When deciding on a third-party cartridge to use with your Alva ST there are a few factors that you may wish to consider:
Applicable cartridge weight range: Between 2.5g and 10g.
Max cartridge height for the ST: 18.3mm
Internal phono stage input impedance: 47kΩ
Internal phono stage input capacitance: 330pF
For further reference it is worth noting that the internal phono-stage of the Alva ST is based on the circuitry of the Alva Duo.