I've read much here about 2nd Violins and would like to contribute the following.
I had a stint as the conductor of a theatre orchestra (as i've mentioned previously)
With 10 first Vls, and 8 seconds, the sound was quite reasonable and a reflection of a full orchestra given the restrictions of space, and type of music played. (Think King and I, Kismet, etc.) When i first arrived the morale was low, a result of an incompetent previous baton waver, and a director who's sense of humanity was not related in any way to the rest of us human beings and our perception of civilized behavior. The second Vls were a throughly dispirited lot, having night after night of offbeats, mournful tremolos, and the odd pizzicato to dream of. I began a program of swapping the players around, and with the exception of the top desk of 1st Violins (I paid respect to their seniority and ability as it should be) 1st's and 2nd's were mixed in a pool, working on a rota system. This had two effects. The seconds cheered up considerably, and although some firsts initially resisted this idea, with careful diplomacy they came around. The quality of playing improved immediately, and other sections showed interest. I was building a team, and after two months, my plan was accepted with enthusiasm. The actors and singers joined this fray too, regularly swapping parts, and the improvement in quality, and friendly competition, gave performances a life that filled the theatre, and gave all the performers both an opportunity to shine, and a rest.
The ONLY difference between 1st and 2nd violins was in the orchestration.
1st's tended to be written on the top strings, where the seconds would incorporate the lower strings more frequently. In addition, the seconds would be doubled more often with the violas, and occasionally cellos, and the COMBINATION of tones created a new sound in itself. It's this that creates the impression of 2nd Violins having a 'sound of their own', coupled with the lesser number of players, and in non professional orchestras, a degree of lesser ability. (In this i generalise)
I'm working on a symphony at the moment, that at several points, requires all strings (with the exception of the Contrabasses) to play unison. It's a powerful sound, and directly reflects the lack of difference between the 1st and 2nd violins.
Contrary to much of what has been written about a separate 2nd Vl section in VSL samples, you actually have something that a live orchestra could lack. An equally competent 2nd violin section, unfettered by the possibilty of lesser ability. It's your orchestration that will reflect any perceived 'difference' between the sections, not some 'unique 2nd violin sound.'
To vibrato and others who are starting their musical journey, write well, and you will understand the difference between violin sections is a result of your creative attributes, and don't get bogged down with reflections on what is different or not. It's the notes, articulation, and pitch that make the difference, because the instruments are the same, played the same way. Combined with, generally, two less players in the seconds (i've played in orchestras with equal numbers), your ability and music will reflect the difference without requiring the urban myth of a 'second violin sound.'
Regards to you all,
Alex.