At Limestone, our passion lies in creating amplifiers that merge the timeless charm of retro sound with the reliability of modern craftsmanship. This vision is shared by our trusted partner, Ray Tubes, whose dedication to authentic tube technology and precision engineering is unmatched. Together, we bring you the best of both worlds: the warm, rich tones of vintage sound paired with the durability and performance of contemporary design. We're proud to say that every Limestone amplifier leaves our workshop equipped with Ray Tubes, ensuring the heart of your sound is built on excellence.

SELECT Series: Premium Tubes Included with every Limestone Amplifier

KT88 SELECT

The Ray Tubes KT88 SELECT Vacuum Tubes enhance your Limestone amplifier with exceptional improvements in clarity, texture, and detail, thanks to meticulous, engineer-led selection and gold pins for superior conductivity and durability.

Designed to unlock your Limestone amplifier's hidden potential, these tubes transform its output far beyond the original sound profile, making them a substantial upgrade from standard NOS tubes.

Ray Tubes is revitalizing the vacuum tube market with hand-selected, rigorously-tested tubes, backed by a 1-year warranty that underscores the quality and reliability of their products.

6SN7 SELECT

The Ray Tubes 6SN7 SELECT Vacuum Tubes enhance your Limestone amplifier with exceptional improvements in clarity, texture, and detail, thanks to meticulous, engineer-led selection and gold pins for superior conductivity and durability.

Designed to unlock your Limestone amplifier's hidden potential, these tubes transform its output far beyond the original sound profile, making them a substantial upgrade from standard NOS tubes.

Ray Tubes is revitalizing the vacuum tube market with hand-selected, rigorously-tested tubes, backed by a 1-year warranty that underscores the quality and reliability of their products.

RESERVE Series: An Optional Upgrade for the Discerning Ear

KT88 RESERVE

The Ray Tubes KT88 RESERVE Vacuum Tube delivers a profound, lifelike audio experience with smooth vocals, balanced treble, and commanding low-end, tailored specifically for audiophile systems. Each tube undergoes meticulous selection and quality checks, featuring gold pins for enhanced conductivity and durability, making it the supreme upgrade for high-fidelity applications.

Ray Tubes is revitalizing the vacuum tube market with hand-selected, rigorously-tested tubes, backed by a 1-year warranty that underscores the quality and reliability of their products.

6SN7 RESERVE

The Ray Tubes 6SN7 RESERVE Vacuum Tube delivers a profound, lifelike audio experience with smooth vocals, balanced treble, and commanding low-end, tailored specifically for audiophile systems. Each tube undergoes meticulous selection and quality checks, featuring gold pins for enhanced conductivity and durability, making it the supreme upgrade for high-fidelity applications.

Ray Tubes is revitalizing the vacuum tube market with hand-selected, rigorously-tested tubes, backed by a 1-year warranty that underscores the quality and reliability of their products.