NEUMANN U-47 MICROPHONE ORIGINAL SCHEMATIC
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POLARITY SWITCH (ON OFF)
THREE CAPACITORS (NOT INCLUDING CAPSULE)
It's easy to see from examining this list of parts that the electronic components which will have the greatest impact on the sound are:
#1. The Capsule (the ear drum of the mic),
#2. The Tube (the amplifier),
#3. The Output coupling capacitor
#4. The Output Transformer (connects the microphone to the rest of the world)
More than any other marketing hype, these components account for 95% of the way a vacuum tube microphone sounds. The physical shape and construction of the head that houses the microphone capsule is the other big determining factor in what creates the sound the microphone produces.
If the Head/Grille sounds like the ocean when you hold it up to your ear and listen through it you're going to need to mod the grille work to get rid of that sound or else the capsule will hear that too and it will bias the tone of your recordings.
The tube used in a Neumann U-47 is no longer made. For cost comparison we'll use the most similar functioning counterparts that are plug and play compatible with the original microphone.
$400.00 Thiersch PVC M-7 Style Capsule from Germany
$750.00 Replacement VF-14K from Telefunken
$300.00 Classic BV-8 from AMI
There is the bulk of the cost for building one of the best U-47 style microphones
If a different, lower cost tube is used then the cost would also be correspondingly lower. As of today there are still good alternative N.O.S. glass tubes which are similar in characteristics to the original steel can VF-14 tubes. One such alternative is the Telefunken EF-800.