Every audio system needs amplification. In a traditional hi-fi set-up, loudspeakers are often “passive”—that is, they do not generate their own power. Instead, they must receive an amplified audio signal from an external source, appropriately called amplifierto do their thing. Even with more modern, self-contained audio systems (eg Sonos 100 erafor example), the drivers that produce the sound must be strengthened to work—it all happens in a singular box rather than across the hi-fi separation.

But if you’ve heard of amplifiers, you’ve probably also heard of preamplifiers (often called “preamps”) and wondered where they fit into an audio system, and if you need them. Let’s answer those questions, shall we?

What Does a Preamp Do?

An audio signal needs a lot of attention before it’s ready to be amplified—so ultimately the question “what does a preamp do?” largely covers its own response. A preamplifier takes care of everything that needs to be done before the audio signal (sent from the music source) is amplified and sent to the system. speakers.

In a self-contained audio system like the Sonos speaker, the preamplifier and the amplifier are in the same enclosure, along with the speaker drivers that actually deliver the sound. Even in a more sophisticated hi-fi separate setup, the preamplifier side of the proceedings is still often managed out of sight, inside the amplifier. These types of amps are known as “integrated amplifiers” and have both preamp and amplifier functionality.

However, some people prefer to separate this function, which is when you find a preamplifier as its own piece of equipment, paired with a power amplifier. In these cases, the preamplifier allows you to choose the source of the music you want to hear (most have a choice of input options to support a system with multiple sources), and also set and adjust the volume.

The preamp also ensures that the audio signal is at the “level line” – that is, the basic voltage strength of an audio signal transmitted between components – and sends it to be amplified, ready to be transferred, finally, to the speakers.

Does an External Preamp Improve Sound Quality?

Hi-fi orthodoxy says that the individual functions of any system should be kept as separate as possible if the best results are to be achieved. The thinking goes that, by keeping electrical activity as shielded and self-contained as possible, the audio signal has the best shot at remaining as pure and uncolored as possible.

By dividing the preamplifier and the amplifier function into separate boxes, there should be a reduction in electrical noise and interference around the signal compared to all of them being contained in one box.