Technics is the curious case of feed-forward design. :) Kind of sort of.
My NAD 3020 D proves your Class D tropes are wrong
I have a desktop integrated, the NAD 3020D which I use with custom near field monitors. It is being fed by Roon via a Squeezebox Touch and coaxial digital.
It is 5 years old and it sounds great. None of the standard myths of bad Class D sound exist here. It may lack the tube like liquid midrange of my Luxman, or the warmth of my prior Parasound but no one in this forum could hear it and go "aha, Class D!!" by itself, except maybe by the absolute lack of noise even when 3’ away from the speakers.
I’m not going to argue that this is the greatest amp ever, or that it is even a standout desktop integrated. All I am saying is that the stories about how bad Class D is compared to linear amps have been outdated for ages.
Great to see new development with GaN based Class D amps, great to see Technics using DSP feed-forward designs to overcome minor limitations in impedance matching and Atmasphere’s work on reducing measurable distortion as well but OMG stop with the "Class D was awful until just now" threads as it ignores about 30 years of steady research and innovation.
It is 5 years old and it sounds great. None of the standard myths of bad Class D sound exist here. It may lack the tube like liquid midrange of my Luxman, or the warmth of my prior Parasound but no one in this forum could hear it and go "aha, Class D!!" by itself, except maybe by the absolute lack of noise even when 3’ away from the speakers.
I’m not going to argue that this is the greatest amp ever, or that it is even a standout desktop integrated. All I am saying is that the stories about how bad Class D is compared to linear amps have been outdated for ages.
Great to see new development with GaN based Class D amps, great to see Technics using DSP feed-forward designs to overcome minor limitations in impedance matching and Atmasphere’s work on reducing measurable distortion as well but OMG stop with the "Class D was awful until just now" threads as it ignores about 30 years of steady research and innovation.
Showing 22 responses by erik_squires
How so? As far as I know, feedback is fundamental to Class D. It simply can't operate without it. Take a look at online documentation for how a triangle wave and the incoming signal are compared, and feedback is used to construct the ouptut. The only real choices are where you take your feedback from. Without feedback there is no output. |
The class of operation isn't important. How much feedback the amp uses *is*. This can have an enormous effect on how much and what kind of distortion is present. Class D feedback works so differently than linear amps that I have trouble believing the amount of feedback behaves the same way, but what do I know? |
hi @atmasphere You are totally right in calling me out here: @erik_squires I missed this earlier. This is not true of all class D amps. I meant to say, I’ve heard it from several ICEPower amp owners as well as my own experience that these amps get cold for days after being turned off. THey are fine being switched on/off daily for HT use but for 2 channel use and stereo the can be glaring until warmed. I find myself less willing to type with the same precision and care that I used to. |
And, to your first point, silly me went over to the Audio Science Review (ASR) forum and started asking if "anyone" had tried pairing up a really good tube preamp with the NAD C298 Purify module based amp. Quickly realized all measurement extremists over there, few wanting to engage into "sound" discussion or anything with higher distortion. And that is the difference between a technician and a scientist. With the exception of Floyd Toole who hangs out there and I have the deepest admiration for, they are technicians pretending they know a thing about science when they don't. Nelson Pass, Revel, Bose, JBL, Meyer Sound. That's where t he actual scientists are. I don't necessarily like the result of all of them, but their science and business practices are rock solid as a result. |
Going along with that, there is something about some Class D that requires DAYS to warm up. Even after being used and on for months my ICEPower monoblocks sound like garbage after being left off for a weekend. I have not run a binary search pattern to correlate time off vs. sound quality, but there have been about half a dozen other encounters with other audiophiles who have had this phenomenon. |
Can someone direct me to a good source to get a better understanding of the differences in Class A, A/B, & D amplifiers? I thank you in advance. Here you go, @allenf1963 https://en.wikipedia.org/wiki/Power_amplifier_classes |
Erik, if this is too much of a rabbit trail, please disregard. If you (or anyone else) are aware, how does the NAD SQ/design compare to Naim? I have an Uniti Atom on my desk, but considered the NAD. Youd have to be more specific, and I haven’t heard that much NAD and almost no Naim at all. NAD has been experimenting with Class D in their products. As far as I know, the hybrid Class D in the 3020D is in maybe 1 or 2 other products. The top end that NAD amps that I am aware of are pure Hypex modules without the hybrid components. |
