Of all the instruments found within the Biblical texts and depicted on the coins of bar Kochba is this strange, string instrument called in Hebrew the në-bal (literally meaning "wine skin bottle"). This instrument, which we will refer to herein as a harp, consisted of a bulbous, hollow sounding chamber into which large animal horns were inserted and secured with metal bands. The main body and sounding chamber of this instrument was constructed much like a large salad bowl with a large, oval hole in the top. This hole (referred to in Amos 6:5 as the mouth of the harp) permitted the instrument maker to carve out the interior of the body and attach the horns within the body chamber.
The ten (or possibly more) strings were attached on either side of an upper string plate and terminated on their opposite ends into tuning keys inserted into the sides of the main body. This floating string assembly consisted of a notched plate which was free to slide on the two horns and three or more vertical support columns that terminated into what looks like a large potato. This plug, not only loosely covered the access hole or mouth of the harp, but also enabled the vibration of the strings to be transmitted to the main sounding chamber. This complete string assembly was vertically kept in place by the tension applied by the strings between the upper plate of the string assembly and the tuning keys.
Unlike traditional harps whose strings vary in length, the ten strings of the Hebrew harp were of the same length and arranged in two sets of five on either side of the instrument. Played with both hands like a modern harp, the Hebrew nebal was primarily a melodic instrument that most likely doubled the melody of the singers or played a counterpoint to it.
It is difficult looking at the pictures of the reconstructed instrument to realize just how large and cumbersome it is in real life. Weighing in at a little less than twenty pounds and standing almost three feet in height, the nebal was steadied with a strap that was attached to large rings inserted through the base of the horns. Even with the supporting strap, the instrument depicted on the coins of bar Kochba was a not something that could be easily carried around and played.
Regarding the tuning of the harps, the determining factors on all fixed-length string instruments like the harp is the diameter of the string and how tight a particular string be tensioned. Unlike the lyre, which could change the pitch of three of the strings, the harp had no facility to change the tuning of a string once it was tuned. From the resulting transcriptions of the Psalm manuscripts, we find that the ten tones that comprised the base for their melodies and a possible tuning for the harp were:
E2 - F2 - F#2 - G2 - G#2 - A2 - A#2 - B2 - C3 -
(where C4 = middle C)
These pitches comprised the lower register of the string section (an octave lower than the lyres) and were similar to the range of the lowest three strings of a standard guitar (i.e., E2 to D3). As was the case with all of the early string instruments, the harps were very soft-spoken instruments and in the early texts of the Levite ensembles, the ratio of harps-to-lyres was always greater (1 Chronicles 15:20-21).