Loar worked for Gibson from 1919 to 1924. His contributions include building the instrument top with F-shaped holes, like a violin; introducing a longer neck, thus moving the bridge closer to the center of the body; and floating the fingerboard over the top, a change from prior Gibson instruments that had fingerboards fused to the top. He also pioneered the use of the Virzi Tone Producer, a spruce disc suspended from the instrument top that acts as a supplemental soundboard.