Audio amp classes as fast as possible!

[@GoldenSound]

Apologies for not including this in the video itself, but the main advantage for class D amps is that they can be made EXTREMELY efficiently, whilst also having extremely low distortion. Class D amps are always either fully 'on' or fully 'off'. Meaning they're either outputting efficiently or using basically no power. This means that class D amps can sometimes be 90-95% efficient, vs the 40-80% efficiency of class AB and the maximum 50% of class A. This makes them really suitable for situations where massive power is needed but an enormous class AB amp would not be feasible. Such as for subwoofers or car audio. You hardly need any heat dissipation and so a very powerful class D amp can be made to be extremely compact. The main disadvantages are that they inherently generate a huge amount of high frequency noise which must be filtered out, and many class D amps are also load dependent, meaning the filter response will change depending on the impedance of the connected load. For speakers this is not really an issue as you know everything will be roughly 8 Ohms. But for headphones where it could be anywhing from ~12 Ohm to 600 Ohm, that's a more difficult challenge. For that reason, and since we don't really 'need' the efficiency for headphone amps anyway which don't use much power, class D is rarely seen in headphone amps.

[@game-tea]

Any class D based on the Universal class D design and especially the modern variations from Hypex, Purifi and such handily beat 98% of A/AB designs in objective and subjective tests. While being significantly more efficient.

[@juanblanco7898]

Please, excuse me this probably dumb question. Do integrated DAC/Amp chips commonly found in Bluetooth devices like Qudelix and FiiO's BTR lineup (ES9218/9218), as well as USB dongles (CS43131) employ class D amplifier technology?

[@DJ_Force]

I'm surprised by the statement that "everything will be roughly 8 ohms". An 8-ohm speaker will present a very different load at 20hz than 20khz.

[@bgravato]

​@@DJ_Force it's not that different... There will be some variance yes, but in practice your ears will hardly be able to tell much of a difference really. Also there are already some class d implementations that solve that problem.

[@AleMagalhaes]

I loved the explanation. And complementing that, it is very easy to use Power MOSFET transistors to implement class D amplifiers, and most MOSFETs I have at home are only limited to its package limits, meaning a small TO-220 transistor handling 75 amps easily (that would be 7kW at 100V) without significant heat. I don't use them on amplifiers (all audio amps I have are AB), but they would be a good choice to make a power amp for sub.

[@metal571]

If only my EE professors in college explained things even remotely this clearly. Fabulous presentation

[@robohofo1]

Absolutely! I have a EE degree and PhD in digital signal processing and very much enjoyed the explanation....Flappy Bird!

[@UntakenNick]

It seems that everyone commenting in these kind of videos had troubles understanding concepts due to having incompetent teachers. Maybe you were just bad students?

[@bfolkens]

Wow - this was the best explanation I’ve ever seen for amp types 🤯

[@TheHEADPHONEShow]

Glad it helped!

[@Grrrr3FKAGrrrrGrrrrGrrrr]

Are you being sarcastic?

[@bfolkens]

@@Grrrr3FKAGrrrrGrrrrGrrrr Not at all... why?

[@basrihs]

​@@Grrrr3FKAGrrrrGrrrrGrrrr lol

[@siberx4]

This is a great explanation of the main amplifier types, but it glosses over _why_ you'd go to the trouble of using a Class D amplifier since it sounds more complicated to implement. The answer, of course, is that they can be vastly more efficient than even a well-tuned Class AB. This is because transistors waste extremely little power when they're either in their fully off or fully on states, while a transistor in its linear region acts somewhat like a variable resistor and dumps the waste energy as heat. Since a Class D amplifier only ever has the transistor fully off (where it wastes no power) or fully on (where it also wastes nearly no power since it's extremely low-resistance) there's very low loss overall. Class A amplifiers are usually 25% efficient or less (somewhat higher is possible with tricks), while AB designs are 40-80% efficient. Class D, on the other hand, is usually 80-90% efficient, with even higher values possible. As such, Class D amplifiers can be absolutely tiny and, if well designed, still produce shockingly good sound. It took a while for the designs and implementations to get good enough to avoid distortions or other issues inherent with trying to keep the complicated harmonic-filled output under control, but nowadays you can get dozens of watts (or more) out of something the size of a deck of playing cards with very few compromises. Purists will insist on linear designs, but a well-designed Class D amplifier can produce excellent audio and allows much more compact designs because the reduced waste power. This is especially important where space is at a premium (such as in small apartments) or in portable applications powered by batteries.

