Hello. I'm very interested in getting your opinion on the newer Class D amplifiers. There has been a couple of very positive reviews (by Guttenberg) of the Bel Canto C6i and NAD M23. These, and perhaps some others are offering new technology that significantly lower the class D noise level and other drawbacks.
I currently use a Class A amp, Pass Labs INT-25 (with Dynaudio Heritage Special speakers) which has a wonderful sound. But I am transitioning to another location, and due to using Roon primarily I find that this system stays on most of the day. Due to heat and power usage of Class A amplifiers, I'm interested in translating to Class D if I find something comparable.
One of the two amps I’m about to mention is hardly new. But I thought my experience might be of interest to to those whose primary interest in class D is musical realism & ear-friendly tonality, not just accuracy and detail.
I have a rather cramped desktop system in the home office. For years I ran a series of powered speakers/monitors + sub here. In 2018 ago I picked up an interesting pair of sealed/acoustic suspension 2-way passive monitors (ATC SCM12 Pro) and had to get an amp to power them. I had done many weeks of reading about class D amps, the only kind that would fit. Positive user comments + a favorable 6Moons led me to the Wyred4Sound ST-500 stereo amp. With some trepidation over what class D would sound like on revealing studio monitors, I found a used ST-500 and installed it. Well, I lucked out. The review and comments were correct: the amp sounded very good, more like solid classic AB amps I’ve had in the past. It had power to spare, but was not bright, edgy, harmonically thin, any of that. I had needed to hit a home run, and the ST-500 was it.
Well, 6 years later the upgrade bug has struck. I have a pair of gently used, recent vintage Harbeth 30.1s on the way here from the UK, and got the itch to try another class D brand I’ve been reading about: Bel Canto, specifically the 600M mono amps--again because of occasional user comments and critical reviews saying these amps sound like music. They arrived and I installed them 2 days ago. Well, NCore vs ICEPower does make a difference. The 600Ms are clearly more resolving, capable of greater detail and subtlety, especially in the entire bass range and at low volumes. But tonally, the Bel Cantos differ little from the ST-500. They don’t have that dreaded edgy, forensic sound too many report with class D, even now. I appear to have hit another home run.
It’s only fair to note that I never tried the high-price names whose class D amps are often described as sounding wonderful: Rowland, Merrill, AGD, Atmasphere, Tambaqui, etc. Even used I really can’t afford to spend that much on an amp. But so far, I’m holding my own in the land of class D amplification.
@milpaiI know that one member here did go from a tube integrated to a Aavik Class D integrated. He seems to jump around a bit (upgrading) a nice guy and knowledgeable. I think his handle is Afriq?
Yep, I just commented on @vsrrrsystem. He replaced a tube amp and First Watt amps with Atmasphere Class D. And again, this is GaN based and not Purifi/Hypex or other Class D.
While this is NOT a true representation, since we do not know what majority of folks have done, but based on the limited data, it seems like GaN has a better adoption compared to other Class D amps.
It looks like my question is confusing you. Did I ask about configuration? I don’t care about that. I was hoping owners to chime in, on which type (solid state OR tube) of amp they replaced with Class D. But good to know that you replaced a tube amp with Class D.
There’s only a handful of user reviews that I have come across that mentioned about replacing tubs amps with GaN. Not come across people who have replaced tube amps with Purifi or other Class D.
Just out of curiosity - anyone here compare between Purifi Vs Nilai Vs GaNFet? I think most posters who have been happy with Class D amps previously owned Solid state amps. Very very few replaced tubes with Class D. Is that right?
Good point about Nilai500. Would be great if someone heard them together with one of the GaN amps mentioned in this thread, especially those in the lower price bracket.
I’ve never owned the Ncore 400’s but always wanted to try them. When I finally went to give them a try the Nilai500 had been released as their replacement.
This is the first time I’ve ever used class D for my stereo mains amplification.
I have Crowns for subwoofer duty, and I’ve tried using them for powering the left and right mains but they sounded just awful to me.
But not the Nilai. Very clean and powerful without the horrible edge (resulting in fatigue) that the Crowns presented.
The balanced line option (xlr) is also nice. Running fully balanced from start to finish is interesting… it really does seem to lower the noise floor in the room, being able to put your ear right up against 100db sensitivity horn loudspeakers and hear absolutely no hiss, hum or buzz of any kind is pretty remarkable in my opinion. I certainly could not do that with my unbalanced lines
I would love to hear more opinions about the Nilai500, I currently have DIY Ncore 400 monoblocks. Is it worth upgrading to the Nilai500? It supposed to be as good or even better than the Purifi amps. I am also considering the new Aavik amplifiers (I180/280/580) which are based on the Pascal modules.
