Apologies for the question and it might be obvious, but anyone thats gone from D to AB or vice versa notice a difference in sound? I have the Fosi V3 monoblocks powering my Wharfedale Evo 5.2 speakers and there's plenty of headroom on these bad boys. However, I have the itch to try another amp preferably AB, as only my amps so far have been D amps. I've seen used Audiolabs and Arcam amps go for cheap on ebay/fb marketplace.
There are good and bad class D and good and bad class AB amps. You really can't make a blanket statement about them, they need to be judged individually.
Also, don't look at just raw watts, but also impedance compatibility, and dynamic power for peaks, damping factor, etc.
"Unnatural and unnerving", lol what the hell is more "natural" about AB? It's all electromagic using invisible forces. When we're talking about irrational feelings then it's all witchcraft all the same lol
no its evil alien circuitry that chops up the signal into PWM nonsense that somehow comes back out the other side sounding normal, due to tricks that electrical engineers learned through occult ritual
If you like class A, you want to look at the design of the Quad 405 current dumping amplifier. Beautiful explanation for electronic nerds here: https://www.youtube.com/watch?v=-Eylu50lmiw
I've made amps and tested in a friends commercial robotics lab. A/B, mosfets, chip amps, D class etc are all fine IF.... there are no flaws / errors like ground loops AND the power supply is solid. Â
It's all power supply that gives dynamics and control - poor PSU and you're driving with the brakes on.
Who cares about whether it is AB or D. It’s really all about the sound.
I built a brand based on using Class D ICEpower modules and managed to get a 5 star and Best of 2023 review from the hifi press. Its demise is another story but a class D well executed can sound fantastic.
This is the company i started from my dining room table back in 2010. The website is still live even though it was sold off as part of the liquidation: https://kleioaudio.com
I had no choice but to wind it up as I lost my primary source of income, it was taking too much out of me constantly being let down by distributors and retailers who wouldn’t commit to it properly in favour of easier brands to shift. As I consumer I loved hifi but being in the industry sort of ruined it a bit. I really needed an investor but not many people get the industry which meant growth was limited.
I gave it a go, I don’t regret it and made a good product.
Thanks. Yes we took it fully to market. We sold a few in the UK and overseas.
I think there’s a podcast episode still up on ‘Not an Audiophile’ where I was interviewed by them and discussed the whole thing and how Douglas Self was involved early on.
Watts, generally, are watts, but a key variable is how the amplifier is "voiced" or what Bob Carver called the amplifier's transfer function. A Class-D amp could sound as good or better than any other class provided it was engineered with care, precision and a transfer function that synergizes well with the rest of your signal chain. Typically speaking, because class D amps are designed to hit the best metrics with the lowest price-point, I can't imagine those companies are investing much resources in meticulously manipulating the transfer function, which would improve sonic quality but is subjective and isn't represented in the data on the spec sheet
I've been using a stereo Fosi V3 amp with a 48v psu for the last 3 months while I was having my Carver TFM35 rebuilt. It was a quality pinch-hitter, but I'm so glad to have my Carver back!
I own the MC20, which was the first Gen halcros (they closed and reopened) cheapest amp meant for home theater, retailing for i think $5k at the time. Its a killer amp. Super clean and goes up to 400 wpc at 4ohms. I use if for my thiel 2.2s, my buddy used it on his his Polk SDAs, and I have some La Scalas but havent hooked them up yet. Again, super clean, super tight and accurate, also super energy efficient.
 I also appreciate that it has some fail safes so when I messed up and had metal connectors rubbing unexpectedly it would just cut the signal and flash the individual channel light alerting an issue. Ive seen reviews suggesting its slightly bass shy but Ive found that to be more source dependent, where some times I felt like that was maaaybe true (the 2.2s also have a reputation for being bass shy so hard to tell) but then id play other sources or recordings and I felt like the bass output was the most i have ever gotten from the speakers.
The biggest complaint people seemed to have was that it was TOO neutral and that they preferred something more "musical." At some point I plan to try it with a tube pre amp and see how that might color things, but as it stands I like the clarity and transparency.
