What are the differences between Class A, AB, and Class D amplifiers?

[@floydloonie4880]

Thank you Paul for continuing to post this terrific series of educational audio system Q&A videos. Your generosity is appreciated by many of us music lovers from all walks of life.

[@jonrohacek3949]

9 to

[@mr.blackhawk142]

@@jonrohacek3949 5? lol

[@psyborg06]

filling ur mind with drivel to sell u gear LMFAO

[@larrybartlett6013]

for such a difficult subject, you managed to make it easy for even a novice audio listener to understand. Thank you sir!

[@howardanderson3061]

I'm 60 years plus and I've played guitar professionally for many years, I have of course played and owned many amps and the mystique of class A and AB Have always been a mystery, this is first time anyone has explained this to me. Thanks Mark, I can now cross off another amp nerd bucketlist question...lol

[@subramaniannamboothiri8365]

I am not a technical man. But I do appreciate the way in which the learned man is explaing with so much easiness without any technical terms is to appreciated.

[@ryanshannon6963]

@@subramaniannamboothiri8365 That's when you know that person is a true master of their craft: They can explain their expertise with very simple and easy to follow examples and illustrations. I just happened to find this series of questions because I'm looking into a "baby" bookshelf speaker set-up, and was recommended to add a desk-top tube amp (more for driving headphones rather than an integrated amp) as a pre-amp to an IotaVX integrated amp. I'm no audiophile, but since owning a 2018 Volvo S90 with Bowers and Wilkins audio, I finally understood why certain audio systems would hurt my ears but others, even when volume turned up quite a bit, didn't hurt at all. Now, I feel comfortable with the most basic principles of how this stuff works, but all the componentry and signal/power classes and such, I'm still unsure about. I've already learned 2000lbs of information just from 3 videos and definitely feel more comfortable reading the amplifier's capabilities and what it actually means. Excellent video series and I'm definitely watching more!

[@JunkRemovalPro]

Same here I am 51 and play guitar entire life. I have GTR tube amps class A, Class A/B I love my B-52 AT-100 as it is switchable from Class A to Class A/B also an added rectifier mode on and off. Underrated GTR Amp. I also used Class A guitar amp "flat" to power 50watt loud speakers running a Marantz stereo two of them for stereo.. ha ha , OMG tons of mids as gtr is mostly mid, and sweet highs not too bright but LOUD!!!!! I'm tellin ya all. TRY it, run your stereo through a two 100wat plexi's on 9 -10 o'clock gain setting and have your sub out seperately and you wont go back. THE MIDS are far better than any audiophile amp period on a high end guitar amp. The voice reproduction is like in your head and so clear and did I say LOUD with out turning it up. It's a PLEXI ha ha ha

[@Exxella]

This is just a good pure hearted man of a person, thank you kindly sir for this Info.

[@KevinBower-gy5be]

Many years ago, I purchased one of the first Krell KSA-100's in the UK. It sounded great - and I never needed to turn the heating on in the winter. Win-win.

[@musicalmrj]

Hey Paul! I've been producing music for a year now. I know this video is old but, this video gave me such a boost in enhancing my understanding of audio and my monitoring setup, and I can't thank you enough. Like an above comment mentioned, "You sir, are Class A."

[@jp-um2fr]

I have just found your channel - it's very good. 50 years ago I built 2 Mullard x 20W RMS into 15 Ohms 0.05% THD valve amplifiers and 3 valve pre amps. 50 years is a long time to go back to a hobby. I can remember the arguments about these new transistor 'things'. It seems that has moved on although valves are now 'THE KING' it seems, at least in price. I have a 2 x 10W in the loft so ..... I have missed A and AB amps and gone straight to D-Class. I have built the power supples but these ltlle black things with legs like spiders webs are beyond me. I have bought far too many from China. I need all the help I can get and your explanation was just what I need - simple and precise. Thank you from across the pond. Come to think of it my 15 Ohm Tannoy's (1953 vintage and perfect) might like a little class A. I have a lot of 2N3055's - I remember them coming out and TIP35C's. Thanks again.

[@sathishr1969]

I was asking this question myself and never search for answers. But, accidentally I got you and understand the difference of Class A, Class AB and Class D amplifiers. Thanks a lot sir. Your explanation is very easy to understand for an amateur music lover like me.

[@RasheedKhan-he6xx]

I have NEVER heard a better explanation. 👏

[@skywriter4330]

Great description of differences in the class of amplifiers. Simplified to a degree that a plain music lover who is not an audiophile could understand the differences clearly and the potential impact to our listening pleasure. Thank you.

[@MrBrightlight66]

Very good non technical summary. There is an ability to communicate a very technical subject in a way that laymen can grasp. And in a very short time too. Not so sure about a 100 W class A amplifier still outputting 100W in quiescent mode though. Granted it would still consume some power and convert it to heat but I suspect it would be much less than 100 W. Whatever the case, Paul makes great videos which any non-technical person can understand and is a great and patient communicator. One cannot but admire him and what he has created. Thanks for sharing and thumbs up.

