


This is correct - the heat is the same, but it does not mean the temperatures are different.

If you are confused by this, there is a very common analogy with simple resistive circuits, with heat represented by current, and temperature by voltage.

Just plug in "electrical analogy" and "thermal resistance" into any old search engine and you should get a few hits which explain it - if you don't understand it, just understand that you need as low a thermal resistance as possible (with better transistors, better mounting methods, and bigger heatsinks) to ensure that the temperature difference between the semiconductor and the ambient air is kept to a minimum. Although this is more heat transfer and thermodynamics, it is quite important that you have some understanding of it if you are interested in electronics.

I would suggest that you do a lot more research before you add information to your site in the future - it would not take long to verify your general beliefs that you heard somewhere off a friend of a friend or completely guessed. Without checking your information, inexperienced readers of your site could be the blind led by the blind and either be turned away from the hobby due to confusion, end up with non-functioning equipment or worse (consider somebody suggesting you leave out ground connections or fuses for an example of this). I'm not suggesting that such things would necessarily happen, but I hope it emphasises the importance of researching your material.
 
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