The quality of your preamp is what is going to make the difference between a mediocre or a Wow Recording. Therefore, choosing the right preamp for your vocal recording is an important task.
The problem is that there are so many different preamps available, some of them cost $80 others cost $4000. Why such a difference in price if they are supposed to do the same thing.
Can my recording sound as good using a cheap preamp instead of using an expensive one? Are there preamps that are not too expensive but still deliver high quality? These and other questions will be answered in this article.
We have created this buyer’s guide to provide you with some of the essential knowledge about the subject to help you understand what the different features and options are, that way you can make an educated decision when choosing one.
Also featured are some of the frequently asked questions about mic preamplifiers to improve your understanding of them.
If you would like to check a list of preamps for vocals carefully selected for their sound quality and features click here.
What is a Mic Preamp?
A mic preamp is an electronic device that increases the low-level signal captured by the microphone and amplifies it to line level.
A line-level signal is the standard operating voltage at which most electronic audio equipment work and the average its around 1 volt.
Preamps can be found internally in many devices such as mixing consoles, audio interfaces, reverbs, compressors, etc. There are also dedicated external preamps which are the devices that we are discussing in this article.
External dedicated mic preamps provide better sound quality because they are designed taking no shortcuts to achieve the best results with the lowest noise and distortion.
They are built using top of the line electronic components and the best manufacturing processes. Many of the top mic preamps in the market are hand-built.
Most internal mic preamps in mixing consoles and audio interfaces struggle to provide 60dB of gain and this will be more noticeable when ribbon microphones are used.
In many cases, mic placement is key to achieve the desired sound, but as the microphone gets farther from the sound source more gain is needed to obtain the correct level. Therefore, having a good mic preamp with enough gain is a key factor in home or professional studios.
Microphone signals are made to work under the nominal operating levels. As a result, you need to get a mic preamp to gain at least 30-80dB. However, if you are using a musical instrument like bass or guitar, you only need to gain 20-60dB.
To check a list of preamps for vocals carefully selected for their sound quality and features click here.
How Does a Microphone Preamp Works?
In simple terms, a mic preamp boosts a very low-level signal from the microphone to line level. This is explained this way so that it’s easy to understand, but in reality, the preamp is generating a completely brand-new signal based on the provided input signal.
To achieve this, the electric signal coming into the input of the preamp acts as a load, modifying the output circuit of the preamp. It applies a varying resistance to the output circuit to re-create the voltage fluctuations of the original audio signal.
In other words, there is a transistor or vacuum tube inside the device that switches on and off depending on the fluctuations of the input signal generating an output with a bigger voltage amplitude.
In that process the new re-created signal is not exactly the same as the original signal, there are always discrepancies. These discrepancies are called distortion, and they are a percentage measure of the original signal.
When designing a preamp, engineers have the difficult task of designing a system that recreates the original signal as close as possible. To achieve this, high-quality components and innovative design techniques are used making the price go up.
This is one of the reasons why there are some mic preamp for vocals or instruments that run in the thousands of dollars.
Why Do I Need a Mic Preamp?
Many people ask this question especially those who own an audio interface or mixer that already has internal preamps.
To answer this question first you need to know what sound you want and what sonic quality you are looking for. You need to know if you want a warm smooth sound that a tube preamp can offer, or a more colorful or transparent sound easily achieved by today’s modern solid-state preamps.
Another thing you need to know is what headroom do you need, in other words, you need to ask yourself if your current internal preamp provides enough gain or could it be that you are running your preamp close to their clipping point (maximum gain) and your audio is starting to distort.
In some cases, the mic preamp in your audio interface is enough if you are recording your vocals at close proximity to the microphone using a typical dynamic, or condenser mics.
Let’s take a look at some of the reasons why you would want to have a preamp:
Improves Sound Quality
A high-quality microphone preamp does much more than just taking your low-level signal to boost it to line level, it will deliver a cleaner, more transparent accurate signal, with more headroom, lower noise, and less distortion.
