KR Audio
300B Vacuum Tube
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Features
More stable tube bias for a longer operational life
Delivers 6–12 watts of pure Class-A power per tube
Fully compatible with classic 300B amplifier designs
Wide, deep soundstage with warm, richly detailed sound
Handcrafted by KR Audio using premium materials and modern techniques
Rigorously tested and matched for exceptional reliability and consistency
What's in the Box?
Introducing the New for 2024, the revised KR Audio 300B Tube. A true powerhouse in the world of high-end audio. These low-frequency, high-power triodes are designed to deliver an unparalleled listening experience, offering 6-12 watts of pure class-A power per tube. Whether you're a seasoned audiophile or a passionate music lover, the KR Audio 300B Tube is sure to elevate your audio setup to new heights. The new version has a Higher Transconductance. In a vacuum tube, transconductance is a measure of the tube's gain or how much it amplifies a signal at a given bias setting. Thus, you have more gain to play with. The Tube Bias is much more stable, which means a longer life.
Fully compatible with classic 300B designs, these tubes are meticulously crafted to provide a seamless upgrade for your existing amplifier. The KR Audio 300B Tube maintains the cherished sonic characteristics of vintage 300B tubes while incorporating modern manufacturing techniques and premium materials to ensure exceptional reliability and consistency. When it comes to performance, the KR Audio 300B Tube is in a league of its own. These triodes effortlessly deliver a warm, rich, and highly detailed sound, with a wide and deep soundstage that immerses you in your favorite recordings. The 300B's ability to reproduce music with unrivaled clarity, dynamics, and emotional impact is why it has remained a favorite among audio enthusiasts for decades.
The KR Audio 300B Tube's impressive power output of 6-12 watts per tube in pure class-A operation ensures that your amplifier has the headroom necessary to handle even the most demanding musical passages with ease. This robust power delivery, combined with the 300B's inherent linearity and low distortion, results in a listening experience that is both engaging and fatigue-free. KR Audio's commitment to quality is evident in every aspect of these tubes' construction. From the carefully selected materials to the rigorous testing and matching process, no detail has been overlooked in the pursuit of audio perfection. Each tube in the matched pair is built to exacting standards, ensuring optimal performance and longevity.
About the 300B Tube: The Legendary Power Triode
The 300B tube, originally designed by Western Electric (WE 300B/Western Electric 300B) in the 1930s, has become a legendary electron tube in the world of hi-fi audio. Known for its exceptional midrange and high-frequencies performance, warm tonal qualities, and ability to deliver a highly musical and engaging listening experience, the 300B has been a favorite among audiophiles and music enthusiasts for decades. As a directly heated power triode, the 300B features a cathode that also serves as the filament, contributing to its unique sonic characteristics. This design allows for a simplified and more efficient electron emission process, resulting in a purer and more lifelike sound quality.
The 300B's anode, coupled with its high amplification factor and low plate resistance, enables it to deliver a robust and dynamic performance in both single-ended and push-pull amplifier configurations. This versatility has made the 300B a popular choice for a wide range of applications, including power amplifiers, tube amps, integrated amplifiers, and preamplifiers (preamp). While Western Electric's production of the 300B ceased in the 1980s, several manufacturers, such as KR Audio, Electro-Harmonix, and JJ Electronic, have continued to produce high-quality 300B tubes. These new production tubes, like the JJ 300B, aim to capture the essence of the original WE 300B while incorporating modern manufacturing techniques and materials to ensure reliability and consistency. We believe that the KR Audio 300B is the superior version of the 300B tube today.
When paired with high-quality transformers and well-designed circuitry, the 300B tube can create an immersive and emotionally engaging listening experience. Its ability to reproduce music with a sense of warmth, smoothness, and natural detail has earned it a reputation as one of the best-sounding power tubes available.
Audiophiles and music lovers in the USA and around the world continue to seek out 300B-based tube amplifiers and preamplifiers for their ability to deliver a truly captivating hi-fi experience. Many manufacturers offer amplifiers designed around the 300B, ranging from single-ended triode (SET) designs to more powerful push-pull configurations.
Whether you're building a new tube amplifier or upgrading an existing one, the 300B tube is an excellent choice for those seeking the ultimate in musical performance, emotional engagement, and the best sound quality. With its rich history, legendary status, and unrivaled sonic qualities, the 300B continues to be a cornerstone of high-end audio.
Enter KR Audio.
KR Audio is one of the world’s top manufacturers of vacuum tubes and high-end vacuum tube amplifiers, all crafted with care right in the beautiful Czech Republic. KR Audio specializes in producing low-frequency power triodes and high-end audio equipment, all made by hand! From selecting the glass to their meticulous artisan work in metal and glass blowing, every step is done with the utmost attention to detail. Their commitment to quality means they never use automated lines—this is what sets KR Audio apart and ensures our products are truly exceptional.
