All about the microphone preamplifier!


Before choosing a good studio microphone, it’s also important to choose a good microphone preamplifier! This blog post is destined to explain what it will be used for and to give you some ideas to guide your choices according to your needs! Enjoy reading!

What is the best microphone preamplifier choice

If you were not satisfied with the sound quality of your old audio and video recordings, it means that you (perhaps) didn’t consider investing in a special microphone preamp. No matter what kind of microphones you’re going to use in your home studio, the use of a microphone preamp is a must to ensure that your audio output is clean and of much higher quality.

So you understand the interest of using a powerful microphone preamp in a recording studio. The real question now is what should be taken into consideration when choosing a microphone preamp.

It will also be necessary to be careful when choosing the type of microphone preamp to use depending on the type of recording to be made and especially on the sound quality that you wish to obtain. That’ s why we have written this guide.



What is a microphone preamplifier used for? 🤔

A microphone preamp is primarily used to amplify the sound signal delivered by a microphone (of any type) when performing a vocal or instrumental recording in a studio. The result is an audio signal of optimal quality that can be processed more easily via an audio interface or a dedicated mixing console.

A microphone preamp serves an essential function in that it increases the audio gain and adds breadth and depth to the sound you wish to record. The choice of a microphone preamp must also obey three fundamental rules. In particular, it should take into consideration:

  • The power reserve (called “headroom”).
  • Phantom power (depending on the type of microphone chosen). If you need to use a condenser microphone, you must activate it. In the case of a dynamic microphone, it is strongly recommended to deactivate it in order not to damage the dynamic microphone, because this type of studio microphone has the particularity of being designed to operate without the need for any phantom power.
  • The attenuator (depending on the rate of the electrical sound signal perceived at the microphone input of the preamp).
  • The use of a good quality, high performance microphone preamp will guarantee an almost perfect recording quality. The sound quality will be much better if you combine it with a mixing desk and a sound card with an internal preamplifier.

    Microphone preamp and regular amp: what’s the difference

    The microphone preamplifier and the classic audio amplifier have (in common) an essential role which consists in amplifying sound, but the similarity ends there! The first, the mic preamplifier, amplifies the sound signal at the input to perfect the audio processing. The second ( the power amplifier) amplifies the sound at the output. The sound that has already been processed and that is to be output through the speakers must also be amplified.

    A microphone preamp cannot perform this function. It’ s the classic audio amplifier, the power amplifier. And similarly for a phono preamp, it amplifies and embellishes the sound emanating from a turntable at the input via a dedicated mixing console. The sound emanating from the turntable with phono cell comes out clean, crisp and perfectly balanced to be amplified with a receiver and output to the speakers and to a headphone or headphone output for monitoring.

    You can also choose to bring out the sound to be able to amplify it further at the output with an Op-Amp. This operational amplifier strongly accentuates the gain at its input to boost the sound that will come out towards the powerful 120 to 150 Watts speakers.

    An ordinary Class A amplifier is used to distribute the line level signal to all types of speakers (Hifi, Home Cinema, Subwoofer, wired or even wireless speakers…). Technically, by “line level” we mean the audio signal that is picked up and amplified from a few millivolts to about 1 Volt. If you intend to connect your mixer or DJ mixer output to a home theater amplifier, the use of an adapter and specific cables may sometimes be necessary. The same is true when you want to bring out the sound from a subwoofer with RCA connections.

    If you are using several multimedia devices, you should also consider purchasing a receiver, a UHF decoder, a signal splitter, and several converters so that you can truly have a complete studio setup.The microphone preamp and the conventional amplifier are not the only devices that can work with line-level signals. Equalizers and compressors can also receive these types of signals. To do this, they will only need to be connected to a microphone preamp (input) and an audio amplifier (output) to distribute the sound through the speakers.

    Why should you invest in the purchasing of a dedicated microphone preamp

    Mixers, audio interfaces and sound cards for professional use generally already have an internal microphone preamp. If you already have one and are using it, you may not need to purchase a dedicated microphone preamp. However, its purchase is recommended for one of the following reasons:

  • Your premium professional microphone (dynamic or condenser) should only be connected to audio recording equipment with line inputs.
  • Your mixer, sound card or audio interface has a microphone preamp built in, but it doesn’t have enough power to generate enough gain. By the way, ribbon microphones, like dynamic moving coil microphones, have a very low signal-to-noise ratio, and therefore require more gain to optimize the perception of the sound signal at the input.
  • You want to increase the number of inputs to your interface or audio system.
  • You want to give more breadth, depth, dimension, detail and clarity to the sounds you are going to record. If this is the case, a tube or valve microphone preamp would be ideal.

  • Whatever your audio recording improvement needs, using a dedicated microphone preamp will result in a finer, cleaner and more transparent sound. The perceived gain levels are also very high, although in the case of a mixer or sound card with a built-in microphone preamp, these gains rarely exceed 60 decibels. However, it should be noted that coil and magnet microphones, or moving coil microphones and ribbon microphones, can require up to 70 dB of gain, or more depending on the case. The use of an external microphone preamp in conjunction with a sound card or mixer can greatly improve the sound quality of a vocal or instrumental recording.