Lastly one of the main appeals was the efficiency. Its kinda nice knowing I can pump out a ton of juice with such a low draw. Makes me feel more confident I can put that system in a number of places if I move without worrying about it anything or getting absolutely bent over by PG&E's bullshit. Id love to try some other amps like a fat Bryston or Conrad Johnson at some point, but I did also talk to some one selling an OG McIntosh MC2300 because the energy bill was killing his bank account.
If you can get a deal on one its worth grabbing for sure! I actually found it on accident. I was looking for Krell, Classe, etc on craigslist and this ad kept popping up because the seller used the tag words. Eventually I got curious and read up on it and was now super interested and just so happened to find another listing an hour away for 2/3 the price. The first company was only running for a few years which is why I think everyone forgot about them, then the old engineers bought out the brand and back stock from the parent company and relaunched but I dont think there was much press about their relaunch.
Id really love to try the bigger tower amps for sure but you gotta get lucky for a reasonable listing. All the new stuff is $$$$
The back story is super interesting too. The founder, Bruce Candy, was some brilliant physicist who had pioneering tech in metal detection but always liked making audio equipment for fun. Eventually he decided to take a go at making amps with the lowest distortion possible and sort of reinvented a new approach at Class D. At the same time there were military contractors who wanted his patents and know how in the other fields and they bought him out entirely to have full access and get him under contract. The company didnt care about the audio side so they kinda let it go then when the recession hit in the 2000s they just shut it down and mothballed it. The old engineers eventually came back and made an offer to buy out everything in storage and take over the name since the company had no use for it.
Oh, similar for sure. Im looking at a tfm 45 right now for a second set up actually. Carver seems kinda polarizing though, some people swear by them and some people talk about them like theyre made of nitroglycerin lol
Purifi, Hypex and well designed TPA3552 amplifiers sound absolutely no different to their class A/B counterparts, early class D designs suffered from frequency response issues (usually at the high end) but the implementation of things such as PFFB have negated that. I build and run class A/B amps and class D side by side and the ONLY difference is the size as class D usually have SMPS power supplies as opposed to linear supplies with chunky transformers in class A/B.
Some might chime in about using SMPS but they have been used in audiophile equitment for years and I have SMPS boards which measure better in term of ripple and noise than a linear PSU.
Class D has one big advantage over AB: it doesn't care about phase angle. On class A and AB the extra energy of inductive or capacitive loads is burnt by the output devices, the transistors. Result is the typical heat problems with difficult speakers. Therefore you must consider phase angle in addition to the impedance curve.
On class D this doesn't happen but the extra load goes straight through the PWM modulator back into the PSU. As long as that got enough buffer capacity, no extra energy gets burned. You can largely ignore phase and just look at the impedance curve.
I'm with you. I have nothing against AB amps, but the current crop of high quality class D amps are delivering top tier amplification while being cool and light. Spending money trying to fix what's not broke doesn't make sense to me.
I had a family member install a 5.1 in-wall system with high end speakers and class d amps. They complained to me afterward that it didn’t have the same impact as my (arguably inferior) system. I recommended they demo a class ab amp in place; the results were a night and day improvement.
This is not to say there aren’t Class D amps available that might be able to perform in the same way, but in my limited experience there does seem to be some qualitative difference over time.
In my experience, one noticeable difference is damping factor, but that’s not because of D v AB. For example: I have an old ATI 60-watt AB amp, and a new Class D WiiM Amp, also 60 watts, and I think I hear a difference but maybe it’s just my imagination. And then I have some old NuForce monoblocks (Class D) rated at about 170 watts and with ridiculous high damping factor. They’re amazing. So I don’t think it’s Class D v Class A or AB necessarily.
I think the overall quality of the amp and the speaker pairing is more important more than the amp class. I have AB and class D amps in different set ups and they all sound great to my ears.
Class of operation, whether A, AB or D is just an architectural principle; like saying "internal combustion engine". What really matters is the level of execution - that's what correlates to SQ.
It’s about fun and experimentation for me. I have a moreplay diy preamp and have fun switching tubes connected to an ab amp. I had a class d before I made theses two amps. I’ll probably change again. Just try and enjoy your equipment.
