We interact with electronics on practically a by-the-minute basis. Between our cars, cellphones, and hi-fis around the house, we’re always clicking, turning, and touching. We often take these things for granted, but sometimes we have that moment where we think: “wait a sec, how does that actually work?” You’re here because you had that same thought about what turning up the volume actually does – and we’re here to answer it.
How Speakers Work
Before we get to the volume knob or buttons, let’s work backward from the speaker itself. How do they work? In essence, the loudspeaker is a cone that vibrates in response to electricity. The cone is mounted to an electromagnetic coil at the back; when an AC signal (we’ll get to this in a second) is passed through the coil, the direction of the current causes the cone to either be attracted to or repelled by, the coil. This means a signal can be accurately converted into kinetic energy – the way we hear things.
Manipulating Signals
But how does this relate to music? Well, turning sounds into electricity is just as easy. Microphones work on the exact same principle, but in reverse – kinetic energy hits a diaphragm, which vibrates proportionally to the sound made. The diaphragm influences an electromagnetic field, with its “pushes” and “pulls” producing a push and pull in voltage: an AC signal!
Of course, sound stored as electricity is a ubiquitous part of our everyday lives at this point, with numerous sophisticated ways to transform, store and create digital audio. But the way in which it reaches your ears is the same – and has been since the invention of the first amplifier. A quiet AC signal is boosted by a series of powered components, whether tubes or transistors, before going through a transformer that converts its high voltage into high current, thus powering the speakers.
The Volume Knob
The volume knob is an essential part of the amplifying process. Electricity and the components used to control it are often explained in terms of running water, where voltage is the pressure in the system and current is the amount of water. Volume knobs in traditional amplifier design are potentiometers, or variable resistors that can increase or decrease the amount of resistance the “water” meets.
Volume knobs are used as something called a voltage divider in electrical engineering, which can be thought of as a form of sluice gate. Turning the knob one way diverts pressure away from the main system – or to “ground” in electrical terms” – removing amplitude from the signal. Turning it the other way means less is diverted away; more signal is sent to the next stage of amplification.
Modern Hi-Fi
Potentiometers are still an extremely popular component in common use across applications – but in today’s devices, they aren’t the knobs to which we’re accustomed. They are tiny and controlled digitally by the press of a button or the touch of a control surface. Just know that whenever you slide the volume up, you’re influencing an intricate system of parts and directly interacting with the signal itself – how cool is that?!
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