Phono stage
A phono corrector is a specially designed preamplifier used when working with vinyl record pickups. Initially, the sound on such records is recorded with distortion of the amplitude-frequency characteristic, namely with an increase in volume from low to high frequencies; this is due to the technical features of the recording process. Accordingly, the phono corrector not only amplifies the signal to a level sufficient for feeding to the power amplifier, but also corrects the amplitude-frequency characteristic, “pulling out” the bass and reducing the volume of the HF. And
the built-in phono corrector allows you to connect the player to the power amplifier directly, without using intermediate equipment. True, in terms of characteristics, built-in preamplifiers-correctors are inferior to external ones. Therefore, some models with this function may provide
a “bypass” mode, allowing you to pass the signal bypassing the built-in phono corrector to an external, more advanced one. And there are also
vinyl players without a phono corrector at all.
Signal to noise ratio
The ratio between the useful signal and extraneous noise at the output of the player. It is also colloquially called "electrical noise" (although this is not entirely true).
The higher this indicator, the quieter the noise (it is impossible to completely eliminate them), the clearer the signal will be. In the case of turntables, the signal-to-noise ratio is considered to be at least 50 dB; and in the most high-end devices it can exceed 90 dB.
Note that this paragraph may additionally indicate the value of mechanical noise. Despite the similarity in name, this is a completely different indicator — it describes the volume of extraneous sounds produced by the motor, drive and other moving parts of the "turntable". Accordingly, for mechanical noise, the lower the decibels, the better. You can estimate its approximate level using special comparative tables.
Knock ratio
The maximum knock factor that the turntable is subject to under normal conditions.
Detonation in this case is called sound distortion associated with short-term periodic irregularities in the rotation of the disk. The lower the detonation coefficient, the lower the level of such distortions; it is believed that for audiophile-class equipment it should not exceed 0.2%, although in more modest models it may be higher.
Note that for different playback speeds, knock coefficients can also be different. Manufacturers in such cases may indicate the minimum value, despite the fact that it can be achieved not at the usual 33 rpm, but at 45 or even 78 rpm. Therefore, when choosing a high-end turntable, it's ok to clarify this point.
Platter weight
The weight of the disk on which the record is mounted. The smoothness of the ride and the ability to compensate for uneven rotation of the engine due to the inertia of the disk directly depend on this indicator. Therefore, among audiophiles, there is a reasonable opinion that the more massive the disc, the better; in top models, its weight can be measured in tens of kilograms. On the other hand, a heavy disk accelerates slowly (in some models it even needs to be pushed by hand at the start), and scratching on such a “turntable” would be very difficult, if not impossible. Therefore, for a DJ player, a large disc weight, on the contrary, will be redundant.