I gave the PeachTree GAN400 a nice long trial run on my office Magnepan LRS+. I used a Holo Audio Serene preamp (amazing) and my trusty old Benchmark DAC3B.
The GAN400 drove the LRS+ very well. Almost as good as my CODA #16. However, the CODA #16 had much more engaging sound to it. If the GAN400 is 8.5/10 then the CODA was a 10/10. I used the CODA with a Benchmark LA4 preamp and DAC3B. However, those components were moved to my main rig so the GAN400 was purchased.
I put the Peachtree GAN1 (modded by EVS) back into the LRS+. It lacks a bit of power compared to the GAN400. I also need to move the volume dial on ROON higher than when using my preamps. However, it is a very engaging sound. Like the CODA #16 but with less deep power. This is tolerable with the LRS+ speakers and my small office.
The PeachTree GAN400 is being returned. It is good but the modded GAN1 is great, even if it could use a small boost in power for the LRS+. I got to figure out how to connect my KEF KC62 sub to the GAN1. It so much easier to hook up the sub when using a preamp like the LA4 or Serene.
I have had the Atma-Sphere Class D now for a couple of months and can't be happier. Sound stage is wide and sound is very real sounding to me, in my system. I liked the sound so much, I ended up upgrading a bit more of my system.
Now
PS Audio Power Plant 12 > Innuos Zen > Weiss DAC 502 > Atma-Sphere MP-3 > Atma-Sphere Class D > Rethm Saadhana
PC LessLoss
IC XLR
Speaker Cable LessLoss with LessLoss firewall for loudspeakers
Happy Listening, all, on your own systems. I hope it brings you the same pleasure my system gives me.
In Conclusion! I have gotten an Orchard audio Starkrimson Stereo Ultra. I've been very happy with this amp, and will not try to repeat the positive reviews it's received. It was primarily by chance that I selected this unit because I got it at a very good price Used. I still have my pass labs, but I'll probably look to sell that in the near future.
My next quandary is selecting a good preamp, I'm using a Schiit Freya S that seems to work well , but I'm really not sure what's the best choice. That's another story...
I don’t understand why Roon requires having your amp on all day, but putting that aside, going from A all the way to D strikes me as somewhat extreme for one who is used to the Pass. Why not look into a good A/B first?
The modded GAN1 is close sonically to my CODA #16 amp. The CODA has the first 100 watts class A and has 150 total at 8. It doubles to 2 Ohm though the Class A likely goes down with Ohms. It is a very elegant sounding amp but with massive power. Too much power for my KEF LS50 Metas. I get a bit of ear fatigue because the #16 puts out a bit too much bass out of the LS50 Meta (without a sub).
The modded GAN1 is ALMOST as good power wise as the CODA #16. That extra bass on the #16 is nice, but not for long periods in my small room.
I use the GAN1 in my office and the CODA #16 sits idle (will be used in a much bigger room later).
Indeed, functionality is higher in the sense user has more options in how to connect the amp to a DAC, be it built in or external.
But my understanding is that at the time of developing their GaN amp Peachtree was solving for how to make that level of amp performance available at a lower price point. And they realized they could do without the analog to digital conversion needed inside the GaN amp. It follows their approach should deliver a given sound quality at a lower price point vs competitors with analog inputs, at the cost of flexibility in inputs. It remains to be seen how GAN 1 compares to other amps in the same price point, though. But I can see use for such an amp and find the concept appealing
Thanks for the quick reply. While the product you linked does indeed have digital input like the GAN1, I believe these are very different concepts. Yours seems to require an internal DAC - effectively a DAC+amp in one box - while the GAN1 is a different concept altogether.
I currently have and use a Parasound A21+ amp and became intrigued with the idea of these new Class D amps. So without even hearing one I purchased the NAD M23 amp. Should be in within a couple of weeks and I cannot wait to compare the two.
But the gold standard sonically remains A. Where heat/weight is not a consideration (eg., preamps) class A is the norm.
This statement is false. What is the 'gold standard' is a benign distortion product, one that allows the amplifier to be smooth, fast and detailed all at the same time. That may or may not be a class A amplifier; any amplifier is easy to mess up if feedback is poorly applied and this is often the case.
Very interesting statement; would you please elaborate on this? What kind of distortion does a class-A's output section produce that the class-D is less vulnerable to?
I cannot speak for all class D amplifiers; in our class D amp, the two sources of distortion are the encoding scheme and the use of deadtime (to prevent the output section from overheating due to finite turn-on and turn-off times of the output devices; if both are on at the same time you get 'shoot-through current' which can heat them up quite rapidly to eventually fail) in the output section. In our circuit, these non-linearities produce lower ordered harmonics rather than higher orders. Because the lower orders are benign and innocuous to the human ear, the result is a smoother sounding amp that sounds a lot like a tube amplifier- the distortion signature is really similar.
