Tubes/SS Power Amps?

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...

Mapman, normally, the cost and weight of an amp that generates that much power, is prohibitive. Since I've never auditioned such a powerful amp, I have no way of evaluating the effect of that much power on the audio; I'm sure it was quite different.

My best audiophile moments are with 2 track reel to reel. While I thought they made all recordings better, they make bad recordings worse; but in the case of good CD's or LP's, the playback is always better than the original source. "Better" does not mean different, but bigger, and in the case of CD's they sound more like audiophile LP's. I imagine this might be the same effect as a more powerful amp. The reel causes the sound stage to fill the room more completely with the same amp.

500 watts into 8 ohms for a 19 lb amp is unbelievable. There are so many factors involving a class D amp that make them worth considering, and if I ever have a desire for power hungry speakers, I'll know which amp to choose.

I'm of the "first watt" school...if an amp is well designed and used properly it can sound amazing, regardless of the wattage, cost, or type. Speaker impedance matching is key of course, and if you expect to fill a gigantic room to sweaty disco levels with a 2 watt amp, you shouldn't be here. Good tube amps generally aren't breaking a sweat at strong listening levels, and I agree with Atmasphere about classic design service issues...where was I supposed to get IBGT transistors for my trusty old Forte' 55? (I was never 100% sure what transistors were in that thing anyway)

Mapman,

I'm using a lower cost class D amp ($630 ClassD Audio SDS440sc stereo amp rated at 440 watts@4ohms) than you are using but I still notice the same attributes that you described.
When I turn up the volume the sound retains it's balance and there is no compression, clipping or tonal changes. The music just gets louder while exhibiting an effortless quality.

But, what's even more interesting and impressive to me, is that it has this character when turning the volume down, as well. I enjoy this amp, whether with music or ht, much more than my previous amp (Aragon4004 that had similar power but was a class A/B type). I never heard, or at least noticed, any other amplifier type that has such good performance at both low and high volume levels.

Atmasphere,
I am definitely not implying that tube amplification is obsolete. Class D amps, imho, do not sound the same as good tubed amps. There will probably always be users that continue to prefer the virtues of good tube sound, myself included. I've achieved some of the tube sound I prefer by combining a tubed preamp in front of the class D amp.

Class D is so neutral, quiet and clean that I'm probably hearing the sound of my preamp and source more than the sound imparted by my amp. I have noticed an improvovent in sound (more tube like) with the VTL/ClassD Audio combo than my previous VTL/Aragon combo. This was further improved when I recently replaced my preamp's NOS Mullards with a fresh set.

Lastly, I just want to mention the improved bass performance of class D in the bass area of my system's performance. The Aragon had good bass with my inefficient Magnepan 2.7qr spkrs. But I felt the need for more bass and added a subwoofer crossed over at 45hz. When I substituted the CDA for the Aragon, I immediately noticed a slight overemphasis in the low bass region. I turned down the sub's high cut flter down from 45hz to 35 hz and this corrected the issue. I think the class D amp's high Damping Factor (in the thousnds) was the cause of this.

This little CDA amp took control of my spkr's woofer panels like the Aragon was never able to, even though it's 1/3rd the size, weight and price of the Aragon. There wasn't just more bass, the bass was tauter, more textured and more nuanced. I confirmed this by turning my sub off for a few days and didn't really miss it that much. I would loved to have used, or at least tried, a tube amp but my spkrs need too much power to use for both music and ht.

I would think the traditional high end solid-state companies should be more concerned with the improvements in class D technology than the traditional high end tube companies. This is probably reflected in the number of ss companies vs tube companies offering class D amps. On the ss side, Mark Levinson, Rowland, Bel Canto(started as a tube amp maker yrs ago) and, I believe, Cary all have introduced class D amps. The only tube company I'm aware of that currently offers class D amps is ARC. I'm sure others know of a few more on both sides. I was just reading that PS Audio is about to introduce a new class D amp this year, too.

As Mapman and others have pointed out on previous threads, there are a slew of new companies that are just beginning their journeys to possibly becoming traditional high end companies utilizing the new class D technology; W4S, Merrill Audio, Mola-Mola, Acoustic Imagery, PS Audio, etc.

I'm sure there will be more companies jumping on the bandwagon.

IMHO, class D just has too much going for it (good and improving sound quality, small size and weight, very efficient, very powerful, relatively low cost, cool running, neutral sound character) for it not to be the wave of the future. I really do hope you decide to jump on this juggernaut bandwagon while there's still some room on it.

Best wishes,
Tim

If you consider NAIM amps as good and if the rest of their gear is the same as my 5i - then they run very cool

My 5i is on 24/345 (vacations) an never gets warm
- Except in winter when my hands are cold :-)

A few gotchyas...
- naim recommends only their speaker cables (see website)
- they only have RCA and DIN inputs
- they work really well with NAIM power supplies - go figure
- sources should be grounded otherwise they may hum

Other than that they are detailed, articulate, dynamic and sound great

They are a lifestyle choice - that sound great :-)