[@jmarianu3976]

You sir, are Class A.

[@anikdey2100]

Actually he is Class D ... More efficient... Because he explained it so clearly in such a small time

[@ronbailey7197]

Nah, they're saying he's hot

[@joshua199628]

Lmao

[@railgap]

Not to be confused with Classé, a competitor. ;D

[@earfors]

AB amp has more ‘crossover distortion’ (and power) than a class A. What is you’re choice?

[@RealWolfmanDan]

Pretty fascinating. I love seeing people that really know their stuff and can communicate it clearly and effectively. Thanks for sharing.

[@10hunterLab]

It's great to hear an explanation from a real pro that knows just exactly what he is talking about. Thank you.

[@sdi1111]

There is no mention of cross-over (switching) distortion which is probably the biggest difference between Class A and Class AB amplifiers. Switching distortion, which can sometimes be audibly heard is when the complementary pair of outputs switch from the positive to the negative cycle. Basically, it is a complex audio sine wave where two outputs are constantly switching on and off and at this point it's the switching of the negative and positive signals that produces this distortion. Class A bias's the outputs in a 'full-on' state, thus eliminating crossover distortion, but most of the power dissipated is in heat and only a small percentage is dissipated as music energy. Therefore, not efficient, but pure (theoretically) in sound. Class AB is the most common form of output when we use the term 'idle' or 'bias' current, we are trying to adjust the amplifier to its ideal (compromised) bias/idle setting where it will then produce the least switching distortion, but not get overly hot or end up with thermal runaway and overheating.

[@oysteinsoreide4323]

He told about it, but not with using cross over distortion term.

[@CyrilleBoucanogh]

Robert was correct, saying Paul did'n say anything about the distortion from the switching phase.

[@repomanband]

Thanks this will really help me find a good amp for my punk band.

[@suj1945]

He's like the Bob Ross of amplifiers.

[@Zack-dk3pt]

i didn;t see any happy capacitors or friendly transistors...

[@markwhitfield3658]

Let's draw them in and give them a friend.

[@BlaBla-ny4bo]

lets build in some happy bass and some happy little overtones :)

[@MrArdytube]

Wow, just what i was thinking, then i scrolled down and see this comment. Lol

[@Sean-wd7ld]

Oh wow man Bob Ross far out man ain't that the guy from that weed movie up in smoke wow man grovey but hey man where is his afro man and his friend that Cheech guy ?

[@bengchiatseah3908]

Thank you very much. May I say, the recording of your voice is the best I experienced in all my years on KZbin!

[@DIYerGuy]

The question about the differences between the various amplifier classes (for audio) is a frequent one. Paul's answers were basically correct, but it's a difficult question to answer in a simple way that makes sense to everyone. As an electronics engineer (and audiophile) I can explain to someone the differences in a technical way but only those that understand electronics, and specifically what "bias" with regards to either tubes or transistors means, a technical explanation would be mostly worthless. For non-technical audiophiles, or anyone that is not trained in electronics with regards to amplifier design, the answer is much simpler and works most of the time. Here it is: Class A produces the least amount of audio distortion in the output signal, but is the least efficient design (produces more heat) and is often the most expensive amp. So, often Class A amplifiers whether they are tubes or transistor amps, are often large in the case of tube class A amps and have a lower wattage output capability than transistor Class-A amps. There are exceptions to the "lower wattage capability", for example Bob Carver, the famous audio amp designer created some rather high-wattage tube class A amps that are behemoths and have equally behemoth prices - but they sound marvelous. But in general, for audio, class A amps produce the least amount of audio distortion. If you're familiar with tube audio gear you will know of the vintage Marantz and in particular McIntosh tube amps - these are all Class A designs because Class A is the lowest for distortion (plus other advantages/disadvantages). Class AB amps can be designed for low distortion but are often not as successful as a well designed Class A amp. Whether you can hear the distortion in a class AB amp is another matter, but when measured with certain instruments even a properly designed class AB amp will have higher distortion than a comparable class A amp. Also, when a class AB amp ages, the components associated with the bias can result in higher distortion over time. Similar can result with class A though it's often less severe or noticable. As the video stated, Class D uses a very different approach (PWM or Pulse Width Modulation) than Class A or Class AB. Class D amps are best for use as sub-woofer amps because they can put out lots of power which is often required for subs, especially small cabinet subs. However, although measured distortion can be high in the bass frequencies with class D amps, the ear is less sensitive to high levels of distortion in the bass region as compared to the mid-range where the ear is most sensitive. So, in terms of selecting a class A, vs a class AB, vs class D amplifier: As a general rule and if you have the dollars to afford it, select class A if your speakers and room can work properly with a lower output wattage at the level you want (as compared to a transistor) amp because the distortion will be minimal with class A. Select class AB if you need lots of power (above 50 watts RMS) and are willing to live with more "measurable" distortion, though you may not actually hear it. Use a class D amp for subs: actually most subs come with their own dedicated amp which will usually be class D, so you don't need to choose the amp for such a sub. Stay away from a class D amps for use with a regular speaker (other than a sub) for serious musical listening. However, I would also add that an improperly biased, or defective, class A amp can produce distortion that can exceed a normally working class AB amp. So my selection suggestions apply to properly working audio gear. There are, and will always be, exceptions to all rules, and audio amplifier design is as much an art as it is a science, but in general, from a distortion point, class A is excellent (lowest distortion), class AB is good to excellent (more measurable distortion than class A), and class D (highest distortion) is really for specialized use such as with subs.

