What's the Difference Between Phono and Line?

Analog audio, like vinyl players and turntables, still has many loyal enthusiasts. If you're one of those, the chance is that you plugged cables into the wrong slot at least once.

At the rear of analog players and speakers, there are usually two ports that look the same in format but have different labels. They're called "phono" and "line."

Both serve the same function: sending the sound to a speaker. However, phono and line work very differently.

What Is Pre-Amplification?

On a turntable or similar player, the sound embedded into the record is decoded by the reading cartridge. This generates an electric signal transmitted to the speakers, which then play back the recording.

However, the signal is very weak, at around 0.005 volts. For it to be properly played, it must be amplified by around 60 times, reaching the "line level." That's where the difference between pre- and post-amplification comes in.

Pre-amplified signals are, as the name suggests, amplified before the wired transmission. Post-amplification means the signal travels in its weaker form and is amplified later, at the destination (like speakers or headphones) or with dedicated equipment, called amplifiers.

What Is Phono?

When plugged into this port, the turntable produces a signal with low voltage, and an external phono preamplifier or amplifier with a phono stage is needed. Many modern turntables have a built-in phono preamplifier to boost the signal, allowing for a direct-to-speaker connection through a line input.

Nowadays, phono is mostly available on stereo systems specifically made to play vinyl records. That way, the listener can use an amplifier of their preference. But connecting a line-only speaker to a phono output results in inaudible sounds plagued by distortion.

What Is RIAA Equalization?

One crucial aspect to understand when discussing Phono outputs and turntables is the role of RIAA equalization. RIAA stands for the Recording Industry Association of America, who established a specific curve, or standard, for equalization in vinyl records.

When a vinyl record is created, the audio signal is modified by an equalization process. This process involves reducing (attenuating) the low frequencies and boosting (amplifying) the high frequencies. This is done for several reasons, including overcoming limitations in the vinyl format, increasing the playback time, and reducing the amount of physical space the grooves take up on the record.

However, this altered signal must be returned to its original form to properly reproduce the music as it was intended to be heard. That's where the RIAA equalization comes into play during playback. The phono input on an audio device (or a standalone phono preamp) applies the reverse of the curve used during recording, boosting the low frequencies and attenuating the high frequencies, returning the audio signal to its original form.

Therefore, when connecting a turntable to an audio device, the device must have a phono input with RIAA equalization if the turntable doesn't have a built-in preamp with RIAA equalization. Without this equalization process, the audio from a vinyl record will sound thin and shrill, with an overemphasis on the high frequencies and a lack of bass.

This highlights the importance of correct connection and the different requirements for phono and line signals.

What Is Line?

Line is used for everything else. Modern record players are pre-amplified, so the speakers don't need to actively enhance the signal. In that case, the line port is used.

However, if you want (or need) to use phono-compatible speakers, that port will also be there. Both inputs use the RCA format, so the same cable can be used for either phono or line connections.

Line or Phono: Which Should You Use?

Nowadays, the best record players and speakers usually have both ports available—many use a single port or embedded RCA cable, with a physical switch between the modes. To play vinyl records, use either one, as long as the cable is connected to the same slot type in the player and the speaker. So, connect a phono output with a preamp direct to a speaker with a phono input or a phono output without a preamp to an external amp, then the speaker, and so on.

Turntables that support phono and line outputs sometimes have a switch that allows you to toggle between both options.

Other sound sources also require a pre-amplified signal. That means CDs, tapes, digital audio, and everything else that can be played through speakers. These audio sources demand a line connection and should be connected to a line input and output, as they already produce a line-level signal.

Also, the setup is slightly more complicated if you prefer to use an amplifier of your choice. The turntable should use the phono output, which will be plugged into the amplifier's phono input. Then, a cable from the amplifier's line output should be connected to the speakers' line input.

Finally, older speakers and turntables may have no line connection. The sole option is to use the phono port, which may be unlabeled in these older devices or simply called "Out" at the player and "In" on the speaker.

Line and Phono Are Similar but Not the Same

Once deemed dead, vinyl records were never gone, and in the past couple of decades have made a significant comeback. Many turntables these days leave nothing to be desired compared to other players, featuring CD drives, USB ports, and even wireless connections.

Both vinyl makers and fans know the value of good, time-tried tech. Therefore, even if the players feature line ports for modern audio sources, having a phono connection allows one to use that decades-old speaker that still rocks like new. That's what vinyl is about, after all.

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