Discussion of Class D Amps Application & Experiences


With all the time off that our current situation has allowed recently, I became intrigued by the idea of class D amplification. I have always been against this type of amplifier but the more I have read the more I have also learned. There are lots of threads here on this subject many of which result in arguments about which amplifier class is better. I do not want to do that here. As I consider a class D amp I need to let you know that I currently use a fairly powerful class A/B SS amp and pre-amp into an efficient pair of speakers rated at 4 ohms. My choice of equipment has always been focused on musicality over absolute detail. I want the music to sound natural and not sterile. I seem to have achieved that sound. If I switched to class D amplification that would also be my intended goal although a bit more refined detail would be fine. I have considered pairing the amp with a tube pre to help achieve my desired sound. So why would I change? My goal would be to save money over my current gear while maintaining my desired sound.

I have researched brands such as Nord, Primare, AGD & Nuprime. I have also looked at brands such as Jeff Rowland & Merrill but those are way out of my price range. My target would be $6000 - $7000 or less. I'm about performance not price. So given that background information I would like to hear from those who have made the leap, what your experience has been (likes and dislikes), what amp did you replace and any comments about one brand over the other. Your experience with demos etc. Do you use a tube or SS line stage?
Thanks
128x128falconquest

djones51
1,651 posts
04-23-2020 10:08am
I wouldn't worry to much about the op amp the stock TI LM 4562 will measure right there with any discrete sparkos or sonic imagery.

I don't know your background, I don't know you. I hope you read
this.

This is from my ears to this forum, I'm very familiar, with the LM4562 NEC, E.I. T.I, op amps. played with them all, rolled them all.  ALL the discretes, I sampled, the SO was much better, even the Burson with the high failure rate due to poor regulator choice and potting problems.  

I worked with Andrew at Sparco labs to resolve some issues with the early Nord buffer boards, and the op amp SM sockets for my Mac
gear, and a few others.

From sparco webb site:

"Our discrete voltage regulators have at least 15 times lower output noise, 52dB (about 300X) better rejection of any noise coming into them, and 4X better load regulation than any other 3 terminal IC regulator that one can find to compare them against."

The regulators are the key to the Class A op amps, without this type of regulator, you can't take FULL advantage of the great discretes available,
or their sonic superiority.

Yamaha, Marantz, B&W, Channel Islands Audio, Meridian, Kharma, MM Audio, and Exodus, and about a dozen more use, Hypex NC modules

The difference in SQ between who does, and who doesn't, is very easy to hear and enjoy.

The comment on "A tube front end" is purely subjective, and you have the right to be WRONG, just as I do. I know how it sounds because I've done Mac, CJ, VTL, Marantz, and two handbuilt line preamps. ALL sounded wonderful, and pure sonic nuggets, with options...

If OPs ears are good, he'll notice the differences and certainly change them if he like. With the op amp/tube roll option, you have a lot of sonic latitude.   

Without those options, what other options do you have, PCs and ICs
No thanks...

Seems to be something djones51 hasn't tried, or, has has he?

WHY would you limit the OP options when it's obvious you, haven't hear the most popular class D boards available, ICE. I use them for bass duty. They are as good as any Hypex without op amp upgrades. For some, that's exactly what they like.. WHY? It's ALL they own. Second some ICE modules have a built in PS, that lets you expand. You can 1 or 2 amp modules depending on the model, at a very low cost. Great option.

SMPS1200 hypex power supply were powering most of 1ET400 amp modules, I listened too. Again not even close to a NCs with buffer board. Apples Oranges...Maybe djones51 listened to something else, DUNO, wasn't real clear.

Second I will only comment on what I've heard. What I've really sat down with. Not a day at a show, or a listening room. normally weeks at least. I read then I listen, and listen and.........

Happy hunting..

Regards
I had a pair of Nord NC500 rev D monoblocks for about 8 months before I decided to sell them and go back to class AB. I used them with Golden Ear Triton 2+ speakers, Bryston BDP-2 streamer, Schitt Yggdrasil DAC. Preamps were Schitt Freya and Parasound JC-2. I tried a variety of cables although nothing too exotic (all under $1K per cable or pair). 

These amps replaced a Krell FPB-300 which died and I couldn't justify the cost of getting it fixed. 

I used both the Sparkos and Sonic Imagery Op Amps. I found the Sparkos to be a little more to my liking - presentation was a bit more relaxed and top end was a bit smoother. 

What I liked: Very efficient. Lightweight and easy to move around. Good dynamics and clarity with very quiet background. Decent but not exceptional sound stage. 

The reason I replaced them: they lacked the excitement I was used to with the Krell. They just sounded boring to me. The imaging was also not as deep and wide as with the Krell. Granted, the Krell was a much more expensive amp in its day, but I was hoping Class D efficiency and more modern design would allow me to get close to the Krell performance at a lower cost. 

I ended up replacing the Nords with a Parasound JC-5 which I'm enjoying very much. A little different sound than the Krell (almost a year between listening to the Krell and JC-5 and I was using a different preamp), but the JC-5 is a beautiful sounding amp with effortless power that is also emotionally engaging. 

I wouldn't rule out Class D in the future, but probably not any time soon. 
@jaytor That's what I was after! Some real world, hey I tried this but didn't like it because, straightforward honest first hand experience. I must admit, I have heard/read a lot about class d build, specs. and prices but not much of anyone extolling their virtues. Thank you for your response!

jaytor138 posts

 These amps replaced a Krell FPB-300

I setting here looking at a pair of KSA-100 mk2s, that I LOVE, thinking do I want to listen to ANY, class a, tube, or other HOT running thing.. LOL.
87 degrees here, now.  In a month over 90, then over 100. 

Class d has its place. But it's not a Krell, Pass, Mark L and few more. BUT some of these class d manufactures sure have a hefty price tag. Considering, what's in the box, I think some of the binding post are more expensive than the whole amp module.. 

A majority of my listening is on multi planars, and ribbons, systems. No large surface systems. Different results, compared to most round speaker setups. Class d does the planars justice, for sure, to what degree, is the question..How good is good? it's not perfect, but pretty darn good, it's just COOL..

Regards
About this time last year, I purchased a Digital Amplifier Company class D amp.  It was used, about ten years old and the most expensive amp I have ever purchased.  I have many different class A/Bs from a multitude of US manufacture's and a couple of Japanese built, all at 200 wpc or greater.  The DAC 4800a was the first amp to let my speakers sound their best.  I use Magnepans and Martin Logan's.  From first listen, it was the absolute quietest amp ever.  Put a disc on walk away-and suddenly sound just erupted from my speakers, whether Greig or Steely Dan, it was incredible.  The sound from deepest notes to highest were clear, single notes lost in the A/B fog now had their own voice.  Soundstage and depth was wide and deep.  In January of this year I purchased 2 DAC Maraschinos, one used and one from DAC direct.  I could not be happier, the build quality is old school USA.  The amps do not use modules from other companies, instead they build it from their own design.  Most of the A/B amps were made at ATI.  Give the Digital Amplifier Co. web site a look see.  Just another opinion.