[@bmorg100]

I remember how superior my Carver M-240's & M-4120 sounded, compared to other amps of the day...only (some of) the early Nakamichi PA series amps sounded better...imho.

[@conorm2524]

Some of the highest fidelity loudspeakers in the world use class D amplification; L-acoustics, Meyer, D&B etc etc.

[@brianf.burkejr.1488]

Try listening to Hypex nCore amps for a revelation in class D amplification.

[@brianf.burkejr.1488]

Bob Carver and Nelson Pass are both geniuses and they designed the Carver and the Nakamichi amps you are referring to.

[@brianf.burkejr.1488]

Some A?B amps have their biases set so they are class A up to and above 40 watts, see Nelson Pass's amps.

[@OmarSharif-mi3ql]

Dear Paul, You can express anything so simply, which is very amazing to us.❤

[@slyspy9819]

I remember in the 70's when I was 14 , and loved music and was fascinated with the equipment in which it was played . The Audiophile was born . I found a magazine during that time called Stereo Review and I was hooked . Paul reminds me of the guy who did the Technical aspects of the magazine where he would explain and test pieces of equipment and discuss pros and cons , it was a great place to start my understanding of what was happening with the signal , his name was Julian Hirsch . I had a subscription to that magazine for well over 20 yrs.

[@chuckaddison5134]

Yeah I got Stereo Review back then too! But I found the same problem that I saw in photography magazines a few years later. Namely they accepted advertising from the very companies whose products they were reviewing. Consequently, nothing was ever garbage. Even if it was, and I'm sure you'll recall there was some really crappy stuff out there.

[@slyspy9819]

@@chuckaddison5134 Hey Chuck , I do remember there was a ton of products on the market and trying to make sense of it all was daunting , Stereo Review gave me a way to sift through the madness and it was plain fun to see the latest and greatest on the market . It prompted me to go to electronics school where I became a tech for a computer company and from there to electrical school where I became and stayed a licensed electrician for 35 yrs. I'm using a pioneer SX-650 right now as I type this to you , the old equipment had flare for sure

[@richardshumate3712]

I learned all I knew about car stereos through those magazines in the early 80s

[@slyspy7609]

@@richardshumate3712 I hear ya Rich I did as well , kind of shaped my future really by exposing the field of electronics to me through music

[@MAXIVINILElCanaldelVinilo]

I have Class A in one of my rooms (Accuphase E-560) and have Class D in other room to my daily job an listening... Believe me, Class A is just amazing.

[@mannyg747]

Hi Paul. As an audiovisual engineer, so far this is the best/simplest explanation I've heard on class A, AB, and D amps !

[@Paulmcgowanpsaudio]

Glad I could help!

[@taraworthington2958]

How come every guy I know who’s name is Paul is a wizard?! This is a master class, thank you for all the free education Paul!

[@tabinavisser7642]

Thank you Paul for explaning how these systems work,even me a dutch man who has very limited knowledge of the english language could understand your explanation,Thanks again from the Netherlands.

[@PM-wt3ye]

Why does a dutch have little knowledge of english language? Aren't you watching all on TV in english? Even if not, you should at least have the same knowledge as every other countryman, or weren't you taught it in school? Beside, your text doesn't seme to be written by someone who doesnt know the language :)

[@SilentKnight43]

Immediate thumbs-up for the statue of Nipper! Our local radio station GiantFM has a DJ that just bought a very old statue of Nipper (somewhat larger than the one in your video) that she's proud as punch - she did a short video segment of it recently and gave a history of it.

[@equilibrium2147]

It’s a very informative video for aspiring Audiophile like me. Thank you.

[@roberthorwat6747]

I have no idea how I got here but glad I did. Always wondered about this, never thought I would ever begin to understand the answer so I never bothered asking. I appreciate the generalisation and oversimplifications made but such an elegant and easy to understand explanation. You win the prize for my video of the day -> 🌟

[@Toid]

Great KZbin voice! Very soothing. I really enjoyed the content. Thank You!

[@bigbro5793]

oops, just saw your comment after I've left mine)

[@kindregardless]

Paul McGowan I have a Bryston amp. How would a PS preamplifier work with another brands amp?

[@abhinavsixfaces]

Any chance you could do a long video about amplifier classes?

