A few years back, we at the newspaper started a music recording project we called Second Story Garage. Through three and a half years and 150 bands — local, national, no-name and famous — we brought the throbbing sounds of live music into the Colorado Daily and Daily Camera newsrooms on a weekly basis.
I can only imagine how many meetings and phone interviews we disrupted. There was that time the uber boss poked his head in and told us to stop recording the loud, headbanging rock 'n' roll while he was on a conference call, but the band needed to be somewhere and couldn't wait, so we locked the door and kept recording. ... That was dangerous.
Oh, so many memories.
But one vivid memory I go back to, which also applies to the subject of amplification, was the utter magic of the sound of a full band from my headphones plugged directly into the mixing board. I always tried my best to get the recorded version back to that original glory, and many factors influenced the final sound. But one major, major influencer was how gain (amplification) or attenuation (reduction of volume) was applied in different stages along the way. More on the headphone thing later.
An easy analogy for many of us in Boulder to understand how an amplifier works is the way a bicycle works. When you turn a big gear and have it connected to a small gear, the small gear spins faster than the big one, so you don't have to spin your legs that fast to get the small gear spinning quickly.
Similarly, in an amplifier, a small fluctuation of electrical signal we call music is connected directly to an element that is built to fluctuate the signal in a large way.
Here's another way to think of it. Picture the power meters you've seen on receivers and at the top of mixing boards. Those little needles are small and move at most about an inch, left to right, to the music. Now if you connected them to 10-foot-tall meters and the connection allowed the big ones to move as quickly as the small ones, you'd have larger-than-life meters swinging left and right with a swing distance of 8 or 9 feet.
That's how amplification works. Tubes do this by design — they permit that small signal to directly drive a larger signal, with (hopefully) little "loss" or distortion of the original signal.
Knowing how hard it would be to construct that type of connection between the featherweight meter needles and those giant 10-footers, you can start to understand why low distortion, meaning less changing of the original signal, is highly prized in amplifiers. Distortion figures in tube amps can tell you a bit about the character of the resulting sound.
But with the advent of transistors — and eventually op-amps — came the ability to mathematically annihilate those old distortion benchmarks. But somehow, those things don't sound the same (as good, to many people) as the old tube amps.
Why? I'll get into that and continue the amp saga next week.