The preamp is a word used in many different ways. Countless manufacturers, marketers, and regular users used preamp when it comes to audio gear discussions. Sometimes, most people confuse preamp with DI boxes where in fact it’s not. There are just some devices includes the functions of both but preamp is greatly different.
A preamp or preamplifier is an electronic device that prepares a small electrical signal to be used for further amplification and processing. Preamps are usually used to amplify signals either from microphones, instrument pickups, and phonographs. A preamp can be built into an instrument, a pedal, a rack-mountable unit, a sound card, a mixer or other forms of devices. A preamp is also considered as the input stage of the head the amps.
Different Types of Preamplifier
The current-sensitive preamplifiers are generally used to measure the energy of several detectors such as photomultiplier tubes and microchannel plates which generate a moderately large and fast-rising output signal in high output impedance. The pulse processing or timing and counting for these detectors are simple. However, if the detector signals are small enough and need a current-sensitive amplifier, the effect of the preamp input noise on time resolution needs attention.
The parasitic capacitance is the most cost-effective preamplifier used for pulse-amplitude measurements. This kind of preamps has high input impedance. Having a preamp with high input impedance and unity gain is sensitive to small changes.
The charge-sensitive preamplifier produces a voltage output proportional to the integrated value of the current input. It also offset the input charge through the use of feedback reference capacitor. These amplifiers are preferred for most energy spectroscopy applications.
What Does Preamp Do?
A preamp processes a signal to make it match for the next signal chain. It boosts the signal to keep from debasing the sound to noise ratio and allow users to understand how far from each other the source and destination are. Preamps are essentially designed to achieve the following:
- Increase gain
- Change tone
- Convert balanced to unbalanced output
- Lower the impedance with the output
The preamps are often placed close to the sensor to lessen the effects of noise and interference. It is also used to boost signal strengths in order to drive cable to the main device without degrading the SNR or Signal to Noise Ratio. When it comes to the noise performance of the preamps, it is critical. Because when the gain of the preamplifier is high, the SNR of the final signal can be determined by the input signal SNR and the noise figure of the preamp itself.
Why use Preamp
Basically, preamplifiers are living with four main functions:
- To match impedance
- To source selection with clean and accurate amplification to line level
- Serves as a very good volume control
- Adds tonal qualities to the sound
Every preamp has many roles such as boosting, cleaning, adjusting and blending signals into one. Preamps are one of the most important instruments in music. The way you select the right one that matches your needs for performances will open the door for outstandingly great sound possibilities.