Zeta Music Systems' Performer Series instruments are traditional acoustic violins, violas, cellos and upright basses that have Zeta's patented pickup systems and active electronics for feedback-free acoustic tone. The 5-string Acoustic Pro violin uses a traditional maple violin bridge with an E-series pickup system, 9-volt preamp, and standard 1/4 inch output jack. The traditionally varnished acoustic violin body features a neck with a fifth, low C string that extends its range into the viola's bailiwick. The fingerboard has to be a little wider that standard violins so the strings are spaced slightly closer together for a playable compromise.