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The Difference Between PHONO and LINE Explained

The inputs on my Denon PMA-1600NE receiver. Showing PHONO and LINE inputs.

The difference between PHONO and LINE is something that frequently causes confusion among new as well as experienced vinyl enthusiasts. So in this article, I will give you everything you need to know about PHONO and LINE.

As a start, let me give you the shortest answer I can give. After that, we’ll dig deeper into the differences.

What is the difference between PHONO and LINE?

There are two main differences between PHONO and LINE. Firstly, a PHONO signal is much weaker than a LINE signal. A PHONO signal is typically 0.005 Volt and a LINE signal is typically 0.3 Volt. Secondly, the lower tones (bass) of a PHONO signal is significantly reduced (RIAA equalized) while this is not the case for a LINE signal.

And, as many of us have experienced, if we connect a PHONO signal to a LINE input on a stereo receiver, the music will have almost no volume and sound very strange with no bass at all. This is due to the low signal level and the reduced bass of the PHONO signal.

PHONO and LINE Overview

The table below shows which kind of signal (and signal level) that is outputted from different kinds of audio sources.

SOURCEOUTPUTOUTPUT
LEVEL
CDLINE0.316 Volt
DVDLINE0.316 Volt
TAPE/RECLINE0.316 Volt
AUXLINE0.316 Volt
DIGITAL
STREAMER
(NETWORK)
LINE0.316 Volt
PC/LAPTOPLINE0.316 Volt
TURNTABLE
MM CARTRIDGE
PHONO0.005 Volt
TURNTABLE
MC CARTRIDGE
PHONO0.0005 Volt
TURNTABLE
WITH PREAMP
LINE0.316 Volt

As we see, all sources output a standardized LINE signal except for turntables without a built-in preamp. Which outputs a PHONO signal.

There are also two different typical voltage levels for a PHONO signal, depending on if there is a Moving Magnet or Moving Coil cartridge mounted on the turntable. The signal from a Moving Coil cartridge is even weaker than the signal from a Moving Magnet cartridge. We’ll look more into the different cartridge types later in this article.

PHONO and LINE Differences in Detail

Let’s dig a bit deeper into the matter and look at the two differences between PHONO and LINE in more detail.

1 Signal Level

A LINE signal has a standardized signal level that is 0.316 Volt RMS. So if you buy a DVD player from Sony, a CD player from Pioneer and a digital streamer from Bluesound, their analog outputs will all have the same signal level. 0.316 Volt.

The signal level of a PHONO signal, on the other hand, will be much weaker. And the PHONO signal level is not standardized. So it will vary from turntable to turntable depending on the type of phono cartridge used.

Phono Cartridge from Audio-Technica

Typical PHONO signal levels range from 0,2 mV (0.0002 Volt) for a very low output cartridge to 7 mV (0.007 Volt) for a high output cartridge. For most mainstream cartridges (and turntables) the PHONO signal level will be around 5 mV.

So a LINE signal is from 50 to 1500 times stronger than a PHONO signal. More or less.

2 RIAA Equalization

When a vinyl record is carved, the low frequencies (bass) are reduced and the high frequencies (treble) are boosted.

And when the record is played on a home stereo, the opposite happens. The low frequencies (bass) are boosted and the high frequencies (treble) are reduced.

So the net result is a flat frequency response. And this whole process is called RIAA equalization. This equalization process is taken care of by the phono preamp (phono stage).

The main reason why the bass is reduced and the treble is boosted when a record is made is that the lower frequencies have wider grooves and take up more physical space on a record. So to increase the recording time (number of songs) on a record, the bass is reduced to make the grooves narrower.

The result is that the PHONO signal outputted from the cartridge totally lacks bass and have way too much treble. This is then corrected by the RIAA equalizer inside the phono preamp or phono stage.

So a LINE signal has a flat frequency curve while a PHONO signal has reduced bass and boosted treble.

PHONO Preamp and PHONO Stage

We have now seen that a PHONO signal that is outputted from the turntable’s cartridge needs to be boosted and RIAA equalized to obtain the same signal level and flat frequency curve as a LINE signal.

This all happens in what is called a PHONO preamp or PHONO stage. Often referred to as just “preamp”.

In a home stereo that plays vinyl records, the preamp can be a standalone unit, or built into the turntable or into the stereo receiver.

