I am posting these here, rather than the sections for kit that use 300B's. My comments specifically cover the Paramounts and BeePre, (because they are the kit I have!!), but probably are valid for the Kaiju, too. We have never had the large selection of 300B's from which to choose. It is really surprisingly exciting!! I tried a new 300B WE "replica" and am quite impressed. These tube are branded Cossor's, (a British label), although identical to the Linlai WE300B. They can be had for about $500 per pair, which I consider a real bargain!
I have about 100 hours on the Cossor WE330B's. The have developed into exceptionally nice sounding tubes! I have use them in my Bottlehead Paramount 300B amps. for over 10 years. I have modified, and upgraded them for over 10 years. So I know how they sound. I also built the Bottlehead 300B preamp about 5 years ago. Over the years I have tried a variety of premium and mid range 300B's from China, Russia and the Czech Republic, (Vaic, KR and JJ). I do not particularly like the sound of the Eastern European 300B tubes. They are good tubes, just not to my taste, Some say that they sound balanced from bass to extended treble. To me. they sound too solid state! (The JJ's not as much.) IMO they lack the full warm midrange that is the main reason to use a 300B in the first place.
The Sophia tubes sounded good, but were very unreliable making their actual cost very expensive. The Royal Princess's sounded really good, but did not last through the warranty period, As soon as I got the replacement pair I sold them. I also tried several variations of Shuguang and Psvane over the years. I settled on the Shuguang Black Glass 50 Year Treasures in my preamp and the Gold Lions in the power amps. They sound really good. Warm detailed mids, good extension in the treble and bass. (My speakers are 1960's EV 3 way horns that I rebuilt and modified, The bass rolls off pretty quickly just above 40Hz.), Most importantly they have proven to be extremely reliable in my system.
At about 100 hours on the Cossor 300B's, they sound much better than the Gold Lions and the Treasures. The mid range is warm, detailed and balanced. The tubes have great timbre, solid imaging and the soundstage is well defined, extending well behind my speakers. The bass and treble are also better than the Shuguang and Gold Lion. As would be expected, they continue to improve as they burn-in. At the price, I know of no other tube that comes close. I mostly listen to jazz, classical, blues, vocals and the occasional dino rock. The Cossors excel in providing both the intimacy of a small ensemble and the grandeur of a full symphony orchestra. They are more dynamic than the Shuguang and Gold Lion tubes with more impact on the leading edge of transients. Males and female voices are rendered very life like, with none of the chestiness of the lesser tubes.
There are many tubes available that claim to be Western Electric clones. The Cossor's are the only moderately priced 300Bs that actually do replicate the WE structure. The plates and the hanging filaments appear almost identical. The hanging filaments make a huge difference in the sound quality. If a 300B has the little filament coils above the top mica, they just are not that close to actual WE structure. I know of no other 300B with hanging filaments that come close to the Cossor's in terms of price. I would say if you are looking at a $250-400 pair of 300Bs, getting the Cossors for $500 would be a wise investment, in terms of sound quality.
I also recently received a pair of the new Western Electric 300B 2019 reissues. I placed the order January of last year! It would be hard to argue that they should not be the default benchmark upon which to do new 300B comparisons. They sound even better than the Cossors, as one would expect at 3 times the price. They do sound a little drier in the mids than the Cossor s, but that is gradually opening up, (at about 50 hours). The bass is tighter and the treble has an effortless detail that the WE's were not available for direct comparison, I could easily enjoy the Cossor's without any thought of missing something.
I am currently running the WE s in the preamp and the Cossors in the power amps. Both pairs still need much more burn in. The bottomline? I know of no other 300B's in $500 range that even come close. In summary, I would not consider any premium 300B replica that did not have a hanging filament design. It makes that much difference. The originals did, as well as the current Western Electric reissues. The next step up from the Cossar's, at least in terms of price, would be the Psvane Acmes or the Linlai Elite E-300B, Permalloy, again these are twice the price of the Cossor 300B WE's and not really designed to sound like the Western Electric tubes, but to compete with the Eastern European tubes.
