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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
hilde45's avatar
hilde45 OP
5,994 posts
 

Thanks! Speaking of Axpona, if anyone sees FRITZ’s speakers, I’d be curious who is using them, the gear they’re pairing with, etc.

I hope people can weigh in here with any of the Class D experiences.

I’m interested in any new experienced designs but also any "copycat designs," even if they’re by companies with no prior experience in solid-state. There’s a lot of stuff flooding the market, so having some show reports about the "good" stuff and also the copycat stuff would be interesting.

 

 

 

decooney
2,564 posts
 

@hilde45 ...There's a lot of stuff flooding the market, so having some show reports about the "good" stuff and also the copycat stuff would be interesting.

Good point. Agree. Sure seems IF  "Class-D" amps were going to make a strong impression with discriminating listeners experienced with top shelf SS or Tube Class A/AB amps - it would be THIS year @ Axpona. Wish I could be there.  wink

 

hilde45's avatar
hilde45 OP
5,994 posts
 

@decooney 

I see that Herb at Stereophile really liked the Laiv monoblocks -- 

https://www.stereophile.com/content/gramophone-dreams-107-laiv-ganm-monoblock-record-doctor-vi-20th-anniversary-edition

Before the LAiV Harmony GaNM amp arrived, I had developed a yawning disinterest in class-D, plus an irrational disdain for fast-acting "high conductivity" GaN-FET transistors. (Last time I checked, free electrons were moving pretty fast already in 1000V vacuum tubes like a 211 or 845.) And everyone knows I’ve never been persuaded by weight, cost, and energy-saving switching power supplies. True to my boomer roots, I’ve stuck to old-school class-A linearity, plus wide bandwidth, tidy transfer functions, clean squarewaves, and lots of standing current.

What I care about most is tone, transparency, tactility, and having enough current and voltage to push the smallest recorded sounds and subtlest captured rhythms through diverse speakers. Which means I am laughing at my own foolishness, because I think I’m getting every one of these "care abouts" with class-D GaN-FET amps driving my Falcon LS3/5a’s. I need the unnamed wizards behind these amps to explain why these things I once mocked are now thumbing their noses at me and mocking me back.

Based on what I’ve heard in my studio and what I’ve read on LAiV’s website, I am guessing the GaNM amps are operating at a sampling frequency that’s so high it does not require feedback, and as a result, current and voltage remain in phase. That probably accounts for the extra punch and transparency. I’m also guessing that in lieu of feedback, there is some amount of DSP shaping or controlling the output signal, and that processing is affecting how I perceive the GaNM amp’s force, density, and transparency. That’s all just speculation, but I don’t care if it’s true. This amp is the closest thing I’ve found to that mythical amp that will drive any speaker. At this moment, it’s my favorite amp with the Falcons. I did not see that coming.

LAiV’s GaNM monoblocks have converted my class-D disinterest into "Oh my God, hallelujah!" Seriously recommended.

So...interesting to me. They’re $4694, GaN, monoblocks, and a really amazing deal if they sound good. Just reading about them now.

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riaa_award_collectors_on_facebook
1,020 posts
 

@hilde45   Might want to look at Jay's Iyagi comparison on Youtube between AGD Audion's vs Laiv.   In a nutshell Laiv has more muscle but comes up short in every other category. 

hilde45's avatar
hilde45 OP
5,994 posts
 

@riaa_award_collectors_on_facebook 

Thanks -- I'll take a look. AGD came up short for me too, but at $7850 I might have had higher expectations for it than for the LaiV. Still, for that $$ the LaiV should sound good enough to keep. The NAD v. 1 Eigentakt failed that for me, and the v. 2 is around $5k (though prices are going up, I think). Still need to try the Atmasphere, which at $6320 is a fair bit more than the Laiv.

Appreciate the reference.

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