Offers More Gain
An audio interface comes with a built-in preamp. The built-in preamp, however, has problems even achieving a 60dB gain. They even offer less than that. That notwithstanding, you will find that depending on the type of microphone being used you might need up to 70 to 80dB.
The amount of gain available from minimum to maximum before distortion is called headroom.
Reduces Noise
Although most internal preamplifiers are made to operate with low noise, you will need an external one if you are recording an extremely quiet source. The reason is that as you increase the gain, the noise will be more noticeable.
Most internal mic preamps or budget units introduce noise background and hiss to your signal. A good mic preamp will be much quieter thus producing cleaner signals for recordings.
This can be easily appreciated when using low output microphones like ribbon mics.
Adds Character to the Sound
A built-in preamp sounds pretty clean with enough transparency. However, you will need an external preamp to achieve any special flavor for your audio interface.
If you want a warm smooth sound like the 60s style, then and external tube preamp will give you that sound.
If you are looking for that cooler thinner sound from the 70s then a solid-state preamp can help you achieve that sonic characteristic.
External dedicated mic preamps can provide you with a thinner or fatter sound character. By experimenting with different types of microphones and preamps many combinations can be obtained.
They Offer Extra features
Although built-in preamplifiers come in handy for users of audio interfaces, they normally come with basic features. To get more advanced features an external mic preamp would definitely come in handy when recording.
These features include but are not limited to phase reverse, low cut, pad switches, ribbon mic mode, HPF Amp, impedance matching, etc.
A list of preamps for vocals has been prepared for you. Each unit was carefully selected for its sound quality and features. Check the full list and reviews here.
Features to Look for When Selecting a Mic Preamp
When looking to acquire the best mic preamp for vocals, you should look out for the following:
Number of Input Channels You Need
When choosing a mic preamp for vocals or instruments the first thing to figure out is how many inputs you’ll need.
Each mic preamp you will find in the market will have at least 1 mic input and a line-level output. While this will do for connecting only one microphone it might be your desire to have an extra high impedance input to connect a guitar, bass, electronic beat generator, keyboard, looper, among other instruments.
In that case, a dual input type will give you the flexibility to record vocals and instruments at the same time.
Other mic preamplifiers are made with 4 or more inputs. This is ideal if you need many vocal microphones or instruments connected at the same time.
Multiple input preamps are used in professional studios but if you are thinking about having a home studio to record your music with a dual input preamp would be more than enough.
The output is usually XLR balanced connector and a 1/4″ TRS output. With this feature, you will get to enjoy a variety of connectivity options.
Moreover, if you get a preamp with multiple outputs, you can rely on it as a signal splitter.
Some mic preamplifiers come with a built-in A/D converter so your digital signal can be run successfully to a recording device. This comes in handy if you are looking to gain a decreased noise floor.
Preamp Type: Tube, Solid State, Hybrid
- Tube: This type of preamp provides the classic vintage sound. They are built using vacuum tubes also known as valves, and classic electronic components. Usually, are handmade and can produce a sound that is hard not to like because is very natural and warm.
- Solid-state: constructed using modern electronic components such as transistors or integrated circuits (chips), this type of preamps can give you higher gain, clear sound with very low distortion.
- Hybrid: are built using vacuum tubes and solid-state circuits providing you sonic characteristics from both types of preamps. They are a good option for professional and home recording studios.
Form Factor
You will get mic preamplifiers in three packages based on their form factor: Rackmount, 500 Series, or Desktop.
- Rackmount: as its name implies this type of preamp is designed to be installed in a 19” rack with other equipment such as compressor, channel strips, etc.
- 500 Series: This form factor is more compact for mounting several modules on a rack-mountable chassis. The modules include but are not limited to mic preamps, compressors, equalizers, effects, and specialty modules. It helps create a compact rig that can be taken anywhere at an affordable yet professional way.
- Desktop: this form factor is the more popular in-home recording studios because as its name implies can be installed in a desk close to the studio interface and easily create a nice sounding home studio recording.