[@TheCyberMantis]

Class D is typically used for subwoofer amps. They run cooler, and can be built smaller. Linear response doesn't matter because they run a LPF crossover.

[@chapstickbomber]

The real life RMS of most speakers is very low, even if it sounds kinda loud. My receiver (plus PC margin for playing back music (lol so prob 1W over idle)) at the wall pulls maybe +12W for silent vs pretty dang loud. Proper RMS 10W is loud as hell. Doesn't seem like 25% efficiency on a class A is a very big deal when IRL RMS is so low unless you are hurting your hearing. Like, oh no my class A amp pulls 50-100W for an hour or two, lol, who gives a shit 😅.

[@TheCyberMantis]

@@chapstickbomber Lower power is fine, if the circuit is super clean. High signal-to-noise ratio and very low THD. But most amps, especially cheaper ones, are not that clean. It's cheaper to make more power, than to build a really clean circuit. Power can compensate for a dirty circuit because it gets loud before it distorts. If you keep it below this threshold, then you won't get the distortion. When you crank it up, you will hear the distortion. On a super clean circuit, you can open it up and it will still remain tight, with less total power.

[@Etheoma]

Is anyone doing GaN amps yet? because a class D amp + GaN transistors seems like you would be able to get to 95 - 98% efficiency and with significantly more compact designs would want a GaN power supply as well at that point or otherwise your amp may end up being smaller than the power supply, also it would enable the transistors run at a much higher frequency making it easier for a filter to filter out the frequencies you don't want.

[@Etheoma]

@@chapstickbomber Well for mobile application yeh that matters if your going to be running on battery and yes if you want a compact design yeh again that matters, halving the power lost to heat means you can probably reduce the size of your amp by ~30%

[@DamirUlovec]

As someone in the matter for decades I found that intro hilarious. NPN refers to the arrangement of semiconductor layers: N-type, P-type, and N-type. N-type is being doped with extra electron, and P-type lacking electron (has a hole instead electron). It's neither "negative" or "positive" in any way. BJT on the other hand stands for Bipolar Junction Transistor. The rest of the video is spot on regarding audio amplifiers.

[@EggBastion]

not neither?

[@DamirUlovec]

@@EggBastion Thanks.

[@karhukivi]

The N material (silicon doped with pentavalent elements like P. As or Bi) has a surplus of electrons in the conduction band, so calling it "negative" is not incorrect. Likewise the P material has a deficit of electrons in the lattice (being doped with trivalent elements like Ga, In or B) and therefore a net positive ratio of cations to free electrons. They certainly are negative and positive in terms of net electronic charge.

[@DamirUlovec]

@@karhukivi You just contradicted yourself. Are pentavalent elements more negative than tetravalent elements like silicon? If yes, what happens when you put them together (similar like bonded PN)? Does the current flow by its own, or you must provide external current source like in ordinary conductor? What's with the forward and breakdown voltages, capacity, etc. Are they just a complex or imaginary properties like impedance?

[@karhukivi]

@@DamirUlovec A pentavalent atom like phosphorous replacing a lattice position of quadrivalent silicon has four bonds with the neighbouring four silicon atoms using four electrons, and the fifth electron is free to move through the lattice. That is why the material is negative and conducts electricity better than pure (undoped) silicon. Lots of information on the web if you look for it!

[@AndreiIsa-kk9jz]

No one, and I mean no one has explained this better for a person to understand how sound is manipulated by different class amplification. I think it is very easy to understand once you get to the 3rd time watching the video. :)

[@varunnarain50]

Learning do be like that. I have to watch these videos over 4-5 times before I really start absorbing what he’s saying.

