In recent years, vinyl has made a resurgence. People who have never used a turntable may expect it to play without a phono preamplifier.
A phono preamplifier, also known as a phono stage, amplifies the signal from your turntable to a level which enables you to connect it to your sound system like any other audio source.
The turntable signal is generated only by the movement of the stylus in the grooves of a record.
The grooves on a record are not big, so when the record is spinning, the stylus does not move more than a tenth of a millimeter in the groove. As a result of that the electric current generated is also not very big.
Phono Preamplifiers boost these tiny currents up to a level that your sound system would expect from any playback device like a streamer or DVD player.
The Revolver Club Phono Pre-Amplifier Recommendations and Comparsion Table:
Rega Fono Mini A2D
Adjustable Gain Level
Best Budget Phono Pre-amp with USB
Pro-Ject Phono Box Classic
MM: 47 Ω
MC: 100 Ω
40dB - 60dB
Best Overall Budget Phono Pre-amp
MoFi Studio Phono
MM: 47K Ω
MC: 75 Ω - 47K Ω
40dB - 60dB
Switchable Mono Mode
Best Feature Set Phono Pre-amp
Rega Fono MM MK5
Best Value MM Phono Pre-Amp
Rega Aria MK3 MC
Best Value MC Phono Pre-Amp
The Components of a Phono Pre-Amplifier include:
RIAA Equalization Circuit: The RIAA equalization circuit of the phono preamp inverses the RIAA curve, and restores the original frequency response of the recorded audio.
Input Capacitance and Impedance Settings: Some phono preamps allow you to customize these settings to your cartridge's requirements, for performance and compatibility
Gain Stage: The gain stage amplifies the low-level signal from the turntable's cartridge.
Grounding: Phono preamps have a grounding connection that reduces the noise and hum caused by ground loops.
Phono Equalization Selection: Certain phono preamps have selectable equalization curves that support various record formats like older mono records or records with non-standard equalization.
Power Supply: A power supply is required for the phono preamp to function. It can be powered by an external power adapter, batteries or an in-built power supply.
Output Stage: The amplified signal is prepared for further amplification by a power amplifier or receiver at the output stage.
Different Types of Phono Amplifiers:
1. Moving Magnet Phono Preamplifier:
A moving magnet phono preamplifier or 'MM phono stage', is specifically designed to amplify the signal created by moving magnet cartridges, which are typically found in turntables.
MM cartridges are one of the most commonly used and affordable cartridge types in vinyl playback.
The MM Cartridge generates an electrical signal through the movement of a tiny magnet attached to the cantilever within the cartridge.
2. Moving Coil Phono Preamplifier:
A moving coil phono preamplifier or ‘MC phono stage’, is designed to amplify low-level signals produced by moving coil cartridges, Moving magnet (MC) cartridges are designed and operated differently than moving magnet (MM) cartridges.
Because MC cartridges are more sensitive and precise in their sound reproduction, they offer superior fidelity and accuracy than MM phono preamps. It should be noted that MC cartridges are costlier than MM cartridges.
3. Adjustable Gain Phono Preamplifier:
Adjustable gain phono preamplifiers allow you to change the amplification level of the input signal from your turntable's cartridge. This feature supports various cartridge types, and enhances the signal-to-noise ratio, and helps you get the ideal volume level.
Technical Specifications and Features To Look Out For:
RIAA Equalization Curve:
The RIAA equalization circuit in phono preamplifiers applies the inverse of the RIAA curve, It returns the music to its original frequency response before it is amplified and supplied to the power amplifier or receiver.
While it is the most commonly used standard, there are different kinds of equalization curves that may be used for certain record formats or playback preferences, such as mono recordings or records with non-standard equalization.
In a phono preamplifier, the signal-to-noise ratio or SNR, refers to the measurement of the desired audio signal level vs the level of background noise produced during the amplification process.
A higher SNR is preferred since it indicates cleaner and more accurate audio signal reproduction.
Total Harmonic Distortion:
The amount of distortion fed into an audio stream by a phono preamplifier is measured as Total Harmonic Distortion (THD). It quantifies the level of harmonic components in the output signal when compared to the original input signal.
THD can have an impact on the fidelity and clarity of the sound reproduced from vinyl records. A phono preamp should ideally have minimal THD to minimize the introduction of additional harmonic components and retain the audio signal's quality.
Input Impedance & Capacitance:
The electrical resistance that the phono preamplifier presents to the turntable cartridge is referred to as input impedance. It should match the cartridge's output impedance for best signal transfer and frequency response.