Strip Channel vs. Preamp
If your budget allows it instead of getting a single or dual-channel preamp, you might want to invest in a channel strip. This is because you will be getting multiple processing tools in one box.
This means that in one unit you will be getting a professional preamp, compressor, equalizer, and other analog audio processing tools. As a result, your recordings will sound much better.
Another plus to using a channel strip vs. a preamp is that there will be less equipment in the audio chain, this means less noise and distortion.
Switchable Transformer Feature
In some cases, it’s necessary to match the output impedance from the microphone with the input impedance of the preamp, and by having a switchable transformer feature you can select the impedance that better suits your system.
Another good thing about having a preamp with multiple impedance selector is that by using a different combination of impedances, different tones can be generated from the preamp.
Just to clarify, in simple terms the input impedance is the measure of the opposition that the signal coming from a source is going to encounter.
If the impedance from the mic and preamp can’t be matched, meaning to be equal, then we want the input of the preamp to be as high as possible and the reason is because that way there will be less opposition to the signal that is coming in and we would get better gain and more amplification of the source signal.
Gain Factor
This is a key factor when choosing a preamp. We want to have as much headroom as possible. What I mean by headroom is to have lots of gain between the minimum and maximum limits. Because is better to have extra gain and not need it, than need it and not have it.
This will become a reality when using dynamic and ribbon microphones. There are also some condenser microphones that are not too sensitive and in those cases, more gain is needed to bring the signal to line level.
Phantom Power +48VDC
Phantom power is another feature needed in a preamp. The reason is because all condenser mics need +48VDC to operate and that voltage is supplied by the preamp through the XRL cable connected to the microphone. Make sure that the unit you select includes this feature.
Pad
PAD is derived from the words “Passive Attenuation Device”. A pad switch is an important feature in mic preamplifiers, but it is probably the least used.
It is turned on when you sense a distortion in the sound. When on, the signal is prevented from hitting the preamp clipping point. Nonetheless, in some cases, it tends to reduce the quality of the signal being recorded. But it can become handy if a very loud sound source is being recorded.
Low-Cut (High Pass Filter)
A high pass or low-cut filter will get rid of the unwanted low end frequencies that create an annoying rumble to the sound. It helps you to record clearer sound eliminated muffled sounds.
This is because when selecting this function, it cuts or eliminates all the frequencies below 150Hz. Any low-end noise can be readily removed with the low-cut feature.
Make sure that the preamp you choose includes a low-cut or high pass filter. This will come handy when recording rap vocals or any vocals in general.
Frequently Asked Questions About Mic Preamps
What is the Difference Between Preamp and Amp?
In simple language, a preamp is used to enhance the strength of a weaker signal from the microphone level to line level.
An amp, on the other hand, boosts the signal from the line level to a higher power level to drive speakers at higher volumes.
A preamp prepares a signal so that an amp can use it to amplify it to a higher level.
What is the Difference Between Tube vs. Solid-State Preamp?
There are many differences between solid-state and tube preamps, but in this article, we are going to focus only on one of those differences which is the most important in my opinion when it comes to choosing the best mic preamp: tone.
There can be some heated debates between audio enthusiast when it comes to choosing sides between tube and solid-state preamps.
Each kind has its pros and cons, but the truth is that tube preamps distort more easily than solid-state, but the way they distorts the sound is what makes tube preamps sound fuller and warmer.
Tube mic preamps, when pushed at higher gains, produce even order harmonics which gives a distinct tone that is hard to miss. It sounds fuller because even harmonics contain the base note plus its octaves.
When a solid-state mic preamp is driven at higher gains it produces odd-order harmonics and as it distorts it clips the signal giving it a sound that it’s not pleasant to hear.
So, you might ask what is the deal with even and odd harmonics? To understand this, we must have some music knowledge. For example, let’s take a base note “A” (440Hz), the second harmonic would be one octave up 880Hz.
The fourth harmonic would be one octave up from the second or 1760HZ, and so on. There is no sonic mush because all these harmonics are basically the base note but up many octaves.
