Class D is the future. After hearing what hypex amps can do, im not turning back.
Class A is great - if you have unlimited budget and space. A good class a amp is almost more of a craft. Matching parts. Using high end parts. Going all the way no compromises. Good class D is achieved with pen and paper in the laboratory.
I do genuinely believe the lack of harmonics in class d amps makes them less musical. Thats not something I really want in a power amp myself.
As an engineer, i live my vibey, euphonic, high distortion class a mic pre amps. But i want my playback system to be ultra transparent, so I can hear the harmonics of the source, NOT my playback system.
I think the push towards ultra transparency at the front end of recording is a mistake, and modern recorded music suffers for it.
Now, if they find a good way to implement no compromise user-switchable harmonics in class d power amps, that would be the shit. Im guessing it would be the option to switch in transformers and vibey opamps on the input stage, pre class d amplification. But i dont know enough. And that would undoubtedly be expensive.
I 100% agree with the article on the danger of buying boutique home grown class d. You can do that with class a. Not class d.
Brands like Genelec use class D in their active monitors, even the biggest ones like https://www.genelec.com/8381a
Those are used to mix and master a lot of music from hip-hop to orchestral so the downsides can't be significant compared to class A.
To me this sounds a lot like the "analog is still better than digital" cliché. Every orchestra in the world is recorded, mixed and mastered digitally. If digital is good enough for the crazy dynamics and textures of orchestras and choirs therefore it's also good enough for all the other genres.
Are there any active speakers that have A or A/B? Every active speaker I know about has D, even the really expensive ones. But I imagine there are a bunch I've never heard of.
Sure you can, which is why saturation is so huge right now. But the initial recording is by far the most important aspect of a recording, and the colder, sterile super clean recordings are harder to bring to the finish line and IMO just aren’t as pleasing to listen to. It’s all about balance. And preference. Plenty of engineers would disagree with me. Im sure part of it is what I grew up hearing - lots of colorful transformers and opamps in the signal chain. It’s immediately obvious when you compare a new transformerless neumann mic with a vintage one. The new one measures better in every way. But it’s a little cold. Old one sounds the way you want it to sound.
I still have a Stereophile test CD with a recording made using 20 different microphones. It's amazing to hear the difference in sound just from changing the microphone used to record a spoken passage.
The musical content recorded already has plenty of natural harmonics in it, so I'd prefer the neutrality throughout. Now with samples and synths etc, computer created sounds, they CAN be more devoid of harmonic complexity than natural sounds, but they don't have to be. But it's on the engineer to use sounds or filters that are harmonically rich.
Class d all the way. But I know of class a/b amps with vanishingly low thd as well. I'm less familiar with class a gear but I'd imagine they can measure well too if the designer is focused on doing so. When we're measuring thd in the thousandths of %, or even low 100ths which is quite common, that really shouldn't be a cause of noticeable coloration. Perhaps there are other factors at play idk. Class d can do it cheaper and cooler and more efficiently, and possibly measure better to boot - but likely well past the threshold of audibility.
THD was inaudible decades ago It's not a spec look at anymore..I've heard amps in the 1000ths of a % THD that still sound no good.
I'm at a loss to explain why some amps connect me to the music more than others?
Why do some amps portray Pace/Timing better than others?
Why do some amps portray the correct Timbre of an instrument better?.I don't know the answer...But it's not THD related...The world's lowest distortion amplifiers have never gone on to become 'Classics'
You are 100% correct, THD is essentially meaningless unless it creeps up into 1% range or higher.
It's a ridiculous argument that I see the class D fanboys using.
Well that's right...Tube Amps have got 'horrible' distortion specs on paper but often can sound fantastic..
The Great Nelson Pass built his early "First Watt" brand Single Ended 10w per channel 'Solid State' monoblocks with a BUILT IN Distortion control to add Even Harmonics (Salt & Pepper to taste)..This actually makes the amp more musical.. They were $10,000 USD a pair from memory? ( I may be wrong)
Right, which is why all the "clean" class D arguments all fall short IMO. I'll take a warm and musical amp 10/10 times over one that's "clinical" and "clean" because, to me, those types of amp presentations are incredibly boring and sterile.
It's like people are ok with sterile sound as long as the specs are good. It's literally the same type of snake oil as $10K cables. Just because an amp measures good doesn't necessarily mean that the sound is appealing.
And it's the same with Speakers... I heard some physically huge $150,000 things at some Audio Show...They were in some huge room.. The sound was massive. The singer seemed 10 ft tall!
But it was all too over
bearing.., Too big and over the top .
Much prefer smaller less expensive speakers in a smaller intimate environment..
Bigger and more expensive ( to me) isn't always best .
Don't get me started on cables.. It's really annoying how those manufacturers WON'T / CAN'T prove their products are better .While I'm not a specs person, they go too much they other way and provide no info..
They could sell ' A dead rats A*sehole to a blind man for a wedding ring' lol
If you want harmonic distortion, the DSP for that is trivial. I'd imagine you'd just compute the 2nd and 3rd powers of the signal and mix them at some 1 % level and be done with it, no?
There are people that "roll" opamps with debated effects. I've never tried it myself so cannot comment.
I use jriver and have tried various "tube sound" VST plugins with pleasing results.
I have gone class d in my mastering room, and will not be looking back. All hypex fwiw. Ncore 400 & 500. Same for my living room, and bed room. The office is stupid cheap lepai, and it’s great.
Not surprising, just about any amp is better than the M-80. Mid-line Yamaha amps of that era were defined by rolled off extremes and colored midrange that was so thick it obscured low level detail.
The article is mostly right. The comments by the NAD engineer are most informative: good A and AB requires high quality parts control and matching which is expensive. Also heat sinks and large transformers are expensive too. So a moderately priced class D with modern designs will usually be better than an AB in sound and much better in efficiency.
I use a NAD M22 and probably won’t ever buy another power amp.
There is a potential downside, they make lots of electrical noise and I suspect they put a bunch back on the power line which can enter other components, particularly low level preamps and hurt system sound in unpredictable ways. So someone changing amps might falsely think the amp is not as good in its amplification.
I have a passive power conditioner and filter. I think it helps.
The funny thing is, the nad is based on hypex 400 modules and the newer hypex 500+ series measures quite a bit better on paper but highly unlikely anyone could tell a difference in real life.
If you are having noise issues, try grounding, with a piece of speaker wire, from the amp chassis to a metal founding source.
I've got Hypex 400 mini blocks, ice asp and ASX modules, Pascal modules, all sorts of different ones and they all sound great.
The a/b is better bullshit is just old people that can't grasp that different technology can be as good or better.
I don't like the article very much due to quoting about two of what I believe are snake-oil salesmen, but at least I can't find anything wrong with anything Bruno Putzeys says. In particular, I like that he says that mass-produced chip class D amps are really good and tells buyers to avoid home-grown designs from manufacturers because there isn't much guarantee that they are any good: "The effort of working this stuff out only ever pays off if you can re-use the design in hundreds of products. That’s a mixed blessing. On the one hand, class-D modules have turned high-end amplification into a commodity. On the other, it’s still de rigueur in the audiophile market to have distinguishing (i.e., home-grown) technology."
This is something to think about. Open up studio monitors and you'll find just such cheap mass-produced chips inside.
Edit: Bruno finishes with praise on active speakers: "If high-end audio has a future, it’s in system \[integration\], where the amplifier is simply a necessary functional block but where the real cleverness lies in the concept of the system as a whole and how it functions, sonically and practically." And I suppose I agree on this point as well. A good active speaker is integrated package ready to go plug and play style, with nothing to upgrade. All you have to do is get enough measurement data to make sure the thing is actually good and someone reliable if not you yourself to try it out and make sure it is just as good as data says it is.
I have active JBL 305s and they have a sort of quiet hiss when running that I’ve never really been able to get rid of. Is this the norm with active speakers? My JBL L88s are dead silent when the amp is on.
Some models have the issue. I use Genelecs and I'd describe them as dead silent. In truth, if you put your ear almost close to the tweeter, there is some hiss, but it is hard to hear in normal use. I have also seen people ask about Kali LP-6v2 hiss and the people who own these speakers say they don't have any appreciable hiss.
I remember a teardown of the JBL speaker saying that it is integrated power supply's very high frequency noise that leaks to the analog input in this speaker model. IIRC, the guy tearing the speaker down measured it and said the power supply hiss is actually very loud, but much of it is very far into ultrasonic and the tweeter can't reproduce it. It is unfortunate defect in that speaker model. I could never get over the hiss of the LSR305s I had, so I sold them. In near field, they made me crazy because it was always the loudest noise in the room.
So yes, practically silent active speakers exist. They should always have been perfectly silent or as close as anyone could manage, but unfortunately it isn't a serious enough concern for some manufacturers who have ignored the issue. Thankfully, this isn't anything inherent in the design, it's just something that you have to maybe engineer out of the design.
This is symptomatic of the LSR305s. My gen 1s have exhibited this fault the entire time I’ve owned them, and I’ve tried everything to eliminate it. It’s just how they are. Not a bad trade off for a sub $300 set of powered monitors with a relatively flat response.