FONO MINI A2D Standalone Preamp from Rega

If the preamp is a standalone box it has a PHONO input and a LINE output. It then connects between the PHONO output on a turntable and one of the LINE inputs on a receiver. (Or to the LINE input on a set of active/powered speakers.)

If the preamp is built into the turntable, the turntable will have a LINE output that connects to one of the LINE inputs on a receiver or on a set of active/powered speakers. Traditionally, turntables did not include built-in preamps, but this has become more common on affordable modern turntables. Modern higher quality turntables still come without a preamp built-in though.

And if the preamp is built into the stereo receiver, the receiver will have a PHONO input that connects to the PHONO output on the turntable.

A problem new vinyl enthusiasts often run into is trying to play records on a stereo that does not include a preamp at all. For example by connecting the PHONO output on a turntable without a built-in preamp to powered speakers or one of the LINE inputs on a receiver.

Playing records on a stereo without a preamp result in very low music volume due to the low signal level of the PHONO signal and a very strange sound as well due to the reduced bass and boosted treble.

So playing records on a stereo without a preamp will unfortunately not work at all.

If you have run into that situation, the solution is usually to buy a standalone preamp and hook it up to the stereo. Two good affordable options are the ART DJPREII Phono Preamplifier (Amazon link) and the Pro-Ject Phono Box MM (Amazon link). If you are picky on the sound quality I usually recommend the slightly more expensive award winning Rega FONO MINI A2D (Amazon link).

Or you can buy a new turntable with a built-in preamp. Feel free to have a look at our recommended turntables page to see which turntables we think are the best buys on the market today. Both with and without built-in preamps.

PHONO MM vs PHONO MC

The turntable’s cartridge that read the grooves in the record and transforms them to an electrical PHONO signal comes in two different versions:

1) Moving Magnet Cartridges (MM)
2) Moving Coil Cartridges (MC)

Standard mainstream (lower-end) turntables almost always come with a Moving Magnet cartridge. While the higher-end “stereophile” part of the market is dominated by Moving Coil cartridges.

So if you are not a hardcore vinyl and stereo enthusiast with a very expensive turntable and stereo, you likely have a turntable with a Moving Magnet cartridge.

The main reason why vinyl enthusiasts often prefer the more expensive Moving Coil cartridges is that MC cartridges have a lower moving mass which enables them to read the grooves in the records with more accuracy, speed and precision. Resulting in a better and more accurate reproduction of the recorded sound.

The MC cartridges produce a much weaker PHONO signal than the MM cartridges. As you can see in the table below.

Cartridge Type Typical Output PHONO Signal Level
Moving Magnet (MM)5 mV (Range from 2 mV to 8 mV)
Moving Coil (MC)0.5 mV (Range from 0.2 mV to 1.5 mV)

As the PHONO signal from a MC cartridge is usually much weaker than the PHONO signal from a MM cartridge, a MC PHONO signal needs more amplification (gain) than a MM PHONO signal to reach the standard LINE signal level of 0.316 Volt.

To solve this, preamps and phono stages often have a switch to choose between MC and MM cartridge. The picture below shows how this looks like on the PHONO input on the receiver I use with my stereo. When the switch is set to MC the built-in phono stage will boost the signal more than when the switch is set to MM.

MC/MM Switch for PHONO

There are, however, also common for a preamp to be designed to suit only one of the two cartridge types. So when buying a standalone preamp it is important to check that is supports the cartridge type you use. Or if it includes a switch to choose between MC and MM.

There are some high-output type MC cartridges on the market that produces nearly the same signal level as a MM cartridge. But in general, a MC cartridge produces a much weaker signal than a MM cartridge.

Conclusion

As we have learned in this article, there are two main differences between a PHONO signal and a LINE signal.

First, the PHONO signal is weaker than the LINE signal and need to be boosted from 50 to 1500 times to reach LINE signal level.

And secondly, the PHONO signal has reduced bass and boosted treble and need to be RIAA equalized to reach the flat (neutral) frequency curve of the LINE signal.

We have also seen that the LINE signal has a standardized signal level of 0.316 Volt while the PHONO signal level varies between 0,2 mV and 8mV depending on the type of cartridge that is fitted to the turntable.

Sources

Wikipedia: LINE Level
Wikipedia: RIAA Equalization
Wikipedia: Magnet Cartridge

  • Tom
  • May 28, 2019