[@كورسسسكوللشبكات]

I have an Bose amplifier: 2x50w @4 ohms, 2x25w @8 ohms And Bose speakers: up to 80w, 4 ohms What is the maximum number of speakers that amplifier can handle?

[@AudioReplica2023]

can anyone of those 2 people who hit dislike give me a better explanation? theres always someone wants to be the savy on videos like this giving dislikes but they never have the guts on commenting their point of view and correct the video....of course thats if theres something wrong said on the video...which I don't think it is. I think this is best explanation I have found til today.

[@PatBloomfield]

Surely the key difference between amplifiers people are interested in is the effect it has on the signal. Thinking of a sine wave the Class A is indeed always on amplifying both the positive and negative signal through a single valve (vacuum tube) or transistor. A Class B amplifier has two valves/transistors; one for the positive part of the sin wave and the other for the negative and is only "switched on" for that duration. This can lead to crossover distortion as the sin wave transitions between positive and negative and back again, which of course the Class A won't have since it's always on. My understanding is a Class AB overcomes this by keeping "switched on" passed the transition of the sin wave being null thus overcoming the issue of crossover distortion. A Class AB amplifier also has the benefit of being able to generate a much larger output signal than the Class A, as most of the individual valve/transistor's amplification is on only one half of the sin wave cycle. Class AB valve amplifiers also use a feedback signal from the speaker to compare to the input signal to remove any distortion (IIRC) and better control the speaker itself. For example, when the music stops and there is no signal a Class A amplifier will let the speaker ring until it comes to a halt whereas a Class AB amplifier will effectively stop the speaker dead so the playback could be considered more precise. That said, in the real world a speaker's ringing may only be a few m/s so isn't really audible. Both Class A and Class AB valve amplifiers can sound fantastic IMHO. I don't know maybe the question was purely concerned with power in which case my comment is totally off point :)

[@astralboy]

thanks for that additional info....didnt know about that speaker wires are bi directional and can be used by amps to remove distortion

[@Salty_Knuckles]

Pat, your clarification is a little better than Paul's (sorry) and if one wanted to peel the onion of the cross-over distortion dilema a little more, one needs to understand the that a bipolar transistor has what is called a forward bias voltage (Vbe=voltage base to emitter) characteristic that needs to be overcome before the transistor starts to turn on. This voltage is about .7 volts. This is what causes the infamous "cross-over distortion". As the music's signal sine wave starts to increase from zero, the transistor dose nothing until this voltage is met, thus the first .7 volts of the signal is lost. This happens in both the positive and negative cycles. Thus where you have a perfect sine wave going in, you end up with a sine wave with flat spots as the signal crosses the zero voltage points. Google "crossover distortion" (bit.ly/2CuytSH) and click images and you'll see it. The whole class A/AB/B discussion stems from C.O.D. more than a power discussion, from the beginners perspective. IMHO.

[@PatBloomfield]

Exactly. It's the crossover distortion and quality of music that's of real interest not many watts electricity we're using :-)

[@brianf.burkejr.1488]

It all depends on how high the bias is set for the amp to go into class b mode, Nelson Pass makes class A/B amps that go rather high in class A before the switch and begin having switching noise etc.

[@flatfingertuning727]

To use a mechanical analogy, a class A amplifier uses a variable amount of force to push against a spring; keeping the spring in the middle position requires applying force constantly, but the spring will always ride smoothly against the mechanism applying the force. A class AB amplifier has a pair of mechanisms that can apply force in either of two directions. This avoids the need to continuously expend effort keeping the output in the middle, and also eliminates the need to waste even more effort on the spring when compressing it to the maximum extent (an optimally designed class A amplifier cannot be more than 25% efficient), but will be more prone to mechanical backlash whenever it reverses direction.

[@matthirn7858]

Thank you, Paul. You are an excellent communicator and educator. Much appreciated.

[@shimric20]

Videos like this make KZbin great. Not that other front page garbage. Thank you for this.

[@lancelefevre351]

Paul, you are a warm and welcome voice and face on KZbin. I've learned so much from your channel. Thank you so much

[@Paulmcgowanpsaudio]

You're very kind. Thanks for watching and being part of the Hi-Fi Family.

[@markmannm2]

Good Job Paul! To recap what this video covers I would like to add in short, CLASS A is still the best audio amp technology however it is "heavy and hungry" (elephant). Class AB is very close to Class A with a little more efficiency, yet a good way to do clean full range signal amplification for audio (horse). Class D is the new technology to save the "planet," not sure which planet, however is light, requires a lot of extra circuitry runs very cool and seems to work well with low power items yielding audio (smart phones, ipods, laptops, etc..) it would be the (hummingbird). Some Class D Amplifiers that are very well designed with the correct support circuitry can be surprisingly clean and great sounding... How LOW quality D set-ups should be avoided... Importantly, Just because a spec mentions Class D and PWN is not a reason to consider it a quality unit... Regards, Mark

[@indic-culture]

Thanks for explaining it simply.