[@Ludwik93]

First 2 to understand, 3rd one for fun🎉

[@chapstickbomber]

Truly superlative explanation. Really glad I found this before spending any serious money in amps. Class A is clearly the most signal-honest design, though less efficient.

[@prodbyhajime]

Actual gem of a series this was

[@jibeji]

As a former electronics engineer, this is the best explanation ever! I wish I had a such explanation during my studies 😀

[@josephpsmithe]

Really appreciate how you got to the point quickly and didn’t fill the video with fluff

[@smolbo1]

need more of these videos. so tired of everyone that just says "but that is a topuc for another video" but never get another one. educational content to educate the consumers have a much better effect than giving opinions in reviews

[@geardawg1358]

Nicely done, in my 50+ years of electronics I've not heard a more accurate easily comprehended explanation! I'd say if more had your knack for instruction the world in which we live would have a much higher rate of proficiency. You've actually made the learning process much less boring! I started my learning process when I was 13 YO, you remind me of the fellow I learned from, he was a 75 YO USNavy EW tech!

[@DJ_Force]

I am surprised that no description of the transistor ever mentions resistance. In essence, it is a resistor who's resistance is controlled by the base signal. This is why they get hot, resistors turn current into heat.

[@gecko82]

This is one of the best instructional videos I have seen in a LONG time!

[@Jahwobbly]

I don't know why i've never seen a better and succinct explanation as this. After watching this, I can now explain this subject to someone else. Thank you.

[@kevinwydler7305]

This is honestly the best explanation I have ever seen on this topic. Very easy to understand yet technically detailed. Thank you so much!

[@bf0189]

Not a headphone person and more into speakers (sorry!) but this is the clearest explanation I've seen for amplifiers. While I have already known all this it's great

[@MaestroCipher]

As an audio amplifier designer, I would like to clarify and refine a few points regarding distortion and amplifier classes: Class A Distortion Characteristics: The statement "Class A can be harder to get low distortion" is misleading. By design, Class A amplifiers inherently have lower distortion due to their continuous operation within the linear region of the output devices. The active device(s) conduct for the entire signal cycle, avoiding crossover and switching distortion entirely. Achieving ultra-low distortion levels (e.g., 0.01% or lower) is relatively straightforward with a well-designed Class A amplifier, thanks to these linear operating characteristics. In contrast, Class AB amplifiers require meticulous design to achieve similar distortion levels. Class AB and Crossover Distortion: While Class AB amplifiers significantly reduce zero-crossing (or crossover) distortion compared to Class B designs, they cannot eliminate it entirely. This limitation arises because real-world transistors are not ideal, they have non-linearities, and variations in gain. Even with techniques like bias optimization and feedback, some residual crossover distortion often remains, particularly in less expensive or simpler designs.

[@gasgas2689]

I'm off to the kitchen to get a frying pan and egg to cook on my Class A amp. In 1963 I learned how valves work. Then came transistors and I learned how they work. I couldn't figure out why electrons travel in a different direction to current. In 1967 I went round a transistor factory and saw how they were made. Then ICs came along and I was totally lost . . . . . till I was aged 56 and passed a technical exam in microprocessor computer systems. As others say this is an excellent presentation of transistor workings.

[@LovroSabljak]

Thank you very much!! I study in the field of computers and electronics but this is the first time I actually understood how solid state amps work!!

[@ianpickering4020]

Brilliant! For years I have struggled to understand this stuff. This video nails it in under 10 minutes! Thank you GoldenSound!

[@CrippleX89]

Well that's by far the best explanation I've seen on this subject. I'm quite new to all this and you've managed to clear things up quite a bit, so thank you!

[@lokermax]

It's the first time I understand the difference in amplifiers, thank you!

[@zzz2496]

Dang it! You explained it VERY CLEARLY! Good job! Loved the video!

