Originally Posted; Mon, 03 December 2007
The following is an excerpt from a chapter entitled "The Big Five", which will appear in a new book I am currently writing, entitled 'The Vintage Microphone Handbook' to be published this Summer by Hal Leonard Publishers.
Describing sensory perceptions with words is like walking on ice- very little to hold on to. But I will try:
To me, the ideal U47 (I've heard a few, so I feel secure, at least within myself, that I'm probably in the ball park with my observations) can do something no other mic does quite as well:
It reproduces the human voice, especially anything between alto and bass, with all its authority left intact.
The treatment and resolution in the vocal range is such, that the mic is not in the way of the emotional delivery. I never think "mic" when I hear such a U47. I may not even think at all, but just be in the voice, the delivery, the lyrics...
Those who are familiar with my philosophy of what a mic can be or do when it's at its best know that, here too, a certain amount of fibbing is at work: the U47 "engorges" the singer's ability, helps him or her out a bit, and does away with unflattering tubbiness in the bass or wispiness in the highs. The range where the mic shines- the lower mids, is rendered with an almost three-dimensional effect, and with an extra amount of what I call "reediness" - the U47 emphasises the vocal cord's undulations (think Nat King Cole.)
The U47 shines also, because it has no boost in frequency ranges we normally might associate with "sheen" or "transparency". Yet, the mic is not opaque by any means, just awfully relaxed, in a way that its delivery is not straining to get right to our souls.
There is no other mic in the "Big Five" as I call them, that achieves its greatness quite the same way, nevertheless, these other mics in the Club where the fat cigars are smoked, do their magic in different, equally enticing ways.
We can then speculate on how this magic in the U47 is created.
Deconstructing these mics to their base components enough times in the past leads me to the belief that only the exact major components present in the U47- capsule, head basket, tube, circuitry, voltages, transformer- will render that specific magic, and substituting just one of them will upset the apple cart and the mic then leaves the stage.
Discussions about M7 vs. K47 strike me as academic, or a matter of taste: both capsules' operating principle and backplates are almost identical, and whatever the PVC or Mylar skins add or subtract is not of enough substance in my experience to negate the mic's magic.
You finally asked, what characteristics might indicate a U47 that is less desirable, or beginning to fail in some way?
The simplest answer would be: if none of the above is easily observed, the mic is not at the top of ist game.
Add to that an imbalance in the frequency range (sometimes you will find "honky"/mid-rangey specimens whose capsules or, in rare cases, VF14's are kaputt) or noise (a well-working U47 has about the same noise floor as a well-working U67), and the magic of a U47 can be obscured real fast...
Needless to say, whatever the well-deserved attraction of some of the clones or Nuvistor-equipped "U47" may be, they cannot and should not be compared to the sound of an original, all-stock, well-working U47.
On December 3, 2007 J.J. Blair added the following under the headline "Midrange Authority":
I was swapping (AKG's) CK12 capsules in a couple of mics tonight, to get the capsules to match their respective mics better. I wound up having four different CK12-equipped mics up, comparing them, and then, just to check the bottom end, I put up my U47. I sang a verse or two of a song into each one, and then went and listened, and the phrase that Klaus uttered to me about the U47 a few years ago immediately jumped out at me: "Midrange authority."
There is simply no better way to put it. There was this presence from what sounded like 400Hz to 2kHz, that just made that vocal so weighted, in a really pleasant way. Sometimes that 400Hz to 1kHz is that last thing I want to hear, but this mic does it in such a musical and pleasing way, that it just makes the the prefect mic for so many applications. And on certain voices, it makes them sit so beautifully in a mix. Authoritative, indeed!
Way to coin a phrase, Klaus!