[@Ali-s110]

Paul, this is to thank you from the other side of the world, I found your page about a week ago and it's more like a university to me. Appreciate all the time you spend to explain to us❤❤❤❤

[@RaindropServicesNYC]

Such a great, straightforward, easy to understand and easy to remember explanation. Just great! Thanks.

[@alancordwell9759]

Hi Paul, and thanks for this excellent description. One of the things that scares me, as a radio engineer, about class D amps is the potential for the radiation of the switching frequency and its harmonics to cause interference to radio, TV and wireless devices. I have no particular axe to grind, and to me any amplifier is "good" if it faithfully reproduces the input waveform at its output. I'm just concerned that manufacturers will seek to drive down costs by minimising the output filtering and leave us with a big problem.

[@noname-gp6hk]

Wouldn't that be caught during FCC certification? I'm pretty sure EMI radiation is one of the FCC certification test items, and it's regulated to be at a level low enough to not mess with radio/tv/misc wireless devices.

[@TyrantTitan.]

Hi Paul, awesome content, found your channel couple of weeks ago and have been learning a lot from your videos. To me, you've become the "go to" person/channel for more technical audio information. Just a few moments ago, I was watching a video on tube amps and the guy was talking about different classes of amplifiers, A, AB, D... and I immediately thought about your channel, and now here I am.

[@andrewweber495]

Love the dog and red swingline stapler in the background. But mainly how well you can explain complicated stuff in a very simple explanation

[@waterlife.1905]

One of my favorite inexpensive box store amps was an onkyo receiver that was in the 2000s with a class D amp. It was half the size (height) of the other onkyos and had zero hiss when turned up all the way. It was dead silent. I sold it to a Dentist. It was such a different sound that I could appreciate. I know it isn't high end but ya I definitely noticed a difference. Reminded me of when CDs first came out and the shock of the sound to everyone. The wow sound.

[@alftupper9359]

Thank you Paul. I l hung in there as long as I could and then had the best afternoon power nap I'v had in ages.

[@mfsperring]

Excellent explanation, at least for someone with my knowledge base. Very timely as well as I have recently been asked to help my niece find a good PA system.

[@jbones360]

Hi Paul! for the first time ever, I'm watching one of your brilliant vids with your voice coming through an AB (valve gain stage) headphone ampI purchased this week!

[@snafu6548]

I sat through the video, wondering what the heck Paul was talking about. (Now, I'll be fare as say I haven't read a years worth of comments, so maybe someone has offered a cleaner, yet more technical definition?) My fortune was to be an audiophile in the golden years of stereo (late 70' to early 80's) and at the same time trained as an electronics technician in the service, stationed in Japan. Those days, you serviced everything to the component level, unlike today's 'toss it in a landfill' mentality, so working with these circuits was a daily routine. Class A, Class AB, and Class B referred strictly to the circuit design used to achieve amplification. The term 'Bias' referred to the pre-loaded voltage provided the base of the transistors necessary for them to function. Class A circuits were always considered the superior circuit, as the transistor input was fed the full sine wave, and the amplified transistor output was also the full sine wave. The problem with class A is that transistors could not tolerate the heat generated by high output demands, so unless you utilized tubes for heavier class A operations, you were restricted to about 12 - 20 watts. Class B used two transistors (or more), one to handle the + voltage of the sine wave, and the other to handle the - side. As each transistor had to only handle half the sine wave and could remain switched off for the opposite voltage, they remained much cooler, and could be run at much higher amplification levels. The crossover point where each transistor took on its respective task is called 'switching'. Switching was the class B Achilles heel. The full sine wave was handed to each transistor simultaneously, but each transistor only passed its respective voltage polarity. Each transistor required a precise base bias to ensure it functioned only in its domain (positive or negative). As the division of the signal had to be recombined at the output of the circuit, the biasing of each transistors was adjusted so neither transistors would attempt to step into the others territory. This hand off , and sequential 'stepping over boundaries' caused 'switching distortion' (the + to - crossover point) on the output. This is where a bench tech would adjust the input transistor bias, to minimize this effect. In closing: Class A was the preferred circuit, as it was an exact amplified replication of its input signal. Many top end manufactures used, and proudly advertised many of their components a 'Pure Class A' Class B was the champ of power, boasting outputs approaching those of tubes in a smaller, cooler, and more energy efficient package. With a well designed circuit, switching distortion was virtually eliminated, and if it drifted after a few years, it was a simple task of the tech to adjust it back to spec. Of additional note: When you lost one or the other transistor in a Class B, you replaced them both with a 'matched pair' to ensure continued sound quality. (Note edited for better clarity)

[@JoeOrber]

Ah yes, the NPN and PNP transistor pair

[@TomAtkinson]

I love it! I did not realise the heat is lower in class A during a max use (the speaker gets hot versus silence) that is a very good point! Then again maybe the impedance is higher for silence versus a sine wave? Either way, its the best explanation I've seen! Best Class D also. Class A/B for me now is the most mysterious. How does a A/B amp notice the zero crossing? I guess it fades to zero when the bias goes negative and there is a small cross-over when both sides run.

