Class B and Class AB Amplification 

Excellent explanation...Especially with the ball

Thank you, so now I know. I didn't even know pure class B existed. This is the first time I heard anthing about class B. I thought only class A, AB, and D existed (basically). Thanks for such a clear and concise and simple explanation.

Excellent explanation and clearly delivered. Thanks

This was short and awesome :)

pure gold..... thank u so much

Mind blowing explaination

Great thanks. Nice and simple way to explain

Interesting but you didn’t show the actual crossover distortion at all. Why show the same graph for B and AB without showing the crossover notches at all? The graphs only confuse people because they are the same, apart from green spots.

superb!!..thank u sir!🙌

great explained

excellent, well explained.

Thank you sir, please kindly explain calss d amplifier working prinspols.

So what would you use a or ab amp for?

Nice one Ben, clear concise and understandable good video

So what is SD amplification? What are those improvements that were not mentioned in this video?

nice video sir

Why do we have two vOmin values in calss A amplifiers?

You would think a content creator posting to RU-vid under the name Cambridge would understand cross over distortion and recognize the description of current flow given for Class B operation was in fact the definition for Class A operation.

So does this mean that Class A has ZERO crossover distortion???

I wonder why they even made class B amps grrr... I bought a old AV receiver recently but it was boxed since 2004 never used and sadly is class B at least that's what it says in the manual however no info on it anywhere. First it says digital amplifiers 7 channels, but then a bit lower in the manual says compliant with class B amplifiers, so I have no freaking Idea what it even is... But I'm very glade to buy it since for me is a very unique device, because it's pretty rare nowadays and it's the only amp ever made by the company and also look very different than usual and would be an amazing project to build a cool PC inside. EDIT: audiozavar.com/wp-content/uploads/2014/10/p1170471.jpg (it's only the receiver that I got, photo is from internet), wish I could also find the DVD player with it just for the looks as it's pretty unusable since it only has composite out (very bad quality) while the receiver has component in\out, but would be nice for collection or a crazy computer build with the receiver being the PC and the DVD player buying a custom watercooling attached to the computer.

*_ARE YOU CALLING MY PLAYING WEAK???_* (because it often is.... 🤔)

I think your volume needs some "amplification".

Thanks I have exam tomorrow

this guy is trying to not dump a science class on us in a few min

Why do we need class AB?

Looks like he is reading the text ,although the content was perfect

Nice try but you don't tell the entire story. As you tell it, you imply that the class-B is just the output transistors WITHOUT the added quiescent current adjustment circuitry. In THAT case, you are right that there is a point when BOTH sides are switched off and there is visible (on an oscilloscope) and very audible distortion (= momentary lack) of the signal. But that is what the quiescent (AKA "bias") current control circuit in the typical class-B power output stage has been invented for. You simply make both (push- and pull-) sides conduct a little ALL THE TIME at the cross-over point (= zero volts) using an approximate 50 milliAmpere current to make sure NO hand-over gaps occur in the cross-over area. You don't throw the ball, you hand it over from one hand to the other hand in a fluent move! Just to be clear here for the readers: a well-adjusted class-B quiescent current makes sure that the very bad "cross-over"-distortion everyone talks about is inaudible for just about everyone. If the amplifier is still not sounding right with a properly (low- and high-frequency checked!) adjusted quiescent current set up, then the design team should look at bad design of the entire power amp with respect to excessive Transient Intermodulation Distortion (TIM) in the feedback loop and you as a customer please DO NOT buy the amplifier. This problem is not fixable by you and will not go away. In case the seller tells you that it needs "run-in" or "burn-in" time, DO NOT buy the amp either. A well-designed amp works fantastic from the first moment or will never! Everything else is your imagination playing tricks on you. Now back to your much beloved class-AB. Class-AB is an "exagerated" version of this quiescent current class-B setup, where the quiescent current has been set at 500 milliAmpere current (10 times or so more than standard class-B) so the overlapping area is even further extended such that the first Watt of output power is basically in this dual-conduct period zone (see Note below). Thereafter, the signal is moving into the area of class-B where only one of the output transistors handles the signal. This has indeed an improved effect in the first Watt or so because any audible distractions are moved to a higher level music output so you don't hear them anymore, but a correctly adjusted and designed classic class-B setup should be just as good for at least 95% of the listeners. I myself cannot hear the difference if I take an amplifier and change the quiescent setup between class-B and class-AB (but that is no reference of course.) NOTE: This extended hand-over area is NOT and has nothing to do with a class-A configuration! In class-AB you still have a push and a pull transistor (or FET or tube even: same applies!). There is NO (need for a) difference in the electronic circuitry of the amplifier. Class-B and class-AB ampifiers are EXACTLY the same. You can change ANY class-B amp into a class-AB at any time. It is just a current settings change in the output stage. Because of the increased current, you may need larger cooling for the power stage, but that is it. Really! Class-A however is an electronically completely different design and has only ONE driving side. The other side is the LOAD (resistors and your speaker) and the power stage of a class-A is always full-ON. It just "diverts" some of its power from the resistor-load to your speaker and back all the time and that depends on your volume level. The power consumption is always "full-blast", therefor the need for enormous cooling blocks. I think this also answers several of the questions of other posters. That said, I think "Cambridge" does a great job of producing quality components. And a well-designed class-AB amp is something to be proud of. Keep doing it! Regards, Luc De Meyer

For a more in depth explanation, see this long but very clear video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-S7jrirsfkNw.html

Hi there. Your visual analogy of the different classes using the ball is flawed. You show the class B operation by THROWING the ball across from one hand to the other and the ball is not controlled by either hand (3:05) A much better way is to hold and move the ball to a midway position in front of you on the table top with one hand, then RELEASE the grip and then pick up the ball with the other hand and continue the full cycle. This would then simulate the operation more accurately than the way you show it...Throwing the ball suggests the ball is being driven by kinetic energy and has become detached from one side or the other of the output stage in the push-pull sequence. The way I suggest would also demonstrate the changeover point at mid-way more accurately showing class B as two distinct cycles with a definite mid-point....throwing it confuses the mid-point crossover process and is not analogous. The class AB can be shown in the same way on the table top but the transference and crossover would mean the grip is released just after the other hand takes it and moves away