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Expanding the Class D Conversation: How Would You Characterize Their Differences?

Expanding the Class D Conversation: How Would You Characterize Their Differences?

I'm currently trialing the NAD M23 (1st gen. Eigentakt-based), and I find it intriguing enough to want to understand it better — which means understanding the broader sonic landscape of class D. So I'm crowd-sourcing.

In a recent exchange, the estimable Ralph Karsten (Atma-Sphere Music Systems) made two comments that stopped me cold. For those who missed it, here's what he said:

"IME, class D amps vary in sound more than tube amps, which is to say, quite a lot."

"IMO there is a bigger difference between various class D amps than you hear between various tube amps. IOW just because you heard one class D amp says nothing about how the next one might sound."

Link: https://forum.audiogon.com/posts/2885828

As I think through this more carefully, these are genuinely important claims. My own experience with tube amps confirms that they produce audibly distinct characters across topologies and designs. If Ralph is right and class D exceeds that range, then generalizing from one class D experience to another is even more hazardous than I assumed.

One specific question for Audiogon members:

If you have a Class D amp or have compared class D amplifiers, how would you describe their character(s)?

Here are some criteria I use:

  1. Frequency balance — Is the tonal response even across bass, mids, and treble, or does it favor certain regions?
  2. High-frequency texture — Are the highs extended and smooth, or edgy, grainy, and fatiguing?
  3. Bass definition — Is the low end tight and articulate, or loose and bloated?
  4. Midrange character — Does the midrange feel present and natural, or recessed and thin?
  5. Transient speed — Does the amp respond quickly to dynamic attacks, or does it sound sluggish and rounded?
  6. Dynamic range — Does it scale convincingly from quiet passages to loud ones, or compress the difference?
  7. Soundstage width and depth — Does it create a convincing three-dimensional image, or sound flat and narrow?
  8. Image specificity — Are instruments and voices placed precisely, or do they blur and wander?
  9. Background noise floor — Is the silence between notes actually silent, or is there grain, haze, or hash?
  10. Long-term listenability — After an extended session, do you want to keep listening, or has something been quietly fatiguing you?

If you can include relevant system context — room, speakers, preamp — please do. Those variables will help me interpret what the amp itself is contributing.

I'm less interested in rankings than in understanding what Ralph mentioned, namely the [vast] range of sonic signatures class D is capable of. Eigentakt, Hypex, Pascal, Purifi, GaN-based, etc. — all fair game.

Price is no constraint here — I'm interested in the full range of what's out there.

hilde45
yyzsantabarbara
5,557 posts
 

Here is my opinion of the Class D amps that I have owned

  • LSA Voyager 350 GAN (modded by Ric Schultz)
    • Very good after the mods with a very clean, detailed, smooth sound. However, the bass was really lacking
  • PeachTree GAN1 (modded by Ric Schultz)
    • this amp was much more than an amp. It had a SPDIF digital input. It did not have a volume control, so your streamer had to manage that and it only did that single digital input. I had the Lumin X1 streamer and that is a great streamer into the SPDIF with the LeedH volume control. After the mods this amp was the very best sounding Class D amp I owned and if it had stronger bass, I would still have it.
  • PeachTree GAN400
    • the second most powerful Cass D amp but was a bit grainy on top
  • D-SONIC M3a-800S
    • Most powerful Class D amp but lack detail like the others.
  • NAD M22 V2 
    • I hated this amp and luckily was able to return it to TMR before my demo period ended. The only piece of audio gear I ever returned.

I am playing the Class D GanFet on my Yanaha NS5000 speaker and the imersiv D-1. I played some vocal oriented music, and the amp was really good. However, I put on Led Zeppelin's Live EP and the song Kashmir (Live from Knebworth 1979) my recent go to song for headphone evaluations. Compared to the CODA #16 the sound was much smaller. The pounding drums on this track do don't pound so hard. It sounds OK, but not anything close to the great sound with the CODA #16. My CODA #11 sounds similar to the #16 and it cost me $2400. The top end sound nice and clean and smooth, but everything else sounds limited compared to the #16 and #11. No way I would use the 6.5 amp on the Yamaha, but on the smaller Magnepan Mini it is very good.

Thie issue is that the Yamaha NS5000 is one of the best speakers around and the 6.5 cannot scale to that level. The Magnepan Mini is not a great speaker, it is a fun and very good speaker (like the Magnepan 3.7 but smaller). The 6.5 scales to this speaker nicely. The #16 is better on the Maggies but not much better because the speaker can only do so much.

My listening test is over, not that great.

 

decooney
2,565 posts
 

"@parkergetdean but until AI can learn to go into hifi shops and listen,..."

And/or, not until the future where let’s think ahead how AI engines with probes and sensors are integrated within MY own listening room, [collecting response samples, best it can] taking into account all of my audio components, cables, speakers, room shape/size, placement of my speakers in the room itself - its easy to say at best, as many shared,  can be helpful to "collect and sort vast amounts of data, quickly, whatever is available", at best. i.e. "Garbage in, garbage out". The creating of gourmet food and contents sourced from the trash [above] was an interesting way of putting it. 

More conversations like this thread will continue to inject itself into the results from all of these AI engine/platforms and vast data sources that grow daily.  I’m comparing this years responses to last and next years btw. I bet if we ask the same questions two years from now, we may be quite surprised at the results. For today, we are still best served listening in our room with our gear that matters most imo, just like @hilde45 is doing right now on this thread :) Fun thread. 

mahgister's avatar
mahgister
15,051 posts
 

I dont need A.I. to know by experience that class D is a vast improvement...

I only use low cost class D with Edifier speakers:

Why most class D   must sound as described by someone here :

Most Class D: Sterility, brittle, thin sounding/lack of body, fatigue inducing

 But some dont sound like that, and it must be relative to design implementation for sure...

Someone added :

Some GaN class D: sterility is tamed, less fatiguing, lack of body persists 

I believe it for sure... Design implementation matter and i dont claim that my low class D Edifier  beat or even rival   some GaN class D , i am no fool...smiley

 

 But now, why my low cost class D sound so good to my ears, not fatiguing, tamed especially without this evident  lack of body as it  the case was when i received it  ?

It is because not only design implementation matter , but optimization of the four working dimensions matter as much if not even more...

All is relative, i dont claim my system is top, i claim optimization matter so much a low cost class D can be enjoyable...it is why it is a revolution not only in high end gear market but in the low cost market if you know how to do basics,...

 

Now when i will win loto i will buy a costly system, but i am happy and in no urge or need now in the incoming crisis...Optimization is key...not just price and design implementation.

 

«My wife is not optimized»--Groucho Marx cool

 

billstevenson
1,195 posts
 

@deep_333 Your post has no merit whatsoever and adds absolutely nothing to the conversation.  It is really a shame that you cannot be challenged in this venue via a double blind test to demonstrate what you claim to hear.  A test, which you would almost assuredly utterly fail.  If you have nothing positive to offer, please stay silent.   

parkergetdean
1,056 posts
 

I have been wondering about this for a while, what does " Blooming Bass" mean?

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