The Psvane T-12AX7, apparently the base version, is a Chinese design that looks much like a vintage one with gray ribbed plates, quality construction, and steel pins. The triple-layed mica also looks good. Bulb size, like so many other new tubes, is slightly larger than my collection of old stock, a mm or two difference in height and circumference..
Break-in was approximately fifty hours as the driver tube in my Frankenstein Eico ST70. This is basically the classic Mullard 5-20 circuit. It's been my general experience that the driver tube - before the phase splitter - has a high impact on the overall amplifier sound, more so than the phase-splitter or even the output tubes.
Listening was initially done while reading a book. There were several times where I had to look up from the pages to truly appreciate what I was hearing. Like the TJ FullMusic, the Psvane has a great almost vintage tone. I was hearing little details - an example is Lonnie Liston Smith's Vision of a New World - that I thought weren't apparent to my standard vintage Mullard. I was beginning to feel some really high hopes for this Psvane.
However some further, more detailed listening, some of it shared with an old audiophile friend with an extensive knowledge of 12AX7s both new and old, began to show some weaknesses. Though the sound was never muffled, the Psvane, like the TJ, also lacked inner detail and bloom around the instruments. But wait a minute, you say, where did that extra detail you mentioned go? It is a strange effect of the Psvane: suppression of reverberation both artificial or natural, pushed some information forward.
Keep in mind this is still the best new production 12AX7 I've heard and I could see use for it in gear or speakers that aren't the most transparent. The bass was excellent, there was a distinct lack of glare unlike some lesser "solid-state in a bottle" new production tubes. The midrange was also even as was the treble. It was just the lack of detail that stopped the Pvane running with the best of the vintage 12AX7s.
Disclaimers: No tube is 100% perfect for all gear. The only way to be sure how a tube will sound in _your_ system is to hear it. Also a tube in a phono stage, for example, may have different audio characteristics than say line, input, or phase-splitter use.
Negative feedback - several dB in this circuit - also reduces the sonic signature of the tube. An example of this came apparent to me when I built a triode-connected EF86 linestage. The tube selection - GEC CV4085 and the Mullard "long mesh" were the best - played a big role in the sound quality. However the EF86 in my Eico HF60 monoblocks were less important, most likely due to the loop negative feedback or perhaps the total number of tubes in play with a more complicated circuit.
It should also be noted that I am not biased towards vintage tubes. I really do want a new tube that can compete with the old.
So take this review as a general guideline, not as hard fact.