Has anyone switched from Class AB/A to Class D? Was it better? Was it worse?

But it really stinks for me to buy them without hearing them.

This happens often in our hobby. 

Even with the 30 day return period. 

This seems like a very fortunate option vs being stuck with unsatisfactory expensive components

OP:  I have not really switched... I have A/B amp with tube pre-amp separates in one system and D integrated in another system. To my ears they both sound excellent with the A/B having a bit better control over the bass.

in my 40y + sound works I haven’t seen such speaker, with purely resistive load (2/4/6/8/12/16)! In order to design output filter properly, we need to take complex model of loading, including variety of speaker cables, DC protection relay ckt, speaker crossover, spkr driver/s complex, often resonating impedances, which is tremendous engineering task!

@westcoastaudiophile Actually its far simpler than that. A good class D amp can double power into a 4 Ohm load like any good class A or AB amp. There's no concern if the load isn't resistive! This is a no worries situation WRT the output filter.

In our case the amp is self oscillating, which means it also employs a lot of feedback. This prevents problems with capacitive or other odd loads causing resonance or the like- the amp is very well behaved with such loads as is any self-oscillating class D and so will be load invariant.

I like and have kept both. I’ve got a vintage Class A Pass Aleph3 (driven direct from a Wyred DAC2DSD) and ICE-based Wyred SX500 mono’s paired with a highly modified Rogue Metis (running Tung Sol VT99’s via adapters). The Aleph3 has an intimate continuity in image depth.. magical midrange while the Wyred’s (paired w my specific pre) have finesse and LF control while painting a detailed but natural cinematic stereo image. One is great for colder months and the other for summer and fall. I have tried the SX500’s driven direct from the DAC2DSD and thought it was nearly unlistenable, however. The right tube pre can have a way of ’sorting out’ older (but w well implemented output stage) class D topology into something that can still work now. The Rogue Metis Magnum is fairly dynamic (and a tube-roller’s dream/nightmare as an unbuffered tube design), but definitely a bit rough in stock form with stock tubes. I’ve got a good dozen other boxes in another room of other good-value separates; tube, Class D, and Class A, Class A/B, but these are the two setups I still use.. and I still go to shows. If I had money burning a hole in my pocket I’d like to try a Riviera Levante, Linnenberg or Kinki Mono’s.. a Nagra Classic amp.. perhaps some AGD Duets. I’d also like to try a Perla S50 integrated some day.. which I’ve heard with two way monitors before.

it’s more system synergy and implementation of the topology than topology, imho.

@atmasphere "target load in mind, which might be 4 or 8 Ohms” - in my 40y + sound works I haven’t seen such speaker, with purely resistive load (2/4/6/8/12/16)! In order to design output filter properly, we need to take complex model of loading, including variety of speaker cables, DC protection relay ckt, speaker crossover, spkr driver/s complex, often resonating impedances, which is tremendous engineering task! I’ve used class D amps in PA systems with active x-overs, where spkr was driven directly by the amp with short cable and w/o any x-overs in the path. For home use, I would definitely look for class D amps if I need power efficiency, that’s it. 

@westcoastaudiophile You might try the AGD Audion, one of the Orchard Audio amps or one of ours.

WRT to the analog filter, its job is to remove the switching artifacts that occur at the switching frequency. What is left will be a sine wave called the "residual". This sine wave is at the switching frequency so might be 500KHz. Its amplitude is so low that its of no concern to any loudspeaker driver, whose inductance will block it.

The filter is designed according to normal filter theory; typically second order. Usually its designed with a target load in mind, which might be 4 or 8 Ohms. Increasing the load (speaker) impedance results in a higher Q (Quality) of the filter effect. The load will shift the frequency a bit but usually its well outside of the audio band so that’s not a problem.

The characteristics of the capacitors and inductors involved is critical, since stray inductance (which might be caused by the leads of the capacitors, which extend not just from the circuit board but well into the part itself) can cause parasitics as well as the design of the choke.

It is for this reason its usually not a good idea to replace the caps or inductor in a class D amp in an effort to get better sound since reducing RFI is part of the filter’s task. Parasitic oscillation may be introduced! We found we had to be quite careful about the inductor in our amp, which uses a ferrite core. It was so critical we had to build our own jig to wind the chokes so we could control the inductance without strays. The vendors we tried to have the part custom wound simply didn’t seem to have the ability to get it right. To make the choke work properly we use a Litz wire. 

