{"product_id":"kr-audio-5u4g-tube-single","title":"5U4G Rectifier Vacuum Tube","description":"\u003cbuilder-component rev=\"d8zq5u3tlu\" api-key=\"48d1cdcd52ec4d289f1ef8c4f75da167\" options='{\"locale\":\"Default\"}' name=\"product-description\" entry=\"97a6e9bd3b8b40fb8e1f54c90e7dce79\"\u003e\n\n\u003c!-- ***** Generated by Builder.io on Mon, 08 Jun 2026 19:46:32 GMT ***** --\u003e\n\n\u003cstyle type=\"text\/css\" class=\"builder-styles builder-api-styles\"\u003e\/*start:h47494*\/.css-h47494{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;-webkit-align-items:stretch;-webkit-box-align:stretch;-ms-flex-align:stretch;align-items:stretch;}\/*end:h47494*\/ 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\/*start:1t1j4rm*\/.css-1t1j4rm.builder-block{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;position:relative;-webkit-flex-shrink:0;-ms-flex-negative:0;flex-shrink:0;box-sizing:border-box;margin-top:20px;line-height:normal;height:auto;content-visibility:auto;contain-intrinsic-size:1104px;}@media only screen and (max-width:991px){.css-1t1j4rm.builder-block{content-visibility:auto;contain-intrinsic-size:1104px;}}@media only screen and (max-width:640px){.css-1t1j4rm.builder-block{content-visibility:auto;contain-intrinsic-size:1035px;}}\/*end:1t1j4rm*\/ \/*start:1n465md*\/.css-1n465md.builder-block{height:0;width:0;display:block;opacity:0;overflow:hidden;pointer-events:none;}\/*end:1n465md*\/\u003c\/style\u003e\n\u003cdiv class=\"builder-component builder-component-97a6e9bd3b8b40fb8e1f54c90e7dce79\" data-name=\"product-description\" data-source=\"Rendered by Builder.io\"\u003e\u003cdiv class=\"builder-content\" builder-content-id=\"97a6e9bd3b8b40fb8e1f54c90e7dce79\" builder-model=\"product-description\"\u003e\u003cdiv data-builder-component=\"product-description\" data-builder-content-id=\"97a6e9bd3b8b40fb8e1f54c90e7dce79\" data-builder-variation-id=\"97a6e9bd3b8b40fb8e1f54c90e7dce79\"\u003e\n\u003cstyle data-emotion-css=\"h47494\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-blocks css-h47494\" builder-type=\"blocks\"\u003e\n\u003cstyle data-emotion-css=\"rm3vjx\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-block builder-9d258df253e049a7bd2b46ca1df595ae builder-has-component css-rm3vjx\" builder-id=\"builder-9d258df253e049a7bd2b46ca1df595ae\"\u003e\n\u003cstyle data-emotion-css=\"1840m1q\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-columns css-1840m1q\"\u003e\n\u003cstyle data-emotion-css=\"1ukkadj\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-column css-1ukkadj\"\u003e\u003cdiv class=\"builder-blocks builder-blocks-child css-h47494\" builder-type=\"blocks\" builder-parent-id=\"builder-9d258df253e049a7bd2b46ca1df595ae\"\u003e\n\u003cstyle data-emotion-css=\"hgfgng\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-block builder-4d4cb20376c64b79bfc01630be7ee375 builder-has-component css-hgfgng\" builder-id=\"builder-4d4cb20376c64b79bfc01630be7ee375\"\u003e\n\u003cstyle data-emotion-css=\"1qggkls\"\u003e\u003c\/style\u003e\n\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003cp\u003eThe 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.\u003c\/p\u003e\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"builder-block builder-2878dd26fc444b299f57e71752579f97 builder-has-component css-hgfgng\" builder-id=\"builder-2878dd26fc444b299f57e71752579f97\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003cp\u003eThe 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. \u003c\/p\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv class=\"builder-block builder-3b04d58bbd0f4d6f9508f96fd2fa1b63 builder-has-component css-hgfgng\" builder-id=\"builder-3b04d58bbd0f4d6f9508f96fd2fa1b63\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003cp\u003eThe 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. \u003c\/p\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cstyle data-emotion-css=\"ur9nhf\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-block builder-f85d7cfcf3f248038ac9a0e470dba576 css-ur9nhf\" builder-id=\"builder-f85d7cfcf3f248038ac9a0e470dba576\"\u003e\u003c\/div\u003e\n\u003cdiv class=\"builder-block builder-2905baeb8f2d497996ca5fb40a443cbb builder-has-component css-hgfgng\" builder-id=\"builder-2905baeb8f2d497996ca5fb40a443cbb\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003ch3\u003eThe Legacy and Popularity of the 5U4 Tube\u003c\/h3\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cstyle data-emotion-css=\"1xes42u\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-block builder-b89806d718314b4fb8aed5e474a8a612 builder-has-component css-1xes42u\" builder-id=\"builder-b89806d718314b4fb8aed5e474a8a612\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003cp\u003eThe 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.\u003c\/p\u003e\n\u003cp\u003eOver 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.\u003c\/p\u003e\n\u003cp\u003eThe 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.\u003c\/p\u003e\n\u003cp\u003eToday, 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.