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300B Comparison Review



  May i first set the "ground rules" here.  Instead of some geeks idea of going through all the manufacturer's claimed measurements and stuff i decided to do all this just like any normal dette/dude would.  That is, as drop in replacements to whatever 300B tube might be in their existing unit(s).  The main monoblock amplifiers used during this review were the very impressive and highly regarded Wavelength Audio Cardinal made by famous tube dude Gordon Rankin.  The Cardinal is a self bias unit with the B+ set at 400 volts with a median current of 65-75 milliamps.  The AC heaters are 5 volts.  This seemed very sane and very standard so it was a "known good".  Tube rectification duties are from my head stash of Mullard brown base CV1377 (military grade GZ34).  i will mention that some tubes were also tried with the Valve Art tube amplifiers which i also find very impressive and could also adjust the bias setting.  What obviously complicated matters here is that, say, the KR Enterprise tubes and the more powerful Valve Art 6300B did sound better when used with an amplifier which was designed specifically for these higher powered, he-man wimp haters 300B-type tubes.   In the end you should only take the below review as a possible guideline if even that!  An equipment manufacturer can, of course, "flavor" his unit to make a certain tube sound best by specifically designing the "sound" of the circuitry around said tube.

Lastly, i did try the Audio Note / AVVT tubes and it worked and sounded wonderful... until it blew up within a few hundred hours, some hours in the Cardinal, the rest in the Meishu where it self destructed, taking with it part of the Meishu's power supply!  AVVT has since changed the tube and it now sings gloriously, yet at the time of this review we did not have the newer version for full review.  If you have a working pair of them consider yourself very fortunate.  The  Tesla 300B is the same as the JJ Electronics as reviewed here.  And now on with the real show!

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The Centron 300B is one of the only two made in the USA 300B tubes (the Western Electric being the other). The audio products division of Richardson Electronics Ltd. are also the keepers of the Bugle Boy name by the way.  i tried to love 'em.  i really did!  Alas, they were so hazy as compared to other tubes here that in my listening they ranked dead last.  i don't know what more to say.  They just seemed slow, hazy, and just not nearly as good as the rest of the bunch.  Not much in the way of microphonics by the way but even if it was totally dead microphonically speaking i still couldn't recommend it due to music reproduction quality issues.
Richardson Electronics, Ltd.
40W267 Keslinger Road
P.O. Box 393
LaFox, IL 60147

voice (630) 208-2200
fax (630) 208-2550


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This tube by Valve Art was one of the reasons why this review has taken so long to hit "print". It is absolutely amazing and i just received them about 2 months ago and wanted to put them through the ringer (making sure these weren't like the AVVT Audio Notes).  Heck, it was my closet fave... until.   No it did not blow up, just that another tube even more recently came my way here within the past few weeks of this writing which blew it out of the head contender position for the best 300B variant for GI Joe drop and go action.  The Valve Art 300B-C60 is actually in the middle of their 300B product line.  They also offer a lower line tube called simply the 300B which one of my friends says betters this one!  Since i only got the middle of the line unit seen here and top of the line 300B (seen below) all i can say is that this was the best i had heard at the time over all others except for the winning tube.
The mids are not quite as liquid as the Western Electric, yet what is?  The bass is more extended and defined the the W.E. though.  The highs are very smooth and defined as well nudging out even the W.E. if you're looking for more upper end extension.  The inner resolution was pretty much the best in the bunch too with a tie between it and the all out winner in some regards.  One of things you'll notice with the Valve Art is that they use small flat pieces to keep the very small wire strands in their place at the top of the tube.  Most manufactures just solder a small connecting piece to keep the tensioning of said wires in place.

The microphonics were very small, yet still evident when i played my system at louder volume levels.  Microphonics can really effect the imaging and this was evident, though to a small degree.  Let's please keep microphonics in check here because if you can better isolate the amplifier from floor and air vibrations then this helps to reduce microphonics to some degree.  In fact the new Vibrapods really helps here as i now use them instead of the usual feet for the Wavelength Audio Cardinal monoblocks.

A real winner here and almost a tie with the REAL winner, yet the REAL winners subjectively has better resolution and were just a teeny tiny bit less microphonic too.

Valve Art
International Electronics Building
Yingbin Road
Changsh, Hunun 410011
P.R. Chine

voice (86) 731-442-8169
fax (86) 731-445-6999


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This is the top of the line tube by Valve Art.  It uses the "upgraded" ceramic base and has other "improvements" which allow it to be driven with a higher plate voltage and current which, in turn, increase the wattage output.  What amazed me, and was also confirmed by a friend of mine who has also played with many 300B-type tubes, is that this tube was worse then the cheaper lower line of Valve Art as reviewed above!  Although i did try it using both the normal and also higher bias setting in the Art Audio amplifier, it seemed to definitely sound better driven with the higher setting.  Unfortunately when she clipped, it was hard and nasty.  i mean nasty nasty as in the mids all broke up horribly.  The worst clippers in the whole 300B-type tube bunch here (worse then the Centron too).  While i can not recommend this tube as a 300B direct replacement, it does have some good qualities when used at the higher bias operating guidelines for higher output.
Ramping up the bias to the higher setting seems to make the mids smoother, the higher a bit more liquid, and the bass is really full here.  Still, the mids and highs sounded better with the lower line Valve Art 300B-C60 then with this upper line 6300B tube.  The only advantage for using this upper line Valve Art over the middle line would be for more (maybe a tad too much) bass.  On virtually all levels the middle line tube was better then this one if we compare them at near their proper operating guidelines as they were used in the Art Audio unit.  Still, when used as a simple drop in replacement for whatever non-testosterone 300B you'd be much better off with the 300B-C60 then this higher priced ceramic based 6300B in my humble opinion.

Valve Art
International Electronics Building
Yingbin Road
Changsh, Hunun 410011
P.R. Chine

voice (86) 731-442-8169
fax (86) 731-445-6999