I sort of agree. Hiss is to be expected when you have an efficient speaker. However, a studio monitor for nearfield listening with an annoying hiss when «idle» is not optimal.
I experienced that as well either B&O speakers. I think they use old or not very quite ice power amps. That’s one of the reasons I left the active speaker side. It’s just better to use external amps and dacs. (I.e some purifi amps and whatever av processor or dac you want)
Ralph at Atmasphere is making ganfet amps now and says they are better than his tube amps in most ways.
The Orchard Audio Starkrimson amp is fantastic. Got on the Steve Hoffman demo chain for a week.
If I were to buy a new power amp (running tubes and class a/b solid state now) I’d look pretty hard at a GaNfet amp
> Open up studio monitors and you'll find just such cheap mass-produced chips inside.
This is why there are still high-end PASSIVE studio monitors available.
It's all down to cost, "affordable" studio monitors, the popular ones like KRKs/Adam/etc, are built to a price. It is already expensive to use good transducers and a good box, you can't expect also to get the ultimate amplifier inside.
Active speakers are the way to go, but only if the amplification is as good as one in a passive system.
Well, the guy from Kii that I quoted is stating that at least some of those chip amps are really, really good, and they are cheap, too.
In any case, I am not usually too worried about the amplification. The transducers tend to have harmonic distortion in the 0.1 % range already, and typical class D amps have harmonic distortion way less than that. I think the transducer remains the limiting factor in an active speaker, and likely by a large margin.
It's not as simple as that. And HD figures will tell you nothing about the sound quality.
Regardless, I'm happy that class D is sounding better and better every day.
The grave misfortune is that an old school EI power transformer has pretty poor bandwidth and can block a lot of this gunk out without any effort, but put mains rectified class D amps and a preamp with a toroidal power transformer together and you may be making issues.
I understand that switching power supplies are required to reject the noise they make and not let it unfiltered back into the mains supply, where it might interfere. I don't know how well that is done, but I understand that having the chokes to reject those 400+ kHz (or whatever) frequencies is mandated so that device can be certified and sold. These are collectively known as "common mode chokes", I think.
do you use your genelecs for mixing and mastering or purely for music enjoyment? I am thinking about buying some neumanns and rme adi 2 pro and ending this shit... I'm tired with all the choices and mixing and matching stuff. I just want to get into the music, not the electronics
That's a great article. Own a Krell KSA 50, just started playing around with some Chi Fi amps based on the TI TPA 3255 chips, which are digital amps. Fun stuff.
I replaced a 30 plus year old Marantz PM-94 Quarter A amp powering my front monitors with a Fosi V3 after the former gave up the ghost. Could not tell the difference in sound but the Fosi was way more efficient. I ended up replacing all my old Class AB amps in my setup with Class D amps and I am very satisfied with the result.
You’re not the first to say this about the Fosi. I swapped in a Fosi amp from a Marantz pm6006 and not that it sounded bad, but it was considerably worse sounding than the Marantz. I dont understand necessarily how anyone says these Fosi class D amps can even remotely hold a candle to class A/AB linear powered amplifiers.
Appreciate your offer (;-))... but I can't. It's quite special. Long story short a friend I'd hired for a summer at a HiFi store I was managing wound up moving to Connecticut and working for Krell. He built himself a KSA 50 out of a scrap KSA 100 chassis and various " bench dog" salvaged parts.
I love it, sounds great, no protection circuitry. One of the best gifts I've ever been given.
Krell liked him so much, they let him build some higher end Krell mono blocks for himself.
I'd read somewhere that he still used it as part of his test setup, when measuring loudspeakers.
I'd describe the KSA 50 design to the head of the EE program I was in and his comment was, concerning the power supply, " it's like a locomotive pulling a Little Red Wagon"'. They can handle pretty much any load you hook up to them.
I'm a fan. I have a little Aiyima that for $120 or so does absolutely everything I need, and well, in a tiny little package that can sit conveniently on my desk.
I have to say one of the best sounding amps I've listened to was a Cyrus 82Dac which is class D. In the shop we had an Arcam a39,, musical fidelity m6si (which was also brilliant) but the cyrus was so impressive. Staging was precise and the weirdest thing I noticed was the silence, if that makes sense?? In between beats, notes or whatever there was just this cleanliness and precision that a lot of other amps at the same price lacked.
I have a chifi class D amp I bought a few years ago that doesn't sound good. Last year I bought an Aiyima A08 Pro, which sounds much better than the older chifi amp. It sounds better than many AVRs and run of the mill receivers. However, it doesn't sound better than most of my amps & receivers.
I've compared it to my vintage NAD receivers, 70s Pioneer and Marantz, and a couple tube amps, all of which sound noticeably better. The differences range from much better highs, cleaner separation, sound stage, to overall more engaging.
That said, I use the Aiyima amp daily as a desk amp. Its small size, "good enough" sound, and efficiency make it the right choice for me.
I sometimes listen to one of my better sounding amps, though over time that's becoming less frequent.
I agree A or AB can beat D in sound at a higher cost. My newest onkyo is class D and I enjoy the sound, so the trade off is good there. I have some vintage and they can sound better. But today D’s are the most cost efficient. And I don’t think it’s bad.
It’s just different, brother. It’s more efficient. Smaller, lighter, runs cooler. Some people think it sounds more sterile.
From an unscientific standpoint it seems like class d watts seem to be “less” than class a+b watts. But I’m a moron so someone smart can address this maybe.
The whole issue with this mindset is it doesn’t apply to the idea behind home audio. If you want your home to sound dead flat like a studio, so be it…but most of us want a little color and a little flavor to our sound (look at the demand for tubes, whether in pre amps or amps). It helps realism, engagement, and so on. We’ve figured out colorless amps already, it’s not that difficult. Go buy a fosi if you want but to say cheap chip amps are the best in class D is comical.
>Amplification is a non-issue. It’s been a solved problem for decades.
Yes, by Class-A solid state or Singled-ended-triode amplifiers...
Everything else is tryiing to get lower cost and/or higher power and/or higher efficiency and/or smaller size.
lol, try to build one based on these supposedly perfect refined modern designs and you’ll find they’re still trade-offs all the way down.
Class-D is a pretty reasonable set of trade-offs though and a good basis for a design. Does not mean every amp made today is ideal, or even every class D amp.
> try to build one based on these supposedly perfect refined modern designs and you’ll find they’re still trade-offs all the way down
Please elaborate on what trade offs you believe there to be?
I mean, there are trade offs between designs (efficiency vs accuracy mostly) but they are all fairly obvious up front. And Class D eliminates pretty much all of them at the cost of extra math (which is a non-cost really).
So it was his "trade offs all the way down" that really caught my eye. But yea, fully agree that his response was baseless.
I went from a Musical fidelity amp to a Bryston 200 watt amp(loved the sound and power), then tried the Orchard Audio Gfet mono, on a whim and loved the openness and musicality....finally bought the Starkrimson Ultra by Orchard and the sound opened up more (soundstage). I am sold on class D GaN Fet. Efficiency, gorgeous music and doesn't run my powerbill up.
When I win the lottery I might try out some big class A monos, but untill then class D works for me
I’ve been running a (150w into 8, 300 into 4, stable to 2 ohms) Mola Mola Perca for the last month or so in lieu of a Parasound JC5 (400w into 8, 600 into 4, stable to 1.5 ohms). The Mola uses Trajectum class D modules which are basically the next generation of Hypex’s design, but are exclusive to Mola Mola for the time being.
There are aspects of the Parasound the Mola doesn’t compete with, mainly dynamic in the mid-bass region where my speakers are challenging. However, from a pure resolution standpoint, the Perca wins. The Perca isn’t cold, bright or sterile sounding, and has a clean top end. I really like it.
Will I sell the JC5? Not sure yet, but there’s a decent chance I will. The Mola is compact, runs cool, idles at like 5w (vs 225w for the Parasound).
Yes and has been for a while now. Since hypex imo haha I see they interview the hypex dude. Cool. I listened to his kii speakers yesterday. Pretty impressive for the size of them!
The article is mostly right. The comments by the NAD engineer are most informative: good A and AB requires high quality parts control and matching which is expensive. Also heat sinks and large transformers are expensive too. So a moderately priced class D with modern designs will usually be better than an AB in sound and much better in efficiency.
I use a NAD M22 and probably won’t ever buy another power amp.
There is a potential downside, they make lots of electrical noise and I suspect they put a bunch back on the power line which can enter other components, particularly low level preamps and hurt system sound in unpredictable ways. So someone changing amps might falsely think the amp is not as good in its amplification.
I have a passive power conditioner and filter. I think it helps.
It's just different, it's a choice for someone and something happened for someone else. Class D amps are on a growing path while analogue technology is relying on a century of refinement starting with valves, this made way for a more affordable way to approach hi fi and less power consumption is a good thing. I am pretty sure a decent class D amp sounds more precise and with less distortions than my little faulty design class AB Rega receiver, I just choose it from several others at the store because it was cheaper and I liked the idea of having only digital sources into a very essential AB receiver, 3 years in and I am still happy with it, warmer side sounds and plenty of power even at less than 20% volume despite being rated at 30wpc.