[@gp.gonzales]

Amazing explanation! I never really understood the application of different classes of amplifiers until now!

[@loryhawley2930]

Wow!!! Fantastic! This must have taken so much thought and work in order to make a complex subject visually simple to follow. It would be great if you could add harmonics to your part two, as I’m trying to get my head around how these all affect what we hear.

[@18yearsoldnot]

That’s never going to happen. You’ll get a ton of trolling from people on audio science review saying you are experiencing placebo. I personally think they need to be told that harmonics do come through better with class a and ab but good luck with that…. They will just ignore you and say the “measurements” can’t prove it so therefore it can’t be true lol

[@daz4627]

Simply the best explanation you'll ever see ... brilliantly done (and I used to be a high school teacher so praise where praise is due!)

[@carlettoburacco9235]

As an explanation of the topic... perfect. Clear, no dependent questions left obscure, simple but explanatory graphic, conclusive. Ever thought of making a course for certain high school, college and university professors on how to explain something?

[@U2WB]

This is a fascinating video, and cleared up a LOT of questions that I’ve had.

[@MattyEngland]

Great explanation. Thanks.

[@theexpatgunner]

A true Masterclass, in how to articulate and explain a complex topic in simple form! 👍

[@deantiquisetnovis]

Great video, thank you for that! I love my Class-A HiFi tube amp. Pure simplicity. Just two tubes and a Transformer for each channel.

[@marine00001]

Excellent educational session. well explained.

[@thedarkknight1971]

I'm still daily driving a fully serviced (bought new) 1989 Technics SU-600 'New Class A' Integrated Amp... And... LOVING IT! 👌😏 😎🇬🇧

[@OrionHellscapeOrion]

Hands down, best explanation video ever.

[@nitraM321]

brilliant explanation !, especially impressed by the D class and the flappy bird, perfect ! i have had fabulous amps for decades and NOW i understand how they work !

[@justincase5272]

Maintaining full digital from capture to just before the speaker simplifies a great many sources of distortion throughout the audio recording, production, transmission and reproduction process, essentially limiting it to the microphone, the ADC, the DAC, and the speakers.

[@christopherviers8302]

Great episode....!!! Kudos and congratulations - great information...!!!

[@Impackon]

One of the best simpele explanations I have seen! 👍

[@fredsalter1915]

Subbed. Quick, but outstanding explanation!

[@swebigmac100]

Excellent presentation specially on the bias side.

[@C0ffeeKing]

I have a sudden urge to play flappy bird

[@circattle]

Because current year, it's coming back soon as a fully monetised, pay-to-play abomination, and Dong Nguyen isn't even getting a cut of it.

[@wrbrown571]

Thank you. Please continue to make content like this. This is great.

[@wchitwood65]

30 years ago i had a Sony class d car audio amplifier that was 60 watts per channel. That was the clearest, cleanest sound I've ever heard and the amp ran cool at full power. Current draw was also very low.

[@sarkardragon]

ok, now i need to know even more about it, class d is even more complex than i expected

[@jonas_oja]

5:30 one of the phases should be shifted in that graph

[@TheHEADPHONEShow]

Yep! I missed that!

[@mm7963]

Great video, thank you for the upload on this short, but very informative, series. Would be great if you could do one on the audio black art that is valve/ tube amps.. Cheers.

[@nosthof9286]

Finally understood. There is a bird in my amp and when I listen too loud it dies. Gotcha

[@billspencer8540]

Great video. You should have included the working principle of a Technics SE-A100 amplifier where the engineers combined a low power Class A with a high power Class B through a bridge to achieve the impossible - Class A sound at Class B efficiency. Reference Class S, by Dr. Sandman.

[@bobsykes]

You did a really good job with this. Now take a crack at explaining the increasingly popular ZOLT amplifier design, as found in Linear Tube Audio’s excellent sounding product line. Not really output transformer-less (OTL) not really but kind of class-D; that one will be a good challenge for you.

[@circattle]

It's all just Lego. Electricity Lego.

