Question: What is the difference between a phono preamplifier and a power amplifier?
Answer: There are distinct differences between a phono preamp and a power amplifier, and they perform different duties. Both are needed in the signal chain between a turntable and speakers. Traditionally, the RIAA phono preamp and the power amplifier were both built into a stereo receiver. When turntables became “out of style,” stereo receiver companies stopped integrating them into their products. Therefore, Audio-Technica put the phono preamp inside of (most of) our turntables for ease of use. The RIAA phono preamp in the turntable may also be removed from the signal chain if you want to use an external phono preamp.
The RIAA phono preamp is required in-line when listening to most records as it serves two major functions. One is to take the very low voltage that is produced by the phono cartridge (typically 0.005 volts and often referred to as “phono level”) and raise it up to 0.3 volts (often referred to as “line level”), which is the level of most stereo input signals.
The second function of the phono preamp is to add in the RIAA EQ correction. In the 1950s, the Recording Industry Association of America (RIAA) introduced an equalization standard that could be applied to the original audio as it was pressed into a record. This equalization, which continues to be used to this day, reduces low frequencies and boosts high frequencies, thereby compressing the audio so that more of it can fit on a record. During playback, the exact opposite function is performed through an RIAA phono preamp, resulting in the reproduction of the original audio.
The power amplifier, on the other hand, is used to drive the speaker components. Nowadays, some speakers, typically referred to as “powered speakers” or “active speakers,” have their own internal power amplifier. This allows you to connect the turntable directly to the powered speakers. For “nonpowered speakers” or “passive speakers,” a power amplifier is required in the signal chain. Power amplifiers are still integrated into stereo receivers. Additionally, standalone power amplifiers may be used if all the functions of a stereo receiver are not required. There is helpful information on the internet for properly matching up a power amplifier with your speakers. You will want to properly match them as you do not want a power amplifier that is too weak to drive your speakers nor one that is so powerful that it might damage your speakers.
If you have additional questions about using an Audio-Technica turntable, please contact the Audio Solutions Team for assistance.