There's a nice one of these in the great Garritan World Library.
But, if you don't have World yet, or you do and would like an additional/alternate instrument - I put one together for you.
ANOTHER BANJO FOR ARIA
Click on that text and you'll get to a Zip file. Unzip it in a logical place on your hard drive. You'll have the Banjo sample set and the SFZ file that controls them. Keep all of that together in one folder.
In Aria, go to load an instrument and use the Import option. In the browser that opens, go to where you parked the Banjo folder, and click on the SFZ file.
Voila- The instrument loads and is ready to be played.
There are two velocity layers, with a value of 80 as the split point. Any velocity above 80 will play the louder samples, below that triggers the softer ones. Of course you still have the complete range of volume of 0 to 127, depending on your velocity values.
These are from the collection of free instrument samples hosted by the Philharmonia Orchestra. Forum member "Sec 2 - Fab" mentioned that great site on another current thread about string harmonics. I'd never heard of this before - Went there and was amazed.
As a test, I used the simplest instrument in the list - the Banjo. Now that I know what to do, I'll experiment with making SFZ instruments with some of the other samples available there.
Note that besides Aria, there are other samplers that use the SFZ format, like Cakewalk's Dimension Pro.
What Philharmonia has to offer is potentially a really nice compliment to what we already have in the Garritan Libraries, so I'm glad Fab told us about it!