Three factors come to mind.
1. Microphones used, pickup pattern of those mics and miking technique. Having made many orchestral recordings using a variety of mics and miking techniques and in a variety of halls, it has been my experience that these variables can make a real difference in the way strings (and everything else for that matter) sound in playback. The best vinyl recordings I have heard seem to be older ones that were made using very simple miking techniques. While there are variations in the smoothness of the string sound among those recordings, they are all very listenable. Much time was typically taken to make tests in order to achieve proper balance of the various orchestral sections as well as the balance of direct to reverberant sound with the goal to get the mics in absolutely the ideal location. There are a number of more recent recordings that were made using similar minimalist techniques that sound impressive as well, some analog and others digital. Many post mid-1970 recordings were made using overly complex miking techniques that sound awful. The development of multi channel recorders and mixing consoles created opportunities for engineers to twiddle away to a fare thee well. Some engineers justify this claiming that it is far easier (and less costly) to achieve proper balance in mixdown if they mic sections of the orchestra more closely. No one listens to strings or any other instrument from 5-6 feet away in a concert hall save the musicians themselves. There are sometimes some nasty mechanical sounds one can hear when very close to an instrument that just naturally get attenuated and mixed with reflected sound in the concert hall and seem to disappear by the time it reaches the audience.
2. There is the psycho acoustic effect of actually being in the concert hall and seeing the musicians play. It has been my observation that we accept sounds in a live performance that we would reject as troubling in some way when in playing back a recording of that same performance in a listening room.
3. When we listen to a recording in a listening room, we hear not only what was recorded, but the influence of the listening environment and the playback equipment. We can chase our tails (and empty our bank accounts) trying this type of tweeter or that type of preamp and never achieve what we heard (or thought we heard) in the concert hall.
1. Microphones used, pickup pattern of those mics and miking technique. Having made many orchestral recordings using a variety of mics and miking techniques and in a variety of halls, it has been my experience that these variables can make a real difference in the way strings (and everything else for that matter) sound in playback. The best vinyl recordings I have heard seem to be older ones that were made using very simple miking techniques. While there are variations in the smoothness of the string sound among those recordings, they are all very listenable. Much time was typically taken to make tests in order to achieve proper balance of the various orchestral sections as well as the balance of direct to reverberant sound with the goal to get the mics in absolutely the ideal location. There are a number of more recent recordings that were made using similar minimalist techniques that sound impressive as well, some analog and others digital. Many post mid-1970 recordings were made using overly complex miking techniques that sound awful. The development of multi channel recorders and mixing consoles created opportunities for engineers to twiddle away to a fare thee well. Some engineers justify this claiming that it is far easier (and less costly) to achieve proper balance in mixdown if they mic sections of the orchestra more closely. No one listens to strings or any other instrument from 5-6 feet away in a concert hall save the musicians themselves. There are sometimes some nasty mechanical sounds one can hear when very close to an instrument that just naturally get attenuated and mixed with reflected sound in the concert hall and seem to disappear by the time it reaches the audience.
2. There is the psycho acoustic effect of actually being in the concert hall and seeing the musicians play. It has been my observation that we accept sounds in a live performance that we would reject as troubling in some way when in playing back a recording of that same performance in a listening room.
3. When we listen to a recording in a listening room, we hear not only what was recorded, but the influence of the listening environment and the playback equipment. We can chase our tails (and empty our bank accounts) trying this type of tweeter or that type of preamp and never achieve what we heard (or thought we heard) in the concert hall.