The Complete Handbook of Phono Preamps

Chapter 1: Understanding Phono Preamps

The vinyl revival brought thousands of people back to records, but it brought with it a degree of confusion about one small, crucial component: the phono preamp. It is not an optional luxury. It is not a magical device that makes records sound "warmer." It is a circuit with two very specific, mandatory jobs. If you don't understand those jobs, you cannot understand why your system sounds the way it does, and you have zero hope of properly troubleshooting or upgrading it.

The most common misconception about a phono preamp is that it is merely an amplifier. It is not. An amplifier takes a signal and makes a copy of it with a higher amplitude, generally preserving the shape of the original waveform. A phono preamp, on the other hand, doesn't preserve the signal shape. It is an equalizer and an amplifier, often called a phono stage or a phono equalizer. It applies a specific, fixed filter curve to the input signal. This curve is called the RIAA curve, and without it, a record would sound thin on the low end and dull on the high end, almost like a telephone call.

To understand why this is necessary, we have to understand the physical limits of the vinyl record. In the 1950s, when the long-playing record was being standardized, engineers were faced with a problem: how to get a long, loud, and durable signal onto a thin spiral of plastic.

If you were to cut