Could Class D really be that good?

@jl35 glad can of some help. enjoy listening.

NAD’s Director of Technology, Greg Stidsen, had this to say: “Like all amplifier classes, there are advantages and disadvantages to class-D.  What is attractive about class-D is its relative efficiency and freedom from the vagaries of parts quality. In a linear amplifier such as class-A or class-AB, parts-matching and very close tolerances are required to get the best results, and even then, there is a limit to performance since the linearity of semiconductors varies considerably with temperature.

“With class-D, it’s more the quality of the mathematics and engineering that determines the performance,” Greg said.  “Another way of saying this is that in a linear amplifier the design is fairly simple, but the execution is critical; in a switching amplifier, the design is very difficult, but the execution is straightforward.”

https://pmamagazine.org/is-class-d-amplification-now-better-than-class-a-b-and-class-a/

(Emphasis added)

Greg put this pretty well. 

The statement from Greg just shows his ignorance. Of course, you do not need to have matched fets at the input of your class D amp.....you can just use inferior sounding integrated circuit ICs.....he he. He does not listen to parts and execution in his class A/B amps nor in his class D amps. NAD is not a high end tweak company like VAC, AGD, Aavik, Gryphon, Merrill, etc. These guys listen to everything including the parts and execution in their class D amps......as stated above about AGD and Aavik. Just read the review on 10 Audio about the NAD C298 Purifi based amp and then read his review of my modded VTV Purifi amp (which costs less with the mods than the NAD does stock). He rated the NAD at a 6 (extremely low rating from him) with mine a 9.5 bordering on a 10. You can keep quoting people who do not tweak all day long but it does not stop the truth as known by actual listening tests.....Emprical knowledge.....directly experienced listening tests are the ONLY proof of transparency......not what someone says (including me) on a forum or what someone believes. Everything makes a difference......and that includes the parts and execution in class D amps. The latest rage Fosi and Ayima cheap amps using the TDA 3255 class D chips all have sockets for changing the op amps that are buffers before the class D chip. People all over the world have changed those op amps and get different sound.....You, however claim that in a low gain circuit that all op amps have no sound. You are again a minority of one here.....thousands of audiophiles and manufacturers would disagree. Look at all the Purifi and Hypex amps out their that are being sold that offer different op amp choices. They are not doing that to just make money.....but to tailor the sound. Again, everything makes a difference.

People all over the world have changed those op amps and get different sound.....You, however claim that in a low gain circuit that all op amps have no sound. You are again a minority of one here.....thousands of audiophiles and manufacturers would disagree.

Not to put too fine a point on it, but when you can change an opamp (if its modern, hi performance) and hear a change (other than noise floor), one of two things is happening: 1) confirmation bias, or 2) the circuit has a design flaw.

Opamps have seen a lot of evolution over the last 75 years; guitar stomp pedals and synthesizers from long ago won't sound right if you install newer hi performance ICs instead of the original types. This is because older opamps indeed have a 'sound'. Modern ones do too if you don't use them correctly.

Put another way, the statement in the quote above is false; I never said that 'all opamps have no sound'. Clearly you don't read my posts or you would know that.

Anyone can open a class D amp and change how it sounds! Quite often their changes result in greater noise.

From your posts it appears to me as if you think you know more than other designers. So its curious that you haven't designed a module of your own long ago!

Wow, you just stated that all modern op amps are perfect. Yes, you did not state that all opamps made since the beginning of time were perfect (yes, I did not quote you correctly). What you stated before was just what you said: "all modern opamps".....you probably mean after 1980?....I quess that is when you stopped listening. All "modern" op amps have a sound and it is not confimation bias or a bad design flaw. This is where thousands of people (including world class designers) disagree with you. They know that certain brands of op amp sound differently (and most believe discrete op amps are the most transparent). But you have to listen to know.....something you do not do (at least with op amps).

The changes I do to class D amps lower the perceived noise. You hear farther into the recording.....more decay, more ambience, better imaging, more correct harmonic structure, more transparent and real......this is REAL noise reduction.....not some number on a graph. I do no know more about basic design than most designers, however I have more practical knowledge of implementaion and parts and how they affect the sound than most designers. I have been doing listening tests since the mid 70s....and was the first person (back in the late 70s), that I know of, that did straight wire bypass tests on wire....yes, no wire was perfect....

The companies that usually make the best sound do both....they design and they tweak like crazy. That is why they keep updating their stuff.....like the guy at AGD. Check out this page on Burson Audio. Go to the bottom of the page and see all the pics of customers products that were upgraded using their op amps.....you can keep loading more and more and more of them. These people have circuits that are flawed and they have expectation bias?.....come on......This is just the tip of the iceberg worldwide. At the top of the page are Utube reviews of the op amps. You can keep making stuff up and believing it and telling the world about it.......but it is not truth unless it passes the listenng tests. The people who have listened do not agree with you. Burson is now in their 7th generation of discrete op amp....they never stop tweaking....for they know there is no perfection. it is a goal. When you get to the top of the mountain......you look for higher mountains to climb......same with our soul. Love is infinite......the more you eat....the more hungry you become. It is the ULTIMATE ADDICTION.....bringing the highest joy......for everyone.