Of course the filter introduces phase shift as any filter. However, in our case the amplifier is using quite a lot of feedback and so is able to correct phase at high frequencies.

@atmasphere "Actually there are a few class D amps that have a better first Watt than a good number of class A amps.” - list of “few” and “good” ones will be helpful! 

Analog output filter question: how output filter is designed, order, phase v frequency., loading considerations (reactive speaker x-over + spkr-dr complex loading), R/L/C components tolerance, frequency dependency, aging / magnetic core inductors nonlinearity? 

I am two weeks in with a Buckeye 8x500 ncore hypex class D and I absolutely love everything about it. It runs cool even after hours of use, if you need to move it you could carry it under one arm, the amount of power is a gamechanger for me because I moved up significantly. My system sounds significantly better to me, and that is all that matters. I also appreciate not paying thousands for a pretty case, I get if you are going to display it in a listening room but for a theater application it is perfect.  The weight and the heat might not matter to most but I appreciate never worrying about the amp running hot. 

In 2025, Class D is the best way to go. 

You may dial 500mW output @ 1kHz sine on any D class and A class amp and compare waveforms to understand D class problems better!

@westcoastaudiophile Actually there are a few class D amps that have a better first Watt than a good number of class A amps. One thing about class D is for the most part (as long as they have an analog output filter) they are immune to crossover distortion. So there can be a complete lack of higher ordered harmonics at very low power levels.

That looks good on paper and sounds good too.

Put another way if you want to show what might be wrong about a class D amp compared to a class A, this particular metric isn't it.

@dman777 I ordered them based on a class A rating in Stereophile and the price for the pair was in my budget. Also, they each have a tube. They are quiet, neutral, dynamic, clear and very accurate. I like how they sound. They run slightly warm.

I'm very happy with them. 

My system is very simple.  My source is a McIntosh CD/SACD player that also has a preamp section. XLR cables to the M1200s then speaker cables to B&W 803 D3, and SE cables to the JLAudio subs. In my treated room, with careful setup, I am very happy with the sound.

@niodari you may read about class D design here: https://people.engr.tamu.edu/s-sanchez/ECEN%20607%20Class%20D%202011.pdf

@westcoastaudiophile , in most of the sonic aspects including the power (per dolar of  price - although it is well understandable that one cannot compare the real  power per-watt, in general,  of any SS amp with that of a tube one). The distortion at 1kHts is standardly  measured. I am not a technician, but it is well-known that, not always, technical data is linearly reflected in SQ (e.g., take HD of the tube amps).  

@niodari "You can certainly have a class D amplifier which is better than many class A ones” - better in what sense, max power perhaps? You may dial 500mW output @ 1kHz sine on any D class and A class amp and compare waveforms to understand D class problems better!

@kofibaffour You are underestimating the age of the members here.

You can certainly have a class D amplifier which is better than many class A ones. Look at this as a gift of technology that gives you almost miracle results in terms of a cost, weight, size and energy consumption.

In 2050 people here are gonna say "yeah the Class D from 5 years ago was pretty bad, but today's Class D has fixed the problems" ;-)  

yeah, but it is older than at least half of the people on this forum. that is the point. it didn't just become a topology @tubesjazznblues 

@kofibaffour It is newer than A A/B and G.

@coltrane1 uhm Class D isn't a new topology for amp implementation

My main listening setup uses a Rogue Sphinx Class D, mostly because I prefer Magnepans and need the juice, but also because I think the differences in quality amps are getting to be vanishingly small. Now, I also keep two casual listening systems that are Class A driving more efficient speakers. And here’s the thing: my diy First Watt M2 from diyAudio Store comes with five different input stages that are swappable and guess what? They sound different. So different implementation on the input stage, different sound from the same power stage. Go with your ears and don’t look back.

Heck no. I stick with what has worked my entire life. Class A, and Class A/B. I don’t need to experiment with some new Class simply because it’s new. Some of are satisfied with tube amps, or Class A or A/B. Done are we. 

I have been using a Schiit Magni 3 (Class D) for years, and only recently invested in an Asgard 3 (Class A) and found that the Asgard has greater clarity and soundstage, but less bottom end.  But there are too many variables to consider to call it a simple difference between Class A and Class D.  But that was my recent experience. 