    This is particularly important when a dynamic microphone is used. You can also obtain a much better sound quality without background noise by coupling the use of an external microphone preamp with a static or condenser microphone. The same applies if you intend to use a microphone with a wide range of frequencies, or with a frequency response of 20 Hz to 20 kHz. The microphone preamp integrated into a sound card, a mixing console or an audio interface often gives a sound quality that is above average: more clarity, transparency and depth…, but to bring a particular dimension to the sound to be recorded, the use of an external microphone preamp is more than essential.

    By the way, audio interfaces and sound cards with internal preamps only provide access to basic and relatively limited settings. If you want more sound equalization options to add color to the voice or sound of an instrument, you will have to customize your audio recording, and advanced features such as phase inversion, bass cut, and attenuation pads are often missing on standard sound cards and audio interfaces. This is despite the fact that they are equipped with a powerful built-in microphone preamp.

    External microphone preamplifiers from API and Neve are (for example) renowned for their clarity, power and near-perfect sound depth. Although there are a variety of high-end mixers with sophisticated internal preamps, the use of a powerful external microphone preamp is still advantageous. By the way, an external preamp can provide specific tonalities and sonic colorations that are complementary to those that the internal preamps can offer.



    The different types of microphone preamplifiers 🎙

    The microphone preamps available on the market can be classified into three main types: tube or valve preamps, transistor preamps and so-called Channel Strips or multi-channel preamps.

    The latter also give access to a wider range of settings. Each of these preamps generates specific sounds. Everything will depend on the recording result you wish to obtain.

    👉 The tube microphone preamp

    API Select T12 Tube Mic Preamp

    This microphone preamp amplifies the sound while adding depth and color. The tube microphone preamp differs from a transistor preamp in that it tends to transform the sound by adding a nice distortion effect. The sound amplified by a transistor preamp remains (on the other hand) cleaner and at the same time neutral. The tube microphone preamp incorporates one or two vacuum tubes to amplify the audio gain from the microphone. It is the ideal choice if you want to add warmth, color, roundness, and dynamism to the tone of your recordings. These vacuum tubes work to generate distortion that emphasizes second-order harmonics and sounds better to the ears.

    Apart from that, the tubes built into this microphone preamp work like compressors. This has the effect of balancing the sound by reducing the sound pressure (Spl) as well as the note attacks (more offensive) by compressing them slightly. The result is a smoother and more pleasant sound. The tube microphone preamp has one or two tubes (12AX7 tubes) which are normally replaceable when they are used. This type of microphone preamp is ideal if you want to give your recordings a retro, vintage and at the same time soft sound.

    It is perfectly suited for capturing low and medium tones. It should be noted, however, that this type of preamp is not entirely suitable for capturing high-pitched sounds such as those of a violin, snare drum, acoustic guitar, or electro-acoustic guitar.

    👉 The transistor microphone preamp

    As its name suggests, the transistor microphone preamp, also known as a “solid state” microphone preamp, uses transistors (instead of tubes) to amplify the sound signal. Because of its specific design, the transistor microphone preamp provides a clearer, high-fidelity audio gain. This microphone preamp eliminates distortion to provide more clarity, sharpness and transparency to the sound perceived during recording. The sound delivered by this type of microphone preamp comes from its amplification circuits or from the transformers that make up the preamp (if its design is based in part on those).

    As mentioned, the transistor preamp delivers a more transparent sound. In contrast to a tube preamp, a transistor microphone preamp is capable of handling a large amount of high-frequency sound. This is particularly true without (almost) any distortion or distortion of the sound signal at the input.

    This makes it particularly effective for recording classical music. The transistor microphone preamp is also more specifically adapted to the listening requirements of an audiophile.

    👉 The ” Channel Strip ” microphone preamplifier


    The Channel Strip is a specific “multi-channel” microphone preamp which has a fairly complete control panel to perfect the amplification of the audio signal perceived at its input. It generally contains an equalizer, a compressor, an attenuator pad, a noise limiter and a de-esser.

    The “De-esser” function acts much like a pop filter, except that instead of reducing “p” plosives, it is used to reduce “s” sibilance (this time) by way of adjustment. This type of preamp alone can therefore be used to fine-tune and optimize the sound signal at the input.

    A Channel Strip microphone preamp gives you access to all the audio settings necessary to rectify, improve, adjust and optimize the sound signal flow perceptible at the microphone input. Buying one can be a smart investment if you want to achieve the best sound quality in your recordings.

    The Channel Strip also provides much more versatility than the previous two microphone preamps. If you’re willing to pay a certain price for a powerful, high-performance Channel Strip audio preamp!

