1. Home
  2. amps-preamps
  3. 197619-139155

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
hilde45's avatar
hilde45 OP
6,046 posts
 

@markmuse Thanks for your comparison — really useful. The "more robust, more physical" description of the Dragons is exactly the kind of thing I was curious about, and it tracks with what I’d expect from a hybrid design with more headroom.

The value proposition is what intrigues me most. The Audion III runs around $7,850, the Atma-Sphere Class D is $6k — both in the same power ballpark. The Rogue Dragons come in at $5,995 and put out significantly more power than either. So you’re getting more power than the AGD Audion III, more power than the AGD Duet (@ $11,500, even), and more power than the Atma-Sphere, at a much lower price than AGD and a comparable price to the Atmasphere. That’s hard to ignore on paper, especially for a speaker like the LRS+ that wants to be driven.

The tradeoff you’re describing — slightly less upper midrange and high frequency emphasis compared to the AGD, compensated by cables and tube rolling — sounds like it left you in a better place overall for your system. Whether that presentation suits my speakers and room is, as you say, something I’d have to find out for myself. My guess is that the somewhat forward midrange and treble presentation I experienced with the Audion’s would make me curious about the Rogue for sure. Its combination of power, price, and your description of the sound makes it worth serious consideration.

N.B. I do realize that the Rogue is NOT GaN and that might have a lot to do with the price differences, though that would not explain the Atmasphere/AGD difference. 

markmuse
336 posts
 

@hilde45  You might give Rogue a call to discuss. Your speakers are cone drivers ~87dB? The Dragon monos are WAY too much power. There is a Dragon stereo amp might be better. And I believe they have other tube/D offerings. They are happy to talk about your needs. They guided me from the stereo Dragon to the mono blocks because of the specific speakers I use. Each mono has as much current as the stereo channels combined. Talk to them.

hilde45's avatar
hilde45 OP
6,046 posts
 

@markmuse Thanks. I might talk with them. I heard that the mono config is better regardless of power. I realized the Dragons are basically like the Purifi I already tried and didn’t care for. Yes there are additional tubes in there and perhaps a better implementation, but I need to think about it. All of this kind of turns my thinking back to Atmasphere’s unique and carefully engineered approach -- at a price point that is 25% less than the Audions. I strongly suspect the difference may come down to pretty casing and bling appeal. Listening is the only real test. We’ll see.

markmuse
336 posts
 

@hilde45 I did try Ralph's amps a few years ago. They are very nice and I think probably more in line with the needs of your speakers. There was a dealer somewhere in NJ that had loaners that I tried. Good luck with it all.

decooney
2,565 posts
 

Looking over a few reviews searching around, a comment about "speaker pairing is critical" surfaced.  Hmm, really? If this is true, it might be helpful for Ralph at @atmasphere  to provide a profile of an ideal speaker to match up with his Class D monos. What would an ideal speaker profile spec [or range] look like?

More to discover