A class A amplifier, because its output section is not perfectly linear, will generate not just the lower orders but the higher orders as well. The class A operation is used to put the output device or devices in the most linear operating region, but that isn't the same as saying its actually linear and no class A output section is, so it generates distortion.
Again:
The ear is keenly sensitive to the higher orders since it uses them to sense sound pressure. This is why an amp with THD of 0.01% can still sound harsh, if the higher orders are not masked by lower ordered harmonics. The assigns tonality to all forms of distortion and higher ordered harmonics are sensed as harshness and brightness.
In addition, the distortion of the output section isn't made in the same way that it is in a class A or AB design. The result can be that the distortion the class D amp generates can be far more benign to the ear.
Very interesting statement; would you please elaborate on this? What kind of distortion does a class-A's output section produce that the class-D is less vulnerable to?
If you take an amp like the LSA Voyager......you can make it sound way more liquid and musical and detailed by changing parts and eliminating parts......and this CANNOT be measured. The amp will measure exactly as it does stock. The amount of measured distortion or the types of measured distortion are just one indicators of sound.....not sole indicators. You can send me 5 pairs of Atmasphere amps and I will mod each one differently and you will hear them as all different sounding and they will all still measure like stock......this is the truth. To think we can measure everything we hear is simply NOT TRUE. Can you tell me how an interconnect SOUNDS via measurement?.......NO, YOU cannot....because all cables measure basically the same (minor amounts of capacitance and inductance differences). Even Belden make a line of audiophile cables called Iconoclast.....made by a very scientific kind of guy.......but they have three levels of cables.....basic copper, OFC copper and PCOCC copper......EVERYONE agrees that the PCOCC copper one sounds best.....yet the cables are all made the same except for the wire purity........and they measure the same. Same with everything in an amp......you cannot measure the filter caps on the output of a class d output stage but every brand will sound different and also if you put the outside foil to ground (it will sound better.....and still measure the same). This game is infinite.
The main reason AB exists is to reduce heat and power consumption, with some of the benefit of class A operation.
And the main reason D exists is to reduce heat and weight, while (hopefully) retaining some of the benefits of AB operation. But the gold standard sonically remains A. Where heat/weight is not a consideration (eg., preamps) class A is the norm.
Roon has an option to become a ’radio’ using the music you listened most recently. When the album/playlist is over, it will find other music that is similar (using your library, or if you are connected to Qobuz/Tidal?etc, a variety of similar songs from the entire available list via the web). I find myself listening for many hours as I go about my business, discovering new music/artists.
I just recently moved to New Orleans. Being much warmer than my previous address, I just ordered the Atma-sphere Class D. Going to put it up against my FirstWatt Sit -3 amp. Not a lot of extra heat from the FirstWatt, but it does add warmth in the summer.
going from A all the way to D strikes me as somewhat extreme for one who is used to the Pass. Why not look into a good A/B first?
The main reason AB exists is to reduce heat and power consumption, with some of the benefit of class A operation.
Class D allows a good designer to sidestep some of the reasons for class A operation in the first place- a classic example being that of crossover distortion. Most class D amplifiers are literally incapable of this kind of distortion. In addition, the distortion of the output section isn't made in the same way that it is in a class A or AB design. The result can be that the distortion the class D amp generates can be far more benign to the ear.
I've heard class D amps that compare more than just favorably to a Pass Labs amplifier. These days its not about class of operation, it simply about the sound.
I don’t understand why Roon requires having your amp on all day, but putting that aside, going from A all the way to D strikes me as somewhat extreme for one who is used to the Pass. Why not look into a good A/B first?
How the measurements reflect the sound that we perceive?
I described that above.
Since the ear uses higher ordered harmonics to sense sound pressure, its keenly sensitive to them since the ear has a +120dB range. If these harmonics are not masked by the lower orders (2nd and 3rd) they will contribute to harshness and brightness, since the ear assigns tonality to all forms of distortion.
That is why you don't hear it outright as breakup in any amplifier that isn't being overloaded. You sense it as tonality instead. For example, the 'dry' quality some amplifier have is due to their distortion signature, which audiophiles call the 'sonic signature' of the amplifier.
@atmasphere, your thorough thoughts and comments are always highly appreciated.
