Usually a string “date” involves 2 or 3 violins, viola, cello & violin bass. A nice medium size room works really well with the players arranged in a semi circle. Mic the instruments individually using high quality condenser mics. Mic the violins and viola from overhead, the cello and bass about 18” in front of the “F” hole. If you don’t have enough mics for the instruments you can also use a stereo pair and mic it like an ensemble. Pay attention to balance and move the players forward and backward, in relation to the microphone, to achieve the desired balance between the different instruments.
Solo instruments: Violin, Viola, mic from overhead using either a small condenser or a ribbon about 18” above the bridge area. Most of the sound comes from the body, like an acoustic guitar. Watch out for bowing angles from the player.
Cello, use a large diaphragm condenser about 18” from one of the “F” holes. Aiming the mic towards the lower body will give you more of a mellow sound, while aiming towards the bridge/fingerboard will give you more of an aggressive/bitey sound.
Violin bass/double bass/acoustic bass, is very similar to the cello. For live sound or recordings using a bridge pickup or a hyper cardioid dynamic mic will keep feedback at a minimum.
These tips will also work quite well with other string instruments as well. Zither, mandolin, auto harp and the like.
What are your favorite string recording techniques?