The King 4BF Sonorous Silversonic from the 1970s stands as one of the most striking and powerful large-bore tenor trombones produced by King during this era. With a serial number of 490308, this instrument features an 8.5" sterling silver bell with a gold-plated inner bell, paired with a .547 bore nickel silver slide designed for large-shank mouthpieces.
The 4BF was King’s answer to the demand for a full symphonic-sized tenor trombone with F-attachment, giving players a larger tonal palette and extended range. The sterling silver bell, one of King’s hallmark features, contributes to the horn’s brilliance and energy. As with all sterling bells, it requires just a little more input energy from the player, but the output is extraordinary—producing a tone that projects with enormous presence and intensity.
This example remains in excellent condition. The bell is in perfect shape, showing no history of damage or trauma. The handslide shows light plating wear on the inner tubes, but still plays smoothly and reliably. Compared to many vintage examples, this slide is in very respectable shape and more than serviceable for regular use.
Players today would find this instrument completely at home in a symphonic band or orchestra setting. Its combination of sterling silver power and large bore warmth makes it an exceptional choice for those seeking a bold, colorful sound.
To provide context, a new King 3B Legend straight tenor with a sterling silver bell (and no F-attachment) sells for approximately $4,800—and does not include a gold-plated inner bell. If the 4BF Sonorous Silversonic were still being produced today, its cost would likely exceed $6,000 given the sterling bell and gold-plated interior. Vintage examples like this offer an attractive and rare opportunity to own a true King classic.
Q&A
📌 What makes the Sonorous Silversonic different from a standard King 4B?
The sterling silver bell with gold-plated inner creates unmatched projection and tonal complexity, giving it more brilliance and power than a standard yellow brass bell.
👉 How does the 4BF compare to smaller-bore King models like the 3B?
The 4BF is a full .547 large-bore tenor with F-attachment, designed for symphonic use, while the 3B models are smaller-bore jazz trombones. The difference in tone and power is significant.
This King 4BF Sonorous Silversonic has been sold and is now preserved in our archive as a historical reference for King collectors and symphonic trombone enthusiasts. Looking for current inventory? Browse our trombones 🔎
