The four-string TRBX304 and TRBX504, along with the five-string TRBX305 and TRBX505, include new equalizers and pickups. All four models use a five-piece maple/mahogany necks along with crafted solid mahogany bodies that are perfectly balanced and lightweight.

The 500-level basses come with new H5 dual-coil pickups and three-band active electronics (with battery alert LED) with EQ that can be turned off to play the bass using the passive pickups. I liked that Yamaha worked out going from active to passive modes without losing any gain--an excellent feature for mid-song changeovers during live performances!

The 300-level models have M5 hum-bucking pickups and a Performance EQ switch lets players toggle between styles and sounds "on the fly". Select Slap, Pick, Flat, Finger and Solo settings and then further refined the sound using the two-band active EQ controls.