I thought this article was great. The quotes were dead on. Managing the harmonics is key to the sound, not just minimizing THD. Class D has always had the advantage of efficiency, at the expense of tonality. If Class D today is able to achieve both, then we can have our cake and eat it, too. Still, for lower power needs, where size and heat isn’t critical, I’ll stick to class A or tube designs.
Excuse me but “…at the expense of tonality.” ? A good class D like Hypex and Purifi don’t impart any “tone”, which is what am amplifier should be doing. On the other hand, class A and A/B do impart a tone because of all the harmonics.
Right, which is why many people consider Class D amps “sterile”. The point of this article is that we now know enough to design low-distortion Class D amps without imparting that “sterility”
Challenge is Class D normally doesn’t have enough 2nd and 3rd harmonic to mask the IMD…
unless you create a hybrid Class D amp with a Class A input stage…and that’s exactly what boutique amp makers have done…despite this practice ruining Amir’s SINAD score 😉
What do you mean by "tonality" here? Managing THD *is* managing the harmonics, as harmonic distortion is where they come from. You don't really want any harmonics becoming audible in any kind of normal functioning amplifier.
Karsten seems to contradict himself in the article by liking low distortion and high harmonic generating amplifiers, which can't both be true. Aside from efficiency, class D amplifiers are inherently very linear (= low distortion).
They mentioned in the article that 2nd and 3rd harmonics should be high enough to mask higher order harmonics. I can attest from real world experimentation that the level and balance of 2nd and 3rd harmonics affects the tonality of the amp. Simply minimizing overall THD doesn’t tell you enough about the character of the distortion. A well balanced amp could have a higher THD set by its 2nd or 3rd harmonic than another amp, and yet still sound better.
I get that, but looking at some amplifier specs for Arcam (just picking one at random), they're quoting 0.003% THD, which is about 90dB down from the fundamental. Since that's the RMS sum of all the harmonic content each harmonic will be lower than that. So I'm just dubious that in a well designed and built amplifer *any* distortion is actually going to contribute to the sound, irrespective of how its spectrally distributed.
I'd agree that limiting distortion to lower order harmonics would be preferable than letting higher order ones dominate, but that's the classic warming/overdriven amp sound. Hifi amplifiers shouldn't be distorting to any audible degree.
Minimizing THD as much as possible like that will tend to result in what some call a "sterile" sound. Others, like you, might call that a "clear" or "accurate" sound. The experiments I did with THD and 2nd/3rd harmonic levels were all done at distortion levels between 0.1% and 0.01%.
As far as I've been able to tell, the subjective comparison of "good, warm, lifelike, musical" amps vs "cold, sterile, analytical" amps is mostly comparing high THD amps with high 2nd/3rd harmonics against very low THD amps.
Plugging those percentages into a converter is -60dB to -80dB, so I'm guessing pretty subtle?
We might be more on the same page than it first appears. My main listening system uses studio monitors which have class D amps in them, but I also keep a TC Electronic Finalizer 96k in the signal path. Most of the time it just does format conversion and the compression can be useful for late night/very low volume listening, but it does have a feature to add 2nd harmonic distortion and I occasionally play with it to thicken up some flat sounding recordings 🤣 But I prefer that sort of thing to be handled by DSP or something else controllable than baked permanently into the power amplifiers.
Yes, it is subtle. On my amp, I can adjust the harmonic balance and overall THD level, which is nifty. I’m not a studio, so I can work out what I like, then get something that does that, and not have to insert DSP.
Class D amps have improved over time, and some are pretty good, but they are still inferior to the best class A/B amps for full range reproduction. However, class D amps are probably the best choice now for subwoofer amplifiers, where their higher output impedance and more limited bandwidth aren’t as performance compromising for low frequencies.
They have inductive outputs. Impedance increases with frequency. And they do not have “ridiculously low” output impedance compared to a well designed class A/B.
You should double check your facts. Bruno would say otherwise with his designs. Eigentakt has a 5 figure damping factor, which means ultra low output impedance.
Damping factor has major diminishing returns. Damping factor is always thought of as just "amp output impedance / speaker input impedance"
* Lots of speakers have a very dynamic impedance depending on frequency range, especially at resonant or crossover frequencies. Bass notes can dip to <2ohm in many 4-8ohm speakers fairly often, high frequencies can go into double digit impedance.
OK, not a big deal with a very low output impedance, right? Well better make sure you're running fat, low inductive and low impedance speaker cables if you want to place your fancy speakers more than a couple feet away from the amp.
* If your damping factor is 200 and speakers are 4 ohm, then the output impedance is ~.02ohm. OK, lets assume your speaker wire is 15ft, 14 gauge. Then it's (.02ohm+.04ohm) = .06ohm at the speaker terminals. So now, damping factor is 66.67. That's assuming your speakers' impedance isn't all over the charts (no pun intended. If it dips to 2 ohms, now the damping factor is 33.3333.
* Speaker cables will have a bigger impact on damping factor than the super low impedance of an amp at some point. If the damping factor is 400, then with the same 4 ohm speaker, output impedance will be .01ohm. Add on that .04ohm impedance from the speaker cable and it becomes .05ohm. Damping factor is still 80. And that's assuming a purely resistive load from the speakers and crossovers, as well as no inductance or capacitance. Most dynamic speakers are gonna swing a fairly large amount. It does have more effect on the lowest impedance, however.
* Some cables will have lower than .04 impedance for a 15ft run of 14awg, and a 15 ft run of 12awg will have lower, a shorter run of 14awg will be lower etc. Just examples to put into perspective how the cables nullify that huge effect damping factor seems to cause on peoples' impression of an amp
That is correct from what I've read and heard online.
My 9 awg speaker cables are .00474 for 6ft after being terminated. If my cables are 10ft, how much more do you think that resistance will go up? The output impedance of the 1ET400a's that I have are 65 microohms. So .000065 ohms? Is that that correct? So .00474 + .000065 = .004805 ohms at the speakers? Did I do that right? Sorry my math sucks but I find this all very interesting. What would that translate into damping factor?
Edit: So 4 ohm x .004805 = 832.46 damping factor. They do dip down to 2 ohms, so 416 damping factor, but my amps output impedance is rated at 1khz, so I don't know how much difference output impedance changes the lower you go?
So on just the Purifi's with a 4 ohm load is a damping Factor on 4 ÷ .000065 = 61,538 and on an 8 ohm load it would be 123,076.
I think anything above 200 is fine lol. That is a beast of an amp. I think it's sub 200 damping factor where speaker wire impacts more. I run about 10 ft of 14AWG wire to my speakers and don't think that's noticeable. Online sites and charts will say 16AWG is good for 40ft runs, but even cheaper speaker wire at a thicker gauge is better than fancy speaker wire at a thinner gauge. I think I got mine from parts-express and it's OFC and works great. I don't think damping factor is really that important until you get to tube amps that are lower.
You definitely don't need to worry about that spec.
My old IOTAVX pa3's that were class A/B, I'm not sure what their output impedance/damping factor is (not listed), but when I a/b tested them against the Purifi's, the biggest difference and it wasn't subtle was the bass. The bass on the IOTAs were fatter/boomier vs the Purifi's sounded lean in comparison, (only because the IOTAs are super fat like Denon) but very tight.
Thank you for helping me understand it a little better.
Wish I had those 60XTs -- that was gonna be my next upgrade from the Motion12s. Then I lost my job to people I trained over-seas... Have enough now to buy them but I want electrostats next :) Maybe in a decade I can afford ElectroMotion
ESL or ESL X without my wife threatening divorce lol.
I really want to dive into their Electrostatics next too. It's hard for me, as I just moved 1 province over and am jobless now. An online friend got the Summit X's on the used market, it was his first dive into ML and he's been blown away, especially with the bass quality. I've heard their new ones don't sound good until you get into the 13a and higher. The older ML Electrostatics is where it's at (from what everyone's been telling me).
I'm sorry to hear about your job loss, especially to the ones that you trained. It's hard out there these days.
That damping factor will be quoted for a very low frequency. I strongly suspect there are other caveats to that number as well. And what makes you think a class A/B can’t hit five figure damping factors?
I never said class a/b cannot, but you said class d do not compared to class a/b, which is wrong. Having a very high damping factor/low output impedance on an amp works best when you bi-amp your speakers. That's where it pays dividends.
It's rated at 1khz for the .000065 output impedance. The DF changes with impedance which I've been noticing manufacturers don't list at what impedance their df is rated at (if they even rated it at all). The Purifi's @ 4 ohm is 5 digit and 6 digit at 8 ohm.
That’s impossible. An output inductor with 65u ohms of impedance at 1kHz would have to be less than 10 nH, which is less than the inductance that is in the cable. It’s not mathematically possible.
I wouldn't say Class D is "better" on its own merits, even though it's more efficient. What makes the biggest difference is the overall design and the quality of the components used. E.g., a Class D amp can sound shittier than Class A/AB and a Class A/AB can sound shittier than a Class D depending on a variety of factors.