I am a little worried that class D is what I am used to, and enjoy very much, but how do I get a larger sound stage? Make sure to consider your room first. :) Your amp and speakers can’t overcome that. However, you should listen to the M33 as well as some linear options, like Luxman or Ayre as well. |
I just recently bit the bullet and ordered a Luxman 590AXII after listening to many different amps. I suppose that if you look hard you can find some poor sounding amps, but nothing I have heard across many typologies sounded bad. In fact, I am rather partial to some Bel Canto models. OTOH, the Luxman sounded sufficiently magical to my ears to spend more money than I should have and to sell off some other kit to pull off the deal. I was looking for a certain sound, not a certain amplifier type. This is a very similar path to mine, but instead of Bel Cantos I was using ICEPower modules in custom cases. I agree. There was nothing wrong with my Class D amps, and a lot of linear amps did NOT best them at all. The Luxmans did and that's when I bought. Again: The Class D naysayers are prejudiced without cause. |
looks like a cool little monitor. Thanks @chicagoblue1977 ! I think if I attempted a similar build again though I might use a FaitalPro mid-woofer instead. While I adore the transparency of the Peerless, it has a lot of limitations, including power, -3dB point and high frequency extension. The Faital would be more versatile, and more compatible with tweeters that don't need to go so low. On the desktop with a little bass or as surrounds they really are fun. |
All I can say is that the OP must have gotten the good one. The 2 I had were nothing to write threads like this about. I think you are misreading the intention of the thread. That the general complaints about Class D don't hold anymore. Not that you would like the 3020D per se. If any of the Class D bashers that float around Audiogon were correct then even the shop would not be possible for you. :) This is not a thread to convince you to buy a 3020D but to stop Class D bashing. I will say that the character of the amp with speakers on my desk is one of pure air and seeing deep into the soundstage. Best, Erik |
One more thing on the subject: One trend that seems to be true often is that Pass owners buy very different speakers than I tend to listen to. My electronics go very much in line with my speaker preferences. It's hard to say what this is since I build my own, but top end Monitor Audio and Fritz are among my favorite commercial speakers. |
Knowing you enjoy this sound, it is now understandable why you never liked Pass designs. Well, I've been pretty vocal about what I do like instead: Luxman, Ayre and Parasound, so the 3020 D alone shouldn't be a surprise to anyone. Keep in mind, again, I’m not calling the 3020D the end all be all. I’d much rather listen to my Luxman all day long, but for a desktop system none of the stereotypes of Class D apply in my listening experience. I’m not at all unhappy with this. Of course the nearfield part of this also means I have different room acoustic issues, so I hear music differently at my desk than in my living room. The NAD 3020 D is good enough that I’m not rending my clothes and wearing sackcloth in despair. |
I'm willing to accept your experience with this system of yours. Why thank you. The monitors are of course an unknown variable to anyone but me, but none of the criticisms levied against older Class D amps could be fixed by my speakers, or if they are, then damn, I designed some amazing speakers. :) The impedance curve for them is also quite conventional. |
The NAD, from my understanding is a hypex. Nope. The 3020D uses an amplifier tech. which most so-called cognocenti don’t even know happened. It _was_ designed by Bruno Putzey but it is NOT the Hypex or nCore tech. It is a class A amp sandwiched between Class D rails. :) NAD refers to it as a "hybrid." I can confirm that for it’s rating, it idles unusually hot. My ICEPower amps at about 8x the power rating don’t get nearly this warm. I’ve tried to grab people’s interest in the tech before but no one was interested. What do I have to do to get people to listen to me on this site? :-D Best, E |
Calling them custom near field monitors kind of oversells them. :) I made them in large part to write about the process of speaker design. You can find a lot of information here: https://speakermakersjourney.blogspot.com/2016/02/the-lm-1-bookshelf-version.html What makes them special in my mind is that they are true bookshelf speakers, designed with on-shelf or on-desk placement in mind thus they lack the bass bloat you’d experience with "normal" bookshelf speakers. |
Real shame I have a great sounding integrated sitting right in front of me that disproves your entire post. Further, I don't know where you get the idea that BASH or similar isn't being used. NAD's hybrid Class-D as well as the Yamaha EEEngine are derivatives. Not sure which are licensed but similar ideas. My ICEpower amps however, definitely not BASH, are the equal of mid-range linear amps, the better of some top end ClassA but awfully warm sounding. |