How sound is made, and what an amplifier does to it
Four experiments, no sign-up and nothing to install. Sound is a vibration you can draw; an amplifier is a valve that copies it larger; and every stage between your music and your ears adds something you can hear if you know what to listen for. Sound only starts when you press a button — this page never plays on its own.
What sound actually is
A sound wave is air pressure rising and falling. Two numbers describe it: how fast it cycles, and how far it swings.
220 Hz
45%
Why this matters: a violin and a piano playing the same note share a fundamental frequency — that is why they sound like the same pitch. What differs is the harmonics stacked on top, and that mix is timbre. Amplitude you hear as volume; frequency you hear as pitch; harmonics you hear as identity.
Build a timbre: the harmonic editor
A musical note is not one frequency, it is a stack. The lowest is the fundamental; the rest are whole-number multiples of it. Set their strengths and you are building an instrument.
Odd harmonics only gives the hollow, woody sound of a clarinet. All harmonics falling slowly gives a bright, reedy tone. Real instruments are never one number — the mix of partials, and how they decay, is the whole character.
The signal chain, one stage at a time
Six stages sit between a recording and your ear. Each one can add noise, shape tone, or run out of headroom. Switch a fault on and you will see it in the waveform and hear it in the sound.
→→→→
Clean path. Nothing switched on: what leaves the speaker is the source signal, just larger. Every fault you add is a real thing that happens in cheap or badly matched equipment.
Why amplifiers come in classes
An amplifier's class describes when its output transistors conduct. It is a trade between fidelity and wasted heat, and it explains why a 50-watt Class A amplifier is enormous and a 50-watt Class D one fits in your hand.
What the numbers on the box mean
Signal-to-noise ratio and distortion are the two figures that decide whether a system sounds clean or tiring. Both are audible, and both are shown below as a spectrum rather than a spec sheet.
85 dB
0.5%
Rule of thumb: below roughly 70 dB of signal-to-noise you start hearing hiss in quiet passages; distortion below 0.1% is inaudible on music. The figures are not the whole story — a system can measure well and sound poor — but a bad figure is a promise the sound will not keep.
Decibels, and why twice the power is not twice as loud
Loudness is measured in decibels, and the scale is logarithmic because hearing is. Doubling the electrical power raises the level by about 3 dB — which you barely notice. To sound twice as loud you need roughly 10 dB, and that is ten times the power.
This is why the numbers on amplifiers mislead. Going from 50 watts to 100 watts buys you 3 dB — a small, real, but modest increase. The last few watts of headroom matter far more for peaks than for average loudness, and a cheap 100-watt amplifier can sound worse than a good 30-watt one because the first one clips on exactly the transients the second one reproduces cleanly.