Let’s use the same example but with odd harmonics. The base note A 440Hz. The third harmonic is an octave plus the fifth above the fundamental frequency 1320Hz. The fifth harmonic is 2200Hz, the Seventh harmonic is 3080Hz. If all these notes are played together it would sound horrible, it would be a sonic mush.
This why a tube vocal mic preamp could sound better if paired with the right microphone. This has to do with personal taste, I am not trying to say that solid-state preamps don’t sound right, I am just saying that depending on your type of music and personal taste a tube preamp can help you achieve a better sonic tone.
Difference Between Cheap vs. Expensive Preamplifiers
The price tag on preamps varies just like in other items in the market. However, the main difference between a cheap and an expensive preamp comes down to the design topology and precision components.
In most cases, an expensive preamp comes with features like phase reverse, low cut, pad switches ribbon mic mode, HPF Amp, impedance matching, etc.
One of the more difficult tasks when designing a preamp is to obtain high gain while keeping the noise and distortion to a minimum. To achieve this many steps and design topologies need to be implemented. This increases the price of the device.
Another factor that differentiates between cheap and expensive preamps is the tone and timbre that the preamp produces. By using different design circuits, the tone and timbre change and this becomes kind of like a trademark sound for the different preamp brands.
One more thing I would like to mention about why there are preamps that cost only a few dollars and others costs thousands is the quality of the components used.
There are some brands of preamps manufacturers that handpick components that are between a very tight range, in some cases less than 0.5%.
What this means is that from hundreds of components they measure each one to make sure that its value falls within 0.5% or less so there is a lot of wasted material increasing significantly the price of each unit.
All these details from design to manufacturing play an important role in the final product, and that is why each brand offer a different tone, timbre, and sound color.
Are you still wondering why producers and artists invest so much on their preamps for their recording studios? If you are, here is why, sonic quality, color, and texture of sound, low noise, and lots of gain headroom.
Most cheap preamp brands are simple, which means that their benefits will be limited. A more expensive preamp is built with sophisticated features aimed at enhancing sound quality.
For a full list of affordable and professional preamps for vocals selected taking into considerations all the guidelines presented in this article click here.
What is the Difference Between Preamp vs. Audio Interface?
A vocal or instrument preamp takes the signal coming from the source and prepares it to be used by a chain of audio equipment to be recorded or played live. On the other hand, an audio interface is used to commute an analog signal to a digital computer.
It basically converts an analog signal (let’s say sound coming from a mic) to digital so that it can be stored or processed by a computer.
An audio interface comes with built-in preamplifiers, phantom power switch, 1 or 2 headphone ports, several audio outs, some have MIDI I/O or S/PDIF. The audio outs are used to route to the out-of-the-box gear as well as studio monitors. The more expensive the audio interface, the higher the quality of the preamp.
What is the difference between preamplifiers vs. channel strips?
Although most of you are probably aware, let me begin by stating that preamplifiers and channel strip are very different.
A Preamp is an electronic amplifier used to prepare signals for further processing. Amplifies a signal coming from let’s say a microphone so that an audio interface or any other equipment can use it.
A channel strip comes with a series of analog signal-processing tools. Most channel strips have their components arranged as follows: a preamp, a compressor, and a section for EQ. Some of the channel strip models are further built with a de-esser that is also known as an enhancer or exciter.
The good thing about using a channel strip is that the signal that is receiving from the mic is processed by an analog circuit. This makes a huge difference to the sound quality when a signal is processed in an analog way and not by using software.
So, for anyone looking to make world-class recordings, a channel strip would be more suitable as compared to a preamp. This is because the former is thoughtfully designed to incorporate every potential signal-processing tool. As such, you get to conduct professional recording using a single box.
How to Connect a Mic Preamp to an Interface
Connecting a microphone preamp to an interface so it is integrated into your workflow is quite simple.
The connection procedure of the preamplifiers, however, varies as per the analog to digital conversion type incorporated in the workflow.
Most systems feature 2 balanced connections where each supports its own channel. Besides the DB25 connectors, the XLR or TRS connectors are most common.
