How Does A Phono Preamp Work? A Comprehensive Guide

Vinyl records have made a comeback in recent years, and with that comes the need for a phono preamp.

But what exactly is a phono preamp and how does it work?

In this article, we’ll dive into the world of phono preamps and explore their purpose, components, and benefits.

Whether you’re a seasoned vinyl enthusiast or just starting out, understanding how a phono preamp works is essential for getting the most out of your turntable.

So sit back, relax, and let’s explore the world of phono preamps together.

How Does A Phono Preamp Work

At its core, a phono preamp is an electronic device that amplifies and equalizes the analog output of a turntable’s cartridge. The output is boosted to a level equivalent to other audio sources such as tapes and CDs, and RIAA equalization is required to restore the original signal.

The purpose of a phono preamp is to ensure that the tiny signal generated by the stylus can be properly amplified and played through a sound system. Without a phono preamp, the signal would be too weak to produce any meaningful sound.

The components of a phono preamp include a set of magnets, coiled wires, and a vibrating cantilever. The vibrating cantilever is connected to the magnets, which then vibrate in close proximity to the coiled wires. The tiny magnets positioned between the two coils vibrate and produce a small electrical current.

The preamp performs a crucial process in the phono audio chain. Instead of just being an added-on component that helps your system run smoothly, it actually shapes your turntable’s performance and ensures it is able to work with the rest of your system.

There are two main types of cartridges used in turntables: moving magnet (MM) and moving coil (MC). Moving magnet cartridges have a magnet attached to the needle, which moves inside a surrounding coil of wire. Moving coil cartridges have the opposite configuration, with the coil riding on top of the needle surrounded by a magnet.

Due to their smaller parts and greater precision, moving coil cartridges tend to be more expensive compared to moving magnet cartridges. The primary difference between the cartridge types is that moving coil cartridges have a much lower output voltage compared to moving magnet cartridges, so they require a higher level of amplification before input to your amp.

Phono preamps are designed to work with both types of cartridges, but it’s important to match the correct preamp to your turntable.

What Is A Phono Preamp?

A phono preamp, also known as a phono stage, is an essential component in a turntable setup. Its primary function is to amplify and equalize the analog output of the cartridge in a phonograph turntable. The output is boosted to a level equivalent to other audio sources such as tapes and CDs, and RIAA equalization is required to restore the original signal.

Without a phono preamp, the signal from the turntable’s cartridge would be too weak to produce any meaningful sound. A phono preamp ensures that the tiny signal generated by the stylus can be properly amplified and played through a sound system.

There are different types of phono preamps available in the market, including built-in ones in some hifi amplifiers and external ones for units without phono inputs or for audiophiles who want the highest-quality restoration. External phono preamps are also used for turntable-to-computer applications.

The components of a phono preamp include a set of magnets, coiled wires, and a vibrating cantilever. The vibrating cantilever is connected to the magnets, which then vibrate in close proximity to the coiled wires. The tiny magnets positioned between the two coils vibrate and produce a small electrical current.

The Purpose Of A Phono Preamp

The purpose of a phono preamp is to amplify the tiny signal generated by the stylus and to re-equalize the signal. The signal from a turntable cartridge is very weak, and it needs to be amplified up to several hundred times its size before it is loud enough for your amplifier to work with. The phono preamp also applies an equalization curve to inverse the standard frequency adjustment made during the record cutting process. This is necessary because when record grooves are carved, the bass is reduced to save space on the record. The phono preamp amplifies the bass and decreases the treble to correct this and create a good listening balance.

Without a phono preamp, the signal from your turntable would be too weak to produce any meaningful sound. A phono preamp ensures that your turntable’s performance is properly shaped and that it can work with the rest of your system. It is an essential component in any turntable setup, and it plays a crucial role in ensuring that you can enjoy your vinyl records to their fullest potential.

It’s important to note that while some amplifiers have built-in phono preamps, these are often outperformed by external phono stages. External phono preamps have their own power supply and better shielding from interference, which can result in better sound quality. Additionally, it’s important to match the correct phono preamp to your turntable, as different cartridges require different levels of amplification.

Components Of A Phono Preamp

A phono preamp consists of several components that work together to amplify and equalize the analog output of a turntable’s cartridge. These components include a set of capacitors, resistors, and transistors.

The first component is the input stage, which receives the signal from the turntable’s cartridge. It is responsible for amplifying the signal to a level that can be further processed by the preamp.

The second component is the equalization stage, which applies the RIAA equalization curve to the amplified signal. This curve is necessary to restore the original signal that was recorded on vinyl.