It is important to match the input impedance since it influences the interaction between the cartridge and the phono preamp. If the input impedance is too low, it might overload the cartridge, resulting in signal loss and changed frequency response.
If the input impedance is excessive, it might cause a mismatch and affect the damping characteristics and overall performance of the cartridge.
Moving magnet (MM) and moving coil (MC) cartridges have differing recommended input impedance values.
Capacitance refers to a system's ability to hold an electric charge. It impacts the frequency response and overall sound quality of your vinyl .
MM cartridges are sensitive to the capacitance seen at the input. The input capacitance range is included in the cartridge's specifications. If the phono preamp's input capacitance deviates greatly from the cartridge's recommendation, the frequency response and sound quality will be affected.
Grounding & Hum issues:
Grounding serves as a reference point for the electrical circuitry, allowing it to operate in a stable and interference-free manner. When grounding isn't done properly, it can cause a variety of issues, including hum and noise in the audio signal. Loose connections, improper turntable grounding, and ground loops are all examples of grounding issues.
Hum is a low-frequency noise that is heard as a persistent buzzing sound. Electronic interference, ground loops, and poor shielding can all generate hum.
It’s Important to read manufacturer specifications to choose the correct phono pre amplifier to go along with your cartridge for the above mentioned features.
How To Resolver Grounding & Hum Issues?
Reduce Ground Loops: Use high quality grounding techniques like star grounding or ground loop isolators
Ensure Proper Grounding Connections: Ensure all grounding connections are secure and properly connected, including the turntable's grounding wire.
Isolate Electrical Sources: Keep the phono preamp away from other electrical devices and cables as that can cause electrical interference.
Use A Separate Power Outlet: Plug the phono preamp and other audio equipment into different power outlets to minimize electrical interference.
Improve Shielding: Use shielded cables and place the phono preamp away from sources causing electromagnetic interference
Choosing The Right Phono Pre Amplifier:
1. Right Phono Preamp for the Right Cartridge:
As mentioned earlier, the phono preamplifier should be purchased according to the phono cartridge on your turntable. MM Cartridges require MM Phono Preamps, MC Cartridges require MC Phono Preamps.
Today, many manufacturers offer MM/MC in one phono preamp. This type of phono stage is versatile and you can easily change the cartridge from MM to MC as per your requirement.
2. Technical Characteristic Standards:
MM phono preamps generally feature a gain of around 40 dB, with a resistive load of 47,000 ohms, and a capacitive load of 100 pF. This value can be adjusted on higher end preamps (0 - 500 pF).
MC phono preamps feature a minimum gain of 58 dB, as well as the possibility of adjusting a resistive load of between 50 and 1,000 ohms.
The precision and quality of the RIAA curve also justifies the price of the phono preamplifier.
3. Choosing The Right Phono Preamp For Your Turntable:
If you already have an amplifier with a phono input, you may not need a phono preamplifier. But in the case it does not satisfy your expectations in sound quality, you can add a phono preamp to your setup.
It helps you unlock your turntable’s complete potential.
Similarly, If you have a USB/digital turntable with an integrated RIAA preamp, you will not need to add a phono preamp to your system, but in this case, you can’t upgrade to a better phono preamp.
However, there are exceptions. The phono preamp integrated in the Audio Technica AT-LP120X vinyl turntable can be disabled. This gives you the option to upgrade to a better phono preamp if you require.
Placing Your Phono Pre-Amp:
Try to place your phono preamp in an open area to ensure maximum ventilation. They generate heat and if kept in a restricted space, heat build up can affect its functioning.
Consider factors like cable reach and accessibility to make setting up and cable management easier.
Along with these, you can refer to the previously mentioned grounding and humming solutions to find the right spot to place your phono preamp.
Phono preamps are recommended for anybody seeking to create a top-notch high-fidelity sound system.
However, if you are new to being an audiophile and are in the early stages, a phono preamp may not be essential. In such cases, it may be more beneficial to invest in a receiver with phono signal amplification capabilities or a turntable that already has a built-in preamp. Nonetheless, if your goal is to achieve the utmost audio quality, an external phono preamp is undoubtedly the best choice.
Built-in phono preamp specifications don’t compare even with low end phono preamps. If you want to make the most of your Hi-Fi setup it’s always best to add a phono preamp.
Some USB Turntables have ceramic cartridges which not only give you poor sound quality, but can also wear your records.
Purchasing a more expensive preamp will generally result in improved performance and sound quality. However, it's important to consider that additional features such as microphone inputs or a power switch may vary in usefulness depending on individual needs. It is advisable to buy only the features that are necessary for your specific requirements.