[@philliberatore4265]

Class B biasing is typical in vacuum tube amplifiers. The tubes don't have the nonlinearity of transistors at low input levels. Two tubes in push-pull configuration, in theory, have lower distortion than two transistors running Class A-B.

[@DrHarryT]

Ab historically have been the most common, I called them push/pull amplifiers. Because of the small overlap where both the NPN/PNP transistors are on at the same time effectively shorting each other out but to such a small degree there is very low idle current/heat. The when the signal is applied they provide a very quiet linear response up to their clipping point. I have a SoundCraftsman PM860 Professional mosfet amp that is amazing It will pump 450W into each channel A and B [900W total] at .05THD

[@KUDJU]

Love those type of videos!

[@helmargesel3972]

Thanks for the very good explanition

[@tomekkruger]

3:41Amplifiers in class A are usualy hot when are mute. In this case all current heat a transistor and a sink. But when play music, part od the current goes to the voice coil and in effect don't heat silicon as much as in mute work. A Class A amplifier that plays loudly will run cooler than one that is silent. 3:53 Amplifier in class A can also run in push pull configuration. It's just a matter of the quantity of the quiescent current, BIAS point. This is like in class AB, by increasing the current you go from class B to class AB, but if you increase it more you will enter to class A, then both transistors conduct current throughout all the cycle. And of course with less efficiency. The SE with sigle transistor can also operate in class B and C, even D, but has huge THD and IM.

[@paulfranken4493]

Brilliant!

[@prinzatago]

Thanks! This is very easy to understand! Keep cooking, chefs!

[@ngocsondinh135]

I used to spend an entire semester learning about how amplifiers work in the past and it was definitely not as easy to understand as this series. Fantastic work! If only you released the videos sooner 😂

[@cobymela]

Fantastic. Well done!

[@PhoticSneezeOne]

01:00 I couldn´t stop laughing at the waterhose scene with the Ducktales NES moon theme 😃 PS: The GOAT of all amplifier explanation videos here on YT !

[@MrSmitheroons]

Thanks for this explainer! I learned a lot. Just one tiny note: 3:27 "quescient current" 🥐might have been a typo or a misread of the script. Seems like this should be "Quiescent"? (Pronounced "kwee-ess-n't", with "kwee" as in "acquiesce" (ack-kwee-ess), or "kwy-ess-n't", with "kwy" as in "quiet".) I guess this is a technical term/synonym with "static current" since it just means "still" or "calm". (Also: 1:30 "Accidental playback of 'Paradise' by Coldplay" 💀Damn, transistors are scary.)

[@SkyhawkSteve]

"quiescent" is indeed the standard term for the static or steady-state current.

[@jungtarcph]

Very cool understanding

[@HobbyTalk]

Amazing video, thank you

[@Kyouske_42]

Great explaination! However, I missed the primary reason we bothered to develop class D amps. By only turning the transistor fully on or off, we avoid the less efficient linear zone, granting a significant gain in overall efficiency.

[@mal2ksc]

This allows for madness like 3 kW amplifiers in a 3U rack mount, where a class A amplifier would probably occupy the entire rack.

[@larsb.6420]

Amazing video, thank you!

[@danaillaysen7632]

You should do a follow-up on all the whacky and rare amp type, like fortnine did for motorcycle engines.

[@scanspeak00]

Amazing explanation. After trying class D for the past year I recently went back to AB and the sound improvement was obvious. It just sounds more natural, at least with the amps I used (Topping vs Rotel). Cheers

[@josephangelodelosreyes4206]

Great explanation! Although there's no example on what each do sonically. So does this mean, they all pretty much achieve the same thing sonically? No inherent "flavor" introduced by being a specific class of amp?

[@levelling2]

What they do sonically, or not as the argument goes, is a bit controversial. The video probably avoided it on purpose. There's already a lot of info to get straight already for one video so best not to muddy the waters more than necessary. But sonically it's another case of a matter of implementation and another tool in the toolbox. Some people definitely have a preference though.