A bit about KR Audio history: KR Audio's journey started in the late 1950s when a young Riccardo Kron, while assisting his professor, became curious about why even the best tubes tended to drift over time. This sparked a lifelong quest to enhance tube performance, a passion he carried through his time at Deutsche Grammophon and Magnadyne. Following the fall of communism, Riccardo teamed up with a talented research and development group from TESLA LABORATORIES in the Czech Republic. Together, they pioneered the creation of hand-crafted vacuum tubes designed specifically for audio, utilizing improved materials, higher vacuum levels, and rigorous quality control. The result? Tubes that deliver incredible dynamics, finer resolution, and an almost tangible sound experience.
KR AUDIO Electronic SRO began as a tube manufacturer and has since evolved into a developer of world-class amplifiers, employing a unique reverse hybrid system to enhance your listening experience. Thank you for considering KR Audio—we're excited to share KR Audio's passion for high-quality sound with you!
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: 1) The tubes were used according to the technical data sheet enclosed with the KR tube. 2) Abuse, accident or unauthorized use of the tube will be determined by KR Audio Electronics. 3) All tubes to be returned with the original factory box and warranty. 4) 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.
F.A.Q
Q: What is a 300B tube and how does it work?
A: The 300B is a directly heated triode vacuum tube used in audio amplification. It operates by passing an electric current through a heated cathode to emit electrons, which are then controlled by a grid to amplify the input signal.
Q: What amplifiers use the 300B tube?
A: The 300B tube is commonly found in single-ended triode (SET) amplifiers renowned for their rich, warm sound signature. Many high-end audio manufacturers like KR Audio produce amplifiers utilizing the 300B tube for audiophile-grade sound reproduction.
Q: What are the sonic characteristics of the 300B tube?
A: The 300B tube is prized for its lush midrange, smooth treble, and natural timbre. It delivers a musical, euphonic sound signature with a captivating sense of realism and intimacy.
Q: Can I replace the 300B tube in my amplifier with a different type?
A: While some amplifiers allow tube rolling, it's essential to consult the manufacturer's specifications and recommendations. Substituting the 300B tube with a different type may alter the amplifier's performance and sound characteristics.
Q: How long does a 300B tube typically last?
A: The lifespan of a 300B tube varies depending on usage, operating conditions, and tube quality. On average, a well-maintained 300B tube can last several thousand hours before requiring replacement.
Q: How do I bias a 300B tube amplifier?
A: Biasing a 300B tube amplifier involves adjusting the bias voltage to ensure proper operating conditions and optimal performance. Consult the amplifier's user manual or seek assistance from a qualified technician for precise biasing procedures. Feel free to Contact Us and we'll be more than happy to assist you.
Q: What are the pros and cons of using a 300B tube amplifier?
A: Pros include exceptional sound quality, musicality, and compatibility with high-efficiency speakers. Cons may include higher cost, lower power output compared to other tube types, and the need for occasional tube replacement.
Q: Are there different brands or versions of the 300B tube?
A: Yes, various manufacturers produce 300B tubes, each with unique construction, materials, and sonic characteristics. Popular brands include Western Electric, KR Audio, TJ Full Music, Sophia Electric, and Shuguang.
Q: What are the differences between vintage and modern production 300B tubes?
A: Vintage 300B tubes are highly sought after for their historical significance and reputed sound quality. Modern production tubes offer advancements in manufacturing techniques and may provide improved reliability and consistency.
Q: How do I select the right 300B tube for my amplifier?
A: Consider factors such as brand reputation, sonic preferences, budget, and compatibility with your amplifier. Researching reviews, seeking advice from audio enthusiasts, and experimenting with different tubes can help you find the perfect match for your system. We consider the version by KR Audio to be one of the best on the market.
| Parameter | Specification |
|---|---|
| Tube Complement | |
| Output Tubes | 2 × 300B |
| Driver Tube | 1 × 6SN7 |
| Input Tube | 1 × 6SL7 |
| Rectifier Tubes | 2 × 5AR4 (Units prior to 2011 used 5U4 rectifier tubes) |
| 300B Output Tube Specifications | |
| Filament Voltage | 5 V (DC/AC) |
| Amplification Factor | 3.9 |
| Maximum Ratings | |
| Maximum Plate Voltage | 550 V |
| Maximum Plate Current | 120 mA |
| Plate Dissipation | 50 Watts |
| Operating Specifications | |
| Plate Voltage (Va) | 450 V |
| Plate Current (Ia) | 100 mA |
| Grid Voltage (Vg) | -90 V |
| Performance Specifications | |
| Transconductance | 6.2 mA/V |
| Product Specifications | |
| Production Status | New production, includes warranty |