There ARE enough VF14 out there, but an increasing number of U47 seekers feel a five figure price is too steep for their pocket book (understandable), and are lured to substantially cheaper supposed alternatives by posters who claim authority- sometimes individuals with a vested interest (not understandable, in my book).
2. UF and EF 14, while somewhat related to the VF14 in construction and outline, have an overheating handicap which is only overcome by feeding a second voltage into the mic- a major mod. While these tubes can theoretically be biased in a similar way as the VF14 (fixed) the less noisy option-cathode biasing- will yield a substantial deviation in sound- thinned out, glassy, quite transparent, yet leaning towards body-less.
There ARE enough VF14 out there,…..
That brings us to the Catch 22 where we are today: mic lovers want the sound of the vintage original. They figure that, if they could swap out one or two magic ingredients of their copy mic, it would get them there. But they are often hesitating to spend the money for these parts, then seek the internet for alternatives, of which plenty are advertised, with plenty of promises to that effect, only to end up where they started (minus the money they had spent): still desiring the sound of the vintage original.