How the measurements reflect the sound that we perceive? This is very interesting question somehow relating theory with practice. I still cannot put these two things together. For example, I have never heard a more complete, realistic and clean sound than my 5 watts SET tube amplifier gives (which unfortunately was broken due to a defective output tube). It has very high distortion including at high frequencies (up to 5%). I perceive no distortion on normal listening levels. On the other hand, i am not sure whether the distortion per se (as it is commonly defined in electric engineering) is that important. Again i perceive no distortion with my LSA GaN Voyager 350, neither at low nor at high frequencies, independently of speaker load. I think the frequency response is adequate. I would not say that it has no soundstage or it is harsh. Apparently all is good but the sound is not alive, realistic and joyful. You see a wax figure, apparently all looks beautiful, but something is missing (you cannot make any real relationship with a wax figure). Perhaps , the problem is not that this and other amplifiers do not do something well, but that it doesn't do something that it should do? You may say that second and third order harmonics are missing. But if there is no distortion, what needs to be masked?
In the interest of my own learning, would you please point out which measurements correspond to what people hear?
Sure- two measurements that have not got the attention they deserve- first, distortion vs frequency, which ideally should be a straight line or decreasing with increased frequency.
If the amp has problems with feedback due to insufficient Gain Bandwidth Product, the distortion will rise with frequency above a certain point (often between 1 and 3KHz). If this happens the amp could be perceived as bright due to how our ears perceive higher ordered harmonics and the Fletcher Munson curve.
The other measurement is the distortion spectra. Its not enough that the distortion be low. The ear has a masking principle; the way that tube amps sound nice and smooth is because they have enough 2nd and 3rd harmonic that those harmonics are able to mask higher orders. If those harmonics are insufficient, the amp may be perceived again as harsh and bright. This measurement is a bit open to interpretation as you have to know what you are looking at to be able to say how the amp is going to sound when you listen to it.
Quite often this last measurement is done with the fundamental at a low frequency - like 50 or 100Hz. If this is so and there isn't a measurement with the fundamental at 1KHz or higher then the measurement isn't all that helpful if distortion rises with frequency! IOW at a low frequency the distortion spectra might appear benign but above a certain frequency things could be considerably different.
So now you can see how an amplifier with 0.005% harmonic distortion might sound harsh and bright if those harmonics are not masked and the THD was measured at a low frequency- this can hide problems in the design. OTOH a zero feedback tube amp might have much higher distortion, but because it does not rise with frequency and the lower orders dominate, it might sound smooth and musical.
Class D offers a means to eliminate the first problem of rising distortion as well as allowing for a more benign distortion spectra.
There should be no difference at all! If you think there is, then you are convinced that we can't make the measurements for everything we hear (which, since about the early 1990s, we can) and also that the human perceptual rules that are shared by everyone on the planet are of no consequence, making things like deciBels irrelevant.
In the interest of my own learning, would you please point out which measurements correspond to what people hear? It would also be interesting to know how the type of measurement is performed and deemed to correlate to how our hearing works. Thanks.
D-Class are exceptionally good. Lots of power, cheap. Here are two different reviews I did and are different prices. One can be bought under $100, and the other around $600 as they Hypex amps.
Not as yet. Still trying to follow this thread even though it seems to have taken on a life of its own. There are several I would like a chance to listen to first. Difficult to arrange.
Just came across this new review of the Technics SU-G700M2 from The Absolute Sound on YouTube:
It's nice to have this deep dive into the inner workings of this amp. He even goes so far as to say it's a taste of the Ultra High End for a tenth of the price. Not perfect, or everyone's cup of tea, but it's got the goods.
I’ve only had them in my rig for a day, but I am very impressed. It blows the doors off my Willsenton R8. And I’m simply running balanced direct from my Pontus II.
The bass is soooo much grippier and textured. I thought my soundstage was more or less limited by my Tecktons and my room boundaries. I was wrong. The AS’s fill the room with energy that gave me goose bumps and pushed to soundstage in every direction. I finally have speakers that disappear. I’ve been told they need 200hrs of break in. Vocals are gorgeous. I’m not missing tubes one bit. I feel like I’ve finally pierced above the clouds and my system is performing at a true “audiophile” level.
I’m going to demo the Gold Note stack next weekend.
The real FUN is in experiencing things......try expeiencing joy and love......you can experience it right NOW.......we create our own reality.....What do you want? It is all right here.....right now. Blessings for everyone!
Ric, depends on what things we experience and if they really give us a joy. Right now i am experiencing a joy that gives me my Megaschino on jazz vocals. Hope soon will experience another joy with your moded *Voyager*. I am sending an email message to you (soon).
Please see the Gan 1 thread for a description of the mods. Of course, we all use our own sonic preferences......there is no objective reality in audio....everything sounds different and there is no consensus. However, all those (95+%) who listen to what I do (since the late 70s) like it. Those that don't listen....well, they just have opinions......based on no real knowledge.
The real FUN is in experiencing things......try expeiencing joy and love......you can experience it right NOW.......we create our own reality.....What do you want? It is all right here.....right now. Blessings for everyone!
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