This tube worked well in both amplifiers, with very good bass. The anode has extra cooling fins for higher maximum dissipation. The vacuum is claimed to be unusually high: 10e-9 Torr against about 10e-6 for a normal tube. Very rugged construction: this tube's weight is twice that of a normal 300B, and it's 15% taller. KR Enterprise 300BXLS: $480/pair, 2-year warranty. In the AudioNote we noted somewhat better dynamics, a bit more control, a little less warmth, pretty impressive bass, and a wider image. The veil was gone, but it still couldn't achieve a higher level of inspiration more of an easy-listening tube. It sounded similar to the C60 as well, with a few improvements. This tube's construction is similar to that of the C60, but it looks as if a different filament wire has been used also, the 5300B is provided with a white base. Weaker points: a bit of boxy coloration, not very dynamic, an emphasis on sibilants, control could be better. In the AudioNote it performed rather better, with a deep stereo image, wide space, and excellent rendition of reverberation. Bass was round and soft, lacking real pressure. It was pretty good rhythmically, if not very inspiring. In the big amp, the rendition of the C60 was somewhat veiled, colored, and smeared, though the midrange was pleasant and velvety. The position of the small slot-pin on the side of the base deviates from its position on the WE. This tube features a solid graphite anode, and its gold-wire grid helps to avoid thermal runaway in fixed bias also, the four pins on the base are gold-plated. The 4.300B was slightly less musical, with slightly more control and better focus, and was slightly better in the bass. Construction is similar to the other Golden Dragon (above), though the plate is a bit different. Focus was a bit vague, but there was no veil in the AudioNote, however, some veiling was evident, and the entire presentation was rather dutiful and uninspired. Bass in the AudioNote was quite good, but lacked real fundament in the former amp. This tube sounded quite musical and considerably more open in the DeJong amplifier than in the AudioNote, where a loss of dynamics was noted, and voices were contaminated by a hard, edgy ring. Bass was still a bit too pronounced in the AudioNote, but was now under control in the big amp. This tube was clearly more musical, with more air and improved rendition of reverberation. The new tube is also said to have a new filament and improved grid-support spring attachments, and comes with a white ceramic base instead of the usual black one. There is no apparent difference in construction between this and the Sovtek 300B, but close inspection brought up a different grid wire. Bass pressure was lacking when inserted in the DeJong amplifier, but the bass came out too fat in the AudioNote. Lacked precision and dynamics, high-frequency range somewhat detached could do with better rhythmic control and a less confined space. A bit flat in tone, voices slightly colored (more so in AudioNote). Some 300Bs tend to abuse the liberty they get, especially in the bass (or the Kit One grabs its chance to run with the tube, if you will). Second, the big deJongSystems amplifier exhibited much tighter control over the 300B than the AudioNote Kit One amp, which left more freedom to the tubes. So even the most modest 300B should bring you some of that magic. Sound-quality differences were by no means irrelevant, but were smaller in my experience than those between the best and the worst 6SN7 or ECC83/12AX7 that I have heard. Group A includes only the Western Electric.īefore we go into the details, I want to emphasize that every 300B tested had the typical 300B sound character. Group B consists of the KR Enterprise 300BXLS, the Golden Dragon 300BLX, the Svetlana, and the JJ Electronics. Group C contains both Valve Arts, the Golden Dragon 300B and 4.300B, and both Sovteks. On the basis of the comments of the listening panel (four experienced listeners, me being one of them), the 300Bs can be divided into three groups. If you count the number of tubes tested, including the backup pairs, and consider that we had three locations where burn-in could take place, and that eight hours of burn-in per day is a realistic figure (we avoided leaving the amps on unattended), you'll begin to realize the vast scope of this project! In doubtful cases, we added an extra 100 hours (see sidebar "A Tale of Burn-In"). One hundred hours are not enough 200 hours seems to be a workable minimum (footnote 5). If one is to give a reliable evaluation of a 300B, it is essential that the tube be burned in for an appreciable amount of time (footnote 4).