Class D amplifiers. What's the future look like?

@soix thanks. I'm glad it is improving if this is the "future" of what sonics we will have. I'm 65 and likely won't have to worry about it, but I hope it will get better and better - at least as good as the best Class AB amps are, and if the transfer function can be attained that gives them a touch of "tubiness", then all the better. 

I'd hope that 10 to 25 years from now, audiophiles will have access to great sound using these continually improved Class-D amps. That is after all why we all got into this, regardless of what technology we use to get there.  Figure Class A, Class AB solid state, and SET or push-pull tube amps will be around for a long time, just because there will be some who will want them. 

Love the idea that you can upgrade the amp along the way with better modules without having to trash it, sort of like Schiit does with their Bitfrost 2/64 DAC. 

I’d hope that 10 to 25 years from now, audiophiles will have access to great sound using these continually improved Class-D amps. That is after all why we all got into this, regardless of what technology we use to get there. Figure Class A, Class AB solid state, and SET or push-pull tube amps will be around for a long time, just because there will be some who will want them.

@moonwatcher Yup. My sentiments exactly. BTW I recently spent $$$ doing full upgrades of my McCormack amp (Class A/B) but came very close to going with a GaN amp. Came down to that I really liked the sound of my amp and the prospect of significantly improving upon that with SMcAudio upgrades just seemed like a low-risk option sound wise while switching to a different amp/technology might just end up being trade offs instead of a total upgrade. The devil you know…plus the upgrade was considerably cheaper than the GaN amps I was considering, so there’s that. It’s a journey fer sure.

Why is there this "push" to Class-D in the first place? What do you gain? In what way would they ever be sonically better than a good Class A or AB amp?

@moonwatcher Class D offers something that is very hard to achieve with A and AB amplifiers: a very high value of Gain Bandwidth Product. Most solid state amps use feedback, but as you might know, feedback has gotten a bad reputation in high end audio, not because it doesn’t work, but because it usually gets poorly applied- and so causes distortion of its own, adding many higher ordered harmonics (to which the ear is keenly sensitive and interprets as harshness and brightness).

So the answer is pretty technical. One reason feedback has this bad rap is because when the GBP limit is reached, feedback decreases on a 6dB slope and perhaps faster with succeeding octaves. This can and does happen as low as 1KHz, so distortion will begin to rise- putting higher ordered harmonics in the most sensitive region of human hearing. What I’m talking about here is easily measured: distortion vs frequency.

When you have enough GBP, distortion vs frequency can be a ruler flat line across the audio band. This allows the amplifier to be smoother in its presentation, with greater detail at higher frequencies (since distortion obscures detail) without harshness. Smoother and more detailed at the same time is a good thing IME.

Class D makes an enormous value of GBP available to the designer. So you can run very high amounts of feedback without getting into trouble; we’re running 10x more than conventional A or AB amplifiers. This makes possible an amp that is smoother and more detailed than conventional A or AB designs (even in tube embodiments), eliminating the benefit that class A used to offer.

The reduced heat, reduced size, weight and cost are all nice side benefits.

@atmasphere THANK YOU for that explanation. Now it finally makes sense.  We are not "doing" Class-D "just to be doing it" for the fun of new technology - there is logic behind the "why" of doing it - which is to achieve lower distortions in the audible range, to make music sound more like music.  That answers my question perfectly.  I visited your website. Beautiful amps. Good luck going forward. 

I would say the future of class D is Lyngdorf.