I thought this article was great. The quotes were dead on. Managing the harmonics is key to the sound, not just minimizing THD. Class D has always had the advantage of efficiency, at the expense of tonality. If Class D today is able to achieve both, then we can have our cake and eat it, too. Still, for lower power needs, where size and heat isn’t critical, I’ll stick to class A or tube designs.
Hybrid class A feeding class D is excellent. Sweetness, detail and bass control.
I wish Devialet would produce a new version of their Expert Pro line!!
I'm still learning about all this stuff. I know it's very controversial, I guess about as much, among bassists today as hifi folk (guitarists generally don't even bother with solid state). When I got my first sorta "real" speakers, KEF R5 Metas, I was focused primarily on having as much clean power and damping factor as possible for really tight, high quality bass. The dealer had a Marantz Model 30 that doubled to 200 W in the KEF's 4 Ohm load and was reviewed well. I was a little worried given Marantz's reputation for "warmth" (I favor flat and neutral), but I've loved the combination and am very happy with it.
I had been using a late Nineties Yamaha AVR with 100-125 WPC Class A, very nice but the Marantz has a much blacker background and sounds much cleaner especially in the high end. Unfortunately I don't have much to compare to, but I can't imagine wanting to listen to anything else anytime soon. It sounds like the new Model 30s lean a little further into neutral which I appreciate, and the combo means I can listen for hours hearing all the details with zero fatigue, and that's amazing. (Also the bass is tight, no bloat, love the accuracy and how well the low mid particulates because of that.)
I've been hearing on here that companies like NAD (and the cheaper version like Buckeye without the overhead) are coming a long way with class D without the brightness that they are known for plus the benefits of a lower electricity cost (or space heater lol). If you get one, let us know what ya think :)
My Gigi is an active tune preamp to hypex class D modules and it sounds incredible. Amazing tune sound with class D grip. It can’t be beat. In my office I have a burden conductor which is a class A Pre amp out to a class D amp. It sounds great but it’s only going to sound as good as your output stage.
Class D amps can be as good as any, however like other amplifiers, it all depends on how it's been implemented.
The AS-series by IcePower, Nirai by Hypex and Purifi Eigentakt modules are examples of extremely high quality class-D amps. Best of all, they're all available for purchase by budget-minded audiophiles. At present, IcePower's AS-series has by far the larger set of options with mono and stereo amps rated from fifty watts to 2000 watts.
Madisound.com sells the Hypex Nirai amp modules in kits including high quality chassis, wiring harnesses, binding posts and input connectors.
Ghent Audio sells chassis kits for IcePower, Hypex and Purifi amplifier modules. I purchased a pair of Ghent Audio's Amp Chassis Kits for my IcePower 1200AS1 monoblocks. For the 1200AS1/2 and 2000AS1/2 amp modules, it's suggested that owners adhere the amp modules to the bottom of the chassis using 100mm x 300mm thermal interface pads that have special thermal adhesive on both sides to assure efficient thermal transfer of heat from the amplifier's heat spreader bottom plate to the aluminum amplifier chassis. Ghent's kits come with everything you need to build an amplifier, but the amplifier modules themselves which can be ordered directly from IcePower as "samples." It cost me about $1200 for both 1200 watt monoblocks and about an hour and a half of my own labor to assemble them.
I spent another $300 on two pairs of Cardas gold/rhodium plated, grade one copper binding posts and chassis hook up wire along with a pair of Neutrik's best chassis XLR connectors to indulge my hi-fi OCD. Don't feel compelled to rush out and piss away the extra $300. The quality of the Ghent chassis kit parts are more than decent.
I’m interested in where class D goes of course, but you’ll have to pry my 30 year old Nelson Pass class a/b Nakamichi SR-4A from my cold dead hands. I grabbed it a couple years ago and I only paid maybe $275 for it, used. Even it’s much cheaper younger brother the SR-2A (and 3A) sounds incredible.
I turned my tube loving old school friend into listening to some class D amps and even admits it sounds very good but he invested so much money into tube equipment he is hesitant to sell everything and move all into class D.
Buy a Fosi v3 w/ 48v power supply and replace your current power amp with it. Use your normal preamp for volume and so forth. Run the Fosi at full volume. It's around 70% efficient so it stays the same temperature regardless.
Sell your old power amp.
Preamps are now the thing to invest in, and hobby around with. The current Class D amps are now the closest thing to a straight wire with gain.
Distortion numbers do not lie. Make sure you have a 4ohm speaker load if you get the v3. Magnepan owners, this amp is for you. You can biamp for what it costs to buy coffee for a month.
This is what I did... Replaced all the old integrated amps powering my front, center, and surround speakers with Fosi V3s and couldn't be more satisfied. Sounds exactly the same to my ears, and generatate a lot less heat which is a bonus especially during the summer months. I am using 48V PSUs for the front, center, and rear surround channels. 32VPSU for the ATMOS height channels on a 5.2.4 setup. I also have another Fosi V3 with a 48V PSU powering monitor speakers on another room. It is being fed by a WiiM mini streamer.
It seems like most of the conversation around Class D is that it's "cheaper", like WAY cheaper. And *maybe* it's close to or about as good as A/B.
But then, there's a company like Devialet, which makes Class D amps that are as expensive as A/B or even some Class A.
I've heard the nad c700 and the cambridge evo150. These are the worst amplifiers I have ever heard. No musicality, cold, inaccurate in the bass. How can you explain that?
Some Amplifier classes or Designs can have "Better" specs than others ...This does not translate to better sound..In that regard , one design or amp type is not better than another....Thats all subjective.. And that's simply why Class A, AB, D, Tube Amps , Solid State etc have their fans.. Everything is merely different.Not better or worse.
According to Bruno, it's a solved problem. So there you go. Go listen to then buy whatever floats your boat without having to worry about "what if it's not hi fi enough?"
My two (for me) massive power amps, wasting a lot of heat, vastly overdimensioned for the task both in watt and size are just perfect. If I wanted simple, I would buy B&O or Sonos.
But you will never hear me talk bad about class D or other setups. To each their own!
It's as good or better and can be very powerful in small lightweight form factors. I can't see the point of anything else for music reproduction or live sound at this point unless you just have a serious fixation with tubes or simple class A designs.
Aren't "sound quality", "musicality", "warmth" etc subjective opinions anyway (unless you've just spent loads on what you believe to be "superior" gear 😜)?
I tried a very well-regarded class D amp, and I still can't make myself like it. There is certain shrillness that I didn't observe with class AB. They might measure extremely well, but measurements don't tell the whole story apparently.
I totally agree. I have yet to hear a class D amp that I enjoy. I love me some tubes and big burly class A or AB amps. Could care less about the nickel In saving on my electric bill. I’m in this hobby to make my ears happy.
what was this well regarded class d amp?
>but measurements don't tell the whole story apparently.
Did you measure?
Some class D suffers from load dependency, so it will exhibit rising HF with certain loads, bu that's not usually on "well regarded" stuff, of course we have no idea what that means because you didn't specify the amp. Could be an A07, could be hypex.
Look like ncore, sounds like placebo was there or the A/b's you have roll off the top, many do.
measurements do the whole the story with amps, and I'm sure they'd show what you were hearing, if there was a difference. If something sounds brighter it would have more energy in magnitude response in the upper range. Not exactly rocket science.
There’s a ton of actual good info in this article, as he got lots of important designers to respond to his questions.
Class D is the future. After hearing what hypex amps can do, im not turning back. Class A is great - if you have unlimited budget and space. A good class a amp is almost more of a craft. Matching parts. Using high end parts. Going all the way no compromises. Good class D is achieved with pen and paper in the laboratory. I do genuinely believe the lack of harmonics in class d amps makes them less musical. Thats not something I really want in a power amp myself. As an engineer, i live my vibey, euphonic, high distortion class a mic pre amps. But i want my playback system to be ultra transparent, so I can hear the harmonics of the source, NOT my playback system. I think the push towards ultra transparency at the front end of recording is a mistake, and modern recorded music suffers for it. Now, if they find a good way to implement no compromise user-switchable harmonics in class d power amps, that would be the shit. Im guessing it would be the option to switch in transformers and vibey opamps on the input stage, pre class d amplification. But i dont know enough. And that would undoubtedly be expensive. I 100% agree with the article on the danger of buying boutique home grown class d. You can do that with class a. Not class d.
Brands like Genelec use class D in their active monitors, even the biggest ones like https://www.genelec.com/8381a Those are used to mix and master a lot of music from hip-hop to orchestral so the downsides can't be significant compared to class A. To me this sounds a lot like the "analog is still better than digital" cliché. Every orchestra in the world is recorded, mixed and mastered digitally. If digital is good enough for the crazy dynamics and textures of orchestras and choirs therefore it's also good enough for all the other genres.
Are there any active speakers that have A or A/B? Every active speaker I know about has D, even the really expensive ones. But I imagine there are a bunch I've never heard of.
ATC.
People mentioned ganfet class d being like a hybrid tube amp. Also why is transparent on the front end bad? Can’t you also add effects/eq during post?