[@Medabang]

That was a perfect Amplifiers for dummies lesson 😊 .. Thanks for explaining in such simple words .. 🙏🏼

[@H2OTOYS-90]

Holy crap!!!!!! It's Nipper the RCA dog!!!!!!!! Well worth 9+ minutes to eloquently describe AMP classes. WTG!

[@BrettsForest]

I seriously cant thank you enough for giving me all the knowledge I've needed to get started into audio appreciation. Thank yoy

[@Paulmcgowanpsaudio]

You're most welcome. How very kind of you. Thanks.

[@horaciosokn]

Excellent. >Now I understand in a simple way how those kinds of amplifiers working. Thanks Paul,

[@RingZero]

Great explanation Paul, sincerely appreciate your knowledge in Audio amplification 🙏🏽

[@NoName-rp6ww]

Although English is not my native language and these are physical processes, I can understand the different principles. Thank you very much for the clear explanation, great video!

[@peterscrace3530]

Class A amps dont have switching distortion since the output stage doesn't switch, switching distortion is the one type of distortion that sounds bad.

[@richpaul8132]

Thanks Paul! That's definitely a good, basic explanation and as you stated several times, the explanation is a 'nutshell' or 'ballpark' level that stays as compact as possible. Still, it's an explanation that offers me a decent starting point or ledge to work from. Personally, I prefer analog system components and presently, my centerpiece is a McIntosh 2105 power amp. I recapped the amp as best as I could last year but because McIntosh wasn't able to pin down exactly which version of the 2105 I had, I went by their 'best-guess' schematics. I think the schematics I used were pretty close but I still saw some references in the prints to make me fall short of being 100% certain. The biggest concern, and one that I need to fix is the degraded wire-wound resisters in the Left channel's output board. The Right channel output board may be OK but rather than trying to replace the resisters, I really need to just go and replace both of those boards. That way I don't have to worry about the transistors that may, or may not, be bad. I did the recap about 7 months ago and I know for sure that the Left channel; will only put out about 68 Watts max, (no clipping). That's not good for an amp that should put out 105 Watts per channel at the very least, (a good working MC-2105 will have no trouble outputting 120Watts and still maintain the maximum rated distortion and specs). Thanks again for the explanation. Rich

[@denfinch5694]

Thank you, Paul. Personally, l don't know what class my hi-fi amplifier is but that's not an issue for me as the system sounds great! I am a bassist and own a Bergantino B|AMP amp running into two Bergantino cabinets... I believe the B|AMP is a class D amp. I know it's one of the finest bass amps on the market and it does sound quite incredible. I remember going to a jam night and all sorts of bass instruments went through it, from active to passive and even a bass ukelele with rubber/plastic strings! Every instrument sounded fantastic without any EQ change, just an increase in input level for the passive devices. How is it that this amp sounds far superior to all the plethora of really high end amps that I've owned previously? Thank you and kindest regards from Den Finch in The UK.....

[@JunkRemovalPro]

You are correct. I have experimented with so many Bass and GTR amps with my stereos, I have a AUDIOPHILE system going thru TWO 100 watt plexi's on 9oclock gain volume on 12 ha ha ha... NOTHING can touch the mids..as GTR is all about mids, and that is the range humans ears hear, -mids. The voices and cymbals sound as if you are next to the peformers. TRY IT. you wont go back. C'mon its PLEXI's ha ha ha LOUD LOUD and clean when set up right.

[@39zack]

Finally someone who explained it a way I could understand 😀 So if I understood it right, a class D takes the sin wave of the signal, converts it to an square wave that gets amplified back to an sin wave for the speakers and this keeps the efficiency high and heat low.? And because it need a lot of mumbo jumbo on the filtering, creating a good class D gets expensive. All class D I have seen that is considered good are way more expensive than a AB counterpart

[@foxpup]

You did a Class-A job explaining that one. Very clear. :-)

[@shadouxg7150]

What would be Class-S

[@rajasankar1245]

I am using Class A, 1972 Sansui 771 +Klipsch R28F with Fiio BTR3(LDAC connected with mobile phone) . When Listening to musical Instruments spatial separation is mind blowing means you will forget where you are in. I took my Sansui 771 to parasound dealer to compare his High end parasound amplifier. The dealer was shocked and speechless after listening the music from Sansui 771, means the Sansui sounds much better than his hi end expensive parasound amplifier.

[@salongoedmondmpungu2928]

This is both good knowledge and skill. Thanks! You know, many have this kind of knowledge but can not pass it on to others using crayons like you have satisfactorily done. I'm following you from now on

[@Town101]

Mr. Paul, this was very helpful. Thank you for taking the time to explain.

[@chasewallace1232]

I think this will be the first time I've ever subscribed after only watching one video!

