Power output of tube amps compared to solid states


I'm having a hard time trying to figure out how tube amp power output relates to solid state power output. I've been looking at the classifieds for tube amps and I see lots of tube amps with 50w or 60w output, but nothing close to the 250w output typical of solid state amps.

So I have no idea what type of tube amp is required for my set up, right now I'm using totem forests with a required power rating of 150w-200w at 8ohms. The bass is so powerful on these that I have the sub crossover set to 40hz.

My question is, are tube amps so efficient that 50w from a tube sounds like 150w from a solid state? Or will 50w output from a tube severely limit how loud I can play my speakers? If so, are tubes usually meant to be driving super-high efficiency speakers?

I had previously tried a tube pre-amp with a solid state power amp (both musical fidelity) and didn't like the results because the imaging suffered greatly, even though the music sounded nicer from a distance. Now I want to try a solid state pre-amp (bryston) with a tube power amp (no idea which brand to look at), but I don't know how much power output I need or if it will even be possible with my speakers. Does anyone know what I would require?
acrossley

Showing 1 response by layman

Arthur,

I just switched from a Class-B (push-pull) tube amp to a Class-A (single-ended) tube amp. My speakers are Rogers Studio 7s (90dbW sensitivity).

Your understanding of the physics of Class-A and Class-B are far beyond mine, but here are my subjective observations.

The Class-A (single-ended) tube amp heats up the room much better than the regular room heater (which I have had to turn off). It gets HOT! I don't know what I am going to do during the summer.

The other thing I have discovered is that my electric bill has doubled (I just got it today)!

Yet it seems to be worth it. The Class-A (single-ended) sounds dramatically more like live music than the Class-B amp does. Everything sounds so much smoother, so much more like what I experience sitting in front of a live string quintet or a live orchestra. It's a dramatic leap up in quality. I have no idea why this is so.

Subjectively, the Class-A amp sounds significantly louder than the Class-B amp even though it has half the wattage. Moreover, the dynamic range seems greater with the Class-A amp. On more than one occasion, I have turned the volume up during a quiet passage only to be blasted out of the sofa during a loud passage. The difference between high and low seem much greater with the Class-A amp, whereas with the Class-B amp dynamic range seems more constricted.

It's hard to cut up the audioband into bass, mid-range, and treble with the Class-A amp. I just hear music. Seemless music. Every note (from high to low) sounds realistic.

Transients seem much more bold and much more dramatic. I dive for cover now during the cannon shots of the 1812.

The class-A amp does not sound soft or romantic in the way that I was expecting. It sounds as sharp, crystalline or as velvety as the music demands. It does not seem to obscure music with an omni-present coloration of its own. It sounds significantly more accurate than my push-pull amp (which gives a slightly rose tinted patina to everything).

Going from Class-B to Class-A has been nothing short of a sonic revelation. I can deal with the heat for the dramatic increase in the beauty and realness of my music.