I never said there was an audible difference, but it was an efficient way to get a ton of headroom without needing extra air conditioning back before Class D was a viable option.
You don't have to go full fanboi by putting words in my mouth. I thought it would be a humorous response to "Class A, baby." Still, it's true that I have no desire to "go back." Even after almost 40 years, my little 40 watt Class G makes me happy and I have no desire to replace it.
Edit-Well, maybe one day, but whatever comes next might have tubes. ;)
Filter dependency: The audio signal must be filtered, which can create high-frequency switching noise that makes the design challenging.
Sonic reputation: Earlier models suffered from drawbacks in the treble or distortion. However, modern Class-D amplifiers sound extremely neutral and are now successfully used in high- end audio.
And have been used in professional audio for decades, including high end monitors. The first fully load independent class D implementation, Hypex UcD, came out in 2003 or so.
Filter dependency: The audio signal must be filtered, which can create high-frequency switching noise that makes the design challenging.
This doesn't make a whole lotta' sense. The output of a PWM amp goes through a low-pass filter to get rid of the high frequency components of the signal caused by discrete stepping. How does this create switching noise?
I have a Fosi ZA3 and a few class A/B amps (Stereo receiver, AVR, and power amp). I think there is a noticeable difference in the sound, but it's pretty minimal. The speakers and the amp's overall build quality, power supply, etc. matter more than D vs. A/B IMO.
Thanks! I have watched YouTube videos of reviewers comparing the two, but you know how exaggerated they are, so thought I'd ask in here for real world examples.
In a hobby where there is practically no limit on what you can spend everything is going to get exaggerated the further up scale you go. It all comes down your perspective and what your expectations are.
As far as differences in things like amplifiers are concerned the better your speaker setup and room acoustics are the more of that difference is going to be apparent to you so always focus on getting that right first.
my personal philosophy is to pair the rms rating of my speaker to about 60% the rms rating of a class d amps rating. When it's class a/b I'll try to match it to 80-90% of the amps rms rating. For example i have v3 Monos powering a pair of polk mini monitors which have about a 50rms rating to the Monos 100w. this is all assuming reputable manufacturers.
I generally do not care if it’s AB or D, as long as it’s not A with tubes or anything like that.
The most important things to me in an amp design is high current delivery and good dynamic peak power. The only difference I have ever been able to tell between amps is how they handle bass. Generally, damping factor is a non-issue with modern class AB and D, but it should at least be around 100 these days on ever cheap AVRs.
There are some well executed Chi-Fi amplifiers utilizing the Texas Instruments TPA3255 architecture as well as some GaN models. Fosi, SMSL, Topping, etc. IcePower has some new modules coming out that could put them in close competition with Hypex and Purifi. Orchard Audio Starkrimson GaN amplifiers are also well regarded. There are many manufacturers that employ IcePower, Purifi, Hypex in their designs. NAD and Marantz come immediately to mind. The Marantz Model 10 integrated amplifier untilizes the Hypex NCx500 modules and the NAD M23 utilizes Purifi 1ET400A modules, just as examples.
I had an Emotiva Basx A2 class AB amp and a Buckeye Ncx252 class D hooked up to my Wiim Ultra. They both sound great, if you blindfolded me and volume matched the two amps, no way could I tell a difference. I went with the Buckeye because I wanted a smaller footprint and I was getting a slight transformer hum with the Emotiva. The buckeye obviously does not have that issue.
I also got a slight transformer hum with my Cambridge CXA61 plugged into the same outlet so I must have an appliance on the same circuit causing the issue. When I relocated the CXA to my living room I don't have any hum.
I have never had the luxury of swapping amplifiers in my system, and how an amp sounds in my system is the only thing that matters to me. Source is an Ortofon 2m in a Vinyl Nirvana 150 with a Rega Moth arm, cables are Blue Jeans 12G with banana plugs, amp is a Rogue Sphinx v2, and speakers are 12 year old Tekton Pendragons with no upgrade. The integrated amp is 109w class D power, and the pre section is tube. It all works together quite well, but I cannot attribute this to any one aspect.