[@mr.blackhawk142]

Hi Paul! My Hitachi SR903 just got here today. I just did a quick listen to FM radio and it ROCKS the house d00d! lol You may be familiar with it as it is a vintage, and quality LEGEND, built in 1977. (MADE IN JAPAN) I have it connected to a pair of Kenwood 3-way vintage bass reflex speakers (LS-N500) that I found a few weeks ago! I can't wait to get a decent turntable now! 🎶

[@bobayersquebec]

Ok, now i have a little bit of knowledges on those types of amps. Tanks sir

[@كورسسسكوللشبكات]

I have an Bose amplifier: 2x50w @4 ohms, 2x25w @8 ohms And Bose speakers: up to 80w, 4 ohms What is the maximum number of speakers that amplifier can handle?

[@gintarasshlizhyus1567]

From my experience top quality class D can produce a very airy and clean, smooth sound. However one trade-off you immediately notice is the "impact", so-called bite, you just notice a slight roll-off in high frequency and also low frequency, which somewhat lessens the presence effect. This is not terrible in any respect, but A class delivers more impact to the music compared to D class.

[@wendywillett9620]

Thanks Paul I have a better understanding how the amplifiers work as my son trys to explain that a digital amp still has to convert the signal back to analogue.

[@dtsdigitalden5023]

Terrific explanation, Paul. Thank you for that.

[@chordkeys]

This man clearly knows his stuff very well. Nice vid

[@justingriffin2546]

all the higher end audio brands are moving towards class d as more research and development comes through. A high end class D will not sound any different from class A or AB. However it'll have a lot more headroom with the power so at higher volumes the amplifier will not be anywhere as stressed. Cheaper class D amps are garbage though.

[@chuckchuck-ei1ss]

This comment tells me (and I guess others) more clearly what we want to know. All these other comments, while quite complementary to Paul, are more suited to the engineers watching. I could care less about the electrical intricacies of the waveforms. What is of practical importance to me, and I'd guess to many others, is how that translates to qualities of part life of the amplifier, and are of significance to my ears as an audiophile. Similarly, if I were the husband of a wife undergoing brain surgery, I'd want to know firstly is she going to live. With that out of the way, we can discuss the neuralogical niceties of the brain.

[@timschutte6924]

You sir are a marvel and wealth of information and knowledge. You are also very easy to listen to in your simplicity explaining things. Nothing a person needs and everything they do need in understanding an issue. Thank you for your professionalism.

[@foxpup]

Makes his own sound effects, I love it!

[@rccravers8059]

It’s like listening to Bob Ross of car audio Love the videos

[@jsngallery]

Class A explanation, tks!!!

[@roberttoll6907]

Thank you Paul, i understand a lot more now between the different classes

[@rurocking]

Perfect explanation, just what I was looking for. Thank you.

[@charlesjefferis8812]

Thank you! I finally understand the differences. stay well, everyone!

[@كورسسسكوللشبكات]

I have an Bose amplifier: 2x50w @4 ohms, 2x25w @8 ohms And Bose speakers: up to 80w, 4 ohms What is the maximum number of speakers that amplifier can handle?

[@paulstringer4099]

This was helpful, thanks for making the video!

[@TheCheck01]

Beeing able to explain complicated things with simple words is a true art.

[@marklowe7431]

Class H is another common type. Using rising rate power supply. Usually used in the kw space pro audio.

[@AragonDubs]

A lot of class more men.

[@KinGzeDK]

My preamp is an AB amp with 4 x 50w @ 8Ω. Happy that it's not A since it's on 24/7 and electricity is expensive here. Don't know the official numbers for my power amp but people have tested it on youtube and it's at least 2 x 1200w @ 8 Ω. Both are great for my needs :) Thank you for explaining, it's appreciated.

[@electronicshelpcare]

thank you,nice expl.

[@كورسسسكوللشبكات]

I have an Bose amplifier: 2x50w @4 ohms, 2x25w @8 ohms And Bose speakers: up to 80w, 4 ohms What is the maximum number of speakers that amplifier can handle?

[@jhvesterjr]

Getting ready to buy my stereo system, wanted to go tube but your explanations are exceptional and made me go another route with getting similar results

[@qnavich]

Thanks a lot sir. Explained in a very pedagogical way .

[@jhi1947]

So Guru....U r into Pedagogy huh?

[@XtianApi]

"if I have a hundred watt class A, with no signal..." I no longer need to run my heat in the winter

[@XtianApi]

@James Cowan that's awesome

[@justinbass8080]

Thank you for making more sense than the last three people combined

[@markwalsham7115]

Paul - love your videos. Question - does a 'big sound' equate to 'big speakers' or can smaller speakers create 'big' sounds (and not necessarily high volume)?

[@IntelligentElephant]

You ever heard of head phones? Don't they make 'big' sounds?

[@jeffpensock3730]

Thank you for the understanding of these amps. Very well done.

[@mortallious1234]

Class A's all the way for me!

[@chuckaddison5134]

How's that power bill doing?

