An audiophile uses several different tools to improve the sound quality of their audio system, especially if their sound is connected to their home theater system. This could mean getting a new record player with hi-fi options, increasing the amplification of the speakers, or using a phono input to bring your vinyl turntable’s sound to the line level. With analog-vinyl playback, upgrading your turntable’s audio is just as important as making sure you spend time cleaning records before playing them.


What is Phono Input?

A phono input is an audio input that can be found on a preamplifier, an amplifier, or a stereo receiver. This type of audio connection accepts signals from analog turntables, which boosts and adds RIAA equalization to recreate the original sound. These records are recorded with the higher frequencies increased and lower frequencies reduced, but during playback, the frequency response is reversed to reduce audible background noise. Most A/V receivers also have this type of input to increase the number of sound options available.


Think of it this way: similar to how you might use an HDMI input to improve on the video quality available through an RCA connection, the same quality upgrade is possible with modern audio inputs. To improve audio quality over what’s available using a line input, using a phono input will bring a more high-fidelity sonic experience when listening to vinyl records on a turntable.


Phono Preamp vs Line Connection

pre box phono input preamp

A phono preamp, which is often referred to as the phono stage, is the audio system required when listening to music on a turntable that you’ll be outputting to a pair of speakers. The voltage level for this type of signal will vary based on the type of cartridge that your record player uses. 


Moving Magnet cartridges (MM) are found on most turntables that you can purchase in mainstream music stores. Pro-Ject’s Essential III uses Moving Magnet cartridges, but many audiophiles prefer to spend more on a turntable with a Moving Coil cartridge (MC) because the needle can read the grooves in the vinyl more accurately. 


With that being said, the signal level of an MC cartridge is much weaker, which is why you need to amplify the sound using a phono audio source. Since there is such a difference in the signal level of these two cartridges, some phono preamplifiers will allow you to switch between cartridge types, while others are only designed to work with one kind.


There are even more differences when you compare phono and line signals. Some of the main differences to consider include:


RIAA Equalization

Records are carved with bass frequencies reduced and treble boosted to take up less space on the record. This creates a flat frequency response that is easily equalized with the phono stage. If the record is played using a line output, the frequencies switch. When using a phono output, RIAA equalization from the preamp is needed to round out the sound.  


Signal Levels 

Whether you listen to music from a CD player or streaming music to your Bluetooth speakers, the analog output when using a line signal level will be 0.316 Volts. This never changes with this type of output, but when using a phono output, the signal level tends to be much weaker and varies based on the type of cartridge that you are using. Signal levels for a phono output will range between 0.0002 Volt and 0.007 Volt. 


Built-In Phono Input vs External Preamp

phono preamp
Turntable with phono preamp

By now, you’ve probably seen devices that include an internal preamp, and while these may sound ideal and space-saving, there are a few reasons to keep the phono preamp separate from your vinyl turntable. Before we get to that, it’s also important that you understand that an audio interface will contain a preamp that will boost your phono line signal before it reaches the amplifier stage. This is critical if you want to boost the weak signals produced by turntables and improve sound quality before it’s amplified out to the speakers.


One of the main reasons that you’ll want to keep the amplifier and preamp separate is noise. When you have a preamp housed within the body of an integrated unit, the device’s internal noise will almost certainly impact the sound quality of the signal that’s being processed by the preamplifier. Generally speaking, all preamplifiers add noise to the weak signal, but with an internal preamp, you’re most likely to have more noise than you would with an external unit.


Secondly, when you’re working with an integrated unit, you can expect some corners to be cut to make the device more compact. Instead of housing the preamp in a dedicated device, manufacturers looking to integrate the functionality will almost surely use cheaper components. This means that the capacitors, resistors, and circuit boards won’t do as well of a job amplifying your turntable’s signal to line level as one with better internal components. As a rule, standalone units will have better components that will transmit and amplify sound better.  


So, are there advantages to an internal preamp? Well, one of the chief benefits of one of these types of integrated turntables is convenience. With a turntable with a preamp, you can send music out to the amplifier immediately without a huge amount of signal loss. Additionally, purchasing a turntable with a built-in preamp means that you’ll be saving cash compared to buying a turntable and an external preamp.  Still, if you’re an audiophile looking for sound quality, go external.


Pros and Cons of Internal Preamps

Pros Cons
  • Space-saving
  • Cheaper on average
  • Immediate playability
  • Typically cheaper components
  • Reduced audio quality
  • Tendency to pick up extra noise


Phono Preamps and Amplifiers

Both of these components are extremely important when using a vinyl record player. Similar to the frequencies generated by a microphone, turntables tend to have a fairly weak signal that must be boosted before reaching the amplifier stage. Phono preamps are positioned near the start of the signal chain so that the weak signal is preamplified to the line level before the amplifier can process it.


Amplification of the phono line signal can be done in multiple ways. For example, some standard wired technologies include RCA or XLR connectors that connect directly from the amp to the speakers. Some amplifiers use internal Bluetooth adapters to send out a signal to the speakers for those who prefer a more wireless profile. In any situation, the signals being processed by the amplifier have to be at line level so that sound quality sounds balanced and not washed out. 


For those seeking a more lossless amplification experience, it’s suggested that you seek out an amplifier that uses Bluetooth 5.0 or above. This will improve the data transmission speed and ensure that more of the data reaches your wireless speakers. Bluetooth technology at this level will also have a larger wireless range; in fact, 5.0 will reach devices that are 800 feet away from the amplifier.


Take your Stereo System up a Notch


Using a phono input is absolutely critical if you’re using a vinyl turntable. With one, much more of the warmer tones inherent in vinyl will make it through the audio chain to your speakers. Fortunately, it’s a relatively simple process to find the phono stage that will fit your audio needs as well as the needs of your budget.