The Ultimate Microphone Preamplifier Buyer’s Guide 2021


So you’re wondering which microphone preamplifier you should buy, rent or otherwise try out. In this comprehensive buyer’s guide, we’ll go through everything worth considering before you make any decisions about a mic preamp.

If you’ve found yourself asking, “which mic pre should I buy?” this extensive resource is for you.

Please feel free to jump around this article and read all additional resources I have provided links to.

Of course, the first question to ask is, “Do I need a hardware microphone preamplifier in the first place?” Audio interfaces, mixers, consoles and portable recorders all have built-in mic preamps that are often good quality. However, if you’re set on getting a dedicated high-end preamplifier, then the information provided below will help to find the best options for your situation.

With that, let’s get into this comprehensive microphone preamplifier buyer’s guide to help you in your next microphone preamp purchase!

Related article:
What Is A Microphone Preamplifier & Why Does A Mic Need One?
Top 13 Best Microphone Preamplifier Brands In The World


Table Of Contents


What Is Your Microphone Preamplifier Budget?

The first thing to consider when making any purchase is your budget. Money can be a touchy subject for some, and so I’ll keep this section brief.

I would never advise anyone to overspend on any audio equipment. Know what you can realistically afford, and do your best to stay within those limitations, whatever they may be.

Microphone preamplifiers, like many audio devices, range significantly in price. The market is rather large, and so there should be a good selection for any budget.

Note that some retailers offer payment plans, which could be an option.

Consider the cost to benefit ratio of the purchase of the mic preamp. For example, if the mic pre is needed for business, perhaps stretching the budget is more appropriate. On the other hand, if you don’t plan on making money with the preamp, perhaps a more conservative budget is appropriate.

Also, consider any upkeep that may be required for your mic preamp.

Only you can determine your budget. All I’m here to say is that you should consider it.

Related My New Microphone article:
How Much Do Audio Amplifiers Cost? (With Pricing Examples)

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How Many Inputs & Outputs Do You Need?

The simplest microphone preamplifier will have a single mic input and a single line output. It will accomplish the basic task of amplifying the mic level signal (from the microphone) to a line level signal (for use in mixing, recording, effects processing, and other audio equipment).

The mic input and line output are most ofter 3-pin XLR connectors. Some preamps offer 1/4″ TRS line outputs for additional output options.

If you only need the microphone preamplifier for your microphone(s), then opting for a simple mic-in, line-out preamp could be the best choice for you.

However, a preamp can have more than these two essential inputs and outputs per channel.

A popular input included in mic preamps is the instrument/Hi-Z direct input. This input is generally a 1/4″ (6.35mm) designed to accept unbalanced instrument signals via TS cables. Some are even designed to accept line level signals (though line level signals don’t necessarily require gain, they may benefit from the sonic character of the preamp and any additional features of the preamp, especially with channel strip preamp combos).

The DI portion of a mic preamp, if applicable, may have a thru output, which effectively passed the DI input directly through the preamp without being affected. The preamp’s outputs will output the amplified/processed DI signal.

Opt for a model with a DI if you ever plan to connect instruments (notably guitar and bass) to the preamplifier.

A microphone preamplifier may also have an insert send and return I/O, whereby other audio processors can be connected inline between the mic preamp’s gain stage and its output. These insert send and return connectors are typically 1/4″ balanced connectors.

Some microphone preamps have built-in analog-digital converters and can act as an audio interface. More appropriately, standalone audio interfaces for studio use often have microphone preamplifiers. These digital “outputs” are generally either USB, Thunderbolt, or some other digital interface.

Oftentimes an audio interface will cover your microphone preamplifier needs. However, a separate mic pre (or several mic pres) may be in order if you’re working with lower-quality audio interfaces or some of the larger interfaces that do not have built-in mic preamps.

Related article: The Ultimate Audio Interface Buyer’s Guide

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The Number Of Microphone Preamplifier Channels

Now that we’ve covered the various input and outputs a mic preamp channel could have, let’s consider the number of channels.

A single-channel microphone preamp could be ideal for your setup, but if you’re recording a larger number of mics at the same time, you may want to consider a multi-channel microphone preamp.

Sure, you could opt for a collection of single-channel preamps. A main benefit of this approach is that you’ll have access to different “sonic characters” from preamp to preamp.

However, multi-channel preamps will often cost less per channel and offer consistency from channel to channel. They’re also generally designed into a tighter form factor, which is more convenient and helps save space.

So, when choosing a mic preamplifier, consider the number of channels it offers. Popular channel counts include 1, 2, 4, 8, 12 and 16.

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Microphone Preamplifier Gain & Microphone Sensitivity

The main purpose of a microphone preamplifier is to apply gain to the low-level microphone signals. However, not all microphones are equal when it comes to their gain needs.