[@stpd1957]

I have watched this video a couple of times and now I get it, thanks Paul. Seán

[@biggityboggityboo8775]

Actually you can feed the output of class D amplifiers directly into your loudspeakers. By 400kHz, or whatever your switching frequency, the speakers impedance, due to the speakers self inductance, is extremely high, so very little power is dissipated. The reason why an output filter is typically necessary is because of EMI. Without the filter your speakers cables, and high impedance voice coil, turn into massive transmitters. If the amplifier is powerful enough this creates loads of EMI and wreaks havoc with other wireless signal transmission. Also there is nothing digital about class D. It's purely analogue. It's an unfortunate coincidence that digital begins with a D, and the amplifier class does, because the two are not related.

[@4Nanook]

Only true if all of your speakers including tweeters are coil / magnet / cone affairs. If your tweeters are pizo, 400 Khz will probably shatter them.

[@BMWBikes-i7n]

Very good explanation, first time I have understand it. Thank you very much.

[@brunobassi2440]

the distortions of the class d are on average 0.2% at low operating power. AB class one tenth (0,02%)

[@mattportnoyTLV]

Bruno Bassi depends on the nuances of the design and the impedance vs frequency behavior. Not all are created equal. B&O ICE modules are Class D but THD is .01% 75% of operating power. For AB the biggest weakness is distortion vs frequency. When the load looks like an artificially low impedance the amplifier can shift out of its class, and the distortion becomes a non harmonic variety-like the sum and difference of the fundamental.

[@marottajoe]

That matters very little when rooms are off by 30 dB.

[@BF4pawntard]

At last someone who actually knows what they are talking about . You sir have earned a subscriber.

[@multimood]

My electronics teacher explained Class A as like having your car in the garage always running, it's always warmed up and ready

[@spencerlong8454]

what class were you taking? looking to get further into this field. thanks!

[@multimood]

@@spencerlong8454 It was B.O.C.E.S. while I was in high school

[@chdjhns]

I just bought a AB International 1100A amplifier. I can't really find much information about it like when it was made and how much they sold for new. I'm really impressed with its performance so far

[@neira.francisco]

Excelent explanation, thank you!

[@LuxorVan]

Most good A/B car amplifiers use PWM on their power supplies! But Blade Technologies used to sell what they claimed were Class A car amplifiers and used a 4050 Hex non-inverting buffer, 555 timer and 4013 flip flop, The 4050 drove SMPS Mosfet gates, the 555 and 4013 generated The switching signal! It was something new to me, but I learned this from a pcb designer working in the new company which had bought out blade technologies! I was lucky enough to upgrade my M252 to a M502, started out as 25 wattsx2 and modified it to be a 50 wattsx2 amplifier, since they did share the same pcb, but it required a modified toroid, extra transistors, missing resistors and caps! The Blade Technologies amplifiers which were labelled Class A had huge heatsinks with internal fins, and the 50 watt and higher output models required an internal 60mm fan! Which I had to install the missing components which made up the circuit to drive the fan! But with Class D amplifiers, really read the specs, look for something with higher Signal to Noise ratios! Back in the Old School days of Car audio Signal to Noise Ratio was sought after and most wanted amps with 105 db or higher!

[@GurnamSinghchannel]

which type is good for subwoofer? I previously think class D, am i right?

[@PatBloomfield]

A valve amplifier Class A or AB will give you a much better bass unless you go down the route of bi-amping with a solid-state amplifier IMHO.

[@theno1deejay]

Class AB is the way to go for subs. D class is good for mids and high, but if you want that sweet, mellow sub you want to stay with AB.

[@tomkocur]

Mikael Helje it's exactly the opposite. Class D amps need to have a lowpass filter on the output, which is why they are not as good on high frequencies as basic AB amps. There are exceptions, of course, like hypex nCore, but that's 400€ per a single amp module without a power supply. There's really not that much sound difference on subbas, if any at all - the way a subwoofer sounds depends mostly on the enclosure, amplifier only plays a very small role.

[@GurnamSinghchannel]

Tomas Kuruc friend and enclosure and Amplifier ,both are playing major roles in Subwoofer

[@tomkocur]

Sound-wise, major role is played by enclosure and by the room. Good amp will just have more power and will let you use more power (higher damping factor). And how good a sub amp is, doesn't have much to do with which class it works in (because bass frequencies are so slow), so why not just be more effective?

[@sowhatdude1]

This guy is GREAT!!.. Always clear and totally understandable.

[@AudiophileTubes]

'Musical Paradise' makes a very affordable and amazing sounding 'Class D' integrated amplifier that sounds amazing! I thought it was Class A!

[@Audfile]

AudiophileTubes so does Hyped. I have Ncore monoblocks. They are MAGIC

[@scottdavis0801]

My Rogue Audio Sphinx V2 sounds pretty sweet also. Class D hybrid.

[@gedkealmen]

That was a great brief explanation! Many thanks Paul, it certainly helped me understand a bit about what the terms actually mean.

[@SamiyuruSenarathna]

Great explanation. Thank you.