Wednesday, January 30, 2013

Tubes versus transistors

There are basically two kinds of amplifiers for audio. Those that use vacuum tubes (valves) and those that use various types of transistors. The tube types came first and were huge, use a lot of power and (according to the purists) have the warmest sound. The transistor types came later, are more efficient, smaller and (again according to the purists) sound tinnier, colder and less dynamic. Sound familiar? Ever heard the analog vinyl record versus digital CD argument?

Anyway, there are a lot of people who don't quite understand how one could sound better than the other considering how they work. I mean seriously, an amplifier really only does one thing. It takes a variable (analog) low-power signal on an input and it gets amplified because the output swings (at most) between the highest voltage at the anode of the amplifier and ground (zero volts) at the cathode. Too technical? The point is that the function is the same in the tube and the transistor. The only difference is that the tube does its magic in the gap of a vacuum and the transistor does its magic at the microscopic level in the gap between layers of various types of semiconductor material.

Well, I know why tube amps sound better. You know how people have said the sound of tubes seems 'warmer'? That's because the amplification is being done in a very hot space. Tubes are heated by an element embedded in the tube. This heat excites the electrons and this in turn makes them sound more musical. In a transistor, there is no heater. The transistor gets hot as a result of the semiconductor material resistance. Unfortunately, because the signal being amplified is what's creating the heat, some of the music is lost, the life is sucked out of the signal.

Sounds like a good theory, huh? I made the whole thing up. I seriously have no clue why people think tubes are better. The purists feel it has to do with the subtle even natural harmonics a tube amp introduces into the signal.

I like my theory better.

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