In all my years of recording, mixing, and producing, I have never needed or been in a situation that requires me to use 2 preamplifiers. I’ve been asked if you can use 2, but I always thought, why would you need to. This article explains why, if, in any case, you would need to use 2 preamplifiers.
Technically you are able to use 2 preamplifiers. However, the amount of distortion, noise, and interference would outweigh any factor that would be the reason you would use 2 preamplifiers in the first place. A preamplifier boosts a low signal, and understanding why and how a preamp works would allow you to record without the need of 2 preamplifiers.
We are going to take a look at exactly what a preamplifier is, how it works, what components they are made with, and how to use them correctly with regards to microphones. Microphones also play a relative part in recording with a preamp, and if you don’t know how mics work or which to use them. That could be a reason why you would think you need 2 preamplifiers. So let’s get into it.
What is a preamp?
The term preamp is short for a preamplifier. A Preamp is a type of amplifier that is designed specifically to take a weak signal and boost it to make it louder. You can think of a preamp like the ones built into a mixer or an audio interface or rather the internal components of those devices that boost a signal. The signals can come from a variety of sources, including microphones, guitars, bass guitars, and more.
Watch Sweetwater explain what a preamp is.
Why do you need a preamp?
You might be wondering why do you need a preamp to begin with or rather why are we sending weak signals to the device in the first place. Why not just send a stronger signal, to begin with?
Well, let’s take a look at how most signals are sent to a mixer or audio interface.
We record any audio signals using microphones. It doesn’t matter what you are recording (tracking), whether it be drums, violin, guitar, vocals, or anything else. We need to record those audio signals using microphones and then send them along to be processed.
Microphones are basically transducers (we won’t get into to much detail here). In its simplest form, a transducer is a device that takes one form of a signal (in this case, airwaves) and changes into a signal that an electrical device can use.
Without getting into to much detail, you can think that microphones are small, and in essence, when they convert the sound waves into electrical signals, those signals in terms of voltage will be small (millivolts). Knowing this, your electrical devices can’t use these small signals because they are too low; hence they get directed into the preamp first.
The preamp then boosts that signal so our electrical devices can use that signal properly. The preamp can add significant gain to the signal without producing a lot of distortion.
How do preamps convert these signals?
Different preamps use a variety of ways to convert and boost the signals we record. Some preamps, as you might be aware of, use tubes, and some use transistors. Essentially, all in all, the only thing we need to concern ourselves with is that the preamp takes the weak recorded signal and boosts it.
Transistor vs tube preamps
You might be wondering how much of a difference there is between transistor and tube preamps when it comes to recording quality and the sound that we get from these two different preamps. If you have the advantage of recording the same audio via a transistor and a tube preamp, you might notice a few things.
Firstly they are not night and day apart. The differences are subtle. A tube preamp provides more warmth and color while a modern transistor preamp is cleaner and shiny (bright), especially on the high end of the frequencies.
You may say that you prefer that the high end should be bright. However, you must remember that you have to add effects and such to the signal (such as compression), and this could tend to make the sound brittle and more “plastic” on the high end.
A tube preamp gives depth and warmth and really separates itself from stock preamps in the high and mid frequencies.
Watch Joe Gilder test and explain the differences between a stock (transistor) vs. tube preamps.
For what other scenarios do you need a preamp?
Unknowingly you also use preamps in a live environment. If you’re playing live, you and your bandmates will plug into a mixing desk, and the mixing desk will have to use a type of preamp to boost (gain knobs) the signals from the various musical instruments and equipment.
By having the preamp built into the desk, we are able to boost and mix the various signals to a pleasant sound and then routing the signal through an amplifier and out through your monitors and speakers of your PA system.
In terms of a studio setup, you could have a preamp built into your audio interface like most common self-starter audio interfaces. Then you could also have an outboard preamp, which is more specialized, and then that would have to run into another device like a converter down the chain of your devices.
How are preamps designed?
With regards to any electrical device just by nature, will incur some noise when converting or routing signals. A preamp is specifically designed to minimize that noise that is produced while still giving you what you need, which is a clean gain on your microphone without getting the extra noise or distortion. Let’s look at some characteristics of what preamps will have in their specifications.
Total harmonic distortion (THD)
The output signal of an audio signal should be the exact replica of the recorded input signal. If the output signal is different from that of the input signal, the signal is said to be distorted. Variations of this signal can be noise and clipping, as well as distortion.
The active elements in your preamp, namely the transistors, are what can cause distortion. The better the preamp and the components that make up the preamp will reduce the amount of distortion considerably.
Watch Simplyinfo explain distortion and harmonic distortion.
The noise floor specification of a preamp refers to the design in the preamp when no signal is being passed through the preamp and what the idle noise floor of the preamp will be.
These specifications are important to keep in mind, but also remember, as we said, you get different types of preamps, and they all provide different flavors. So, it is up to your discretion to choose which preamp or device suits your situation best.
Can you use 2 preamps and should you?
One thing to remember is that you should choose your preamp with regards to what microphones you are recording with. With this, I mean that some microphones output a hotter signal than other microphones.
A condenser microphone using phantom power would output a much hotter (louder) signal than that of a low-gain dynamic microphone that does not use phantom power. Therefore, a condenser microphone would not need a strong preamplifier.
When looking at ribbon microphones and how their transducers work, they also output a smaller signal than that of a condenser microphone. There are even preamplifiers explicitly designed for ribbon microphones.
Getting to the question of can you use 2 preamps? If you are in a situation that requires you to use two preamplifiers, than there is something drastically wrong with your studio setup. You should have specked your equipment before purchasing anything, and knowing all the factors that go into preamplifiers and microphones, there is no scenario where you should ever be using 2 preamplifiers.
If you have specked and purchased the correct equipment, then there will be no need to ever even think of using 2 preamplifiers. I personally have never tried to use 2 preamplifiers, and in all my years of playing, recording, and producing, have ever come across someone who would use 2 preamplifiers.
The risks outweigh the pros if there are any. The noise, distortion, and interference from 2 preamplifiers would be uncontrollable, and the amount of pre and post-production trying to rid your audio signal of all that audio noise, distortion, and interference would be enormous.
In conclusion, we arrive at the fact that if you understand how a preamp works along with microphones, there will never be a need or a situation you will find yourself in that requires you to use 2 preamplifiers.
The amount of interference, noise, and distortion, when considering using 2 preamplifiers will not benefit your audio recording in any way, when you can get the amount of gain you need for whatever instrument you are trying to record, just by specking, purchasing, and using your audio equipment correctly.