Interested in the 240 to 120V input are you using converters and or inverters @slimpikins5 

My experience with Class D amps demonstrated to me that the quality of the sound was completely based upon which amp I had used.  One particular amp was nice, but it grated on me with extended listening time.  It was just too bright on the upper frequencies with a harshness.  I suspect it was the generic Class modules which were used in the amp; it was not a very expensive amp, and I'd say it was a perfect starter piece for kids in college who want a lot of output, very light weight and easy to move around and as I noted, affordable.   I was comparing it against my A/AB amp at the time too which was my baseline. 

I got a great deal on a pair of not very used Anthem Statement M1 Class D mono blocks, these are very expensive amps, but the price was great from the original owner who had a bad case of habitual upgrading syndrome.  He just had to have the super expensive $30K class A monobloc amps, so he let me have the M1's at less than half cost.   When I installed these amps (with dedicated 240V 15 amp each with direct runs to my service entrance), I was blown out of the park with what I heard vs. my A/AB fancy amp.  I knew within 2 minutes of listening to some very familiar vinyl these were game changers.  By the end of the weekend, I moved my A/AB amp out of the rack and put into a home theater application.

The Anthem M1's are very sophisticated design amps using internal liquid cooling heat pipes for the output devices and they use a proprietary feedback circuit which is makes them so amazingly smooth in the upper ranges vs. other Class D's I have heard.  I also experimented with them on 120V input vs. 240V input and it's still very good, but the dynamics on 240V make it definitely worthy of using.  Plus, they jump up to around 2300 watts output per amp for amazing headroom.

I will never sell these amps!  It doesn't get much better than this as it's like being in a live venue.

I made the switch from A to A/B and finally Class D (AGD) and not looking back!

@atmasphere +1 "If you know what you are doing you can build a class D amp that is in the driver’s seat rather than the back seat WRT any other kind of amplifier technology."

its applicable to everything! 

Thank you Ralph for your thoughts.  I can see your points, they are best to be considered .  Atma-Sphere systems at home can be somewhat problematic especially if not placed in dedicated audio rooms, the heat alone and then to a lesser degree, pocket $ impacting tube replacements for those hi powered OTLs can have us second guessing one’s financial priorities.  In an open air environment, they are some of the best I’ve heard! 

I might think about this further the next time I buy an octet of KT150s.  😵‍💫😵‍💫

 But tubes are not something I hear and can easily go to a class D system unless heat or space is the consideration.  A preference for tubes is in a class by itself.  The differences are easily distinguishable in a blind test.  SS v tubes, if you enjoy tubes; my advice is don’t even bother, over time you will be sorry, have spent more money, just to go back to the sound you like, tubes.

@daytrader I like the sound of tubes a lot as you might surmise. I like the sound of the class D amp in my home system better. Its just as smooth in the mids and highs and seems to delineate information in the rear of the soundstage with more clarity than the best tube amps I’ve heard. I don’t miss having to replace tubes or the heat which is a nice side benefit.

1. I don’t think we really know how long class D amps will last, how they will most likely fail, or whether they can be maintained in the same sense as a conventional amp.  They could last longer.

2. Class D amps use far more complex designs.  Many of the amplifier boards are built as modules and used by multiple amp makers.  That’s why a class D amp will often be identified as a Nilai, NCORE, Purifi, PASCAL, etc.  Some (all?) of these companies also build and sell compatible power supply boards.  Add a case, power switch, input buffer. wires & connectors, and you’re done!  I don’t think all class D amps are built this way, though.

3. The more recent introduction of GAN FETs has made for another family of class D amps.  I don’t know if these are also mostly being based on modular sub-assemblies; what makes them distinct is the use of a specific kind of transistor.

None of these are necessarily negatives, just things that occurred to me recently.  Hopefully, @atmasphere will drop by and fill in the blanks (please?)

Class D amps will last as long as any conventional solid state amp; perhaps longer since the filter caps will have less heat around them. 

Class D amps are not particularly complex except in the case of the formula to determine values in the feedback network of class D amps that are of the variety known as ’self oscillating’. In terms of components used our class D amp is simpler than most class AB solid state amps.