[@Shoshiroll]

if they behave perfectly there is no difference: just an amplification of an input signal. your headphone, speaker, or room will probably have a greater impact on the sound flavor than the amplifier or dac. there are exceptions, but this is largely down to the device being *designed* to have that flavor rather than an inherit quality of the amp type.

[@samtdl]

Excellent...subscribed

[@markc2643]

Class D amplifiers are analogous in audio to switch-mode power supplies in phone chargers. Smaller, lighter, and far less heat. You wouldn't want to carry around an old-fashion AC adapter to charge your phone.

[@SimonPepper]

Hi Cameron, Although I admire what you are doing here, with this speedy overview of a very complex subject, your description of the basic transistor types, leaves me uncomfortable, as someone that actually studied the subject (Electronics that is, and semiconductor theory, and the maths, oh the maths! 😆). The NPN & PNP classification comes from the semiconductor makeup A NPN transistor is a type of bipolar junction transistor (BJT) that is composed of two layers of N-type semiconductor material, with a layer of P-type material sandwiched in between. The term NPN is derived from the sequence of these semiconductor layers. The three layers of the NPN transistor correspond to three regions: the emitter, the base, and the collector. The emitter is the region on one side that emits electrons or holes (depending on the type of transistor) into the base. The base is the middle region, which is thin and lightly doped. The collector is the region on the other side that collects these charge carriers from the base. Of course, the was an overview of amplifier types not of transistor theory and semiconductor properties, but they fundamentally linked. The operation of an NPN transistor is based on the movement of electrons as the majority charge carriers. When a small current is applied to the base-emitter junction (forward-biased), it allows a larger current to flow from the collector to the emitter (reverse-biased).

[@rene_magritte]

Allright, but what class is best suited for fun headphones?

[@TerryClarkAccordioncrazy]

Transistors actually switch on due to base emitter voltage Vbe. The collector current and base current are both consequences of the base voltage.

[@Grrrr3FKAGrrrrGrrrrGrrrr]

This video is confusing Class A with single-ended amplifier circuits. Push-pull amplifiers can also be Class A, so long as the output devices remain powered up throughout the cycle.

[@TheHEADPHONEShow]

This is true, thought it wasn't confusion, just too much to pack into a 10 min video unfortunately and trying to keep things simple. There's a few other things I'd like to have touched on like feedback too

[@TheHEADPHONEShow]

Although actually, it'd also be worth noting that there is a bit of debate as to whether push pull class A amps are "real" class A or not. Personally I'm of the view that they are, but some people argue that they don't count. It's a weird one!

[@ilyanikulin6543]

Very interesting! Would be fantastic to have a part 2 advanced version of this where you go into these further. Content like this really gets people into the rabbit hole which builds the community!

[@Grrrr3FKAGrrrrGrrrrGrrrr]

@TheHEADPHONEShow Class A means the output device is conducting throughout the cycle (a conduction angle of 360°), Class B means an output device is only conducting for half the cycle, either the positive or negative of the electromagnetic wave (180°), and Class AB means the output devices have a conduction angle between 180° and 360°. It's as simple as that, not too complicated or lengthy to describe for a short video. The problem is that you are conflating two separate things, power amplifier classes and circuit typology. All single-ended amplifiers are Class A, but not all Class A amplifiers are single-ended.

[@twoften]

This was great. I wouldn't mind hearing more about the long term reliability of Class D, though. I sometimes wonder about the environmental impact of efficient tech that dies early, vs inefficient tech that is near indestructible. It would be interesting to find out where that tipping point is.

[@wingracer1614]

Generally speaking and theoretically, more efficient is also more reliable. Less power lost means less waste heat, less strain on everything. In the case of audio amplifiers, their is nothing inherently unreliable about class D but class D is often the choice for making the cheapest possible low end consumer products so they are unreliable not because they are class D but because they were built to be as cheap as possible from the cheapest components. Also, class D is a very popular choice for building powered speakers where the amp is built into the speaker. This means the amp is bolted to the same enclosure that the speaker is bolted to. That's a VERY high vibration environment (especially in high powered audio equipment) and that vibration can kill anything, class D or otherwise.

