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Description

The U 87 was designed as a solid-state version of the U 67 tube microphone. It retained the K67-style capsule of the U67, but replaced the tube amplifier circuit with a FET/transformer design. In short, the U87 was a tripolar FET condenser with a transformer-coupled output. A switch below the headbasket allowed selection of Cardioid, Omni, or Figure-8 patterns. U 87i, U 87A iThe mic’s capsule, called the K87, was a center-terminated, dual-backplate, dual-diaphragm 34mm design, like the K67. It differed from the K67 in three acoustically-transparent respects:

  • the K87’s two backplates were electrically isolated from one another,
  • and it therefore connected to the amplifier circuit by four wires rather than three.
  • The capsule mounting screws were “sleeved” to prevent an electrical connection between backplate halves.
These changes were required to support the Figure-8 polar pattern, which otherwise would have required more power than the 48V phantom power supply could provide (without a DC-DC converter). Note that both the K67 and K87 capsules used a 40-micron spacer between the two backplate halves. In the K67, the spacer is aluminum. In the K87, the spacer is made of (non-conductive) plastic. The K67 (now called K870/67) and K87 capsules are said to be mechanically and acoustically identical. The K87 capsule was designed for a 60V polarization voltage, but was run in the U87(i) at ~46V; as a result, the U87(i) had ~10mV/Pa lower sensitivity, and 3dB lower signal-to-noise ratio than the AB-powered U77 or the revised U87, called the U87A(i), both of which employed a DC-DC converter to produce a ±60V supply for the capsule. U 87 i CircuitThe body of the U87(i) housed an optional pair of 22.5V batteries. This space was repurposed to store a DC-DC converter when the U87A(i) was developed in 1986. The mic’s output impedance was 200Ω. It could be changed to 50Ω by the user; this modification required a solder gun, according to Neumann literature.

Discussions

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Does Ryan Lewis do everything?

...X and Robert Lang At my little studio I had B-average AD/DA conversation with an SSL AlphaLink AX. I used a Neumann U-87 for damn near everything because that was my only good condenser, and a Neve Portico 5032 pre-amp for pretty much everything as well. All of the recording was done in this little...

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U87 or save my money

I was going to write, "just buy the cheapest, dented up, painted, original U87 you can find and use that". That's what I did. But after a quick search I found out that there is no such thing anymore! Dented up studio workhorses are advertised at $2500.

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