Not everyone uses modules from other companies- we certainly don’t; ours is designed and built by us as are power supplies we use. What we found prototyping our amp is that the power supply is critical and for best results should be designed for the application rather than bought off the shelf. That so many people do the mix and match thing is IMO why class D has had trouble getting traction in the last 20 years. 

If you know what you are doing you can build a class D amp that is in the driver’s seat rather than the back seat WRT any other kind of amplifier technology.

I can understand the attraction from A/b or even A if current is a problem to a class D amp.  But tubes are not something I hear and can easily go to a class D system unless heat or space is the consideration.  A preference for tubes is in a class by itself.  The differences are easily distinguishable in a blind test.  SS v tubes, if you enjoy tubes; my advice is don’t even bother, over time you will be sorry, have spent more money, just to go back to the sound you like, tubes.  
 

In 10 years, as Ralph says….then maybe? 

@tomcarr ya, I was eyeing the Class D PS audio monoblocks. But it really stinks for me to buy them without hearing them. Even with the 30 day return period. Were able to hear them first before buying them? 

I'm not Tom, but I also own the M1200 monoblocks.  A friend has them and I did get the opportunity to hear them a number of times before I bought them.  I needed more power than the class A/B monoblocks I had, which I loved and thought would be hard to beat for the money.

After a speaker change to some very power hungry speakers I decided to try the M1200s in my system.  They sound every bit as good as my previous amps and are able to deliver the power the new speakers wanted.  I have also owned the m700 amps, which were surprisingly good, but not as good as my previous amps or the m1200.  

There's always something "better" or "different" that might suit your tastes more than the m1200s, but they are very neutral, light, quiet, and have none of the negative traits I've experienced with other class D amps. 

As a bonus, you can roll the input tube.  I've tried a number of tubes in mine and like Amperex Orange Globe 6dj8 and Genalex Gold Lions the best.

There are a few differences:

1. I don't think we really know how long class D amps will last, how they will most likely fail, or whether they can be maintained in the same sense as a conventional amp.  They could last longer.

2. Class D amps use far more complex designs.  Many of the amplifier boards are built as modules and used by multiple amp makers.  That's why a class D amp will often be identified as a Nilai, NCORE, Purifi, PASCAL, etc.  Some (all?) of these companies also build and sell compatible power supply boards.  Add a case, power switch, input buffer. wires & connectors, and you're done!  I don't think all class D amps are built this way, though.

3. The more recent introduction of GAN FETs has made for another family of class D amps.  I don't know if these are also mostly being based on modular sub-assemblies; what makes them distinct is the use of a specific kind of transistor.

None of these are necessarily negatives, just things that occurred to me recently.  Hopefully, @atmasphere will drop by and fill in the blanks (please?)

@tomcarr ya, I was eyeing the Class D PS audio monoblocks. But it really stinks for me to buy them without hearing them. Even with the 30 day return period. Were able to hear them first before buying them? 

I've had class A/B amps from Denon, PS Audio, Vincent, and Krell.

Very happy with my class D PS Audio M1200 monoblocks.

@freediver  that's great feedback ... thank you!

I loved my Panny SA XR 50 in my bedroom system until it died.

I bought a Panasonic SA XR 50 with an Energy Star sticker on it for my transition to class D. Not a reference piece but it can do 5.1 signals and it never gets hot. Now I run B&O Ice Modules in two sizes: Red Dragon M500 monoblocks; Wyred4Sound SX 1000 R monoblocks. Also a Peachtree Carina 300 running Hypex modules. 

Class AB can sound wonderful but there is more more waste heat, complexity and weight. Not as good an idea if you run your air conditioner a lot or you are off grid.  

I prefer the sound of my Technics SU-G700M2 to what I've owned in the past, which have been various Class A/B makes, a Vinnie Rossi battery powered integrated (RedWine) and a EL34 tube integrated. Just don't call the Technics a Class D amp as they chafe at the mention of it. They call it a digital DAC with the power supply built in house using Gan FET output devices. So many shades of grey. Nothing off the shelf in the design.

The sound borders on the fantastic at times, compared to what I've owned. I can't say more than that.

All the best,
Nonoise

@hbarrel always a good point in these sorts of discussions.  Ultimately that is all that matters.

However, discussing brands and topology can be a fruitful conversation if people always remember the point you bring up as they discuss these things and remember that we all have different ears, systems and are at different points of our journey.

All the matters in the end is how the amp sounds in our system. 