    Which microphone preamp to choose for your audio recording? 🎛

    The choice of the microphone preamp type must depend primarily on the use you wish to make of it. Here are the main recommendations for choosing the type of microphone preamp to use according to your audio recording needs:

    • If the sound source from which the audio signal is being picked up is quite weak (it may be a voice or a particular type of instrument), a tube preamp should be used to add breadth, power and depth.
    • If you wish to obtain a pure and (almost) faithful sound, it is recommended to use a transistor microphone preamp. This will give you a clean, neutral and richly nuanced sound. The same applies to the sound of high-pitched vocals and instruments that generate quite powerful acoustic pressures in Spl (including percussion and drums).
    • If you really want to clean and process the sound beforehand to optimize its quality, long before the signal reaches the input of an audio interface or mixing console, it is advisable to use a multi-channel preamp or Channel Strip.

    Each microphone preamp has its own specificities 🎯

    Even though a mixing console or audio interface already has a preamplifier to process the audio signal, it’ s always a good idea to improve the quality by using a dedicated external preamp. This will allow you, in addition to amplifying the sound, to improve its rendering; even to increase it. Whether it is a vocal or instrumental pickup, a microphone preamp can add timbre to the sound you want to achieve. Tube preamps give more or less distortion without deteriorating the sound signal. On the contrary, the perceived sound will get more roundness, dimension and depth.

    The transistor preamps reduce distortion to a minimum, resulting in clean, low-noise sound with no peaks. All of this is done in a way that makes the sound more pleasant to listen to. Channel Strips, on the other hand, are more versatile, because in addition to adding gain, removing noise and enriching the sound, they allow you to optimize the sound setting of the audio recording. This is done long before the signal is fed into a sophisticated mixer or soundboard.

    Does a microphone preamp optimize the digital audio transfer ❓

    Indeed, this is possible depending on the type of microphone preamp chosen and provided that it is equipped with one or more digital inputs for connecting a USB cable. Thanks to this wiring, you can optimize the digital audio transfer.

    The advantage of a microphone preamp with USB connection and compatible with a Dsp (Digital Signal Processor) is that it doesn’t lose any audio signal. This is true even if you want to export the audio in dsd (Direct Stream digital) format.

    The sound heard in input ( meaning at the input) in analog mode comes out as it is in output and is even purified and colored in its digital version. Therefore, the sound will be much more easily exploitable on a computer with a dedicated USB audio interface.

    How to perfect the instrumental recording by using a microphone preamp? 🤔

    It may be a good idea to connect an electric guitar, an acoustic guitar or an electro-acoustic guitar to a microphone preamp. This can be a tube microphone preamp, a transistor microphone preamp or a multi-channel microphone preamp. Of course, you can also use a guitar amp as an output.

    Just be careful not to connect these high impedance instruments! First make sure that the preamp has a dedicated input that can be easily recognized by the indication (Hi-Z) or “Instr”. The preamps that have it also have an XLR input as well as a jack input.

    You should also be careful with instruments that have a line output, such as synthesizers or electric pianos. These instruments deliver an audio signal that often exceeds the power that the microphone preamp itself is able to deliver.

    If you want to connect a synthesizer to it without risks, you must absolutely pay attention to the volume control of the output. It should be reduced as much as possible!

    For what other functions does an external microphone preamp perform? ✅

    A microphone preamp (of any type) normally has three main functions:

    • The 48 V Phantom power supply: it allows only condenser microphones to be powered using a dedicated XLR signal cable. Be careful, however, because this function must be disabled when using a dynamic moving coil microphone. This will prevent damage to the microphone.
    • Phase inverter: The phase inverter is very useful when you want to use several microphones at the same time (cardioid, omnidirectional, bidirectional, etc.).
    • Low-cut filter: this function reduces the saturation of the sound signal that can be generated by sounds whose pitch is too low.

    In addition to these functions, a microphone preamp can also provide access to a wider range of functions. This is particularly true of the Channel Strip or multi-channel microphone preamp, which provides access to the following four main functions

    • EQ: This sound equalization function allows you to modify the sound timbre in the middle of a recording, especially when the audio signal is being sent in. It allows you to amplify or reduce certain frequencies (bass, midrange, treble) and to reduce the noise level.
    • Compressor: This compression function reduces the dynamic range of the sound signal at the microphone input. Weaker signals are emphasized and amplified.
    • Gate/expander : this function is used to remove noise and grain.
    • De-esser : This function is used to reduce “S” whistles to a minimum. You can also set this function to ensure optimal sound clarity when using a condenser microphone with a pop filter.


    Our selection of Microphone preamp ❤️

    For a perfect recording, we have made a selection of the best microphone preamps on the market. It is important to note, however, that before you buy a preamp, you should try it out. Remember that each preamp produces its own unique sound.

    1. 🎛 DBX 286s : A console unit with an exceptional quality/price ratio
    2. 🎛 SPL Goldmike 9844 :An excellent and versatile tube microphone preamp
    3. 🎛 AMS Neve 1073 DPX :The reference in high-end and vintage sound
    Buy it now 👉 AMS Neve 1073 DPX

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    About us

    Mic & Mod is specialized in DIY Vintage Microphone Kits since 2013. Why buy expensive vintage microphones in poor condition when you can build them yourself?

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