Why buy a preamplifier ?
Choosing a stereo preamplifier, combining one or more audio power amplifiers, involves a greater investment than buying an integrated (where the preamp section and the power amp are within the same frame).
This solution, therefore, is the most suitable for enthusiasts looking to get the best performance from their Hi Fi.
In another dedicated guide we will consider, in particular, the phono preamplifier, an increasingly important component, since integrated amplifiers rarely have a standard input to connect a turntable.
Which elements affect the quality of a preamplifier?
The role of the preamplifier is to add some gain to the input line signal and then pass it on to the power amp.
In addition, the preamplifier also allows the adjustment of the listening volume, sometimes allows the adjustment of the tone controls (treble, bass, loudness, equalization) and the selection of sources (audio sources).
Some preamplifiers are also equipped with a headphone amplifier.
Unlike what usually happens with an integrated audio amplifier, in an independent preamplifier the selection of the components used is always carefully taken care of, in order to minimize background noise and distortion (THD).
To obtain these results it is necessary a very careful tuning work and a specific design with separate sections, able to allow an extremely silent operation.
The quality and selection of all active components is of paramount importance.
Between two operational amplifiers (a basic component) there can be huge differences in sound performance.
An operational amplifier is an active component that is widely used in audio preamp sections.
The main manufacturers are Burr-Brown and Wolfson.
Some models of preamplifiers use instead the so-called discrete components (and not integrated op-amps) with very low noise transistors.
The sonic results are certainly better, but the greater number of components required to make these circuits considerably increases the price of these devices.
The presence of audio tubes in a preamplifier does not imply superior performance from the point of view of the available audio band or harmonic distortion.
Rather, in a valve preamplifier what you hear when you listen is a richer, warmer timbre: a sonic result that is much appreciated and sought after by audiophiles.
The tube preamplifier can have a single thermionic tube or more than one audio tube. In the first case, the other preamplification functions are performed by traditional circuits.
Digital preamps are used to manage more complex functions. They usually integrate an audio section based on a high level digital/analogue converter (DAC), digital inputs, a DSP circuit for equalisation functions and analogue conversion circuits.
Usually this type of audio preamplifier is used in the professional field and there are few models of this type intended for high fidelity two stereo channels.
A passive preamplifier is a particular type of preamplifier that has no internal amplifier and, generally, not even a power supply section.
These models have only one source selector and one volume control.
There are models of passive T.V.C. transformer preamps. (such as the Opera Audio Consonance R1.3) and passive permalloy transformer preamps (such as the Xindak MP-1).
The volume control in these models has a very high precision.
Which factors should be taken into account when choosing the best model?
A particularly important factor in choosing a preamplifier is to verify that the model of your interest is equipped with a sufficient number of audio inputs to meet your needs.
Are there a number of inputs suitable for connecting all the Hi Fi components of your stereo system?
Is there an adequate number of audio outputs?
Do you need specific functions, such as sound equalisation functions?
Is the gain level suitable for the audio sources you are going to connect?
Will the output impedance match well with your power amplifier?
These are the main questions to ask before purchasing a Hi Fi preamp.
If you need further suggestions, please do not hesitate to contact us to obtain all the information that will help you choose the most suitable preamplifier model for your HiFi system.