I came from an AT 6007 Signature Series amp to class D Legacy Audio V:I Amplifiers. At the same time, I went from Marantz 8805 to a Lyngdorf MP-40 processor with Room Perfect. The ATI weighed hundreds, and the Legacy weighs much less, but does it ever pack a punch. Plus, it runs cool with absolutly no buzz, no hiss. I love the combo  

@dman777 I used class D amps for 80kW front end PA gig setup, and I am using AB/A class amps for home sys.. class D has too much harmonics at low output level, RF noise, “weird” pulse response.. 

Starkrimson 25 Mono Premium - Amplifer Tour | Steve Hoffman Music Forums

Try it for yourself.

In my case, better.  After the second repair of my 65 lb. Odyssey Stratos amp, which required lugging it to and from shipping facilities, I gave up after it failed a third time.  I was determined to find something powerful, yet much lighter.  My solution was Mike Kallelis' Arion Audio S500 stereo Class D amp.  It was more powerful, at 500 watts per channel, than the Stratos.  But the big surprise was the excellent synergy between the S500, my McIntosh C220 tube pre, and my Ohm Walsh 2000 speakers.  An annoying peak at about 7kHz, which I had attributed to the Ohms, vanished.  The Arion might be very slightly more neutral and less warm than the Stratos, but the elimination of that peak was worth way more to me.  I have had the amp for 6 years now, with no issues and no interest in upgrading it.  It runs cool, and weighs only about 22 lbs.  A very good value, too, IMHO.

"Think of BMW - they make various models and then they offer the M series. What is the difference."

The BMW M series’s original intent quickly diverged to a "M = Marketing" strategy to sell more upgraded BMW’s to those desiring the M badge of honor.

Originally, BMW had to sell a minimum number of street-legal cars to qualify for the European Motorsport series. They were true street-legal race cars at first and they sold out quickly. That is when the BMW marketing dept. realized an opportunity to increase profits. The M cars of today are far from the original spirit of M.

In the audio world, we see this sometimes with upgraded casework that gives the audio-jewelry effect that if it looks good, it must sound good, just like with the M-series’ aggressive styling and colorful racing stripes. Anyway.

Lots of advice and opinions already given.

Here is my 2 cents worth.  Disagree, agree, send me a note telling me I am an idiot it is all good.

This is a false statement - They have one purpose: to reproduce what is given to them accurately. Changing the character of your sound should be done at the preamp level. Enjoy!

I can prove that any day of the week.  Not trying to pick on anyone but each component does what it does for a reason.

My company manufacturers tube base products.  We have repaired and upgraded all audio products for 30+ years now.  In our shop we currently have this month CJ, ARC, VAC, VTL, Marantz, Plinus, Tron, Counterpoint, Prima Luna, Rotel, Cary, on and on.  We have heard more equipment that most anyone in various systems.  So what I am about to say is based on these experiences.

Most of the input here is from experiences of products that are similar.  Designs have not changed much over the years.  You are comparing similar products in YOUR own system.  That is not the best way to judge a product but rather a good way to select something for your system.  What sounds good in your system may not sound the same way in another persons system.  Preference is what that is.

In one of our systems we have Vandersteen model Seven speakers.  After fixing a Art Audio 28wpc tube integrated power amp, we put that amp in the system to make sure it was working properly.  To our surprise,  it drove the 83db speakers amazingly well.  Who would have thought.  I almost kept the amp for that reason alone. 

Think of BMW - they make various models and then they offer the M series.  What is the difference.  Well the M series is an upgrade to the stock model in general terms.  Some want that and are willing to pay the price and some aren't.  Same goes for audio.  In most cases, upgrading an existing component can get you close the the M series without the cost of the M series if you follow me.  That is where we come in on repairing and upgrading components.  We get to hear the stock versions and the upgraded versions.

So like what has been mentioned already, choice selection is a preference but you can upgrade your component to sound even better for less than you think. You simply don't know what will work unless you hear something in your own system.  The goal is to enjoy music in your own system IMO.

Happy Listening.

I can no longer chuck around 50+ pound components. I switched to PS Audio class D monos. I’ve never heard my Magnepans sound better. Very clean(quiet) background. Totally non fatiguing, open, billboard size soundstage. My speakers sound like they just breathe easier. Happy! 

@kofibaffour I apologize then for my false accusation.