[@twoften]

@wingracer1614 The vibration thing is a really good point I hadn't considered. Subs and active speakers tend to be the things that die most regularly from what I've seen and heard. I have one hypex amp in the house and so far no issues, although it's a stand alone stereo power amp so it has a much gentler life. I get what you're saying about efficiency where it relates to heat especially, although I feel like there's conversely a parts count variable that increases the likelihood of failure as circuit complexity increases, by simple virtue of the fact that there's more that can go wrong. It seems the attitude with a lot of class D stuff is that if anything fails on a module, you bin the module and replace it, which is fine (if moderately wasteful) so long as the module is still manufactured. Whereas with Class A you whack some MOSFETs on a big enough heatsink and the longevity is probably down to the life of the power supply caps or the thermal gunk, both of which are usually very easily sourced. I'm not in any particular camp with this stuff, but there's a few things like this that make me hesitant to go all in on Class D.

[@wingracer1614]

@@twoften That's down to a matter of costs. Class d can be repaired just as easily as anything else but like I said before, most of them are cheap consumer electronics that just isn't worth it. Who is going to pay some tech a couple hundred bucks to fix an amp that can be replaced with a brand new one for 50 bucks? While a 100 watt class A tube amp might cost a grand so if it fails, it's usually cheaper to fix it. Unless the transformer is blown. Good luck trying to find an exact match transformer for something built in the 60s.

[@twoften]

My point is simply this - class D is touted as cheap and efficient, but if it is (due to the market) cheap to the point it breaks easily and no one wants to repair it, that's not really efficient in the long run, environmentally, even if it is economically. At least, it seems that way. I'd be interested in someone running the numbers. I appreciate that not everyone cares about that aspect, however. 🙂

[@martinpetrov7228]

@@twoften My class d amp costs $40 with solid capacitors. I suspect it's much more reliable than any complicated class A or AB with 2378665 electrolytic capacitors inside. I've been using class D for 3-4 years and just recently replaced it for better quality one, the previous one (Also with solid capacitors) was working with no issues (And of course it was on 24/7, very convenient).

[@SilverSpoon_]

class D are really just op amps, want more punch, grab a pair of mosfets for output, but class AB with a couple of resistors in the input also does a good job for small things. edit : just don't forget good caps.

[@jungtarcph]

Could you explain analog vs digital volume in a video? And implications for poweramp input stage resistance. Would be fab!

[@prithvib8662]

Is there a mistake in the class-d section of the video? It says "triangle > input signal, turn output on" but then GoldenSound says the opposite, and that "if the input signal is greater than the triangle, turn output on"

[@TheHEADPHONEShow]

Yep this bit was the wrong way round (although technically either way would work. You'd just end up with inverted polarity at the output)

[@BrentLeVasseur]

The best all rounder amp on the market right now is the LTA-Z10e, because it can drive virtually anything including IEMs, Planar magnetics like Susvara, and even electrostat headphones like Shangri La Sr or Stax SR9000. Basically it’s the ultimate buy once drive anything swiss army knife headphone amp.

[@dmn1n]

Class D flappy bird example was an Excellent !

[@si1208]

Good job! Flappy Birds vs Forza ... simples!

[@harisjaved1379]

Omg this reminds of my circuits class!

[@stefanegger]

nice explaination, well made videos. Maybe it could have been a bit simpler or some parts were a bit too much for the basic explaination but interesting nontheless.

[@flatearthphysics1921]

At 2:27, and already spotted two errors. Bipolor, not 'Bridge' JT. And the 'cutoff' is only in the base voltage, not in the current. (Where the exact current amplification is highly variable anyway, and needs to be controlled by feedback.)

[@robjordan63]

At 7:10 the red line seems to be inverted compared to what you say in the script.