The third component is the output stage, which further amplifies the signal and prepares it for input to a sound system. This stage also includes a volume control, which allows you to adjust the level of the output signal.

Another important component of a phono preamp is its power supply. A high-quality power supply ensures that the preamp operates with minimal noise and distortion.

Finally, some phono preamps include additional features such as switchable gain settings, adjustable impedance settings, and subsonic filters. These features allow you to customize the sound of your turntable to match your personal preferences and the characteristics of your sound system.

Moving Magnet Vs. Moving Coil Cartridges

When it comes to choosing between moving magnet and moving coil cartridges for your turntable, there are a few key differences to consider.

Moving magnet cartridges are generally heavier and have greater inertia, which can make them less effective at tracking high-frequency content. This means that some listeners may feel they lack transient detail. However, moving magnet cartridges are more robust and produce a medium to high output level, which requires less gain in the phono stage to amplify the sound. They are also typically more compatible with a wider range of household stereo equipment, making them an easier choice for installation. Moving magnet cartridges often come with a replaceable stylus, making it easier to swap out or replace the stylus as needed.

On the other hand, moving coil cartridges are preferred by audiophiles because they use far less moving mass. This makes the stylus and cantilever more nimble in the record groove, allowing it to reach more of the surface area and react accordingly. Moving coil cartridges also have a lower output voltage compared to moving magnet cartridges, which requires a higher level of amplification before input to your amp. However, they tend to have a lower noise floor and better noise characteristics due to their low signal level. Moving coil cartridges are also more precise and create a more delicate sound, but they are more expensive to manufacture and maintain due to their smaller parts and greater precision.

When choosing between moving magnet and moving coil cartridges, it’s important to consider your budget and specific needs. Moving magnet cartridges are generally more affordable and easier to install, while moving coil cartridges offer greater precision and sound quality but come with added expenses for manufacturing and maintenance. Ultimately, the choice between the two comes down to personal preference and what works best for your turntable and sound system.

The Benefits Of Using A Phono Preamp

There are several benefits to using a phono preamp in your audio system. First and foremost, it ensures that your turntable’s signal is properly amplified and equalized, resulting in a higher quality sound output. Without a phono preamp, the signal from your turntable would be too weak to produce any meaningful sound, and the RIAA equalization curve would not be applied, resulting in a distorted sound.

Additionally, using an external phono preamp provides better shielding from interference and its own power supply, which eliminates the need to share power with other components in your audio system. This results in a cleaner and more stable signal, which translates into better sound quality.

Furthermore, using a phono preamp allows you to connect your turntable to any sound system that doesn’t already have a turntable in mind. This is particularly useful if you want to connect to an active set of speakers or any other sound system that doesn’t have a built-in phono preamp.

How To Choose The Right Phono Preamp For Your System

Choosing the right phono preamp for your system can be a daunting task, but it doesn’t have to be. The first step is to determine what type of cartridge your turntable uses. If you have a moving magnet cartridge (MM), then you will need an MM phono preamp that is compatible with this type of cartridge. Most preamps are compatible by default, but it’s always a good idea to double-check.

If your system features a moving coil cartridge (MC), then you will need a phono preamp that is compatible with low output cartridges. Many manufacturers offer MM/MC phono preamps, which offer both options in a single device. This type of phono stage is versatile and can facilitate possible changes of the cartridge. For example, if you wanted to upgrade your MM cartridge later on by an MC cartridge, you will not necessarily be obliged to change your phono preamp.

It’s important to note that moving magnet cartridges have high output voltage, typically in the range of 4-8 millivolts, while moving coil cartridges have much lower output voltage, typically below 2.5 mV. As a result, the gain settings on your phono preamp will need to be adjusted accordingly. A setting of 40 dB is a good place to start for high-output cartridges like moving magnet cartridges, while higher gain settings (60 dB or higher) are for low-output moving coil cartridges.

Your budget and existing system will also play a role in choosing the right phono preamp. If you have an entry-level hi-fi system with a budget turntable and moving magnet cartridge, then an affordable phono stage that’s simple to use and is compatible with your cartridge is all you need. However, if you’re a hi-fi enthusiast with a premium turntable and enjoy fine-tuning your system and swapping out different MM and MC cartridges, then you’ll want a phono stage with plenty of flexible cartridge loading and gain adjustments to suit your matching high-end system.

Ultimately, the key is to choose a phono preamp that is compatible with your turntable’s cartridge and offers the necessary gain adjustments for optimal sound quality. It’s always worth demoing your new phono preamp with your existing deck and system if possible, to ensure you get the best-sounding performance when spinning your vinyl records.