The connections should then be carried out with the balanced and differential connections. All connectors that are either XLR, TRS, or DB25 are said to be both balanced and differential.
For each digital set-up, you will achieve the signal chain below when you connect the preamp:
Mic -> Preamp -> A/D Converter -> Digital Audio Workstation (DAW)
- Mic -> Preamp
This is the first step, and it involves the connection of the XLR from your microphone going into the specific input connector where the preamp is located. Some microphones may need phantom power (+48VDC), and this can be achieved through the activation of the selection found on the preamp front panel.
- A/D Converter -> DAW
In this step, you will need to connect the USB, firewire, or Thunderbolt connection so the converter and DAW are linked. The involved software and drivers are connected automatically once the preamp and interface are connected to the computer.
The challenge with this comes about when linking the preamp to the converter. In such a case, you will have to pinpoint the balanced as well as line-level signal input. Some of the types you might come across are inclusive of:
- Pure A->D Converter
- A->D Interface with Optional Preamps
- A->D Interface with Switchable Preamps
- A->D Interface with Fixed Preamps
How to Set Up a Mic Preamp
When setting up a mic preamp, you should first decide on the gain structure. Most preamplifiers are made with two or more knobs that are adjusted to set the desired gain and level.
The functions of each control featured in a preamp vary depending on the model you are using. As such, it is advisable for you to check the manufacturer’s manual for easier setup.
To allow for the setting of in-between values, some high-end preamplifiers feature a stepped gain control alongside a continuous trim potentiometer. Other models are made with either a stepped or continuous gain control.
Such a type comes with an additional output level pot that is used as the fader. As a result, if you turn such a preamp model counter-clockwise, it will respond by muting the signal.
With such a preamp, you will be able to make various analog saturation effects. To create this, all you need to do is switch on the gain control and turn it up beyond the required level. This way, the input stage will surpass the output stage of the preamp.
The next step should be for you to weaken the signal with the output level control. As a result, you will have avoided any potential digital clipping that could have occurred in the audio interface.
You should only follow the above set up procedure if you want some analog crunch in your recording process.
Nonetheless, most individuals in this digital era are leaning more towards attaining a pristine and undistorted sound. In such a case, you will need to have the output level turned up and avoid using the input gain anymore. This precaution will prevent any possible internal distortion that could lower sound quality.
You should know that how the input gain and output level pot are set up will impact the sound cleanliness as well as its saturation degree.
If you realize that the microphone tends to produce a higher level, like when using condenser mics, you might want to consider reducing the signal so you don’t clip in the AD-converter.
In case you set up your preamp and notice any distortion in the sound being emitted, you should;
- Ensure that the preamp has not overdriven the AD-converter. You do this by turning down the gain control on the preamp.
- If the distortion continues, check the preamp for any clipping. You can do that by turning on the pad switch with the aim of weakening the said signal. This prevents it from hitting the input stage of the preamp.
- Once you are certain that both the converters and preamp are not distorted, you might want to lock the pad switch of the mic in place, this will ultimately attenuate the signal. The problem with taking this measure is that it makes the noise performance of the mic worse while lowering the sound quality. As such, you should only consider using the pad switch as your last option.
Conclusion
Preamplifiers are a key piece of equipment in any recording studio whether is for home or professional use. This is the first device where your signal comes in to be be used by the audio interface or the rest of the equipment in the audio chain.
Choosing the right preamp will make all the difference in your recordings. I have presented all the information that you need to make an educated decision of choosing the best mic preamp for vocals and instruments.
If you would like to check a list of preamps for vocals carefully selected for their sound quality and features click here. The preamps suggested in that article will meet or exceed your expectations when recording your vocals.
The suggested devices include top of the line, mid-range, and affordable priced units from the three categories: solid-state, tube, and hybrid mic preamps for vocals. All these units will meet or exceed your expectations.
These suggested products have been around for many years and have been used repeatedly in professional recording studios as well as in-home studios producing high quality sounding recordings.
I hope this buyers guide helps you make the right choice.