Tubes/SS Power Amps?

Based on observations/listening experiences to date, I'm finding good Class D seems to sound more like good tube amps I have heard than most other SS amp technology. Plus they have the ability to drive many difficult load speakers out there today that tube amps are more challenged to do, without great cost, expense, size and heat.

Based on listening alone, I find my Class D amps, Bel Canto ref1000m monoblocks, hard to fault in any real way. But on paper, the very highest frequencies that might be heard are the area where Class D historically may not be up to snuff with the very best amps otherwise. That technical bottleneck as I understand it is due mostly to switching frequency limit and effects on associated low pass filtering needed. The latest Class D amp modules I read about seem to indicate that switching frequency continues to increase and improve as the needed technology improves. That would seem to push what is possible even higher.

Practically, I think Class D has arrived not just as being viable but the most practical approach to high performance amp design. Technically, the frontier is still moving with Class D technology it would seem, much as it is still with computers and related digital technologies.

The sky is probably the limit down the road, to the extent that it matters practically. Practically, what it means is though performance will continue to go up, becoming even more practical for even the most demanding applications, even more importantly, cost/prices will continue to go down as top performing Class D technology becomes more mainstream for high end audio applications.

Outside of high end audio, where Class D appears to already have a firm foothold, Class D seems to have already clearly arrived and is starting to take over.

Mapman, transistors switch on and off, as opposed to always on as is the case of Class A tubes. AB amps have two halves of a cycle that match. "Audibly", these three can sound so close to the same when the best parts are used, that "most" people can't tell the difference.

In motion pictures, what in reality is many still frames becomes a "moving picture". This analogy of still frames is good for transistors, digital, and switching amps, which is why extreme audiophiles preferred class A tubes. While none of us can detect still frames at a movie, "some" audiophiles seem to be able to tell the difference between switching and non switching amps.

It's for certain I can not instantly tell the difference when comparing "high quality" amps with different designs; but for me, I've found it to be cost effective to follow in the footsteps of "extreme audiophiles" who can; and that's where the critical decision making process comes in.

When I first heard the Bel Canto ref1000m monoblocks in my system as a replacement for Musical Fidelity A3CR amp that ran largely Class A I believe, the sound was stunningly different in every way. PErhaps the single biggest difference I have ever heard switching components. IT was like a simulated reproduction of the music had been replaced with something much more resembling the real thing. I thought the bass was gone at first until I was able to get tuned back in. Then it was there in spades and way more dimensional, articulate and controlled than ever, which seemed to enable all the rest to be revealed much better than before as well. It seemed like a thick layer of distortion that existed prior was removed. I did not know what to make of it at first, but I quickly realized I could now turn the volume up much louder than prior without any discomfort or fatigue, and the music just seemed to continue to expand naturally rather than making me want to stop. One of my more shocking audiophile moments for sure.

Driving my tube amp is one of the places where it really differs from SS amps I've owned...it gets rounder with a still listenable tone at highish levels, and that works for me somehow...my sub is SS though, and it just has to be turned down to compensate, as I'm not insane. Or maybe I am.

Orpheus10, just FWIW if you think we can't see the frame rate at a movie theatre, go see the Hobbit and then go see the HFR (High Frame Rate) version of it!

One thing that Class A tubes have over Class D is bandwidth. How about full power -1/2db at 150KHz, only 2 db down at 300KHz? Some might argue that class D (and for that matter, traditional transistor technology) have more current (and they would be right) but the question is 'Is that important?'

The correct answer is no. High current ability is not particularly important. Why? First, look at the specs of any transistor amp, any class D amp, in particular the distortion spec into 4 ohms. You will see that the distortion is higher into 4 ohms than it is into 8 or 16 (likely the 16 ohm distortion will not be spec'ced, but it is lower...).

To put this more clearly, if you want to have the system to sound smoother and more detailed, even if you have solid state, that will be easier if you are driving a higher impedance. This is because that increased distortion (driving lower impedances) will mask detail and come off as brightness. This is the difference between a good hifi and a music system that sounds like real music- the lack of electronic artifact.

Now, on top of that, about 50 years ago tubes were being declared obsolete, much like vinyl LPs were in the 1980s. The fact that tubes are still very much a part of the audio marketplace is not some sort of fluke- they are still here because they are still popular half a century on. This is the more telling fact actually. If tubes were really obsolete they would have been gone decades ago. In fact these days its easier to find old tubes than it is to find old obsolete semiconductors...