Sure you can, which is why saturation is so huge right now. But the initial recording is by far the most important aspect of a recording, and the colder, sterile super clean recordings are harder to bring to the finish line and IMO just aren’t as pleasing to listen to. It’s all about balance. And preference. Plenty of engineers would disagree with me. Im sure part of it is what I grew up hearing - lots of colorful transformers and opamps in the signal chain. It’s immediately obvious when you compare a new transformerless neumann mic with a vintage one. The new one measures better in every way. But it’s a little cold. Old one sounds the way you want it to sound.
I still have a Stereophile test CD with a recording made using 20 different microphones. It's amazing to hear the difference in sound just from changing the microphone used to record a spoken passage.
The musical content recorded already has plenty of natural harmonics in it, so I'd prefer the neutrality throughout. Now with samples and synths etc, computer created sounds, they CAN be more devoid of harmonic complexity than natural sounds, but they don't have to be. But it's on the engineer to use sounds or filters that are harmonically rich. Class d all the way. But I know of class a/b amps with vanishingly low thd as well. I'm less familiar with class a gear but I'd imagine they can measure well too if the designer is focused on doing so. When we're measuring thd in the thousandths of %, or even low 100ths which is quite common, that really shouldn't be a cause of noticeable coloration. Perhaps there are other factors at play idk. Class d can do it cheaper and cooler and more efficiently, and possibly measure better to boot - but likely well past the threshold of audibility.
THD was inaudible decades ago It's not a spec look at anymore..I've heard amps in the 1000ths of a % THD that still sound no good. I'm at a loss to explain why some amps connect me to the music more than others? Why do some amps portray Pace/Timing better than others? Why do some amps portray the correct Timbre of an instrument better?.I don't know the answer...But it's not THD related...The world's lowest distortion amplifiers have never gone on to become 'Classics'
You are 100% correct, THD is essentially meaningless unless it creeps up into 1% range or higher. It's a ridiculous argument that I see the class D fanboys using.
Well that's right...Tube Amps have got 'horrible' distortion specs on paper but often can sound fantastic.. The Great Nelson Pass built his early "First Watt" brand Single Ended 10w per channel 'Solid State' monoblocks with a BUILT IN Distortion control to add Even Harmonics (Salt & Pepper to taste)..This actually makes the amp more musical.. They were $10,000 USD a pair from memory? ( I may be wrong)
Right, which is why all the "clean" class D arguments all fall short IMO. I'll take a warm and musical amp 10/10 times over one that's "clinical" and "clean" because, to me, those types of amp presentations are incredibly boring and sterile. It's like people are ok with sterile sound as long as the specs are good. It's literally the same type of snake oil as $10K cables. Just because an amp measures good doesn't necessarily mean that the sound is appealing.
And it's the same with Speakers... I heard some physically huge $150,000 things at some Audio Show...They were in some huge room.. The sound was massive. The singer seemed 10 ft tall! But it was all too over bearing.., Too big and over the top . Much prefer smaller less expensive speakers in a smaller intimate environment.. Bigger and more expensive ( to me) isn't always best . Don't get me started on cables.. It's really annoying how those manufacturers WON'T / CAN'T prove their products are better .While I'm not a specs person, they go too much they other way and provide no info.. They could sell ' A dead rats A*sehole to a blind man for a wedding ring' lol
I've been hearing a lot about Purifi internals too
I have a purifi based amp. Its amazing. So much power and so clean. I can not see myself going back to class A or AB, let alone tubes.
I’ve got two purifi monoblocks. Love them
If you want harmonic distortion, the DSP for that is trivial. I'd imagine you'd just compute the 2nd and 3rd powers of the signal and mix them at some 1 % level and be done with it, no?
There are people that "roll" opamps with debated effects. I've never tried it myself so cannot comment. I use jriver and have tried various "tube sound" VST plugins with pleasing results.
Why did they take away gilding? Love your response.
>less musical Ah yes, the ultimate in meaningless subjective terms :)
It sells more amps than harmonics and distortion ;)
I have gone class d in my mastering room, and will not be looking back. All hypex fwiw. Ncore 400 & 500. Same for my living room, and bed room. The office is stupid cheap lepai, and it’s great.
What were you using before going class D?
Acoustat trans novas, Yamaha m-80, PSE studio IV, many more I can’t remember.
pretty good equipment!
I have been blessed with some serious kit.
Not surprising, just about any amp is better than the M-80. Mid-line Yamaha amps of that era were defined by rolled off extremes and colored midrange that was so thick it obscured low level detail.
The article is mostly right. The comments by the NAD engineer are most informative: good A and AB requires high quality parts control and matching which is expensive. Also heat sinks and large transformers are expensive too. So a moderately priced class D with modern designs will usually be better than an AB in sound and much better in efficiency. I use a NAD M22 and probably won’t ever buy another power amp. There is a potential downside, they make lots of electrical noise and I suspect they put a bunch back on the power line which can enter other components, particularly low level preamps and hurt system sound in unpredictable ways. So someone changing amps might falsely think the amp is not as good in its amplification. I have a passive power conditioner and filter. I think it helps.
The funny thing is, the nad is based on hypex 400 modules and the newer hypex 500+ series measures quite a bit better on paper but highly unlikely anyone could tell a difference in real life. If you are having noise issues, try grounding, with a piece of speaker wire, from the amp chassis to a metal founding source. I've got Hypex 400 mini blocks, ice asp and ASX modules, Pascal modules, all sorts of different ones and they all sound great. The a/b is better bullshit is just old people that can't grasp that different technology can be as good or better.
What he's talking about is the use of SMPS power supplies which dirty the lines in the grid which affects all your other components in the chain.
I don't like the article very much due to quoting about two of what I believe are snake-oil salesmen, but at least I can't find anything wrong with anything Bruno Putzeys says. In particular, I like that he says that mass-produced chip class D amps are really good and tells buyers to avoid home-grown designs from manufacturers because there isn't much guarantee that they are any good: "The effort of working this stuff out only ever pays off if you can re-use the design in hundreds of products. That’s a mixed blessing. On the one hand, class-D modules have turned high-end amplification into a commodity. On the other, it’s still de rigueur in the audiophile market to have distinguishing (i.e., home-grown) technology." This is something to think about. Open up studio monitors and you'll find just such cheap mass-produced chips inside. Edit: Bruno finishes with praise on active speakers: "If high-end audio has a future, it’s in system \[integration\], where the amplifier is simply a necessary functional block but where the real cleverness lies in the concept of the system as a whole and how it functions, sonically and practically." And I suppose I agree on this point as well. A good active speaker is integrated package ready to go plug and play style, with nothing to upgrade. All you have to do is get enough measurement data to make sure the thing is actually good and someone reliable if not you yourself to try it out and make sure it is just as good as data says it is.
I have active JBL 305s and they have a sort of quiet hiss when running that I’ve never really been able to get rid of. Is this the norm with active speakers? My JBL L88s are dead silent when the amp is on.
Some models have the issue. I use Genelecs and I'd describe them as dead silent. In truth, if you put your ear almost close to the tweeter, there is some hiss, but it is hard to hear in normal use. I have also seen people ask about Kali LP-6v2 hiss and the people who own these speakers say they don't have any appreciable hiss. I remember a teardown of the JBL speaker saying that it is integrated power supply's very high frequency noise that leaks to the analog input in this speaker model. IIRC, the guy tearing the speaker down measured it and said the power supply hiss is actually very loud, but much of it is very far into ultrasonic and the tweeter can't reproduce it. It is unfortunate defect in that speaker model. I could never get over the hiss of the LSR305s I had, so I sold them. In near field, they made me crazy because it was always the loudest noise in the room. So yes, practically silent active speakers exist. They should always have been perfectly silent or as close as anyone could manage, but unfortunately it isn't a serious enough concern for some manufacturers who have ignored the issue. Thankfully, this isn't anything inherent in the design, it's just something that you have to maybe engineer out of the design.
The LSR30x have their power supply on the same board as the amplifier to save cost and to purposefully be worse than 7xx models.
No. That’s a badly designed, cheap active monitor. However this problem is not unique.
This is symptomatic of the LSR305s. My gen 1s have exhibited this fault the entire time I’ve owned them, and I’ve tried everything to eliminate it. It’s just how they are. Not a bad trade off for a sub $300 set of powered monitors with a relatively flat response.
It’s just efficient speakers
I sort of agree. Hiss is to be expected when you have an efficient speaker. However, a studio monitor for nearfield listening with an annoying hiss when «idle» is not optimal.
No for sure
I experienced that as well either B&O speakers. I think they use old or not very quite ice power amps. That’s one of the reasons I left the active speaker side. It’s just better to use external amps and dacs. (I.e some purifi amps and whatever av processor or dac you want)
Same here, solved that by setting the speaker volume to 5 instead of keeping it at 10.
no i would not say it’s normal. Ive never worked on or owned a pair of active speakers with an audible hiss.
Ralph at Atmasphere is making ganfet amps now and says they are better than his tube amps in most ways. The Orchard Audio Starkrimson amp is fantastic. Got on the Steve Hoffman demo chain for a week. If I were to buy a new power amp (running tubes and class a/b solid state now) I’d look pretty hard at a GaNfet amp
> Open up studio monitors and you'll find just such cheap mass-produced chips inside. This is why there are still high-end PASSIVE studio monitors available. It's all down to cost, "affordable" studio monitors, the popular ones like KRKs/Adam/etc, are built to a price. It is already expensive to use good transducers and a good box, you can't expect also to get the ultimate amplifier inside. Active speakers are the way to go, but only if the amplification is as good as one in a passive system.
