YAMAHA began making the TRB 1005 in 2005

YAMAHA made the first TRB 1006 in 2005

The TRB 4 had a double cutaway ash body with a bolt-on maple neck (24-fret rosewood fretboard with pearl dot inlays). The scale lenghth was 34 inches. Hardware was a solid brass bridge, 2-a-side gold colored tuners. It had 2 stacked single coils (alnico magnets) with active electronics (volume, treble, mid, bass and mix controls). The finish options were: Natural, Brown Satin, Blue Satin or Cherry Sunburst.

Sources of information:

Yamaha.com

Blue book of electric guitars, 9th Edition. Z.R. Fjestad

The TRB 4 II was introduced in 1998, as an update to the original TRB 4. The TRB 4 II has has since been discontinued. The 4-string TRB4 II has a rosewood-on-maple neck, ash body, ergonomic cutaway and neck joint, and bottom-anchoring brass bridge. The differences from the original TRB 4 include a pair of humbuckers (2 active single coils with dummy coils), 35 inch scale length (an inch longer than the TRB4), and active electronics with accurate three-band EQ. Finish options were: Amber Burst, Translucent Blue Burst, Magenta Burst.  Its recommended retail price, when new, was $1600.

The TRB 4 P was introduced in 1996

The TRB 5 II was introduced in 1998, as an update to the original TRB 5. The TRB 5 II has has since been discontinued. The 5-string TRB5 II
has a rosewood-on-maple neck, ash body, ergonomic cutaway and neck
joint, and bottom-anchoring brass bridge. The differences from the
original TRB 5 include a pair of humbuckers (2 active single coils with
dummy coils), 35 inch scale length (an inch longer than the TRB5), and
active electronics with accurate three-band EQ. Finish options were:
Amber Burst, Translucent Blue, Magenta Burst.

The Yamaha TRB 5PII was a through neck, 5 string electric bass guitar. The scale length was 35 inches, with a 20 inch radius ebony fretboard (24 frets). The body was made from light ash, topped with  a choice of maple, ovangkol or bubinga. Bridge was a row of yamaha BPZ-7 units. Pickups were 2-double coils (alnico V magents) and a piezo bridge transducer. Controls were master volume, balancer, piezo volume and 3-Band EQ. Finish was natural.

The six string Yamaha TRB6 bass was introduced in 1994.  It had the Yamaha 5-control Active System Electronics with a custom 3-band EQ and the 3 position Midrange control, with user adjustable settings. The TRB6 model also featured the Yamaha all-access bolt-on neck joint. The TRB6 was replaced by the TRB6-II model in 1998.

The Yamaha TRB 6PII was a through neck, 6 string bass guitar. The scale length was 35 inches, with a 40 inch radius ebony fretboard (24 frets). The body was made from light ash, topped with  a choice of maple, ovangkol or bubinga. Bridge was a row of yamaha BPZ-7 units. Pickups were 2-double coils (alnico V magents) and a piezo bridge transducer. Controls were master volume, balancer, piezo volume and 3-Band EQ. Finish was natural wood.

The Yamaha TRB JP (John Patititucci Model) was a 6 string electric bass. The bolt on neck had 24 frets and a 40 inch radius ebony fretboard. The scale lenght was 34 inches. The body was made from ash and alder topped with figured maple. The bridge was solid brass, pickups were side by side double coil (with alnico V magnets). Controls were active controls (5 knobs) . Finish options were amber or charcoal grey.

The Yamaha TRB5 5-string bass was introduced in 1994 and made until 1998 when it was replaced by the Yamaha TRB5-II model. The TRB5 had two double coil alnico pickups controlled by Yamaha's 5-control Active System Electronics. The custom 3 band EQ gave the TRBs extensive tonal versatility and the 3 position Midrange control, with user tweakable settings, enabled fast and repeatable presets.

The first TRB5 P was produced by YAMAHA in 1996