Microphone sensitivity is the measurement of a microphone’s efficiency as a transducer (how well it converts acoustic energy to electrical energy). A microphone’s sensitivity rating is determined by its output voltage (audio signal strength) relative to the sound pressure level it is subjected to.

In general, condenser and active ribbon microphones are the most sensitive and, therefore, require the least amount of gain to reach line level.

Dynamic (moving-coil) microphones require more gain.

Ribbon microphones are notoriously insensitive. Passive ribbon mics (those without built-in amplifiers) will require additional clean gain from the microphone preamplifier to achieve the same level at the output of the preamp.

Sensitivity ratings are generally given as dBV/Pa (decibels relative to 1 volt per Pascal) or mV/Pa (millivolts per Pascal).

Professional nominal line level is defined as +4 dBu, which is equal to 1.782 dBV or 1.228 volts.

1 Pascal is equal to 94 dB SPL (decibels sound pressure level). A 3 dB SPL increase results in a doubling of the Pascal value.

Check out the following table for typical Pascal and dB SPL values:

dB SPLPascalSound Source Example
0 dB SPL0.00002 PaThreshold of hearing
10 dB SPL0.000063 PaLeaves rustling in the distance
20 dB SPL0.0002 PaBackground of a soundproof studio
30 dB SPL0.00063 PaQuiet bedroom at night
40 dB SPL0.002 PaQuiet library
50 dB SPL0.0063 PaAverage household with no talking
60 dB SPL0.02 PaNormal conversational level (1 meter distance)
70 dB SPL0.063 PaVacuum cleaner (1 meter distance)
80 dB SPL0.2 PaAverage city traffic
90 dB SPL0.63 PaTransport truck (10 meters)
100 dB SPL2 PaJackhammer
110 dB SPL6.3 PaThreshold of discomfort
120 dB SPL20 PaAmbulance siren
130 dB SPL63 PaJet engine taking off
140 dB SPL200 PaThreshold of pain

From that information, we may figure out how much gain will be needed for a microphone with a specific sensitivity when recording a specific sound source (so long as we can estimate or know the level of the sound source).

Opt for a mic preamp that will offer more clean gain than you need. Oftentimes the gain gets noisy near the preamp’s limits.

For example, mic preamps designed for passive ribbon mics will benefit from over 80 dB of gain. Condenser mics may only require 40-60 dB of gain max before they’d overload the preamp.

Related My New Microphone articles:
What Is Microphone Gain And How Does It Affect Mic Signals?
What Is Microphone Sensitivity? An In-Depth Description

What Are Decibels? The Ultimate dB Guide For Audio & Sound

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Microphone Preamplifier Features

Microphone preamplifiers come with all sorts of features. Let’s discuss a few of the most popular features in this section.

First, I’ll mention that some “preamps” come with EQ, compression and other built-in audio processors. Though these are certainly features, I’d consider these units to be channel strips rather than strict microphone preamps. I’ll discuss channel strips in an upcoming section of this article.

For now, we’ll focus on the features worth considering in true microphone preamplifiers:

Signal Level Monitoring

Signal level monitoring allows users to monitor inputs levels on the microphone preamplifier itself.

Phantom Power

Phantom power is a common feature on microphone preamplifiers. It outputs +48V DC (ideally) on pins 2 and 3 of a connected XLR cable. Phantom power is used to power the active circuitry within many “non-tube” condenser microphones and active ribbon microphones.

Sometimes phantom power is available on a per-channel basis. Other designs will have multi-channel phantom power switched (1-4 and 5-8, for example).

Related My New Microphone articles:
What Is Phantom Power And How Does It Work With Microphones?
Will Phantom Power Damage My Ribbon Microphone?

High-Pass Filter

Some microphone preamplifiers offer high-pass filters (HPFs) to filter low frequencies from the input signal effectively. High-passing at the preamp stage can help clean up electromagnetic interference and mechanical noise/rumble before the signal is amplified.

Related My New Microphone articles:
What Is A Microphone High-Pass Filter And Why Use One?
Audio EQ: What Is A High-Pass Filter & How Do HPFs Work?

Phase Flip

Phase flip is another popular feature for preamps/inputs to have. As the name suggests, a phase flip switch will flip the input signal phase (±180°).

Related My New Microphone article:
Microphone Polarity & Phase: How They Affect Mic Signals

Pad

Pads (passive attenuation devices) effectively reduce signal levels. Pads at the inputs of a microphone preamplifier allow users to bring down signal levels to increase headroom and avoid overloading the rest of the circuitry.

Pads can be especially useful if you’re after the sonic character achieved with high levels of preamp gain.

Related My New Microphone article:
What Is A Microphone Attenuation Pad And What Does It Do?

Low/High Impedance Switch

Mic preamps with direct inject options will have input impedance switches that allow users to switch the input impedance to best suit the incoming signal. High impedance is particularly useful when recording passive guitar and bass directly.