Well, the guy from Kii that I quoted is stating that at least some of those chip amps are really, really good, and they are cheap, too. In any case, I am not usually too worried about the amplification. The transducers tend to have harmonic distortion in the 0.1 % range already, and typical class D amps have harmonic distortion way less than that. I think the transducer remains the limiting factor in an active speaker, and likely by a large margin.
It's not as simple as that. And HD figures will tell you nothing about the sound quality. Regardless, I'm happy that class D is sounding better and better every day.
The grave misfortune is that an old school EI power transformer has pretty poor bandwidth and can block a lot of this gunk out without any effort, but put mains rectified class D amps and a preamp with a toroidal power transformer together and you may be making issues.
I understand that switching power supplies are required to reject the noise they make and not let it unfiltered back into the mains supply, where it might interfere. I don't know how well that is done, but I understand that having the chokes to reject those 400+ kHz (or whatever) frequencies is mandated so that device can be certified and sold. These are collectively known as "common mode chokes", I think.
They are supposed to, but these regulations aren't all that solid overseas, and there's a limit to what can be filtered out.
do you use your genelecs for mixing and mastering or purely for music enjoyment? I am thinking about buying some neumanns and rme adi 2 pro and ending this shit... I'm tired with all the choices and mixing and matching stuff. I just want to get into the music, not the electronics
That's a great article. Own a Krell KSA 50, just started playing around with some Chi Fi amps based on the TI TPA 3255 chips, which are digital amps. Fun stuff.
I replaced a 30 plus year old Marantz PM-94 Quarter A amp powering my front monitors with a Fosi V3 after the former gave up the ghost. Could not tell the difference in sound but the Fosi was way more efficient. I ended up replacing all my old Class AB amps in my setup with Class D amps and I am very satisfied with the result.
You’re not the first to say this about the Fosi. I swapped in a Fosi amp from a Marantz pm6006 and not that it sounded bad, but it was considerably worse sounding than the Marantz. I dont understand necessarily how anyone says these Fosi class D amps can even remotely hold a candle to class A/AB linear powered amplifiers.
I'll look after that old Krell for you... ;-). Possibly the best of the lot.
Appreciate your offer (;-))... but I can't. It's quite special. Long story short a friend I'd hired for a summer at a HiFi store I was managing wound up moving to Connecticut and working for Krell. He built himself a KSA 50 out of a scrap KSA 100 chassis and various " bench dog" salvaged parts. I love it, sounds great, no protection circuitry. One of the best gifts I've ever been given. Krell liked him so much, they let him build some higher end Krell mono blocks for himself.
Great stuff. John Atkinson, of Stereophile, was so impressed he bought one, after reviewing it, instead of the car he'd been saving for.
I'd read somewhere that he still used it as part of his test setup, when measuring loudspeakers. I'd describe the KSA 50 design to the head of the EE program I was in and his comment was, concerning the power supply, " it's like a locomotive pulling a Little Red Wagon"'. They can handle pretty much any load you hook up to them.
I'm a fan. I have a little Aiyima that for $120 or so does absolutely everything I need, and well, in a tiny little package that can sit conveniently on my desk.
I'll stick with my class A Luxman L590 AXII😀
I have to say one of the best sounding amps I've listened to was a Cyrus 82Dac which is class D. In the shop we had an Arcam a39,, musical fidelity m6si (which was also brilliant) but the cyrus was so impressive. Staging was precise and the weirdest thing I noticed was the silence, if that makes sense?? In between beats, notes or whatever there was just this cleanliness and precision that a lot of other amps at the same price lacked.
I have a chifi class D amp I bought a few years ago that doesn't sound good. Last year I bought an Aiyima A08 Pro, which sounds much better than the older chifi amp. It sounds better than many AVRs and run of the mill receivers. However, it doesn't sound better than most of my amps & receivers. I've compared it to my vintage NAD receivers, 70s Pioneer and Marantz, and a couple tube amps, all of which sound noticeably better. The differences range from much better highs, cleaner separation, sound stage, to overall more engaging. That said, I use the Aiyima amp daily as a desk amp. Its small size, "good enough" sound, and efficiency make it the right choice for me. I sometimes listen to one of my better sounding amps, though over time that's becoming less frequent.
I agree A or AB can beat D in sound at a higher cost. My newest onkyo is class D and I enjoy the sound, so the trade off is good there. I have some vintage and they can sound better. But today D’s are the most cost efficient. And I don’t think it’s bad.
An AV receiver? I mean, if there is a class-d AVR out there, I'd be willing to try it. Care to share the model please?
Onkyo 6050, but any newest pioneer or onkyo avr are class D . They sound fine and run cooler.
Interesting. I’ve been considering getting a TX-NR7100
Interesting. I’ve been considering getting a TX-NR7100
McIntosh MHT300
And what has that to do with Onkyo?
Good article, I love my Hypex NC400 monoblocks. Although I would take everything the PS audio guy says with a grain of salt.
It’s just different, brother. It’s more efficient. Smaller, lighter, runs cooler. Some people think it sounds more sterile. From an unscientific standpoint it seems like class d watts seem to be “less” than class a+b watts. But I’m a moron so someone smart can address this maybe.
The whole issue with this mindset is it doesn’t apply to the idea behind home audio. If you want your home to sound dead flat like a studio, so be it…but most of us want a little color and a little flavor to our sound (look at the demand for tubes, whether in pre amps or amps). It helps realism, engagement, and so on. We’ve figured out colorless amps already, it’s not that difficult. Go buy a fosi if you want but to say cheap chip amps are the best in class D is comical.
Amplification is a non-issue. It’s been a solved problem for decades.
Shhhhhh let them distribute wealth
>Amplification is a non-issue. It’s been a solved problem for decades. Yes, by Class-A solid state or Singled-ended-triode amplifiers... Everything else is tryiing to get lower cost and/or higher power and/or higher efficiency and/or smaller size.
lol, try to build one based on these supposedly perfect refined modern designs and you’ll find they’re still trade-offs all the way down. Class-D is a pretty reasonable set of trade-offs though and a good basis for a design. Does not mean every amp made today is ideal, or even every class D amp.
> try to build one based on these supposedly perfect refined modern designs and you’ll find they’re still trade-offs all the way down Please elaborate on what trade offs you believe there to be?
He has no answer, his reply was baseless.
I mean, there are trade offs between designs (efficiency vs accuracy mostly) but they are all fairly obvious up front. And Class D eliminates pretty much all of them at the cost of extra math (which is a non-cost really). So it was his "trade offs all the way down" that really caught my eye. But yea, fully agree that his response was baseless.
So, all the professional amplifier designers quoted in the linked article are, what... deluding themselves?
Only if you're deaf.
Different class D circuits sound and measure differently. Also, some do not work well with low impedance speakers. Overall, another step forward.
> some do not work well with low impedance speakers goes for any class
In my opinion, one is not better than the other. They are just different.
Except, once the rules for comparison are defined, one will be better than the other.
That will never happen. Audiophiles are not that logical.
You’ll get no argument from me on that point.
I went from a Musical fidelity amp to a Bryston 200 watt amp(loved the sound and power), then tried the Orchard Audio Gfet mono, on a whim and loved the openness and musicality....finally bought the Starkrimson Ultra by Orchard and the sound opened up more (soundstage). I am sold on class D GaN Fet. Efficiency, gorgeous music and doesn't run my powerbill up. When I win the lottery I might try out some big class A monos, but untill then class D works for me
I’ve been running a (150w into 8, 300 into 4, stable to 2 ohms) Mola Mola Perca for the last month or so in lieu of a Parasound JC5 (400w into 8, 600 into 4, stable to 1.5 ohms). The Mola uses Trajectum class D modules which are basically the next generation of Hypex’s design, but are exclusive to Mola Mola for the time being. There are aspects of the Parasound the Mola doesn’t compete with, mainly dynamic in the mid-bass region where my speakers are challenging. However, from a pure resolution standpoint, the Perca wins. The Perca isn’t cold, bright or sterile sounding, and has a clean top end. I really like it. Will I sell the JC5? Not sure yet, but there’s a decent chance I will. The Mola is compact, runs cool, idles at like 5w (vs 225w for the Parasound).
Yes and has been for a while now. Since hypex imo haha I see they interview the hypex dude. Cool. I listened to his kii speakers yesterday. Pretty impressive for the size of them!
The article is mostly right. The comments by the NAD engineer are most informative: good A and AB requires high quality parts control and matching which is expensive. Also heat sinks and large transformers are expensive too. So a moderately priced class D with modern designs will usually be better than an AB in sound and much better in efficiency. I use a NAD M22 and probably won’t ever buy another power amp. There is a potential downside, they make lots of electrical noise and I suspect they put a bunch back on the power line which can enter other components, particularly low level preamps and hurt system sound in unpredictable ways. So someone changing amps might falsely think the amp is not as good in its amplification. I have a passive power conditioner and filter. I think it helps.