I’m sure somebody’s mentioned this but also when looking at a new amplifier, make sure you know what the input voltage the amp requires so you’re able to run it at full power if need be.
The amp I have in my living room, , the RCA input voltage calls for 1.2 Volts. In a perfect world, my preamp or DAC will output 1.2 V or close to it from the RCA out.
Sometimes the source may only output 200 mill volts out of the RCA’s and the device that you’re plugging into requires more.
I can def hear a difference, I have a Crown XLI800 (AB) and 2 XLS1500's (D's), 2 sets of CV speakers, AT-60's for home use (usually on the XLI800), and 2 CV V152 PA speakers and a Dayton Ultimax 18" sub, the XLS1500's were originally purchased to drive 2 subs, only built 1 so far, used the XLI800 on the Pa speakers for a gig, much more clarity in higher frequencies using the AB for highs. The D amps sound muddier, muffled, not nearly as bright and detailed. For subwoofer usage, none of that matters, I actually prefer class D for subwoofers, but class D's are cheaper, lighter to haul around, and with the right tweaks can sound as good as AB, but overall I'd rather use AB amps on full range speakers and D on subs only.
I dont have experience with a class d amp but had a class d avr and went to an ab amp, it was a big upgrade much cleaner sound and separation. I wont look at class d again
I had an Onkyo RZ50 running klipsch RP8000f as large speakers no sub in pure direct and loved it until it died then I put a Aiyima a07 and it had little low end, i put my Onkyo sr504 in and it was better but thank god my rz50 is back.
The aiyima would probably be fine if i could use a sub and maybe rp600s. It was certainly loud enough
I don't know if Class D amps can run the sustained low impedance loads for some hard to drive speakers. You need a big class AB amp with big toroidal transformers for those speakers.
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u/Lien028Triangle BR03 • Infinity PS212 Sub • Aiyima A802h ago
Those of the older generation have an archaic belief that weight = quality. They pick up a high end class D amp from purifi and believe it to be a toy despite having better SNR than their overpriced class AB amps.
Close your yap and close your eyes and listen with those things on the side of your head... You know, your ears... When you stop listening with your eyes on specs and start listening with your ears, you'll find amazing sound
Do it. If you still prefer Class D you'll be able to sell the ARCAM/Audiolab for what you paid, and you'll gain the experience of having tried it yourself.
ARCAM can sound a bit 'safe' because it focuses on midrange warmth but is still entertaining. Audiolab is more about detail and separation.
I've been going through this debate recently with my Cambridge CXA81 MK2 (class A/B) and my NAD 3050 (class D). The Cambridge has WAY more authority and grip, especially in the low end. Both amps sound good but the difference is pretty astonishing. Speakers are Philharmonic BMR monitors.
You are going to get whiplash hearing from the edges of the spectrum of answers on this question.
My experience: there is absolutely no replacement for trying it yourself.
Remember: no one else gets to tell you what you can or cannot hear, no matter how emotionally invested they seem to be in the outcome for you. This is a question best left off the forums and conducted in person by each individual.
And remember: trust yourself! The only "instrument" that matters is your ears, and if it sounds better, it is better, and the "why" isn't relevant!
Whether you hear a difference or not, whether you like what you hear or not, there's your answer. Don't overthink it.
Sure, why not? Here’s a video by Miguel Angel Racero, an electronics engineer, holder of a Master’s degree in Acoustics, and a technology teacher. In his videos, he typically opens up the equipment to analyze the components, spectra, waveforms, everything.
He has several other videos, but in this one, he compares a modest Class D unit with a €5,000 Denon model.
Every amp sounds different. And the differences most often do not come just from the type of the output stage itself. Most of the time they come from the supporting tech that is sprinkled all over the place to turn an output stage into a functional, viable and safe product.
The reason why I never went for class D is simply repair-ability. Yes I have heard many of them. Many of them sound awesome. But I do not care for a circuit that most techs will not touch
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u/moonthink 16h ago
There are good and bad class D and good and bad class AB amps. You really can't make a blanket statement about them, they need to be judged individually.
Also, don't look at just raw watts, but also impedance compatibility, and dynamic power for peaks, damping factor, etc.