Preamp why

The purpose of a preamp is to amplify low level signals to line level, i. Microphone signals are usually way below the nominal operating level, so a lot of gain is required, usually around dB, sometimes even more.

Even line sources such as synthesizers may require some amplification to match studio level, because there are various standards. So you need a preamp for just about any sound source. Most audio interfaces already come with built-in preamps. At a later point, you may want to add an external preamp to your home studio setup. Instead, get a slightly more expensive audio interface with decent built-in preamps. Footnote 2: In the clearest exception known to me, the Jeff Rowland Design Group argues for maximum power transfer by matching input and output impedances.

This requires, however, that the source and amplifier be carefully designed to operate in this fashion, something which Rowland preamps and power amps definitely are. Most random source or preamp combinations cannot be assumed to be so compatible, making the ratio a more universally applicable recommendation.

Footnote 3: Buffering is a design technique used to isolate one part of a circuit and keep it from adversely affecting the stage which follows. It is generally realized by using an active zero-gain stage, the output of which presents a constant low impedance to the next gain stage. A buffer may itself have gain, though we usually don't think of it in this way.

An entire active preamp with a low and constant output impedance does, technically speaking, perform a buffering function, with gain. Log in or register to post comments. Related Latest Galleries Recommended. What a Difference a Wire Makes. The Uncertainty Principle. JA on Loudspeaker Measurements. Harmonic Convergence: the Effect of Component Tweaking.

Subjective Loudspeaker Testing. Blind Listening at Harman International. MQA Contextualized. MQA Tested, Part 1. MQA: Questions and Answers. Capital Audiofest It's a Wrap. Infigo Audio plus Alta Audio and Resonessence. Semrad Audio. Superior Mass Audio Speaker Cable. A Recording's Analog Noisefloor. RDacoustic Hybrid Diffusers. Main System. Current config. This changes the amount of harmonic distortion your signal will receive, which is the pleasant color saturation we talked about above.

Some don't give you this option. It's pretty subtle either way. Finally, you'll see buttons for things like Invert, which just flips the phase of the signal. This is helpful when you're recording a stereo signal like a double-mic'd acoustic guitar and you're getting constructive or deconstructive phase issues.

You'll invert either the left or right channel and that typically solves it. You'll see the ability to deliver 48 volts of phantom power as well. A lot of mics need this and the preamp delivers it. Some microphones have their own built-in or external power source though, so in that case you'd turn off the phantom power. If you're unfamiliar with different outboard studio gear, you'll wonder why so many different preamplifiers have various shapes.

Some are weird shaped boxes that sit on your desktop, while others are long and horizontal that get mounted into a rack of other equipment. Then you have the lunchbox that accepts Series shaped equipment, which can be racked or sit on your desk! Above is a single channel desktop preamp. There are lots of musicians, such as rappers or singers who only need one high quality channel for their vocals. They don't end up with a lot of other equipment other than a preamp and a mic, so they are happy to have it sit right there on their desk.

For anyone collecting several pieces of studio gear of various types, it makes sense to purchase the rackmount form factor. The width of the chassis and the holes on the side are standardized for inch rack rails. This is what I do, because I have compressors, EQ's, and interfaces as well. Finally, there is also the Series units. They are racked vertically into a "lunchbox" that often has a handle as pictured above on the left.

There are lunchboxes with four slots, six slots, and eight slots. The widest ones can have rack ears attached and be converted to a rackmount style. They are cheaper because they are single channel and only have a faceplate versus a giant chassis. This is good for those who want to collect a lot of different options. You can create your own channel strip if you want by adding in gear of all types into your lunchbox.

You've seen the single channel types above in the desktop format and the style. Dual channels are desirable so you can record stereo signals on the same electronics. What I haven't shown you yet are the types that feature four channels or even eight or 16! This is your most cost effective way to collect enough channels to record an entire band live or for a concert. The problem with these is that most of the time you're getting mediocre preamps. Now multiply that by 8 or I'm sure you catch my drift.

This isn't to say they aren't acceptable quality, but you aren't going to wow anybody either. A Preamp can be a simple passive signal router with no power supply or active circuitry or it can be a complex multi-box multi-voltage device with highly sophisticated active circuitry.

In either case the preamp does the same thing — get the signal from point A to point B with as little sonic deterioration as possible.