KR Audio
Expected Oct 10, 2025
5U4G Vacuum Tube
$650.00 USDThe KR Audio 5U4G rectifier tube is a high-end full-wave thermionic vacuum tube that sets the standard for exceptional performance and audiophile-grade sound quality. This meticulously crafted tube is designed to elevate your audio experience by providing a stable, regular voltage and superior current rectification, ensuring that your amplifier delivers the rich, detailed sound you demand. Ideal for use in tube amps, guitar amps (Fender, Mesa Boogie), preamp tubes, and pedals, the KR Audio 5U4G is a versatile addition to any hi-fi setup.
The KR Audio 5U4G is the result of years of research and development, combining advanced engineering with the finest materials and filaments to create a rectifier tube that stands head and shoulders above the competition. Its superior design ensures long life and reliable operation, making it the perfect choice for discerning audiophiles who refuse to compromise on sound quality. At the heart of the KR Audio 5U4G's outstanding performance is its ability to deliver a stable, regular voltage to your amplifier's circuit. By providing a clean and consistent power supply, this tube allows your amplifier to operate at its full potential, reproducing music with unparalleled clarity, dynamics, and emotional impact.
The 5U4G's excellent current rectification capabilities ensure that your amplifier has the necessary power to handle even the most demanding musical passages with ease. This tube's superior rectification process minimizes voltage drops and reduces noise, resulting in a cleaner, more transparent sound that brings out the best in your favorite recordings. Available in variations such as the jj5u4gb rectifier vacuum tube, 5U4GA, and GE 5U4GB RCA, and produced by renowned manufacturers like Electro-Harmonix, KR Audio, Sylvania, Mullard, JJ Electronic, and Tung-Sol, this new production tube maintains the heritage of high-quality USA-made power tubes. We consider the KR Audio version one of the best on the market.
The Legacy and Popularity of the 5U4 Tube
The 5U4 tube, a venerable component in the world of audio electronics, boasts a rich history that dates back to the golden age of tube amplifiers. First introduced in the early 20th century, the 5U4 tube quickly became a standard for full-wave rectification in high-fidelity audio systems and professional audio equipment. Its ability to convert alternating current (AC) to direct current (DC) efficiently and reliably made it an indispensable component in ensuring the smooth operation of tube amplifiers.
Over the decades, the 5U4 tube has earned a reputation for its durability, stability, and superior performance. Its robust design allows it to handle high current loads while maintaining a steady and regular voltage output, which is crucial for preserving the integrity of audio signals. This reliability has made the 5U4 a favorite among audiophiles and audio engineers who seek to maintain the highest standards in sound quality.
The resurgence of interest in vintage audio equipment and high-fidelity sound systems has further cemented the 5U4 tube's popularity. Audiophiles appreciate the tube's ability to contribute to a warm, rich sound that many find lacking in modern solid-state devices. The 5U4 tube is often lauded for its role in delivering a natural, detailed audio experience that enhances the subtleties of music playback.
Today, the 5U4 tube remains a sought-after component for those looking to achieve an authentic, high-quality audio experience. Its enduring legacy is a testament to its exceptional performance and the timeless appeal of tube-based audio technology. As more audiophiles continue to seek out the best possible components for their systems, the 5U4 tube's popularity shows no signs of waning, solidifying its place as a cornerstone in the world of high-fidelity audio.
KR Audio WARRANTY ON TUBES ONLY
Please take a moment to return your warranty registration form included with the tubes. Unregistered KR tubes will not be warranted. Customers must return the warranty registration when the tubes have been received.
KR Audio Electronics will respect valid warranty claims. Incorrect claims or late warranty registration will void any guarantee. KR Audio Electronics will replace the tube provided the following conditions are met:
- The tubes were used according to the technical data sheet enclosed with the KR tube.
- Abuse, accident or unauthorized use of the tube will be determined by KR Audio Electronics.
- All tubes to be returned with the original factory box and warranty.
- To obtain a replacement for a faulty tube, KR Audio Electronics reserves the right to obtain dealer or distributor authorization prior to shipping products pre-paid back to us.
KR Audio Electronics gives a one-year warranty for your tube from the date of purchase. The purchase date should be written or stamped by the dealer or distributor on the day you buy the tube. Only expert technicians can change the work point of the tube. Improper use of the tube or incorrect application of the tube to a circuit cannot be covered by our warranty.
Moon Audio Tube Testing Process
Our high-end audio systems achieve sonic purity through the use of carefully selected NOS vacuum tubes. We take time to search for NOS tubes, understanding their unique potential for audio reproduction. Each tube is rigorously tested using legendary HICKOK 800K 600K Dynamic Mutual Conductance Tube Tester and TV7-A/U Vacuum Tube Testers to measure critical parameters, including mutual conductance, emission, and gas levels. By precisely matching tubes based on these measurements, we deliver balanced, dynamic, and lifelike audio that elevates your listening experience to an art form.
FAQ
What is a 5U4 rectifier tube and what does it do?
The 5U4 rectifier tube is a full-wave thermionic tube used to convert AC to DC, providing stable voltage for audio equipment and ensuring smooth operation of tube amplifiers.
What are the differences between 5U4 and other rectifier tubes?
The 5U4 tube is known for its robustness and ability to handle high current loads, while other rectifier tubes like the 5AR4 or GZ34 might offer different voltage drops or current capacities.
Why is the 5U4 tube popular among audiophiles?
Audiophiles favor the 5U4 tube for its ability to contribute to a warm, rich sound quality and its reputation for reliability and long life in high-fidelity audio systems.
How do I know if my equipment is compatible with a 5U4 rectifier tube?
Check the specifications of your audio equipment or consult the manufacturer's documentation to ensure compatibility with the 5U4 tube.
What are the benefits of using a 5U4 rectifier tube in my amplifier?
Benefits include stable voltage output, improved sound quality, and enhanced performance and longevity of the amplifier.
How long does a 5U4 rectifier tube typically last?
The lifespan of a 5U4 tube varies based on usage and operating conditions but can often last several years due to its robust construction.
Can I replace a 5U4 rectifier tube myself, or do I need a professional?
While some experienced users can replace a 5U4 tube themselves, it is often recommended to seek professional assistance to avoid damaging the equipment or the new tube.
What are the signs that my 5U4 rectifier tube needs replacing?
Signs include noticeable drops in audio performance, increased hum or noise, or visible damage to the tube itself, such as burn marks or cracks.
Are there different versions or brands of 5U4 tubes, and do they vary in quality?
Yes, various manufacturers produce 5U4 tubes, and quality can vary. Researching and selecting reputable brands is crucial for optimal performance. We believe the KR Audio version of the 5U4G tube is one of the best on the market.
| Parameter | Specification |
|---|---|
| Technical Specifications | |
| Filament Voltage | 5 V (DC/AC) |
| Filament Current | 1.8 A |
| Amplification Factor | 3.7 |
| Maximum Ratings | |
| Maximum Plate Voltage | 600 V |
| Maximum Plate Current | 160 mA |
| Plate Dissipation | 70 Watts |
| Operating Specifications | |
| Plate Voltage (Va) | 450 V |
| Plate Current (Ia) | 100 mA |
| Grid Voltage (Vg) | -94 V |
| Performance Specifications | |
| Transconductance | 5.7 mA/V |
| Product Specifications | |
| Production Status | New production, includes warranty |