Tips on buying phono pre-amplifiers
Phono pre-amplifiers do not have an easy job. Not only is the incoming signal pretty weak and feeble (between 0.15 and 8 mV, depending on the system) but it also has a totally distorted frequency response. This is because before a record is pressed, the music’s frequency response is warped, so as to minimize the mechanical limitations of the record as a sound carrier. Due to the first of these two factors, a higher gain is necessary. And as a significant number of record players are delivered with astonishingly poor (and unfortunately hard-wired) signal cables, this means that unwanted interference in these cables is also amplified. Moreover, the distorted frequency response calls for equalization, which naturally also has a certain influence on the basic purity of the sound. But these are not the only worries, because unlike high-level sources, pickup units present us with a really broad range of different impedances and capacities.
Therefore, with phono pre-amplifiers, the distance between the desired signal and the interference signal has to be greater, and the impedances and capacities should be taken into account. Simpler phono pre-amps prove to be rather ignorant in this regard and muddle through with average values. Those in a higher price range, however, can be adjusted individually, often by means of mouse pianos, commonly known as DIP switches.
In hi-fi systems, all components should be as well-matched as possible. For this reason, don’t buy the phono pre-amplifier until you know what pick-up system you are using. If you already have solid information in this regard beforehand, you don’t necessarily have to choose a pre-amp that offers all possible applications (MM, MC and mouse piano). Instead, you can specifically purchase one that really matches your system, in every sense.
Tip: Keep an eye out for pre-amps that are battery-buffered. To put it simply, when activated, these run “on battery power”, i.e. using steady direct current – rather than laboriously filtered and sieved alternating current. “Only buy what’s absolutely necessary, but if it’s necessary, make sure it’s good”: this should be your motto when buying a phono pre-amplifier.