Phono Stages (Phono Preamplifiers)

Phono stages boost the tiny voltage signal from a phono cartridge about a thousand times to line level voltage (such as from a CD player) while applying frequency replay equalization (bass boost-treble cut) to correct the frequency equalization (bass cut - treble boost) applied when cutting a record. Handling such tiny voltage signals well can not be done by a few cheap electronic parts.

Phono stage implementation

How well a phono stage boosts the tiny noisy signal from a cartridge without loosing or distorting information largely depends on the way in which it is implemented:

- simple on board chip in a mass market receiver
- basic board in a entry level turntable
- integrated amplifier containing a phono stage section or dedicated internal board
- stand-alone phono stage component powered by a wall wart
- stand-alone phono stage component with it's own internal power supply
- stand-alone phono stage component powered by a separate external power supply.

Types of phono stage

Entry level phono stages are usually for moving magnet cartridges only. More expensive ones add moving coil cartridge capability while some are moving coil cartridges only. In those with moving coil capability some use internal step-up transformers prior to a moving magnet circuit design, while others are designed from the ground up for moving coil cartridges without using a step-up transformer. To cater to the different moving coil cartridge outputs, moving coil phono stages have a range of load and sensitivity options that will affect the sound.

Sonic benefits of higher priced phono stages

With better power supplies, circuit board layout and higher quality closer tolerance electronic components you get better bass, purer timbres, soundstage width and depth, dynamics, air, and clarity. The signals from phono cartridges are noisy especially those from moving coil cartridges which require lots of voltage gain. Circuit board layout and the physical separation and shielding of the R and L circuits become even more critical than line level components. Balanced versus non-balanced, how load settings are implemented, and the purity of the power supply and potential interactions are all critical. The high gain amplification has to manage the significant amount of low frequency boost/high frequency attenuation RIAA equalization applied without overload and distortion. The choice of high quality electronic parts used critically affects sound quality.

There is a large range of cartridges in the market place which require different settings and a phono stage with a wider range of settings allows best sound for a large percentage of cartridges. We can demonstrate how changing gain and loading settings affects the sound.