With the great vinyl resurgence that the world is going through right now – even in the 2020 lockdown where this year’s Record Store Day still brought people (and profits) together – the need to blend analog and digital tech together is essential.
Why is this? Well, for one, a turntable doesn’t work like other plug and play devices can. This means you can’t just connect your turntable into speakers or audio output devices like you’d be able to do with your phone, iPod, or an MP3 player. A vinyl playback setup needs something to amplify the very low signal that comes out of it.
What Is A Phono Preamp?
The audio signal coming from even the best record player turntables is around 1000 times lower than one coming from streaming devices or a CD player. The signal needs boosting in order to enjoy or just hear the music or sound from the turntable. This is what a phono preamp does. The cartridge on the turntable finds the sound signal amplified with the help of the phono preamp.
If ever you’ve plugged in the turntable directly into an amp (the input is usually named aux or TAPE), you’ll have heard that the sound is incredibly tinny, and the signal is weak.
In fact, in most cases, a turntable isn’t even directly ready to be plugged into an amplifier. A phono preamp (also known as a phono stage, turntable preamp, or RIAA preamp) is the audio component that is required.
Phono preamps were, in fact, built-in to receivers and amps back when vinyl was the only format sound was played on (or the most popular). Amplifiers removed these when CDs became popular and overtook vinyl, leading to, ironically, an increased spotlight on the importance of phono preamps today.
What Is A Phono Preamp’s Function?
A phono preamp does two things: the signal is amplified to a level that suits the amplifier’s standard AUX input, and it also equalizes the standard frequency adjustment that the vinyl cutting process employs by inverting it.
To understand the first point (about the signal) better, consider that the signal that the record cartridge produces is 1 mV – the required signal that the amp needs is 100 mV. A boost of ~50 dB is needed, which the phono preamp provides. It also equalizes the signal because a record is cut with the high frequencies boosted and the bass reduced, allowing for better sound quality, more durability, and longer playing times on the vinyl record. The equalization curve process equalizes the signal to bring it back to the frequency response of the master recording, as close as it can cut it, no pun intended.
Internal VS External Preamps
Some of the best phono preamps can be of either type: internal, or external.
Most turntables (or phonographs, hence the name phono preamp, where this preamp handles the pre-tuning before the signal is sent out by the amplifier) come with an internal phono preamp.
However, the ease of use and the reduced cost (of purchasing an external phono preamp and wiring it) is made up for by the lack of control that the user has over the music quality.
External phono preamps also protect you from interference and electrical noise, since they don’t share their power supply with the amplifier, shielding them from the noise that can potentially come from the power transformer.
However, the same thing can be considered a disadvantage, as you need an external power supply and cables and wiring.
This makes this a case of deciding between what you want and what your needs are. The trade-off will determine what product you buy.
What Is A Phono Preamp’s Required Quantity Level?
This is a vital point to note and an important clarification to close on. A higher-quality phono preamp will always work better than a cheaper one because the phono preamp not only amplifies the thin PHONO signals to LINE-level ones but also adjusts the turntable cartridge signal to minimize any distortion in the sound playback.
Thus, the quality of the phono preamp directly determines the quality of the sound you hear.