Favorite 300B: Sophia vs KR

Which tube is better for you really depends upon the amp itself, and the extent to which you need specific voicing to compensate a sonic anomaly elsewhere in the system, or for tuning to your preferences. I'll go further in saying that even a given amp can be altered to completely change your perception of relative ranking of tubes.

For example, I have a stash of KR Audio 300B, Sophia perforated plate 300B and Sophia Princess 300B. I also have Vaic VV32BL, Emission Labs, Shuguang and others. While I did find the Sophia 300B to have a lot of top end "spray" and euphonic bass bloat, and preferred the stiffer, more revealing and dynamic sound of the KRs, a change to my 300B monoblocks also changed this preference.

I had my Audion Golden Dream PSET 300B monoblocks recapped by Bob Hovland (highly recommended). There was a small issue I needed diagnosed and took the amps to Bob. That issue was inconsequential but while he had the amps open I asked him to give me an opinion about whether he thought the power supply caps were worth keeping or replacing, given that the amps are a decade old and used heavily. Bob came back to me saying first that he is reluctant to change caps when an amp is already exceptional, and those Golden Dreams are truly outstanding. But he did believe that if I was willing to take some risk, a recap with Nichicon skinny cans would improve dynamics, definition and transparency further without degrading the tone density those high silver-content amps already offer.

He was right. The Golden Dreams came back better in all respects after the recap. I was curious enough, however, to run my 300B tube rankings again. The Audions recapped with Nichicons, the Sophia mesh plates lost their bass bloat and the aerosol top end lost the glitter and gloss to settle back to a natural frequency extension with even finer definition, while all of the midrange tone density was left intact. Bass is deep, tight and comparatively lean. Spatial dimensioning is convincing and scales appropriately to the music.

The Sophia mesh plates sounded beautiful in my Softone office amp but thick and syrupy in the stock Audion Golden Dreams, which is not remotely a quality of that amp. Meanwhile the KR Audio 300B sounded hard and spatially flat in the Softone but energetic, clean, lean and toneful in the Golden Dreams. After the Audion recap, The Sophia mesh plate is the more dynamically assertive tube with bass cleaner than the KR. The KR 300B now has a comparatively pinched soundstage width and it is dimensionally flatter than the Sophia.

There are a lot of factors in play on resolving this question. If you don't like a given tube, it may not be that there's anything generalizable that's deficient about the given tube. It may be that the tube just isn't a good match to your amp, as it came voiced from the factory.

Phil

Maxmad,

I can say that I would never recommend matching Sophia mesh (really, perforated) plate 300Bs with Cary amps. That's doubling down on the same basic sonic aberration. If someone likes that combination, one can't argue with that, but it would be a piling on of the same euphonic colorations that obscure what you value.

I have a pair of KR VV302 Blue glass that sound beautiful and bell-like in some amps, yet hard and overbearing in others. I also have the older KR Enterprises straight tube 300B with the AVVT-like interior structure. Those tubes have strong, vivid transient clarity, probably the firmest bass of any 300B I have, and good top and bottom extension. But in amps I've used them in, their spatial presentation is great in height and width but cmparatively limited in depth. I'm aware of the Takatsuki but haven't tried/heard them yet.

The Shuguang Treasure 300B has been unfailingly good in every amp I've heard them in, albeit a more modern sound than the typically vintage mesh plates. The current production KR AUdio balloon glass 300B nicely resolves a lot of the spikey differences between all these tubes. For me, a polar graph of its relevant sonic attributes is close to a circle in most amps. My mesh plates sound sensational in my re-capped Audion monoblocks, but I consider that a highly-specific match arrived at by chance since they didn't happen to be in the amp when the caps were chosen and installed.

I will say the Sophias were much less expensive when I bought them. But so were KRs. About $900/pr. now for the KR Audio 300B in the US. Partly a result of the dollar's slide and partly result of that company and its distribution chain realizing they had to own up to the true costs of running a business. In all this discussion, interesting that this decade's production of the WE 300B isn't in the mix.

Phil

I suppose the notion implied in my initial reply here, but left unsaid in a direct sense, should be expressed unequivocably:

The differences between power supply capacitors in an amplifier have, in my long experience making this change in push-pull tube and SET amps, been greater and more musically influential than the differences realized between any two alternative tubes. That's right, and I'll say this power supply cap difference is, further, much greater sonically in SET amps than in push-pull. Now, I'm not talking about mods that change the total power supply reserve in total capacitance. I'm citing changes in electrolytic capacitor construction between brands (or models in the same brand), that leave the total power supply reserve quantitatively unchanged from stock. I had the same experience with recapping my 845 SET amps.

It's not a convenient plug'n'play change like tube rolling, so not DIY accessible for most. But everyone should understand that recapping can introduce improvements (or if not chosen well, changes of the better OR worse kind) that can dwarf the results from changing tubes.

Another way to think about it: After my Audion Golden Dreams were recapped by Hovland, their performance with the cheapest, most prosaic $20 Chinese solid plate 300B everyone ships as stock, was better than their sound with my most exotic, scarce and expensive 300Bs prior to replacement of capacitors.

Bob also loaned me a simple Glow amp (5w, SE, EL84) that he recapped and made a few other small circuit changes to, as an experiment and to ask my opinion. I could get reasonable dynamics and SPLs from it on my 101db/w/m Zu Definition 2 speakers, and my Zu Druids. Within its clean dynamic range, the little Hovland-modified Glow wiped the floor with a number of $1500 - $5000 amps I put up against it, musically. And compared to a stock Glow, which is a well-liked tyke of an amp, the modded version was transformed, musically. No change in power tubes from among many I had on hand could remotely approach the difference.

Phil