[@FOHGeek]

So technically 1-bit sigma-delta DAC's and Class-D amplifiers can be combined to create a new form of high-efficiency, noise-free full digital audio amplifier... As I imagined the audio data stream is fed into a high-speed microcomputer, which converts it to high-frequency PWM signal. The PWM signal is then amplified by a high-speed MOSFET H-bridge and fed into a lowpass filter to remove ultrasonic "carrier wave" component. The whole weak-signal process is fully digital, which not only can easily interface with modern PC's or audio mixing consoles but also totally immune to any analog interference like AC hum, common-ground noise, cable-related noise etc. There'll also be no hassles caused by analog signal level alignment or "gain structure" - Zero is zero, max is max. Unless the input data is already corrupted by digital clipping, the output signal will never saturate and distort. A variable digital trim and a compressor/limiter can be programmed into the microcomputer to give a safe, smooth and noiseless volume scaling control. Thanks to the nature of Class-D(-ish) amplification, the output volume can also be attenuated losslessly by lowering the power voltage, which can easily be achieved by using a variable SMPS power supply.

[@TheHEADPHONEShow]

This is true! And there are some designs which actually already do this. You do still have the challenges of full 1-bit modulation though, which can be fairly compute intensive and can mean that this approach if wanting to do it really well can be a bit expensive. But it definitely works. I'd be careful about describing any sort of volume control as 'lossless' though, since that technically isn't true for anything as SNR will always be reduced to some degree.

[@bazrazin1]

y & the transistor or fet is either fully on or fully off resulting in minuscule power dissipation from transitioning from off to on, resulting in an power efficiency of over 90%, so no big heat sinks.

[@technoman9000]

Great explanation, but how does this apply to a "push-pull" amplifier? Is that just describing the class B configuration?

[@bills48321]

If you rank the the types in the order of quality of audio would A, AB, D the order?

[@howitworks3607]

This video seems extremely well done - simple and clear. But for a smooth brain like me I still don’t understand a thing 😂

[@DMSparky]

It’s pretty laughable how slow the hobby audio community is to embrace new technology. I’d be willing to bet that the resolution and accuracy of the newest well designed class d amplifiers are far beyond what the human ear is capable of discerning. Guys the chips in new smartphones have component density greater than 100000000 transistors per sq mm. Modern digital oscilloscopes can measure several orders of magnitude faster than any frequency used in uses in audio. The fastest transistors can switch at hundreds of GHz. It’s based on mathematics by people who are much much much smarter than you or I. Why not just embrace it? Remember we are talking about technology from 2024 not 1994.

[@stephenbates5237]

Fascinating… but which one sounds best? I have a pair of class D monoblocks 600w per channel from PS Audio.. I like they don’t burn up the house and sound pretty clean.

[@ferchuu9]

1:27 BJT stands for Bipolar Junction Transistor, not "Bridge"!

[@shis10]

Amazing 💯.

[@martinfox2244]

Thank You!!!

[@bunnatang2081]

is there any portable Tube Lamp true wireless headphone ?

[@Dawwwg]

You forgot to compare Class D to AB at the end. They are the most power effect (upto 90% instead of 70% for AB) but do have more distortion than AB.

[@tharun7290]

So tell me if I'm getting this right, you can apply a lowpass filter to the square(ish) wave from the switching output, which itself is derived from an output of a simple comparison function, and just like that you get back the original signal?! That seems crazy to me, Am I missing something here?

[@GoldenSound]

Pretty much! Some things were simplified for ease of understanding in the video, for one being that the switching frequency will usually be hundreds of khz. Whereas the intended analog signal will only go up to 20khz. So the switching freq is many many many times higher. But in the video the overlay diagram had them very close in frequency so it was easier to see. This image is a bit closer a representation of what you might see in reality: dlbeer.co.nz/articles/pdm-sine.png

[@gaborhajdu4692]

If sound is the primary consideration, who cares about efficiency(?)

[@jamesrbrindle]

Yes I did pause to read the disclaimer

[@EggBastion]

wiggly ear enthusiasts? ( 9:20 )