Introduction: Why Valve Choice Matters
Whether you’re shopping for a bass trombone, upgrading your current setup, or replacing a damaged component, one of the most important decisions you’ll face is the valve section. For players considering S.E. Shires Co. instruments, understanding the differences in valve types and series options—especially between the Q Series and the Custom Series—can help ensure the right choice for both your playing needs and your budget.
Independent vs. Dependent Valve Sections
Before diving into valve types, it’s essential to understand how valve sections are configured.
In a dependent setup, the second valve (usually tuned to G♭) only activates when the F valve is already engaged. This means the second valve is dependent on the first. Dependent systems are slightly lighter and may feel more compact, but they offer fewer tuning options and alternate positions.
In an independent valve system, both valves function separately. The player can use either the F valve or the G♭ valve independently—or both combined (typically giving D tuning). This configuration is now more common among orchestral and jazz bass trombonists, offering more flexibility in alternate positions and low register access.
Shires Valve Types Explained
S.E. Shires Co. offers three main valve types in its bass trombone lineup:
Rotor Valve
This is the most traditional and widely used valve design in brass instruments. Rotor valves are:
Mechanically simple
Quick in response
Familiar to most trombonists
Shires Rotor valves are precisely manufactured, offering smooth mechanical action and excellent reliability. Most Q36 models feature traditional independent rotors, making them a great choice for players transitioning from student horns or for those seeking a responsive, predictable setup.
Axial Flow (Thayer-style)
Originally introduced in the 1980s, Axial Flow valves were a game-changer for many professional players. Sometimes referred to as Thayer valves, they feature:
A more open-blowing feel
Minimal resistance compared to traditional rotors
A straight-through design that preserves tone quality
Shires has refined the Axial Flow system over the years, and it remains a popular choice among orchestral players looking for clarity and freedom in the low register.
TruBore Valve (Custom Series Only)
The TruBore is Shires’ proprietary valve design, available exclusively in the Custom Series. This system uses a true straight-through airflow path with very low resistance, offering:
Seamless transitions between open and valve notes
Evenness in tone and feel
Minimal disruption to air column
While not available in the Q Series, the TruBore is often chosen by experienced players building a boutique-level horn tailored to their exact needs.
Q Series vs. Custom Series: Key Differences
Both series share the modular design Shires is known for, allowing for interchangeable bells, tuning slides, and valve sections—but they serve different audiences:
Q Series (e.g., Q36GR, Q36YR)
Factory-assembled modular instruments
Cost-effective with professional-level playability
All models include independent valve sections
Valve types limited to Rotor or Axial Flow
Pitched in B♭/F/G♭/D
Components like valve sections and bells are not usually sold separately
Ideal for students stepping into pro-level gear or working musicians seeking value
Custom Series
Built-to-order based on customer specs
Choose independent or dependent setup
Full choice of Rotor, Axial Flow, or TruBore
Customizable bell alloys, finishes, leadpipes, and tuning slides
Higher price point, but unmatched in flexibility
Appeals to top-level professionals or advancing players with highly specific preferences
Real-World Scenarios: Which Setup is Right for You?
Are you a college student in a performance degree program who needs a horn that can handle orchestra, wind ensemble, and jazz? A Q36 with independent rotors is a smart, versatile choice.
Are you a professional orchestral player seeking ultimate airflow and balance? A Custom Series with Axial Flow or TruBore may be the better fit.
Are you a repair technician or educator needing to replace a valve section or rebuild a modular setup for a student? Knowing whether the horn is Q or Custom—and which valve type it uses—is critical, especially since most manufacturers don’t sell these parts separately.
Why Modular Matters at The Brass Exchange
At The Brass Exchange, we frequently stock pre-owned Shires Q and Custom Series components including:
Valve sections
Bells
Tuning slides
Hand slides
Because Shires doesn’t typically offer Q Series parts à la carte, finding a replacement or upgrade through traditional channels can be challenging. We specialize in acquiring high-quality trade-ins and matching musicians with hard-to-find modular components.
Final Thoughts
If your bass trombone valve section fails or you’re looking to switch configurations, you may ask:
Can I just buy a replacement valve section?
With most brands—no. With us—yes, if you act fast when inventory becomes available.
Understanding the distinctions between Shires valve types, Q vs. Custom Series, and independent vs. dependent systems helps you make informed decisions—whether you're upgrading, building, or repairing.
Need Help?
Not sure what kind of valve setup you have—or want to build?
Please call or Contact us through our website. Here is a link to our current inventory page: https://thebrass-exchange.com/trombones