Related My New Microphone articles:
Microphone Impedance: What Is It And Why Is It Important?
What Is A Good Microphone Output Impedance Rating?

Transformer Lift

Some microphone preamplifiers offer a transformer lift switch, which effectively includes or excludes the transformer from the signal path.

Transformers are passive electrical devices that physically isolate two circuits while maintaining an electrical relationship between the circuits. They adjust voltage, current, and impedance.

Mic preamps may have input and/or output transformers that will affect the sonic character of the sound. By that statement, we can infer that a mic preamp with a transformer lift option can potentially yield two different sonic characters: a more transparent character (with the transformer(s) lifted from the circuit) and a more coloured character (with the transformer(s) included in the circuit).

Ground Lift

A Ground lift switch can lift the ground of the microphone preamplifier and eliminate hum at the risk of ungrounding the preamp electrically.

Stereo Linking

Microphone preamplifiers with 2 or more channels may offer stereo linking between two adjacent channels. Stereo linking effectively matches the parameters of both channels (ideally driving a pair of identical microphones) so that the preamp applies the same amount of gain and the same processes to both.

Related My New Microphone article:
Complete Guide To Microphone Preamplifier Specifications

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Coloured Vs. Transparent Microphone Preamplifiers

Microphones and microphone preamplifiers are often chosen for their sonic character. These units have a certain quality about them that colours the audio/sound in a pleasing way.

Other mic preamps are designed to be as transparent as possible, providing clean gain with little to no effect on the sound quality of the signal.

The “colour” or “transparency” of a microphone preamplifier will often be included in the preamp’s marketing/description. Otherwise, you can check out forums to find out what others think of the sonic character of the preamps you’re interested in.

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Tube Vs. Solid State Vs. Hybrid Microphone Preamplifiers

Speaking of colour and character, a mic preamp’s gain stage could be based around a tube, a solid-state circuit, or a hybrid combination of the two.

Tubes tend to saturate the more you push them (the more gain that’s applied). This can be incredibly pleasing to the ear when done right. Tube preamps are often more colourful and smooth. Note that tubes are also relatively fragile and are sensitive to temperature.

Solid-state gain circuits are often more clean, clear or clinical, though they can also have their own sonic character. These circuits are often preferred when less sonic colouration is wanted. Solid-state circuits are much less sensitive to temperature.

Hybrid preamps utilize both tubes and solid-state circuitry in the gain staging. Some offer the option, some combine the two, and some do both.

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Microphone Preamplifier Form Factor

Let’s consider the typical form factors for microphone preamplifiers. They are:

Rackmount Microphone Preamplifiers

Rackmount microphone preamplifiers are designed to incorporate into 19″ studio racks. Of course, these preamps can be placed on desktops as well. They are not portable.

Note that some microphone preamplifiers will come with ears to integrate them into a rack if need be.

Related My New Microphone articles:
Top 11 Best Audio Studio Equipment Rack Brands On The Market
Top 11 Best Rackmount Case Brands On The Market

Desktop Microphone Preamplifiers

Desktop microphone preamplifiers range in size and are meant to sit on a desktop, hence the name. They are not designed to fit into studio racks, nor are they particularly portable (designed to move around while in use).

500 Series Microphone Preamplifiers

500 Series microphone preamplifiers are designed for the 500 Series modular format.

Related My New Microphone articles:
What Is 500 Series Audio Equipment & Is It Worth It?
Top 11 Best Audio Brands For 500 Series Modules/Equipment

Inline Microphone Preamplifiers

Inline microphone preamplifiers tend to offer one or two channels with single mic input and a single line output per channel. They’re portable and easy to use.

These preamps will often run off of phantom power and only provide a small amount of gain (25 dB, for example).

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Considering Channel Strips

A channel strip technically refers to a single channel on a mixing console, though channel strips can be purchased as standalone, modular, and software units.

Channels strips generally have a mic input and mic preamp and can also include instrument (Hi-Z) and line inputs. This makes them similar to “regular” mic preamps, with the major difference being that channel strips will offer greater capabilities than amplification alone.

Channel strips feature EQ, compression, gates, and even more, depending on the model. They’re designed to offer all the basic signal processes we’d need to record superb audio at the source.

Like mic preamps, channel strips come in a variety of formats. These formats include modular form factors for specific modular mixing consoles, 500 Series, desktop, and rackmount units. Channel strip plugins are also available for digital audio workstations.

For my take on the top channel Strip plugins on the market, check out My New Microphone’s Top 11 Best Channel Strip Plugins For Your DAW.

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This article has been approved in accordance with the My New Microphone Editorial Policy.

Arthur

Arthur is the owner of Fox Media Tech and author of My New Microphone. He's an audio engineer by trade and works on contract in his home country of Canada. When not blogging on MNM, he's likely hiking outdoors and blogging at Hikers' Movement (hikersmovement.com) or composing music for media. Check out his Pond5 and AudioJungle accounts.

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