The Yamaha YTR-9445CH (Serial Number D57889) configured with a Bob Reeves Valve Alignment and a Jim Becker (Osmun Music) 3rd Vented Slide modification is a masterfully optimized orchestral instrument. This precise combination of modifications transforms a standard Chicago Series Gen 3 C trumpet into a high-performance machine by fixing native physical imbalances. 

This is Yamaha’s premier Chicago Series Custom C Trumpet. Designed in collaboration with John Hagstrom of the Chicago Symphony Orchestra, it features a heavy-wall valve casing, a Malone MB1 long-taper leadpipe, and a reversed tuning slide. It provides massive orchestral projection and an incredibly locked-in core sound. [3, 4]

Even top-tier factory trumpets experience “accumulated tolerances” where the internal ports of the pistons do not align perfectly with the casing ports when up or down.

• The Fix: Bob Reeves Brass measures the exact travel distance of your unique valves and installs customized, highly durable pads.
• The Result: It eliminates turbulent air “cliffs” inside the horn. You will experience laser-defined note slotting, improved intonation accuracy, an easier upper register, and perfect resistance consistency across all fingerings. [1, 5, 6, 7]

When you move the third valve slide out to correct sharp low D and C# notes, air pressure creates a vacuum seal inside the tubing. Normally, you must press the third valve down just to move the slide. [2, 8, 9]

• The Fix: Legendary brass tech Jim Becker at Osmun Music micro-drills a small, precise vent hole through the third valve piston. This vent perfectly aligns with the slide leg casing only when the valve is in its resting “up” position.[2, 
• The Result: Air passes freely in and out of the slide, completely eliminating the acoustic “pop” or suction resistance. You can effortlessly throw the 3rd slide out for rapid-fire adjustments without touching the piston, and it stops the slide from aggressively flying out or bouncing back.