Amplifiers
1920s onwardsA cartridge produces thousandths of a volt. A speaker needs volts and real current. The amplifier bridges that gap — and because everything passes through it, its character is on everything you hear.
What it actually does
An amplifier does not make the signal bigger in the way a magnifying glass makes print bigger. It uses the small incoming signal as a set of instructions for how to shape a much larger flow of power drawn from the mains.
That is why a good power supply matters so much. The music you hear is, quite literally, mains electricity being sculpted into the shape of the input signal — and an amplifier that cannot deliver current quickly enough will run out of headroom exactly when the music gets demanding.
Valves and transistors
Valve amplifiers came first and dominated until the 1960s. They tend to distort gradually as they are pushed, adding harmonics that many listeners find pleasant, and they run hot and need periodic replacement.
Transistors are efficient, cool, cheap to make and capable of far more power. Early solid-state designs earned a reputation for hardness — partly because when they do run out, they clip abruptly rather than softening.
The disagreement between the two camps is now sixty years old and shows no sign of resolving, which is usually a sign that both sides are describing something real.
Integrated, pre and power
A preamplifier selects the source and controls volume. A power amplifier does the heavy lifting. An integrated amplifier puts both in one box, which is what most people own.
Splitting them lets each be optimised and keeps the sensitive low-level circuitry away from the heat and magnetic fields of the power section. It also doubles the number of boxes, cables and decisions.
A receiver adds a radio tuner to the same chassis — for many households in the 1970s, that one box was the entire system.
Why watts mislead
Loudness does not scale with power the way people expect. Doubling the watts produces a modest increase in perceived volume, which is why a 100-watt amplifier does not sound twice as loud as a 50-watt one.
Speaker sensitivity often matters more. An efficient speaker can go louder on ten watts than an inefficient one does on a hundred. Matching amplifier to speaker is the real skill; the number on the front panel is the least useful part of the specification.
Names that mattered
Listed because of what they did, not as recommendations. Velorex Music did not make any of these.
Did you know?
- Perceived loudness roughly doubles for about a tenfold increase in power, not a doubling.
- A phono input is not just a louder line input — it applies a standard equalisation curve without which records sound thin.
- Most amplifiers spend nearly all their life delivering a fraction of a watt; the rated power is headroom for peaks.
- Valve amplifiers need a speaker connected before being driven hard — an unloaded output transformer can be damaged.
Remember this?
The amplifier was the piece you saved for, and the one with the physical controls worth touching: a heavy volume knob with a little resistance in it, a row of switches that clicked, and a faint warmth on the top panel after an evening.
Sources & further reading
- IEEE ETHW — Stereophonic Sound
- Audio Engineering Society — A History and Evolution of the Recording Studio
Written from these sources, not copied from them. External links open in a new tab.