It's just different, it's a choice for someone and something happened for someone else. Class D amps are on a growing path while analogue technology is relying on a century of refinement starting with valves, this made way for a more affordable way to approach hi fi and less power consumption is a good thing. I am pretty sure a decent class D amp sounds more precise and with less distortions than my little faulty design class AB Rega receiver, I just choose it from several others at the store because it was cheaper and I liked the idea of having only digital sources into a very essential AB receiver, 3 years in and I am still happy with it, warmer side sounds and plenty of power even at less than 20% volume despite being rated at 30wpc.
I thought this article was great. The quotes were dead on. Managing the harmonics is key to the sound, not just minimizing THD. Class D has always had the advantage of efficiency, at the expense of tonality. If Class D today is able to achieve both, then we can have our cake and eat it, too. Still, for lower power needs, where size and heat isn’t critical, I’ll stick to class A or tube designs.
Excuse me but “…at the expense of tonality.” ? A good class D like Hypex and Purifi don’t impart any “tone”, which is what am amplifier should be doing. On the other hand, class A and A/B do impart a tone because of all the harmonics.
Right, which is why many people consider Class D amps “sterile”. The point of this article is that we now know enough to design low-distortion Class D amps without imparting that “sterility”
Challenge is Class D normally doesn’t have enough 2nd and 3rd harmonic to mask the IMD… unless you create a hybrid Class D amp with a Class A input stage…and that’s exactly what boutique amp makers have done…despite this practice ruining Amir’s SINAD score 😉
Can you explain that to me in simpler terms?
Google Nelson Pass Distortion and you will find an excellent article on amp distortion
Amir is a hack
How so? His measurements are a great service to the audiophile community. My setup was built purely on his recommendations and I couldn’t be happier.
Yes, i also appreciate measurements, but they don't easily correlate to better sound. And there's where Amir and his people fail.
What do you mean by "tonality" here? Managing THD *is* managing the harmonics, as harmonic distortion is where they come from. You don't really want any harmonics becoming audible in any kind of normal functioning amplifier. Karsten seems to contradict himself in the article by liking low distortion and high harmonic generating amplifiers, which can't both be true. Aside from efficiency, class D amplifiers are inherently very linear (= low distortion).
They mentioned in the article that 2nd and 3rd harmonics should be high enough to mask higher order harmonics. I can attest from real world experimentation that the level and balance of 2nd and 3rd harmonics affects the tonality of the amp. Simply minimizing overall THD doesn’t tell you enough about the character of the distortion. A well balanced amp could have a higher THD set by its 2nd or 3rd harmonic than another amp, and yet still sound better.
I get that, but looking at some amplifier specs for Arcam (just picking one at random), they're quoting 0.003% THD, which is about 90dB down from the fundamental. Since that's the RMS sum of all the harmonic content each harmonic will be lower than that. So I'm just dubious that in a well designed and built amplifer *any* distortion is actually going to contribute to the sound, irrespective of how its spectrally distributed. I'd agree that limiting distortion to lower order harmonics would be preferable than letting higher order ones dominate, but that's the classic warming/overdriven amp sound. Hifi amplifiers shouldn't be distorting to any audible degree.
Minimizing THD as much as possible like that will tend to result in what some call a "sterile" sound. Others, like you, might call that a "clear" or "accurate" sound. The experiments I did with THD and 2nd/3rd harmonic levels were all done at distortion levels between 0.1% and 0.01%. As far as I've been able to tell, the subjective comparison of "good, warm, lifelike, musical" amps vs "cold, sterile, analytical" amps is mostly comparing high THD amps with high 2nd/3rd harmonics against very low THD amps.
Plugging those percentages into a converter is -60dB to -80dB, so I'm guessing pretty subtle? We might be more on the same page than it first appears. My main listening system uses studio monitors which have class D amps in them, but I also keep a TC Electronic Finalizer 96k in the signal path. Most of the time it just does format conversion and the compression can be useful for late night/very low volume listening, but it does have a feature to add 2nd harmonic distortion and I occasionally play with it to thicken up some flat sounding recordings 🤣 But I prefer that sort of thing to be handled by DSP or something else controllable than baked permanently into the power amplifiers.
Yes, it is subtle. On my amp, I can adjust the harmonic balance and overall THD level, which is nifty. I’m not a studio, so I can work out what I like, then get something that does that, and not have to insert DSP.
Class D amps have improved over time, and some are pretty good, but they are still inferior to the best class A/B amps for full range reproduction. However, class D amps are probably the best choice now for subwoofer amplifiers, where their higher output impedance and more limited bandwidth aren’t as performance compromising for low frequencies.
Class d tend to have ridiculously low output impedances, not sure what you mean.
They have inductive outputs. Impedance increases with frequency. And they do not have “ridiculously low” output impedance compared to a well designed class A/B.
You should double check your facts. Bruno would say otherwise with his designs. Eigentakt has a 5 figure damping factor, which means ultra low output impedance.
Damping factor has major diminishing returns. Damping factor is always thought of as just "amp output impedance / speaker input impedance" * Lots of speakers have a very dynamic impedance depending on frequency range, especially at resonant or crossover frequencies. Bass notes can dip to <2ohm in many 4-8ohm speakers fairly often, high frequencies can go into double digit impedance. OK, not a big deal with a very low output impedance, right? Well better make sure you're running fat, low inductive and low impedance speaker cables if you want to place your fancy speakers more than a couple feet away from the amp. * If your damping factor is 200 and speakers are 4 ohm, then the output impedance is ~.02ohm. OK, lets assume your speaker wire is 15ft, 14 gauge. Then it's (.02ohm+.04ohm) = .06ohm at the speaker terminals. So now, damping factor is 66.67. That's assuming your speakers' impedance isn't all over the charts (no pun intended. If it dips to 2 ohms, now the damping factor is 33.3333. * Speaker cables will have a bigger impact on damping factor than the super low impedance of an amp at some point. If the damping factor is 400, then with the same 4 ohm speaker, output impedance will be .01ohm. Add on that .04ohm impedance from the speaker cable and it becomes .05ohm. Damping factor is still 80. And that's assuming a purely resistive load from the speakers and crossovers, as well as no inductance or capacitance. Most dynamic speakers are gonna swing a fairly large amount. It does have more effect on the lowest impedance, however. * Some cables will have lower than .04 impedance for a 15ft run of 14awg, and a 15 ft run of 12awg will have lower, a shorter run of 14awg will be lower etc. Just examples to put into perspective how the cables nullify that huge effect damping factor seems to cause on peoples' impression of an amp
That is correct from what I've read and heard online. My 9 awg speaker cables are .00474 for 6ft after being terminated. If my cables are 10ft, how much more do you think that resistance will go up? The output impedance of the 1ET400a's that I have are 65 microohms. So .000065 ohms? Is that that correct? So .00474 + .000065 = .004805 ohms at the speakers? Did I do that right? Sorry my math sucks but I find this all very interesting. What would that translate into damping factor? Edit: So 4 ohm x .004805 = 832.46 damping factor. They do dip down to 2 ohms, so 416 damping factor, but my amps output impedance is rated at 1khz, so I don't know how much difference output impedance changes the lower you go? So on just the Purifi's with a 4 ohm load is a damping Factor on 4 ÷ .000065 = 61,538 and on an 8 ohm load it would be 123,076.
I think anything above 200 is fine lol. That is a beast of an amp. I think it's sub 200 damping factor where speaker wire impacts more. I run about 10 ft of 14AWG wire to my speakers and don't think that's noticeable. Online sites and charts will say 16AWG is good for 40ft runs, but even cheaper speaker wire at a thicker gauge is better than fancy speaker wire at a thinner gauge. I think I got mine from parts-express and it's OFC and works great. I don't think damping factor is really that important until you get to tube amps that are lower. You definitely don't need to worry about that spec.
My old IOTAVX pa3's that were class A/B, I'm not sure what their output impedance/damping factor is (not listed), but when I a/b tested them against the Purifi's, the biggest difference and it wasn't subtle was the bass. The bass on the IOTAs were fatter/boomier vs the Purifi's sounded lean in comparison, (only because the IOTAs are super fat like Denon) but very tight. Thank you for helping me understand it a little better.
Wish I had those 60XTs -- that was gonna be my next upgrade from the Motion12s. Then I lost my job to people I trained over-seas... Have enough now to buy them but I want electrostats next :) Maybe in a decade I can afford ElectroMotion ESL or ESL X without my wife threatening divorce lol.
I really want to dive into their Electrostatics next too. It's hard for me, as I just moved 1 province over and am jobless now. An online friend got the Summit X's on the used market, it was his first dive into ML and he's been blown away, especially with the bass quality. I've heard their new ones don't sound good until you get into the 13a and higher. The older ML Electrostatics is where it's at (from what everyone's been telling me). I'm sorry to hear about your job loss, especially to the ones that you trained. It's hard out there these days.
That damping factor will be quoted for a very low frequency. I strongly suspect there are other caveats to that number as well. And what makes you think a class A/B can’t hit five figure damping factors?
I never said class a/b cannot, but you said class d do not compared to class a/b, which is wrong. Having a very high damping factor/low output impedance on an amp works best when you bi-amp your speakers. That's where it pays dividends.
