Meet the 5U4

The 5U4 is a common full-wave rectifier tube used in power supplies to convert alternating current to direct current. Its twin-diode design uses a shared cathode and two anodes to convert both halves of the AC cycle. Rectifiers like the 5U4 are sometimes overlooked by audiophiles, but like power and signal tubes, they can greatly influence the sound of a tube amplifier.

A New Dimension of Sound

The SELECT Collection not only maintains the exceptional manufacturing quality of the CORE Collection but makes a significant leap in sound quality. Engineered for audiophiles who want an immersive auditory experience, this tier far surpasses what “factory vacuum tubes” can offer.

Make Your Good Amp Great

The SELECT Collection significantly upgrades the performance of your vacuum tube amplifier, even starter models. These vacuum tubes are engineered to enhance the hidden capabilities of your amp, transforming its output into something far beyond its original sound profile. With each vacuum tube rigorously selected by our audio engineers, the SELECT Collection ensures a profound enhancement in clarity, texture, and detail. Every note resonates with more realism, every harmony carries more emotionality, and every rhythm pulses with tighter low-end precision.

The SELECT Vacuum Tube Difference

Despite originating from the same batches as Ray Tubes' CORE Collection, SELECT vacuum tubes are distinguished not by automated manufacturing differences but by the expert judgment of a professional. Their engineers assess each vacuum tube individually for its sound profile, dynamics, microphonics, gain, conductance, noise, and overall performance. This human touch ensures that only vacuum tubes that meet a superior level of sonic excellence are chosen. This meticulous, engineer-led selection is what makes the SELECT Collection exceptionally reliable and capable of delivering next-level sound quality.

Silk-Screen Printed Logos

Even the logos deserve a special mention. Silk-screen-printed onto the tubes, they demonstrate Ray Tubes’ commitment to superior craftsmanship down to the smallest detail. This time-honored printing technique yields results that are not only aesthetically pleasing but also durable, ensuring the design work remains vibrant and intact over time.

Superior Sound, Secured

An exceptional 12-month warranty—a rarity in the world of vacuum tubes, especially NOS vacuum tubes—reflects Ray Tubes’ confidence in their vacuum tubes’ performance and durability. This warranty is your safeguard against any manufacturing defects, making sure that your investment is protected.

Product highlights

• Hand-selected and tested

• A substantial upgrade from standard NOS tubes

• Low noise and microphonics

• Fewer than 5% of the tubes commissioned for production meet our voltage, current, and sound signature standards

• 12-month warranty against manufacturing defects

Specs

• Tube type: 5U4

• Socket: 4-pin

Compatible Amps

Explore Ray Tubes' Tube Amp Compatibility List

What's included

• Single Ray Tubes SELECT 5U4 OR Matched Pair of Ray Tubes SELECT 5U4 OR Matched Quad of Ray Tubes SELECT 5U4

• Manual booklet

Explore More

• What Tube Amps Are Compatible with Ray Tubes?
• How Do You Maintain Your Vacuum Tubes?
• How Do I Roll the Tubes of My Tube Amp?
• Why Upgrade Your Tubes?
• What Are Matched Tubes?
• FAQ