I have a session coming up where I will be recording a couple violins. I've done a few violin sessions in the past and never been happy with the violin sound I've ended up with - it's always been too thin and harsh. Any tips on mic placement to get a more mellow sound? I'm in a home studio with a mediocre room at best so I don't want a lot of room sound.
There's a lot of personal preferences that goes into this decision, but I personally prefer recording acoustic instruments with a large diaphragm condenser microphone. You can position the microphone very closely to the instrument, provided the violinist doesn't move around a lot when playing, and you can experiment with placing the microphone closer to the body or the neck. When placed properly, you should be able to capture a much more full bodied sound.
Alternatively, you can get dedicated violin microphones that are attached to the instrument. They will give you a very intimate sound, and some would argue unnatural or intimate, since the recorded sound will be closer to that of the violin player than of a typical listener. The freestanding microphone gives you a lot of freedom to try to get the sound you want before you hit the mixer.
For a more thorough setup, consider setting up two microphones; a condenser microphone close to the instrument and another microphone to pick up ambient room sounds. Between the two microphones you can decide how much fret noise and other noises from the violin you wish to pick up and thus how "intimate" you want the sound to appear to the listener. You might even find that the room's effect on the ambient microphone sometimes work as a nice subtle effect in your mix.
When you record multiple violins, especially if you capture all violins with one microphone, make sure you position the players to avoid phasing problems. Try varying how the players stand around the microphone, e.g. facing each other, side by side, or at an angle. Just a few degrees can sometimes make a huge difference for other instruments and I don't see how violins would be any different in this regard.