\u003c\/p\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv class=\"builder-block builder-63f9ad7dc84b4adebe5eab494c410a0d css-ur9nhf\" builder-id=\"builder-63f9ad7dc84b4adebe5eab494c410a0d\"\u003e\u003c\/div\u003e\n\u003cstyle data-emotion-css=\"5yng5f\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-block builder-6d00a93682044e16acebb28df2ad200c builder-has-component css-5yng5f\" builder-id=\"builder-6d00a93682044e16acebb28df2ad200c\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003ch3\u003eKR Audio WARRANTY ON TUBES ONLY\u003c\/h3\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cstyle data-emotion-css=\"qj5sun\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-block builder-97ff6ce109ba406b9828269999fa4be8 builder-has-component css-qj5sun\" builder-id=\"builder-97ff6ce109ba406b9828269999fa4be8\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003cp\u003ePlease 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. \u003c\/p\u003e\n\u003cp\u003eKR 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: \u003c\/p\u003e\n\u003col\u003e\n\u003cli\u003eThe tubes were used according to the technical data sheet enclosed with the KR tube. \u003c\/li\u003e\n\u003cli\u003eAbuse, accident or unauthorized use of the tube will be determined by KR Audio Electronics. \u003c\/li\u003e\n\u003cli\u003eAll tubes to be returned with the original factory box and warranty. \u003c\/li\u003e\n\u003cli\u003eTo 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. \u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp\u003eKR 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. \u003c\/p\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv class=\"builder-block builder-96e625b451374a96aa994e4c68de4e08 builder-has-component css-hgfgng\" builder-id=\"builder-96e625b451374a96aa994e4c68de4e08\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003ch3\u003eMoon Audio Tube Testing Process\u003c\/h3\u003e\n\u003cp\u003eOur 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.  \u003c\/p\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv class=\"builder-block builder-758d3691bd614a8e9908040a05a1af5f css-ur9nhf\" builder-id=\"builder-758d3691bd614a8e9908040a05a1af5f\"\u003e\u003c\/div\u003e\n\u003cdiv class=\"builder-block builder-a1df7b4c908e459292e78124b9e721be builder-has-component css-5yng5f\" builder-id=\"builder-a1df7b4c908e459292e78124b9e721be\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cstyle data-emotion-css=\"1t1j4rm\"\u003e\u003c\/style\u003e\n\u003cdiv class=\"builder-block builder-03cfd6af833845d585fb5f1b82a21d40 builder-has-component css-1t1j4rm\" builder-id=\"builder-03cfd6af833845d585fb5f1b82a21d40\"\u003e\u003cspan class=\"builder-text css-1qggkls\"\u003e\u003cp\u003e\u003cstrong\u003eWhat is a 5U4 rectifier tube and what does it do?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 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.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat are the differences between 5U4 and other rectifier tubes?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 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.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhy is the 5U4 tube popular among audiophiles?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAudiophiles 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.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow do I know if my equipment is compatible with a 5U4 rectifier tube?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eCheck the specifications of your audio equipment or consult the manufacturer's documentation to ensure compatibility with the 5U4 tube.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat are the benefits of using a 5U4 rectifier tube in my amplifier?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eBenefits include stable voltage output, improved sound quality, and enhanced performance and longevity of the amplifier.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow long does a 5U4 rectifier tube typically last?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe lifespan of a 5U4 tube varies based on usage and operating conditions but can often last several years due to its robust construction.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I replace a 5U4 rectifier tube myself, or do I need a professional?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eWhile 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.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat are the signs that my 5U4 rectifier tube needs replacing?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eSigns include noticeable drops in audio performance, increased hum or noise, or visible damage to the tube itself, such as burn marks or cracks.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAre there different versions or brands of 5U4 tubes, and do they vary in quality?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, 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.\u003c\/p\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003c\/div\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cstyle data-emotion-css=\"1n465md\"\u003e\u003c\/style\u003e\n\u003cimg src=\"https:\/\/cdn.builder.io\/api\/v1\/pixel?apiKey=48d1cdcd52ec4d289f1ef8c4f75da167\" aria-hidden=\"true\" alt=\"\" role=\"presentation\" width=\"0\" height=\"0\" class=\"builder-block builder-pixel-0io6q0o11k64 css-1n465md\" builder-id=\"builder-pixel-0io6q0o11k64\"\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\u003c\/div\u003e\u003c\/div\u003e\u003c\/builder-component\u003e\n\u003cscript async src=\"https:\/\/cdn.builder.io\/js\/webcomponents\"\u003e\u003c\/script\u003e","brand":"KR Audio","offers":[{"title":"Single ($675)","offer_id":49668337074490,"sku":"5U4G-KR-1","price":675.0,"currency_code":"USD","in_stock":true},{"title":"Matched Pair ($1350)","offer_id":49668337107258,"sku":"5U4G-KR-2","price":1350.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0834\/0245\/7402\/files\/5U4GTubeSingle.jpg?v=1780514559","url":"https:\/\/www.moon-audio.pro\/products\/kr-audio-5u4g-tube-single","provider":"Moon Audio","version":"1.0","type":"link"}