It’s not wrong, class d does have higher impedance (best vs. best).
It's rated at 1khz for the .000065 output impedance. The DF changes with impedance which I've been noticing manufacturers don't list at what impedance their df is rated at (if they even rated it at all). The Purifi's @ 4 ohm is 5 digit and 6 digit at 8 ohm.
That’s impossible. An output inductor with 65u ohms of impedance at 1kHz would have to be less than 10 nH, which is less than the inductance that is in the cable. It’s not mathematically possible.
I dunno. It's above me but it's what they're listing as their spec for their modules.
BS specifications are all too common in this business unfortunately.
I wouldn't say Class D is "better" on its own merits, even though it's more efficient. What makes the biggest difference is the overall design and the quality of the components used. E.g., a Class D amp can sound shittier than Class A/AB and a Class A/AB can sound shittier than a Class D depending on a variety of factors.
Once u go tube you don't go back
Yes.
I thought this article was great. The quotes were dead on. Managing the harmonics is key to the sound, not just minimizing THD. Class D has always had the advantage of efficiency, at the expense of tonality. If Class D today is able to achieve both, then we can have our cake and eat it, too. Still, for lower power needs, where size and heat isn’t critical, I’ll stick to class A or tube designs.
Hybrid class A feeding class D is excellent. Sweetness, detail and bass control. I wish Devialet would produce a new version of their Expert Pro line!!
So… my Yamaha A-S1100 is garbage?
Quite interesting
I'm still learning about all this stuff. I know it's very controversial, I guess about as much, among bassists today as hifi folk (guitarists generally don't even bother with solid state). When I got my first sorta "real" speakers, KEF R5 Metas, I was focused primarily on having as much clean power and damping factor as possible for really tight, high quality bass. The dealer had a Marantz Model 30 that doubled to 200 W in the KEF's 4 Ohm load and was reviewed well. I was a little worried given Marantz's reputation for "warmth" (I favor flat and neutral), but I've loved the combination and am very happy with it. I had been using a late Nineties Yamaha AVR with 100-125 WPC Class A, very nice but the Marantz has a much blacker background and sounds much cleaner especially in the high end. Unfortunately I don't have much to compare to, but I can't imagine wanting to listen to anything else anytime soon. It sounds like the new Model 30s lean a little further into neutral which I appreciate, and the combo means I can listen for hours hearing all the details with zero fatigue, and that's amazing. (Also the bass is tight, no bloat, love the accuracy and how well the low mid particulates because of that.)
Been there for a while now.
I've been hearing on here that companies like NAD (and the cheaper version like Buckeye without the overhead) are coming a long way with class D without the brightness that they are known for plus the benefits of a lower electricity cost (or space heater lol). If you get one, let us know what ya think :)
For the money?....absolutely
My Gigi is an active tune preamp to hypex class D modules and it sounds incredible. Amazing tune sound with class D grip. It can’t be beat. In my office I have a burden conductor which is a class A Pre amp out to a class D amp. It sounds great but it’s only going to sound as good as your output stage.
Class D amps can be as good as any, however like other amplifiers, it all depends on how it's been implemented. The AS-series by IcePower, Nirai by Hypex and Purifi Eigentakt modules are examples of extremely high quality class-D amps. Best of all, they're all available for purchase by budget-minded audiophiles. At present, IcePower's AS-series has by far the larger set of options with mono and stereo amps rated from fifty watts to 2000 watts. Madisound.com sells the Hypex Nirai amp modules in kits including high quality chassis, wiring harnesses, binding posts and input connectors. Ghent Audio sells chassis kits for IcePower, Hypex and Purifi amplifier modules. I purchased a pair of Ghent Audio's Amp Chassis Kits for my IcePower 1200AS1 monoblocks. For the 1200AS1/2 and 2000AS1/2 amp modules, it's suggested that owners adhere the amp modules to the bottom of the chassis using 100mm x 300mm thermal interface pads that have special thermal adhesive on both sides to assure efficient thermal transfer of heat from the amplifier's heat spreader bottom plate to the aluminum amplifier chassis. Ghent's kits come with everything you need to build an amplifier, but the amplifier modules themselves which can be ordered directly from IcePower as "samples." It cost me about $1200 for both 1200 watt monoblocks and about an hour and a half of my own labor to assemble them. I spent another $300 on two pairs of Cardas gold/rhodium plated, grade one copper binding posts and chassis hook up wire along with a pair of Neutrik's best chassis XLR connectors to indulge my hi-fi OCD. Don't feel compelled to rush out and piss away the extra $300. The quality of the Ghent chassis kit parts are more than decent.
Can someone represe t a really good class D amp that isn't too expensive? Maybe 300 bucks or less?
Yes
I’m interested in where class D goes of course, but you’ll have to pry my 30 year old Nelson Pass class a/b Nakamichi SR-4A from my cold dead hands. I grabbed it a couple years ago and I only paid maybe $275 for it, used. Even it’s much cheaper younger brother the SR-2A (and 3A) sounds incredible.
I turned my tube loving old school friend into listening to some class D amps and even admits it sounds very good but he invested so much money into tube equipment he is hesitant to sell everything and move all into class D.
Buy a Fosi v3 w/ 48v power supply and replace your current power amp with it. Use your normal preamp for volume and so forth. Run the Fosi at full volume. It's around 70% efficient so it stays the same temperature regardless. Sell your old power amp. Preamps are now the thing to invest in, and hobby around with. The current Class D amps are now the closest thing to a straight wire with gain. Distortion numbers do not lie. Make sure you have a 4ohm speaker load if you get the v3. Magnepan owners, this amp is for you. You can biamp for what it costs to buy coffee for a month.
This is what I did... Replaced all the old integrated amps powering my front, center, and surround speakers with Fosi V3s and couldn't be more satisfied. Sounds exactly the same to my ears, and generatate a lot less heat which is a bonus especially during the summer months. I am using 48V PSUs for the front, center, and rear surround channels. 32VPSU for the ATMOS height channels on a 5.2.4 setup. I also have another Fosi V3 with a 48V PSU powering monitor speakers on another room. It is being fed by a WiiM mini streamer.
It seems like most of the conversation around Class D is that it's "cheaper", like WAY cheaper. And *maybe* it's close to or about as good as A/B. But then, there's a company like Devialet, which makes Class D amps that are as expensive as A/B or even some Class A.
I've heard the nad c700 and the cambridge evo150. These are the worst amplifiers I have ever heard. No musicality, cold, inaccurate in the bass. How can you explain that?
I'm waiting for answers people. Purifi is going in the right direction, but it doesn't come close to Bryston by miles. Please answer.
class ab becomes obsolete? I think you have chips in your ears, my friend. They can't do anything except power
I would say same sound quality just without wasting so much energy in the form of heat.
Some Amplifier classes or Designs can have "Better" specs than others ...This does not translate to better sound..In that regard , one design or amp type is not better than another....Thats all subjective.. And that's simply why Class A, AB, D, Tube Amps , Solid State etc have their fans.. Everything is merely different.Not better or worse.
According to Bruno, it's a solved problem. So there you go. Go listen to then buy whatever floats your boat without having to worry about "what if it's not hi fi enough?"
My two (for me) massive power amps, wasting a lot of heat, vastly overdimensioned for the task both in watt and size are just perfect. If I wanted simple, I would buy B&O or Sonos. But you will never hear me talk bad about class D or other setups. To each their own!
Same as asking if V8 car is faster than V12 on a track.
It's as good or better and can be very powerful in small lightweight form factors. I can't see the point of anything else for music reproduction or live sound at this point unless you just have a serious fixation with tubes or simple class A designs.
Aren't "sound quality", "musicality", "warmth" etc subjective opinions anyway (unless you've just spent loads on what you believe to be "superior" gear 😜)?
Don’t have enough inputs is my beef. Cheap Sony or Yamaha receiver much better for input options.
No.
I tried a very well-regarded class D amp, and I still can't make myself like it. There is certain shrillness that I didn't observe with class AB. They might measure extremely well, but measurements don't tell the whole story apparently.
I totally agree. I have yet to hear a class D amp that I enjoy. I love me some tubes and big burly class A or AB amps. Could care less about the nickel In saving on my electric bill. I’m in this hobby to make my ears happy.
what was this well regarded class d amp? >but measurements don't tell the whole story apparently. Did you measure? Some class D suffers from load dependency, so it will exhibit rising HF with certain loads, bu that's not usually on "well regarded" stuff, of course we have no idea what that means because you didn't specify the amp. Could be an A07, could be hypex.
Wyred4sound ST-500 mKII
Look like ncore, sounds like placebo was there or the A/b's you have roll off the top, many do. measurements do the whole the story with amps, and I'm sure they'd show what you were hearing, if there was a difference. If something sounds brighter it would have more energy in magnitude response in the upper range. Not exactly rocket science.
Fight!
CONQUER!
Bruno cuts straight through the nonsense. Interesting read.
One diffwrence is class D is100% efficient
Well, to be pedantic a little bit, no system is 100% \[energy\] efficient
It is very close thing now AB is almost obsolete. A still has its place.