Preamplifier and Power Amplifier Guide: Understanding Audio Components
Preamplifier
A preamplifier consists of several amplification stages that raise the weak input signal from a source to a sufficiently high level.
Input Selector
The input selector adapts the preamplifier’s input to the specific characteristics of the selected audio source (analog or digital).
Preamp Adapter and Level/Impedance
This stage adapts the input level, impedance, and sensitivity to deliver an output signal with suitable amplitude for the main preamplifier input.
RIAA Preamplifier
This component amplifies the phono input signal and corrects the equalization applied during vinyl record production.
Signal Control
Electronic devices that modify the original audio signal by adjusting various parameters. These controls help eliminate or mitigate unwanted effects.
Tone Control
Allows modification of specific frequency bands to correct imbalances and compensate for acoustic differences.
Tone Control Canceller
Bypasses the tone controls for a flat frequency response.
Subsonic Filter
A high-pass filter that removes frequencies below 20 Hz.
Bass Filter
Affects the frequency spectrum between 50 and 80 Hz, reducing mechanical noise.
Treble Filter
Works with cutoff frequencies from 7 to 8 kHz, eliminating high-frequency noise.
Acoustic Compensator
Enhances bass and treble frequencies while maintaining a constant midrange level.
Volume Control
Controls the loudness of the speakers by adjusting the output signal amplitude.
Mute
Reduces the output noise level to a preset value.
Balance Control
Adjusts the power level of each channel for balanced sound.
Power Amplifier
Amplifies the input signal to a level suitable for driving speakers.
Speaker Protection Circuit
Protects speakers and output stages from damage during power-on.
VU Meter
Indicates the peak or average power level at the amplifier output.
Peak Detector
Indicates transient distortion peaks that are too short for the VU meter to detect.
Surround Sound Processor
Generates surround sound and handles multiple analog and digital inputs and outputs.
Specifications
Input Sensitivity
The input signal level required to produce maximum output power.
Input Impedance
Linked to the input signal level, ensuring proper amplifier excitation.
Output Level
Specifies output levels for preamplifier, recording, and headphone outputs.
Output Power
The maximum power the amplifier can deliver to a load.
Continuous Power
The sustained output power at a specified impedance and frequency range, with a defined total harmonic distortion.
Music Power
The maximum short-term power output before reaching a specific distortion level.
Peak Music Power
The absolute maximum power output, regardless of distortion or duration.
Power Bandwidth
The frequency range where the amplifier maintains 70% of its total power with minimal distortion and a maximum 3dB drop in output level.
Total Harmonic Distortion (THD)
The ratio of harmonic distortion to the pure fundamental signal.