Forforsterker

Forforsterker, or preamplifier, is an electronic device that increases very weak electrical signals to a level suitable for processing by subsequent stages, such as a power amplifier or an audio interface. In audio systems, the preamplifier raises signals from sources like microphones, electric guitars, or line-level devices before they reach the power amp or recording equipment. The aim is to provide adequate gain with low added noise and to match impedances between stages.

There are several types of preamplifiers. Microphone preamps boost the very low mic-level signal and often provide phantom power for condenser microphones. Instrument or guitar preamps tailor the signal from pickups or pedals for further processing. Line-level preamps prepare signals at standard line levels for mixers or recording devices. Preamps can be active, requiring a power supply, or passive, using the source signal with little or no gain. They may include features such as gain controls, impedance matching, padding, and sometimes tone controls or equalization.

Key design considerations include input impedance, gain range, noise performance, dynamic range, and bandwidth. Valve (tube) preamps are valued for their harmonic coloration, while solid-state designs tend to be cleaner and more linear. Preamps may be standalone units, rack-mounted, or integrated into mixers and audio interfaces.

In practice, the preamplifier is typically the first gain stage in an audio chain, shaping signal quality before it is amplified for listening or recording.